Research Article Improved Mechanical Properties of ...downloads.hindawi.com/journals/ijps/2015/742540.pdf · Improved Mechanical Properties of Compatibilized Polypropylene/Polyamide-12

Research ArticleImproved Mechanical Properties of CompatibilizedPolypropylenePolyamide-12 Blends

Nora Aranburu and Joseacute Ignacio Eguiazaacutebal

Departamento de Ciencia y Tecnologıa de Polımeros and POLYMAT Facultad de Ciencias QuımicasUniversidad del Paıs Vasco UPVEHU PO Box 1072 20080 Donostia Spain

Correspondence should be addressed to Jose Ignacio Eguiazabal joseieguiazabalehues

Received 6 November 2014 Accepted 2 March 2015

Academic Editor Tianxi Liu

Copyright copy 2015 N Aranburu and J I Eguiazabal This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Compatibilized blends of polypropylene (PP) and polyamide-12 (PA12) as a second component were obtained by direct injectionmolding having first added 20 maleic anhydride-modified copolymer (PP-g-MA) to the PP which produced partially graftedPP (gPP) A nucleating effect of the PA12 took place on the cooling crystallization of the gPP and a second crystallization peakof the gPP appeared in the PA12-rich blends indicating changes in the crystalline morphology There was a slight drop in thePA12 crystallinity of the compatible blends whereas the crystallinity of the gPP increased significantly in the PA12-rich blendsTheoverall reduction in the dispersed phase particle size together with the clear increase in ductility when gPP was used instead of PPproved that compatibilization occurred Youngrsquos modulus of the blends showed synergistic behavior This is proposed to be bothdue to a change in the crystalline morphology of the blends on the one hand and on the other in the PA12-rich blends to the clearincrease in the crystallinity of the gPP phase which may in turn have been responsible for the increase in its continuity and itscontribution to the modulus

1 Introduction

Polymer blending has been extensively used over the lastfew decades to produce new polymeric materials whichcombine the individual attributes of the component neatpolymers [1] However compatibilization is usually necessaryin polymer blends [2] due to the immiscibility and incompat-ibility of most polymer pairs [3] Compatibilization improvesthe blend morphology enhances interfacial adhesion andconsequently improves the performance of the blend [4]

Blends of polypropylene (PP) with polyamides (PAs) areinteresting because they allow the thermomechanical prop-erties of the PAs to be combined with the processability ofthe PP [5] However these blends are incompatible due to thedissimilar polar-non-polar nature of PAs and PP respectivelyTherefore compatibilization was attempted mainly throughmodifying the PPwithmaleic anhydride (MA) [6ndash18] acrylicacid (AA) [13 16 17] and glycidyl methacrylate (GMA) [1519] groups These groups are able to react with the terminalamine groups in the PA forming graft copolymers which

locate at the interfaces These copolymers should reducethe interfacial tension and coalescence rate and improveinterfacial adhesion between the components [8]

Polyamide-12 (PA12) has longer aliphatic chains as wellas a lower melting point and water sorption than other PAssuch as PA6 and PA66 PA12 also shows greater flexibilityresistance to pressure and impact and good mechanicalproperties at extreme temperatures thermal stability andchemical resistance [20] PP is easy to process and shows goodstrength and solvent resistance Despite this papers dealingwith the compatibilization of PPPA12 blends are scarce Thecrystallization and morphology of these blends [21 22] andtheir thermal degradation and crystallization [14] have beenpartially studied When kneading-compression molding wasused [8 9] a critical compatibilizer concentration was identi-fied relative to the particle size but the elongation at break didnot improve as a result The morphology and the elongationat break improved in an 8020 PA12PP blend modified witheither PP-g-MA or PP-g-AA with the former proving thebetter compatibilizer [17]

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2015 Article ID 742540 8 pageshttpdxdoiorg1011552015742540

2 International Journal of Polymer Science

For this study the PP was first modified by a PP-g-MA copolymer to obtain gPP and the gPPPA12 blendswere prepared directly during the plasticization step of aninjection molding process through the whole compositionrange Next they were characterized by dynamic-mechanicalthermal analysis (DMTA) and differential scanning calorime-try (DSC)The compatibilization level reachedwas tested anddiscussed by themorphology (scanning electronmicroscopySEM) and the tensile properties before and after compatibi-lization

2 Experimental

The polymers used in this work were an isotactic polypropy-lene (PP) Isplen PP070 G2M by Repsol YPF and apolyamide-12 (PA12) Rilsan AMNO TLD by ArkemaThe maleated polypropylene (PP-g-MA) was FusabondPMZ203D supplied byDuPont with 074maleic anhydridecontent (min 055 max 115) Drying before processingwas performed at 50∘C in an air circulation oven for 4 h forPP-g-MA and at 80∘C in a vacuum oven for 24 h in the caseof PA12

To obtain the compatibilized blends first PP and PP-g-MA were mixed by extrusion in an 8020 proportionas explained below Then the PPPP-g-MA blend (gPPhereafter) was directly mixed-injection molded with PA12

