Research Article New Green Polymeric Composites Based on

Research ArticleNew Green Polymeric Composites Based on Hemp andNatural Rubber Processed by Electron Beam Irradiation

Maria-Daniela Stelescu1 Elena Manaila2 Gabriela Craciun2 and Maria Dumitrascu2

1 National Research and Development Institute for Textile and Leather-Leather and Footwear Research Institute93 Ion Minulescu Street 031215 Bucharest Romania

2National Institute for Lasers Plasma and Radiation Physics Accelerators Laboratory 409 Atomistilor Street077125 Magurele Romania

Correspondence should be addressed to Elena Manaila elenamanailainflprro

Received 29 August 2013 Accepted 31 October 2013 Published 28 January 2014

Academic Editors P Dallas and K Jayakumar

Copyright copy 2014 Maria-Daniela Stelescu et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A new polymeric composite based on natural rubber reinforced with hemp has been processed by electron beam irradiation andcharacterized by several methodsThemechanical characteristics gel fraction crosslink density water uptake swelling parametersand FTIR of natural rubberhemp fiber composites have been investigated as a function of the hemp content and absorbed dosePhysical andmechanical properties present a significant improvement as a result of adding hemp fibres in blends Our experimentsshowed that the hemp fibers have a reinforcing effect on natural rubber similar to mineral fillers (chalk carbon black silica) Thecrosslinking rates of samples measured using the Flory-Rehner equation increase as a result of the amount of hemp in blends andthe electron beam irradiation dose increasing The swelling parameters of samples significantly depend on the amount of hemp inblends because the latter have hydrophilic characteristics

1 Introduction

Green composite combines plant fibers with natural resinsto create natural composite materials Natural fibers such ashemp kenaf flax jute sisal and so forth have attracted inter-est especially as a synthetic fibers substitute in the rubber andplastics industry The advantages of natural fibers over syn-thetic are low cost low density acceptable specific strengthproperties ease of separation carbon dioxide sequestrationand biodegradability In fibers-reinforced composites thefibers serve as reinforcements by giving strength and stiffnessto the composite structure [1 2]

In this paper the results of our study on obtaining andcharacterizating a new green polymeric composite based onhemp and natural rubber crosslinked by irradiation withelectron beam (EB) are presented There are few studiesregarding the use of hemp fiber for the achievement ofcomposites based on natural rubber Osabohien and Egboh[3] conducted a study on the use of bowstring hempfiber as filler in natural rubber compounds compared with

carbon black The hemp fibersrubber had lower tensilestrength (only 23 of the carbon blackrubber) but the hempfiberrubber showed superior hardness (126 times that ofcarbon blackrubber) So hemp fibers could replace activefillers such as carbon black or silica from natural rubberSilica is known to have adverse effects on health silico-sis cancer (Group 1 according to IARCmdashthe InternationalAgency for Research on Cancer) autoimmune diseasestuberculosis kidney disease and so forth and in 1995the IARC rated carbon black as IARC classification 2Bmdashpossibly carcinogenic to humans and definitely carcinogenicto animals [4ndash8] Cho and collaborators [9] specify that anintroduction of ecofriendly natural fibers to natural rubbercan play a role not only in reinforcing rubber but also inreducing the amount of carbon black used in rubber and tireapplications In the mentioned study [3] the curing of naturalrubberhemp composites has been achieved by the classicalmethodof crosslinking that is using sulfur and vulcanizationaccelerators In another study [10] elastomer crosslinkingwas performed using benzoyl peroxide in order to obtain also

Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 684047 13 pageshttpdxdoiorg1011552014684047

2 The Scientific World Journal

a natural rubberhemp composite This method of crosslink-ing results in a better composite resistance to aging thanthose obtained by the classical method [11] In additionto elastomer crosslinking peroxide can perform chemicalsurface modification of hemp fibers [10] As a result of ourstudy a green composite based on natural rubber and hempwas obtained and elastomer crosslinking was performedby EB irradiation thus eliminating the use of sulfur andcrosslinking agents which lead to the appearance of toxicsubstances (such as N-nitrosamines which are suspected inhuman carcinogens) [4 12] Crosslinking technology by EBirradiation is a relatively new technology globally The firstpatented process for rubber curing by means of ionizingradiation was developed by Dunlop Rubber Co Ltd in1956 Since that year application of ionizing radiation inthe polymer field has been investigated by many researcherswho have developed modern environmentally friendly andfast techniques for polymer crosslinking and grafting [13ndash15] Elastomers crosslinking using EB irradiation present aseries of specific advantages over the traditional thermalcuring such as (1) lack of curing agents except activatorsfor rubber (2) obtaining new highly purematerials (intendedfor medical devices rubber items for food industry toys forchildren etc) (3) enabling new rubber typeswhich cannot becrosslinked chemically or can be hardly crosslinked by usualcuring procedures to be processed into finished productswithmajor industrial applications (aircraft army medicine) (4)the process is very fast and can be controlled precisely it isvery clean requires less energy permits greater processingspeed and operates at ambient temperature (5) the electronbeam can be steered very easily to meet the requirements ofvarious geometrical shapes of the products to be cured (6) thehigh penetrating power of radiation allows the efficient anduniform curing of thick polymeric articles (7) the process ispractically waste-free (8) and no polymer degradation dueto high temperature as EB crosslinking occurs at room tem-perature [13ndash18] Because of their reliability flexibility low-cost along with no environmental impact the irradiationtechnologies are particularly attractive The advantages ofsuch technologies lead to the appearance of more and moreEB irradiation stations there are more than 1200 electronaccelerators for industrial applications intended particularlyfor polymerization crosslinking grafting and so forth allover the world Only in China there are 45 industrial electronaccelerators and 123 gamma radiation for various radiationprocessing applications Malaysia has six EB accelerators forcommercial use [13]

2 Material and Methods

21 Materials In preparing the above polymer compositesthe following materials were used natural rubber (NR) Crep1X (Mooney viscosity is 74 ML

1+4at 100∘C 032 volatile

materials 038 nitrogen 022 ash 0021 impurities)antioxidant pentaerythritol tetrakis(3-(35-di-tert-butyl-4-hydroxyphenyl) propionate Irganox 1010 polyethylene glycolPEG 4000 (1128 gcm3 density 4ndash8∘C melting point range)and ground hemp (thread length of max 3mm)