The mixing of PP and PP-g-MA to obtain gPP wasperformed in a Collin ZK25 corotating twin screw extruder-kneader The screw diameter and the LD ratio were 25mmand 30 respectively A melt temperature of 200∘C and ascrew rotation speed of 200 rpm were used The extrudateswere cooled in a water bath and pelletized The compatibi-lized gPPPA12 and uncompatibilized PPPA12 blends as areference were obtained by direct mixing-injection moldingof the components Blending was carried out during theplasticization step of the injection molding process devel-oped in a Battenfeld BA-230E reciprocating screw injectionmolding machine to obtain tensile (ASTM D638 type IVthickness 184mm) and impact (ASTM D256 thickness31mm) specimens The neat polymers were also molded asreference materialsThe screw of the plasticization unit was astandard screw with a diameter of 18mm an LD ratio of 178and a compression ratio of 4Themelt temperaturewas 200∘Cand the mold temperature was 15∘C The injection speedand pressure were 102 cm3sdotsminus1 and 2750 bar respectivelyThespecimenswere left to condition for 24 h in a dessicator beforeanalysis or testing

Dynamic mechanical analysis was carried out in a TAInstruments DMA Q800 apparatus that provided the plot ofthe loss modulus (11986410158401015840) against temperature The scans werecarried out from minus100 to 140∘C at a constant heating rate of4∘Cmin and at a frequency of 1Hz The melting behaviorwas studied by DSC using a Perkin-Elmer DSC-7 calorimetercalibrated with an Indium standard A heating scanwasmadefrom 30∘C to 200∘C at a heating rate of 20∘Cmin and thesubsequent cooling scan was made in the same conditionsThemelting temperature (119879

119898) and enthalpy (Δ119867

119898) of PP and

PA12 were determined from the heating scans using the peak

maximum and area respectively As the melting peaks ofthe PP and PA12 in the blends partially overlapped thepartial areas were used in order to estimate the crystallinityof each component of the blend To do this the total areawas first calculated and then a separating line was drawnfrom theminimumbetween themelting peaks to the baselinein order to calculate the partial area belonging to eachcomponent of the blend The crystallization temperatures(119879119888) were determined from the cooling scans using the

minimum temperatures of the crystallization exothermsThecrystallinity of PP and PA12 was calculated assuming amelting enthalpy of 209 Jg for 100 crystalline PP [11] and2092 Jg for 100 crystalline PA12 [23] respectively XRDpatterns were recorded in an Xrsquopert X-ray diffractometeroperating at 40 kV and 40mA using a Ni-filtered K

120572Cu

radiation sourceCryogenically broken surfaces of the tensile specimens

of the blends were observed after gold-coating by scanningelectron microscopy (SEM) using a Hitachi S-2700 electronmicroscope operated at an accelerating voltage of 15 kV

Tensile testing was carried out using an Instron 4301machine at a cross-head speed of 10mmmin and at 23 plusmn 2∘Cand 50 plusmn 5 relative humidity The mechanical properties(yield strength and ductility measured as the elongation atbreak) were determined from the load-displacement curvesYoungrsquos modulus was determined bymeans of an extensome-ter at a cross-head speed of 1mmmin A minimum of fivespecimens were tested for each reported value

The orientation of the injection molded specimens wasestimated by means of birefringence measurements carriedout using a Metricon Model 2010 equipped with an infraredlaser with a wavelength of 1550 nm The samples were pre-pared by sectioning the central part of the specimens with aLeica 1600 microtome

The density of the blends was determined by the displace-ment method in a Mirage SD-120L electronic densitometerusing butyl alcohol as the immersion liquid The estimatedresolution was 00003 gcm3

3 Results and Discussion

31 Phase Behavior The amorphous phase behavior ofthe gPPPA12 blends was studied by dynamic mechanical-thermal analysis (DMTA)The plots of selected compositionsare shown in Figure 1 and the corresponding 119879

119892values are

shown on Table 1 The 119879119892values of the PP blends showed

similar trends Figure 1 shows that irrespective of the com-position of the blend two glass transitions always appearedclose to those of pure gPP and PA12 indicating the existenceof two phases No significant trend is observed in the 119879

119892of

the PA12 in the blends but a slight increase is observed in the119879

119892of gPP in the PA12-rich blends This slight increase also

occurred in the PP blends which makes it more significantThis increase will be discussed later and is unlikely to be dueto the presence of slight amounts of PA12 resulting from acompatibilization reaction because it also appeared in the PPblends and besides it is known that the different polarity ofboth components causes full immiscibility [8]

International Journal of Polymer Science 3

Table 1 Glass transition temperatures of the gPPPA12 blends Theaverage standard deviation is 1∘C

Composition 119879

119892

(∘C)gPPPA12 gPP PA121000 8 mdash8515 8 517525 8 496040 8 515050 9 494060 10 492575 10 511585 9 490100 mdash 52

10 30 50 70 90

Loss

mod

ulus

100085157525

604050504060

2575

1585

0100

minus30 minus10

T (∘C)