22 Sample Preparation Blends were prepared on an electri-cally heated laboratory roller For preparation of polymericcomposites the blend constituents were added in the follow-ing sequences and amounts 100 parts natural rubber (NR)roll binding (21015840) embedding 3 phr (parts to 100 parts rubber)PEG 4000 and 1 phr Irganox 1010 antioxidant (21015840) adding 510 15 and 20 phr ground hemp (2ndash41015840) and homogenisationof blends and removing from the roll in the form of sheet(41015840) Process variables temperature 25ndash50 plusmn 5∘C friction 11and total blending time 8ndash141015840 Plates required for physico-mechanical tests with sizes of 150 times 150 times 2mm3 wereobtained by pressing in a hydraulic press at 110 plusmn 5∘C and150MPa

23 Experimental Installations and Sample Irradiation Thesamples were irradiated using the electron beam acceleratorcalled ALIN 10 in the dose range of 15ndash60MradThe ALIN 10is a travelling-wave type operating at a wavelength of 10 cmand having 164 W maximum output power The acceleratingstructure is a disk-loaded tube operating in the 1205872 modeThe optimum values of the EB peak current 119868EB and EBenergy 119864EB to produce maximum output power 119875EB for afixed pulse duration 120591EB and repetition frequency 119891EB are asfollows 119864EB = 623MeV 119868EB = 75mA and 119875EB = 164W(119891EB = 100Hz 120591EB = 35 120583s) The EB effects are related to theabsorbed dose (119863) expressed in Gray or J kgminus1 and absorbeddose rate (119863lowast) expressed in Gy sminus1 or J kgminus1 sminus1 [19ndash21]Layers of three sandwiched sheets covered in polyethylenefoils were irradiated in atmospheric conditions and at roomtemperature of 25∘C Samples were irradiated with 75 150300 and 600 kGy

24 Laboratory Tests

241 Mechanical Characteristics Tensile strength tests werecarried out with a Schopper strength tester with testing speed460mmmin using dumb-bell shaped specimens accordingto ISO 372012 The tests measurement uncertainty wasplusmn064 for tensile strength and plusmn295 for elongation at breakHardness was measured by using a hardener tester accordingto ISO 7619-12011 using 6mm thick samples (the tests mea-surement uncertainty was plusmn005) Elasticity was evaluatedwith a test machine of type Schob using 6mm thick samplesaccording to ISO 46622009

242 Gel Content The gel content was performed oncrosslinked NR rubber (with and without hemp) to deter-mine themass fraction of insoluble NR (the networkmaterialresulting from network-forming crosslinking process) sam-plesThe sampleswereweighed in the dry condition (119898

119894) then

immersed in the toluene during 3 days at room temperaturein order to remove any scissioned fragments and unreactedmaterials The samples were then dried in air for 6 days andin an oven at 80∘C for 3 hours and reweighed (119898

119904) The gel

content was calculated as

Gelcontent =119898119904

119898119894

times 100 (1)

The Scientific World Journal 3

where 119898119904and 119898

119894are the weight of the dried sample after

immersion and the weight of the sample before immersionrespectively [22 23]

243 Crosslink Density The crosslink density (]) of thesamples was determined on the basis of equilibrium solvent-swellingmeasurements (in toluene at 23ndash25∘C) by applicationof the well-knownmodified Flory-Rehner equation for tetra-functional networks The samples (2mm thick) were initiallyweighed (119898

119894) and immersed in toluene for 72 h The swollen

samples were removed and cautiously dried to remove excesssolvent before beingweighed (119898

119892) and during this operation

the sampleswere covered to avoid toluene evaporation duringweighing Traces of solvent and other small molecules werethen eliminated by drying in air for 6 days and in an oven at80∘C for 3 hours Finally the sampleswereweighed for the lasttime (119898

119904) and volume fractions of polymer in the samples at

equilibrium swelling ]2119898

were determined from swelling ratio119866 as follows

]2119898=1

1 + 119866 (2)

where

119866 =119898119892minus 119898119904

119898119904

times120588119890

120588119904

(3)

where 120588119890and 120588

119904are the densities of elastomer samples and

solvent (0866 gcm3 for toluene) respectivelyThe densities of elastomer samples were determined by

the hydrostatic weighing method according to the SR ISO27812010 (the tests measurement uncertainty was plusmn009)By this method the volume of a solid sample is determinedby comparing the weight of the sample in air to the weightof the sample immersed in a liquid of known density Thevolume of the sample is equal to the difference in the twoweights divided by the density of the liquid The samplescrosslink densities ] were determined from measurementsin a solvent using the Flory-Rehner relationship

] = minusLn (1 minus ]

2119898) + ]2119898+ 12059412]22119898

1198811(]132119898minus (]21198982))

(4)

where 1198811is the molar volume of solvent (1065 cm3mol

for toluene) ]2119898

is the volume fraction of polymer in thesample at equilibrium swelling and 120594

12is the Flory-Huggins

polymer-solvent interaction term (the value of 12059412is 0393 for

natural rubber - toluene) [22 23]

244 Water Uptake Test The effect of water absorption onfiber reinforced natural rubber composites is investigated inaccordance with SR EN ISO 203442004 The samples weredried in an oven at 80∘C for 2 hours and then are allowedto cool to room temperature in desiccators before weighingWater absorption tests were conducted by immersing thesamples in distilled water in bottles and kept at room tem-perature (23 plusmn 2∘C) Samples were removed from the bottlesat periodic intervals and the wet surfaces were quickly wiped

using a clean dry cloth or tissue paper and weights of thespecimen after swelling were determined at regular intervalsuntil no further increase in solvent uptake was detected Themoisture absorption was calculated by the weight differenceThe percentage weight gain of the samples was measured atdifferent time intervals The water uptake was calculated as

water uptake () =119898119904minus 119898119894

119898119894

times 100 (5)

where 119898119904is the weight of the water saturated specimen at

periodic intervals and 119898119894is the initial weight of the oven-

dried specimen The tests measurement uncertainty wasplusmn004

245 Fourier Transform Infrared (FTIR) Spectroscopy Chan-ges in the chemical structure of natural rubber samples withwithout hemp irradiated with 75 150 300 and 600 kGy weredeterminedwith an FTIR spectrophotometermdashJASCOFTIR4200 by the ATRmeasurement method Samples spectra arethe average of 30 scans realized in absorption in the range of4000ndash600 cmminus1 with a resolution of 4 cmminus1

3 Results and Discussion

31 Mechanism of Crosslinking and Grafting of PolymericComposites Based on Natural Rubber and Hemp by ElectronBeam Irradiation The effects of electron beam on polymershave been investigated by many researchers [24 25] overthe past few decades Among the effects is that high energyirradiation causes crosslinking and degradation in polymersThese reactions are reported to follow the free radicalmechanism As a result of crosslinking the tensile strengthelasticity andmodulus increase while the elongation at breakdecreases Degradation on the other hand leads to a decreasein tensile strength elasticity and modulus [25] Elastomercrosslinking by means of electron beam is done withoutheating and in the absence of vulcanization agents Oneof the proposed mechanisms for the radiation crosslinkingof NR is summarized in Scheme 1 Mechanisms for theradiation crosslinking of different rubbers were developed bythe authors in other articles [14 15 26]

The chemistry of the process is based on macroradicalformation from elastomer chains which recombine causingstructuring

Hemp fibers are obtained from the bast of the plantCannabis sativa L It grows easilymdashto a height of 4mmdashwithout agrochemicals and captures large quantities of car-bon Long strong and durable hemp fibers are about70 cellulose and contain low levels of lignin (around 8ndash10) hemicelluloses lignin waxes and so forth The fibersdiameter ranges from 16 to 50microns Hemp fibers conductsheat dye well resist mildew block ultraviolet light and havenatural antibacterial properties [27 28]

Cellulose chain consists of anhydro-120573-dextroglucosewhich are connected by 120573-glucosidic 1 rarr 4 bridges(see Scheme 2) The effects of electron beam irradiation oncellulose have been evaluated in several studies [29ndash32] and


(EB irradiation)NRndashHminusrarr NRndashHlowast (excited state)NRndashHlowast

rarr NRndashH+ (positive ion of rubber) + 1eminus

(electron)

NRndashHlowastrarr NR∙ (free radical of rubber) + H∙

(hydrogen radical)

NRndashH++ NRndashH rarr NR∙

+ NRndashH+2 (radical ion of

rubber)

NR∙+ NR2ndashH+

+ 1eminusrarr NRndashNR (cross linkedrubber)

NR∙+ NR∙

rarr NRndashNR (crosslinked rubber)NR1ndashHlowast

+ NR2ndashH rarr NR1ndashH + NR2ndash Hlowast (energytransfer)

H∙+ NRndashH rarr NR∙

+ H2

Scheme 1 Mechanism for the radiation crosslinking of NR

0

10

20

30

40

50

60

70

80

Absorbed dose (kGy)

Har

dnes

s (∘Sh

A)

75 150 300 600

NRNR5phr hempNR10phr hemp

NR15phr hempNR20phr hemp

Figure 1 Hardness variation as a function of hemp amount andirradiation dose

it was observed that the atmospheric oxygen affects theirradiated cellulose

In our study hemp fibers having high cellulose contentare in the form of filler in a natural rubber matrix So atmo-spheric oxygen affects these types of fibers less than thoseirradiated in the mentioned studies [29ndash32] By irradiationmainly occur crosslinking grafting and degradation of thesetypes of NRhemp fibers composites Crosslinking processleads to the increase of composites crosslinking degree andto the improvement of some physical and mechanical prop-erties NR macromolecules grafting leads to the formation ofa grafted copolymer at the interface between the two phaseswhich will significantly improve their compatibility leadingto obtaining a polymeric composite having optimum prop-erties Scheme 3 presents the formation of two macroradicalswhich can further react withNRmacromolecules (Scheme 4)

0

10

20

30

40

50

Elas

ticity

()

Absorbed dose (kGy)75 150 300 600



Figure 2 Elasticity variation as a function of hemp amount andirradiation dose

00

08

16

24

32

40

Mod

ulus

at100

el

onga

tion

(Nm

m2)




Figure 3 Modulus at 100 elongation variation as a function ofhemp amount and irradiation dose

forming a grafted polymer at the interface This graftedpolymer can act as a material which can assure compatibilityimproving adhesion between the two phases of NR and hempmixture

32 Physical and Mechanical Characteristics Physical andmechanical characteristics of NRhemp polymer compositescrosslinked by electron beam irradiation are presented inFigures 1ndash6


O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

HO

OH

H

H

H

H

OH

HOHO

OH

O

H

HH

H

HOH

OH

HOO

OO

n

Scheme 2 Structure of cellulose

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HOHO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

HO

OH

OO

Excited state Excited state

or

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

OH

OO

O

Free radical Free radical

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

OH

OO

Hlowastlowast

∙∙

Scheme 3 Radical formation on the cellulose chains

The hardness (Figure 1) increases with the increase of theabsorbed dose and with the fiber amount in polymeric com-posites Hardness increases with the increasing of absorbeddose as a result of crosslink density and increases with thehemp amount in polymeric composites because the hempleads to reinforcement of samples The maximum value of70∘ShA was obtained at an absorbed dose of 150 kGy and20 phr hemp amount much higher than the same sampleswithout hemp (12∘ShA) This is because the incorporationof hemp into natural rubber reduces elasticity of the rubberchains leading to more rigid rubber vulcanizates Elasticity(Figure 2) slightly decreases with the increase of EB dose andvaries irregularly when the hemp amount increases

In the same way modulus at 100 elongation (Figure 3)and tensile strength (Figure 4) increase when the absorbeddose increases and when introducing hemp in natural rubberblends The maximum value of 34Nmm2 (for modulusat 100 elongation) was obtained at an absorbed dose

of 150 kGy and 20 phr hemp amount much higher thanthe same samples without hemp and vulcanized at thesame absorbed dose (002Nmm2) In the case of tensilestrength the maximum value (41 Nmm2) was obtained atan absorbed dose of 300 kGy and 10 phr hemp amountcompared to the samples without hemp and vulcanized atthe same absorbed dose (106Nmm2) The tensile strengthof a polymer is a function of crosslink density and energydissipation The tensile strength increases with crosslinkat lower crosslink density However at higher crosslinkdensity the network is so dense that there is little energydissipation in the matrix and the energy supplied is used forbreaking the bonds At higher crosslink density the segmentsof macromolecules become immobile the system becomesstiffer and the elasticity decreases

Elongation at break changes (Figure 5) depend alsoon absorbed dose and fiber amount Elongation at breakdecreases with the increasing of absorbed dose (compared


O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO

Cellulose-free radical

CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)

Scheme 4 Proposed mechanism for the interaction between cellulose and natural rubber


0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)




Figure 4 Tensile strength variation as a function of hemp amountand irradiation dose

0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)




Figure 5 Elongation at break variation as a function of hempamount and irradiation dose

with the samples without hemp) up to 150 kGy and afterthat begins to grow This decrease indicates that the networkstructure of the crosslinked rubbers becomes tighter and lessflexible so that molecular movements are restricted It can beobserved that this parameter (elongation at break) decreaseswith the hemp amount increasing at the same absorbeddose Obtained values are better compared to those of blendswithout hemp and vulcanized at the same absorbed dose

Figure 6 shows that the tearing strength increases whenthe absorbed dose increases and when introducing hemp innatural rubber blends The maximum value of 25Nmm was

0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)




Figure 6 Tearing strength variation as a function of hemp amountand irradiation dose

obtained at an absorbed dose of 150 kGy and 20 phr hempamount much higher than the same samples without hempand vulcanized at the same absorbed dose (7Nmm) Thisindicates a vulcanization process

33 Gel Content and Crosslink Density of the Blends Table 1shows the gel content (mass fraction of the network mate-rial resulting from a network-forming polymerization orcrosslinking process the gel fraction comprises a singlemolecule spanning the entire volume of thematerial sample)the volume fractions of polymer in the swollen mass (]

2119898)

and crosslink density (number of crosslinks per unit volumein a polymer network) of the samples vulcanized by electronbeam as a function of the absorbed dose and flax contentThedetermination is based on the absorption of a proper solventand subsequent swelling of the rubber [33 34]

The results presented in Table 1 show that when the EBdose and hemp amount increase there is an increasing ingel content (119866) volume fractions of polymer (]

2119898) and

crosslink density (]) of samples This is due to the formationof a three-dimensional network structure [35]

34 Water Uptake The water uptake results of samplescrosslinked by electron beam irradiation (with and withouthemp) are presented in Figures 7 8 9 and 10 From thesefigures it can be observed that the percentage of waterabsorption in the polymeric composites NRhemp dependedon two parameters hemp content and absorbed dose Thewater uptake increased with increasing of fiber content anddecreased with absorbed dose The increase of water absorp-tion is due to the hydrophilic nature of fiber and the greaterinterfacial area between the fiber and the elastomer matrixIn polymer composites with fibers water is absorbed mainlyby the fiber because the rubber material is hydrophobic andits water absorbability can be neglected [34]


Table 1 Gel content (119866) volume fractions of polymer (]2119898) and crosslink density (]) of samples

Sample 119866 ]2119898

] (times10minus4 molcm3)NR 0 75 kGy 3624 00335 00403NR 0 150 kGy 9364 00877 02476NR 0 300 kGy 9414 01164 04471NR 0 600 kGy 9592 02979 11076NR + 5 phr hemp 75 kGy 8840 00518 00898NR + 5 phr hemp 150 kGy 9444 00903 02643NR + 5 phr hemp 300 kGy 9555 01291 05459NR + 5 phr hemp 600 kGy 9596 01701 09990NR + 10 phr hemp 75 kGy 8370 00601 01189NR + 10 phr hemp 150 kGy 9299 00952 02916NR + 10 phr hemp 300 kGy 9532 01249 05098NR + 10 phr hemp 600 kGy 9637 01672 09567NR + 15 phr hemp 75 kGy 8029 00532 00950NR + 15 phr hemp 150 kGy 9291 01042 03504NR + 15 phr hemp 300 kGy 9555 01315 05692NR + 15 phr hemp 600 kGy 9653 01863 12411NR + 20 phr hemp 75 kGy 8030 00611 01243NR + 20 phr hemp 150 kGy 9167 01072 03727NR + 20 phr hemp 300 kGy 9571 01494 07459NR + 20 phr hemp 600 kGy 9720 02128 16544

0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)

NRNR + 5phr hempNR + 10phr hemp

NR + 15phr hempNR + 20phr hemp

Figure 7 Water uptake of polymeric composites at absorbed doseof 75 kGy

Irradiation may change the solubility properties of hempActivation of the samples by low-dose irradiation (Figures 7ndash10) is most likely achieved in terms of increased accessibilityfor the solvent and weakened hydrogen bond networks thattranslate into better solubility At higher irradiation dose thiseffect is suppressed by cross-linking (intra- and intermolec-ular) [29 36] The mechanism of this irradiation activationmust again be assumed to be the weakening of the hydrogen

0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




bondnetwork inwhich hydroxyl groups (H-donating andH-accepting) are converted into carbonyls (only H-accepting)[29 37]

35 FTIR Study The main components of our polymercomposites are NR and hemp Natural rubber is composedof hydrocarbons (893sim924 wt) protein (25sim35 wt) and


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




other ingredients (41sim82 wt) The main component ofNR is cis-1 4-polyisoprene with a high degree of longchain branching generally associated with the presence ofnonhydrocarbon groups distributed along the chains Hempfibers are about 70 cellulose and contain low levels oflignin (around 8ndash10) hemicelluloses lignin waxes and soforth Figures 11 12 13 and 14 show the infrared spectraand characteristic infrared bands (observed in the region of4000ndash560 cmminus1) of natural rubber with and without hempbefore and after irradiation at absorbed doses of 75 kGy150 kGy 300 kGy and 600 kGy

It can be noticed the presence of absorption bands inthe spectral region located between 1670 and 1640 cmminus1due to the valence vibration of homogeneous double bonds(]C=C) in the NR structure Their intensity decreases for irra-diated samples compared with nonirradiated samples Thespectrum exhibits for nonirradiated NR samples absorptionbands with maxima at 3050ndash3010 cmminus1 corresponding to CHstretching in the ndashCH=CH

2group Irradiation of the poly-

meric compositions under study between 75 and 600 kGyresults in consumption of the double bonds in NR so that theintensities of these absorption bands decrease and move tothe same extentThe specific absorption bands of single bondscorresponding to R

2C=CHndashR group are observed at 850ndash

830 cmminus1 (see fingerprint region) These changes occur as aresult of elastomer crosslinking and double bonds consumingor polymers degradation with the formation of double bondsThe characteristic bands of the saturated aliphatic sp3 CndashHbonds are observed at 2970ndash2830 cmminus1 which are assignedto ]as (CH

3) ]as (CH

2) and ]s (CH

2) respectively (as

three corresponding bends) [38] These bands are specific tonatural rubber and cellulose lignin or hemicellulose fromthe hemp fibers existing in the mixture [39] It can be noticedthat with the hemp amount increasing in the mixture theintensity bands vary out of uniformity The absorption bandof CH

2deformation occurs at 1440ndash1460 cmminus1 and of CH

3

asymmetric stretching at 1350ndash1380 cmminus1 It is known that theNR contains also other compounds such as lipids neutralglycolipids and phospholipids and so forth The absorptionbands at 3250ndash3300 cmminus1 were identified in the proteinsand both monopeptides and dipeptides present in naturalrubber [40]This band is specific also for cellulose lignin andhemicellulose from the hemp fibers existing into the mixture[39] Band intensity significantly decreases for irradiatedsamples with the amount of fiber hemp increasing in themixtureThese are the consequences of proteins and peptidesdegradation Saeman et al noted a considerable introductionof oxidized groups upon irradiation of cellulosewhilemakingan effort to quantify the amount of introduced carboxylicacid groups [41] Some authors also observed an increasein carbonyl group content [42 43] This effect is observedalso for NRhemp polymer composites irradiated with EBand is highlighted by the presence of the specific C=O bandsbetween 1800 and 1650 cmminus1 But in our study hemp fiberswhich contain high levels of cellulose are in the form of fillerin an NR polymer matrix As a consequence atmosphericoxygen affects these types of irradiated fibers less than inthe case of the noticed studies Although the samples werewrapped in PE foil and after that irradiated in atmosphericconditions surface degradation of NRhemp samples canoccur Also the mechanism of irradiation activation mustagain be assumed to be the weakening of the hydrogenbond network in which hydroxyl groups are converted intocarbonyls [29] It can be noticed that with the hemp fiberamount increasing there is a decreasing of absorption bendsintensity in this region indicating a decrease in the numberof double bonds that form with the EB dose increasing(ie the number of ndashOH groups which converted intondashCOOH decreases) The absorption band around 1730 cmminus1


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance

NR nonirradiated75kGy150kGy

300kGy600kGy

Wavenumbers (cmminus1)

(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)Figure 11 FTIR spectra for NRhemp mixtures with 5 phr hemp content (a) between 2500ndash4000 and (b) between 500ndash2500

2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)

Figure 12 FTIR spectra for NRhemp mixtures with 10 phr hemp content (a) between 2500ndash4000 and (b) between 500ndash2500

was identified to the fatty acid ester groups din NR [44] Inthe fingerprint region there are some specific single bendsfor cellulose lignin and hemicellulose from hemp fibers butalso for NR some of them are mentioned above With thehemp fiber amount increasing significant changes occur inthe specific absorption bands of hemp fiber fingerprint

4 Conclusions

For obtaining new green composites based on natural rubberactive fillers of carbon black or silica type were replaced

with hemp fiber and crosslinking classic system based onsulfur and vulcanization accelerators has been replaced byan ecologic method of crosslinking namely electron beamirradiation Our experiments showed that the hemp fibershave a reinforcing effect on natural rubber similar to mineralfillers (chalk carbon black silica) Thus by increasing thehemp amount in the mixtures there occurs an increase inhardness tearing strength and crosslinking density and adecrease in elongation at break When the EB dose increasesis obtained an increase of gel content (119866) volume fractionsof polymer (]

2119898) and crosslink density (]) of samples due


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


to the formation of a three-dimensional network structuresimilar to elastomer crosslinking by other crosslinking sys-tems (ie sulfur and crosslinking agents) The water uptakeincreases with fibers content increasing and decrease withabsorbed dose The increasing in water absorption is due tothe hydrophilic nature of fibers and activation of the samplesby low-dosage irradiation (this leads to an increased acces-sibility of solvent and weakened hydrogen bond networksthat translate into better solubility) At higher irradiation

dose this effect is suppressed by crosslinking (intra- andintermolecular) so the water uptake decreases for higherirradiation dose

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper


References

[1] G Pamuk and F Ceken ldquoComparison of themechanical behav-ior spacer knit cotton and flax fabric reinforced compositesrdquoIndustria Textila vol 64 no 1 pp 3ndash7 2013

[2] G Bogoeva-Gaceva M Avella M Malinconico et al ldquoNaturalfiber eco-compositesrdquoPolymer Composites vol 28 no 1 pp 98ndash107 2007

[3] E Osabohien and S H O Egboh ldquoUtilization of bowstringhemp fiber as a filler in natural rubber compoundsrdquo Journal ofApplied Polymer Science vol 107 no 1 pp 210ndash214 2008

[4] N Chaiear ldquoHealth and safety in the rubber industryrdquo RapraReview Reports 138 vol 12 no 6 2001

[5] IARC Silica Some Silicates Coal Dust and Para-Aramid Fibrilsvol 68 of IARC Monographs WHO Geneva Switzerland 1997

[6] L S Beliczky and J Fajen ldquoRubber industryrdquo inEncyclopaedia ofOccupational Health and Safety J M Stellman Ed chapter 80International Labor Office Geneva Switzerland 4th edition1998

[7] HSC Rubber Industry Advisory CommitteeHealth and SafetyExecutive Control of Fume at Extruders Calenders andVulcan-izing Operations TSO London UK 1994

[8] HSC Rubber Industry Advisory CommitteeHealth and SafetyExecutiveDust and FumeControl in RubberMixing andMillingTSO London UK 1994

[9] Y S Cho H S Lee and D Cho ldquoEffect of chemical pre-treatment on the cure mechanical and abrasion properties ofkenafnatural rubber green compositesrdquo in Proceedings of 18thInternational Conference on Composite Materials (ICCM rsquo09)Edinburgh Scotland 2009

[10] E Manaila M D Stelescu G Craciun and L Surdu ldquoProp-erties of composites based on hemp and natural rubbercrosslinked in presence of benzoyl peroxiderdquo in Proceedings ofthe International Conference TexTeh VImdashThe Future of Textiles(TEXTECH VI rsquo13) pp 11ndash19 Bucharest Romania October2013

[11] E Manaila M D Stelescu and G Craciun ldquoCharacteristicsof natural rubber blends vulcanized with electron beam andmicrowaverdquo Leather and Footwear Journal vol 11 no 1 pp 43ndash52 2011

[12] IARC Monographs on the Evaluation of Carcinogenic Risks toHumans Re-Evaluation of Some Organic Chemicals Hydrazineand Hydrogen Peroxide vol 71 1999

[13] A G Chmielewski ldquoWorldwide developments in the field ofradiation processing of materials in the down of 21st centuryrdquoNukleonika vol 51 supplement 1 pp S3ndashS9 2006

[14] M D Stelescu E Manaila and G Craciun ldquoVulcanizationof ethylene-propylene-terpolymer-based rubber mixtures byradiation processingrdquo Journal of Applied Polymer Science vol128 no 4 pp 2325ndash2336 2013

[15] M D Stelescu E Manaila and N Zuga ldquoThe use of polyfunc-tional monomers in the radical cure of chlorinated polyethy-lenerdquo Polymer Journal vol 43 no 9 pp 792ndash800 2011

[16] M D Stelescu EManaila DMartin G Craciun D Ighigeanuand L Alexandrescu New Technologies of Grafting and Cross-Linking Rubber Blends by Electron Beam and Microwave Irradi-ation Performantica Publishing House 2011

[17] E Manaila G Craciun D Martin D Ighigeanu and DM Zuga ldquoEB and MW processing of rubber mixtures withMPFsrdquo in Practical Aspects and Applications of Electron BeamIrradiation pp 199ndash212 Kerala India 2011

[18] E Manaila M D Stelescu and G Craciun ldquoAspects regardingradiation crosslinking of elastomersrdquo inAdvanced ElastomersmdashTechnology Properties and Applications chapter 1 pp 3ndash34InTech Rijeka Croatia 2012

[19] M Dumitrascu M G Albu M Vırgolici C Vancea andV Meltzer ldquoCharacterization of electron beam irradiatedpolyvinylpyrrolidone-dextran (PVPDEX) blendsrdquo Diffusionand Defect Data B vol 188 pp 102ndash108 2012

[20] R Suvaila E Stancu and O Sima ldquoOn within sample homo-geneity testing using gamma-ray spectrometryrdquo Applied Radia-tion and Isotopes vol 70 no 9 pp 2144ndash2148 2012

[21] A Scarisoreanu F Scarlat S Bercea and R Popa ldquoCalibrationmethod for dosimetric filmsrdquo Optoelectronics and AdvancedMaterials vol 4 no 6 pp 871ndash876 2010

[22] M A Lopez-Manchado B Herrero and M Arroyo ldquoPrepara-tion and characterization of organoclay nanocomposites basedon natural rubberrdquo Polymer International vol 52 no 7 pp1070ndash1077 2003

[23] J-M Chenal L Chazeau L Guy Y Bomal and C GauthierldquoMolecular weight between physical entanglements in naturalrubber a critical parameter during strain-induced crystalliza-tionrdquo Polymer vol 48 no 4 pp 1042ndash1046 2007

[24] C T Ratnam M Nasir A Baharin and K Zaman ldquoElectronbeam irradiation of epoxidized natural rubberrdquo Nuclear Instru-ments andMethods in Physics Research B vol 171 no 4 pp 455ndash464 2000

[25] J Sharif S H S A Aziz and K Hashim ldquoRadiation effects onLDPEEVA blendsrdquo Radiation Physics and Chemistry vol 58no 2 pp 191ndash195 2000

[26] M D Stelescu M Georgescu and E Manaila ldquoAspects regard-ing crosslinking of a natural rubber blendrdquo in Proceedings of the3rd International Conference onAdvancedMaterials and Systems(ICAMS rsquo10) pp 313ndash318 Bucharest Romania September 2010

[27] Industrial Hemp Agriculture and Agri-Food Canada Govern-ment of Canada 2013

[28] M Karus ldquoEuropean hemp industry 2002 cultivation process-ing and product linesrdquo Journal of Industrial Hemp vol 9 no 2pp 93ndash101 2004

[29] UHennigesMHasani A Potthast GWestman andT RosenldquoElectron beam irradiation of cellulosicmaterials-opportunitiesand limitationsrdquoMaterials vol 6 pp 1584ndash1598 2013

[30] B G Ershov ldquoRadiation-chemical degradation of cellulose andother polysaccharidesrdquo Russian Chemical Reviews vol 67 no 4pp 315ndash334 1998

[31] E Iller A Kukielka H Stupinska and W MikolajczykldquoElectron-beam stimulation of the reactivity of cellulose pulpsfor production of derivativesrdquo Radiation Physics and Chemistryvol 63 no 3-6 pp 253ndash257 2002

[32] J Bouchard M Methot and B Jordan ldquoThe effects of ionizingradiation on the cellulose of woodfree paperrdquo Cellulose vol 13no 5 pp 601ndash610 2006

[33] H N Dhakal Z Y Zhang and M O W Richardson ldquoEffectof water absorption on the mechanical properties of hempfibre reinforced unsaturated polyester compositesrdquo CompositesScience and Technology vol 67 no 7-8 pp 1674ndash1683 2007

[34] H Ismail M R Edyham and B Wirjosentono ldquoDynamicproperties and swelling behaviour of bamboo filled naturalrubber composites the effect of bonding agentrdquo Iranian PolymerJournal vol 10 no 6 pp 377ndash415 2001

[35] R Manshaie S Nouri Khorasani S Jahanbani Veshare andM Rezaei Abadchi ldquoEffect of electron beam irradiation on the


properties of Natural Rubber (NR)Styrene-Butadiene Rubber(SBR) blendrdquo Radiation Physics and Chemistry vol 80 no 1pp 100ndash106 2011

[36] A Potthast M Kostic S Schiehser P Kosma and T RosenauldquoStudies on oxidative modifications of cellulose in the periodatesystem molecular weight distribution and carbonyl groupprofilesrdquo Holzforschung vol 61 no 6 pp 662ndash667 2007

[37] F Berthold K Gustafsson R Berggren E Sjoholm and MLindstrom ldquoDissolution of softwood kraft pulps by directderivatization in lithium chlorideNN-dimethylacetamiderdquoJournal of Applied Polymer Science vol 94 no 2 pp 424ndash4312004

[38] A M M Ali R H Y Subban H Bahron T Winie F Latifand M Z A Yahya ldquoGrafted natural rubber-based polymerelectrolytes ATR-FTIR and conductivity studiesrdquo Ionics vol 14no 6 pp 491ndash500 2008

[39] C Y Liang and R H Marchessault ldquoInfrared spectra of crys-talline polysaccharides I Hydrogen bonds in native cellulosesrdquoJournal of Polymer Science vol 37 no 132 pp 385ndash395 1959

[40] A H Eng Y Tanaka and S N Gan ldquoFTIR studies on aminogroups in purified Hevea rubberrdquo Journal of Natural RubberResearch vol 7 pp 152ndash155 1992

[41] J F Saeman M A Millet and E J Lawton ldquoEffect of highenergy cathode-rays on celluloserdquo Industrial amp EngineeringChemistry vol 44 no 12 pp 2848ndash2852 1952

[42] S-J Shin and Y J Sung ldquoImproving enzymatic hydrolysisof industrial hemp (Cannabis sativa L) by electron beamirradiationrdquo Radiation Physics and Chemistry vol 77 no 9 pp1034ndash1038 2008

[43] E Takacs L Wojnarovits J Borsa C S Foldvary P Hargittaiand O Zold ldquoEffect of 120574-irradiation on cotton-celluloserdquoRadiation Physics and Chemistry vol 55 pp 663ndash666 1999

[44] O Chaikumpollert Y Yamamoto K Suchiva and S KawaharaldquoProtein-free natural rubberrdquo Colloid and Polymer Science vol290 no 4 pp 331ndash338 2012

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


a natural rubberhemp composite This method of crosslink-ing results in a better composite resistance to aging thanthose obtained by the classical method [11] In additionto elastomer crosslinking peroxide can perform chemicalsurface modification of hemp fibers [10] As a result of ourstudy a green composite based on natural rubber and hempwas obtained and elastomer crosslinking was performedby EB irradiation thus eliminating the use of sulfur andcrosslinking agents which lead to the appearance of toxicsubstances (such as N-nitrosamines which are suspected inhuman carcinogens) [4 12] Crosslinking technology by EBirradiation is a relatively new technology globally The firstpatented process for rubber curing by means of ionizingradiation was developed by Dunlop Rubber Co Ltd in1956 Since that year application of ionizing radiation inthe polymer field has been investigated by many researcherswho have developed modern environmentally friendly andfast techniques for polymer crosslinking and grafting [13ndash15] Elastomers crosslinking using EB irradiation present aseries of specific advantages over the traditional thermalcuring such as (1) lack of curing agents except activatorsfor rubber (2) obtaining new highly purematerials (intendedfor medical devices rubber items for food industry toys forchildren etc) (3) enabling new rubber typeswhich cannot becrosslinked chemically or can be hardly crosslinked by usualcuring procedures to be processed into finished productswithmajor industrial applications (aircraft army medicine) (4)the process is very fast and can be controlled precisely it isvery clean requires less energy permits greater processingspeed and operates at ambient temperature (5) the electronbeam can be steered very easily to meet the requirements ofvarious geometrical shapes of the products to be cured (6) thehigh penetrating power of radiation allows the efficient anduniform curing of thick polymeric articles (7) the process ispractically waste-free (8) and no polymer degradation dueto high temperature as EB crosslinking occurs at room tem-perature [13ndash18] Because of their reliability flexibility low-cost along with no environmental impact the irradiationtechnologies are particularly attractive The advantages ofsuch technologies lead to the appearance of more and moreEB irradiation stations there are more than 1200 electronaccelerators for industrial applications intended particularlyfor polymerization crosslinking grafting and so forth allover the world Only in China there are 45 industrial electronaccelerators and 123 gamma radiation for various radiationprocessing applications Malaysia has six EB accelerators forcommercial use [13]

2 Material and Methods

21 Materials In preparing the above polymer compositesthe following materials were used natural rubber (NR) Crep1X (Mooney viscosity is 74 ML

1+4at 100∘C 032 volatile

materials 038 nitrogen 022 ash 0021 impurities)antioxidant pentaerythritol tetrakis(3-(35-di-tert-butyl-4-hydroxyphenyl) propionate Irganox 1010 polyethylene glycolPEG 4000 (1128 gcm3 density 4ndash8∘C melting point range)and ground hemp (thread length of max 3mm)

22 Sample Preparation Blends were prepared on an electri-cally heated laboratory roller For preparation of polymericcomposites the blend constituents were added in the follow-ing sequences and amounts 100 parts natural rubber (NR)roll binding (21015840) embedding 3 phr (parts to 100 parts rubber)PEG 4000 and 1 phr Irganox 1010 antioxidant (21015840) adding 510 15 and 20 phr ground hemp (2ndash41015840) and homogenisationof blends and removing from the roll in the form of sheet(41015840) Process variables temperature 25ndash50 plusmn 5∘C friction 11and total blending time 8ndash141015840 Plates required for physico-mechanical tests with sizes of 150 times 150 times 2mm3 wereobtained by pressing in a hydraulic press at 110 plusmn 5∘C and150MPa

23 Experimental Installations and Sample Irradiation Thesamples were irradiated using the electron beam acceleratorcalled ALIN 10 in the dose range of 15ndash60MradThe ALIN 10is a travelling-wave type operating at a wavelength of 10 cmand having 164 W maximum output power The acceleratingstructure is a disk-loaded tube operating in the 1205872 modeThe optimum values of the EB peak current 119868EB and EBenergy 119864EB to produce maximum output power 119875EB for afixed pulse duration 120591EB and repetition frequency 119891EB are asfollows 119864EB = 623MeV 119868EB = 75mA and 119875EB = 164W(119891EB = 100Hz 120591EB = 35 120583s) The EB effects are related to theabsorbed dose (119863) expressed in Gray or J kgminus1 and absorbeddose rate (119863lowast) expressed in Gy sminus1 or J kgminus1 sminus1 [19ndash21]Layers of three sandwiched sheets covered in polyethylenefoils were irradiated in atmospheric conditions and at roomtemperature of 25∘C Samples were irradiated with 75 150300 and 600 kGy

24 Laboratory Tests

241 Mechanical Characteristics Tensile strength tests werecarried out with a Schopper strength tester with testing speed460mmmin using dumb-bell shaped specimens accordingto ISO 372012 The tests measurement uncertainty wasplusmn064 for tensile strength and plusmn295 for elongation at breakHardness was measured by using a hardener tester accordingto ISO 7619-12011 using 6mm thick samples (the tests mea-surement uncertainty was plusmn005) Elasticity was evaluatedwith a test machine of type Schob using 6mm thick samplesaccording to ISO 46622009

242 Gel Content The gel content was performed oncrosslinked NR rubber (with and without hemp) to deter-mine themass fraction of insoluble NR (the networkmaterialresulting from network-forming crosslinking process) sam-plesThe sampleswereweighed in the dry condition (119898

119894) then

immersed in the toluene during 3 days at room temperaturein order to remove any scissioned fragments and unreactedmaterials The samples were then dried in air for 6 days andin an oven at 80∘C for 3 hours and reweighed (119898

119904) The gel

content was calculated as

Gelcontent =119898119904

119898119894

times 100 (1)


where 119898119904and 119898











]2119898=1

1 + 119866 (2)

where

119866 =119898119892minus 119898119904

119898119904

times120588119890

120588119904

(3)

where 120588119890and 120588





2119898) + ]2119898+ 12059412]22119898

1198811(]132119898minus (]21198982))

(4)










119898119894

times 100 (5)













(electron)


(hydrogen radical)



rubber)

NR∙+ NR2ndashH+


NR∙+ NR∙




+ H2


0

10

20

30

40

50

60

70

80

Absorbed dose (kGy)

Har

dnes

s (∘Sh

A)

75 150 300 600






0

10

20

30

40

50

Elas

ticity

()





00

08

16

24

32

40

Mod

ulus

at100

el

onga

tion

(Nm

m2)








O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

HO

OH

H

H

H

H

OH

HOHO

OH

O

H

HH

H

HOH

OH

HOO

OO

n


O

H

HH

H

HOH

OH

HO

H

H

HO

H

HOHO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

HO

OH

OO


or

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

OH

OO

O


O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

OH

OO

Hlowastlowast

∙∙







O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)



0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




where 119898119904and 119898











]2119898=1

1 + 119866 (2)

where

119866 =119898119892minus 119898119904

119898119904

times120588119890

120588119904

(3)

where 120588119890and 120588





2119898) + ]2119898+ 12059412]22119898

1198811(]132119898minus (]21198982))

(4)










119898119894

times 100 (5)













(electron)


(hydrogen radical)



rubber)

NR∙+ NR2ndashH+


NR∙+ NR∙




+ H2


0

10

20

30

40

50

60

70

80

Absorbed dose (kGy)

Har

dnes

s (∘Sh

A)

75 150 300 600






0

10

20

30

40

50

Elas

ticity

()





00

08

16

24

32

40

Mod

ulus

at100

el

onga

tion

(Nm

m2)








O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

HO

OH

H

H

H

H

OH

HOHO

OH

O

H

HH

H

HOH

OH

HOO

OO

n


O

H

HH

H

HOH

OH

HO

H

H

HO

H

HOHO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

HO

OH

OO


or

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

OH

OO

O


O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

OH

OO

Hlowastlowast

∙∙







O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)



0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






(electron)


(hydrogen radical)



rubber)

NR∙+ NR2ndashH+


NR∙+ NR∙




+ H2


0

10

20

30

40

50

60

70

80

Absorbed dose (kGy)

Har

dnes

s (∘Sh

A)

75 150 300 600






0

10

20

30

40

50

Elas

ticity

()





00

08

16

24

32

40

Mod

ulus

at100

el

onga

tion

(Nm

m2)








O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

HO

OH

H

H

H

H

OH

HOHO

OH

O

H

HH

H

HOH

OH

HOO

OO

n


O

H

HH

H

HOH

OH

HO

H

H

HO

H

HOHO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

HO

OH

OO


or

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

OH

OO

O


O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

OH

OO

Hlowastlowast

∙∙







O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)



0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

HO

OH

H

H

H

H

OH

HOHO

OH

O

H

HH

H

HOH

OH

HOO

OO

n


O

H

HH

H

HOH

OH

HO

H

H

HO

H

HOHO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

HO

OH

OO


or

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HO

OH

OO

O


O

H

HH

H

HOH

OH

HO

H

H

H

H

OH

HOHO

OH

OO

Hlowastlowast

∙∙







O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)



0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

HO

OH

OO

C

C

H

Addition

∙

∙

+

+

CH3

CH3

CH2

CH2

CH2

CH2

O

H

HH

H

HOH

OH

HO

H

H

HO

H

HO

OH

OO


CH

C

Natural rubber

O

H

HH

H

H

OH

OH

HO

H

H

HO

H

HO

OH

OO

C

C

H

HO

O

H

∙

∙

+

+

CH2

CH2

CH3

CH3

CH2

CH2

(a)

(b)



0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0

1

2

3

4

5

6

7

Tens

ile st

reng

th (N

mm

2)





0

100

200

300

400

500

600

700

800

900

1000

Elon

gatio

n at

bre

ak (

)







0

5

10

15

20

25

30

Tear

ing

stren

gth

(Nm

m)







2119898)



2119898) and





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Sample 119866 ]2119898


0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)





0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)







0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)




0 200 400 600 800 1000 1200 14000

5

10

15

20

25

30

35

40

45

Wat

er u

ptak

e (

)

Time (h)










3) ]as (CH

2) and ]s (CH

2) respectively (as



3



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




2500 3000 3500 4000

00

02

04

06

08

10

12

14

16Ab

sorb

ance


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy



2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)



4 Conclusions





2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)


2500 3000 3500 4000

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(a)

500 1000 20001500 2500

00

02

04

06

08

10

12

14

16

Abso

rban

ce


300kGy600kGy


(b)







References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




References






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



Documents

Research Article New Green Polymeric Composites Based on