Figure 1 Loss modulus curves of the gPPPA12 blends and the neatpolymers

Themelting (119879119898) and crystallization (119879

119888) temperatures of

the blends studied by DSC are shown in Table 2 The 119879119898119904

of the PP blends are not shown because as in other works[14 24] they were very similar to those of the gPP blendsIt was the same in the case of the 119879

119888 As expected [11 14 25]

and reflected onTable 2 the values for the two119879119898119904 are similar

to those of the corresponding pure polymers The same wasobserved for the 119879

119888of the PA12 which remained almost

constant throughout changes in the blend composition The119879

119888of the gPP was slightly higher than that of pure gPP

due to a nucleation effect of the already solid PA12 particleson crystallization of the PP as previously reported in aPPPA12 8020 blend [24] and in other PPPA blends [1926 27] However in the PA12-rich compositions a second 119879

119888

appeared at a lower temperature In compatibilized blendscrystallization of the PA6 was also observed to occur over awider temperature range [28] This additional crystallizationindicates that the crystalline morphology of (at least) the gPPmay have changed upon blending

The crystalline content of each component in the blendswas calculated from the corresponding melting heat values

Table 2 Melting and crystallization temperatures of gPP and PA12in the blends The average standard deviation is 05∘C

Composition 119879

119898

(∘C) 119879

119888

(∘C)gPPPA12 gPP PA12 gPP PA121000 1690 mdash 1105 mdash8515 1690 1800 1125 14507525 1700 1820 1120 14456040 1690 1815 1120 14405050 1690 1800 1130 14554060 1690 1805 10451125 14402575 1690 1805 10451105 14501585 1680 1800 1045 14500100 mdash 1810 mdash 1445

Table 3 Crystallinity of the components in the gPPPA12 andPPPA12 blends The average standard deviation is 5

Crystallinity ()Composition gPPPA12 PPPA12

gPP PA12 PP PA121000 45 mdash 45 mdash8515 45 15 45 157525 45 20 45 156040 45 20 45 155050 50 20 60 204060 55 20 60 202575 65 20 75 201585 75 25 55 250100 mdash 30 mdash 30

obtained from the DSC plots and the results are shown inTable 3 It was also tested by X-ray diffraction but the twodiffraction peaks almost fully overlapped As can be seen inTable 3 the crystalline content of the PA12 decreased slightlyin the blends That of the gPP phase remained constant inthe gPP-rich blends but it clearly increased in the PA12-richcompositions This increase in the crystallinity of the gPP inPA12-rich blends also occurred in the PP blends this wasalso observed in another PA6PP blend [29] However in thisstudy these changes were accompanied by the appearance ofthe new 119879

119888peak All of these changes are consistent with the

increase in 119879119892observed in the gPP (shown in Table 1) and

are believed to be responsible for itTheymay also have someeffect on the mechanical properties of the blends

32 Phase Morphology The SEM micrographs of the cryo-genically fractured surfaces of the 7525 6040 4060 and2575 gPP blends are shown in Figures 2(a)ndash2(d) respectivelyand those of the uncompatibilized blends with PP are shownin Figures 3(a)ndash3(d) as a reference The micrographs ofFigures 3(a) and 3(c) were taken with an incidence angleof 40∘ and those of Figures 3(b) and 3(d) at an angle of0∘ It can be seen that the PP blends in Figure 3 show abiphasic and coarse (typically 2ndash5120583m) morphology whichis consistent with their immiscibility Moreover the surfaces


(a) (b)

(c) (d)

Figure 2 SEM micrographs of (a) 7525 (b) 6040 (c) 4060 and (d) 2575 gPPPA12 blends

(a) (b)

(c) (d)

Figure 3 SEMmicrographs of (a) 7525 (b) 6040 (c) 4060 and (d) 2575 PPPA12 blends taken with incidence angle of 40∘ (a and c) and0∘ (b and d)


of both the holes and the particles look very smooth withno adhered matrix residue This strongly suggests poorinterfacial adhesion In addition while the dispersed particlesappear to be spherical in the micrographs taken at 0∘ theimages taken at 40∘ prove that most of the particles areelongated in a direction perpendicular to the fracture surfacethat is parallel to the flow directionThis is caused by the flowduring injection molding

Figure 3(b) shows that the morphology of the 6040 PPblend was close to cocontinuity indicating that the phaseinversion occurred close to that particular composition Toprove this the melt viscosities were estimated by means ofthe torque for kneading of the components at the processingtemperature (200∘C) The values were 945Nsdotm and 820Nsdotmfor PP and PA12 respectively Substituting these values in theequation for the composition for phase inversion [30] thevolume composition for the phase inversionwas 5446whichis consistent with the micrographs

When gPP was used instead of PP (Figure 2) the changeinmorphologywas drasticThis is because the compatibilizedgPP blends show a very fine phase dispersion typically inthe 05ndash1 120583m range despite the fact that a direct injectionmolding procedure was used This indicates a decreasein interfacial tension and coalescence inhibition which isattributed to the formation of PP-g-PA12 copolymers result-ing from the reaction of the PP-g-MA maleic groups withthe terminal amine groups of PA12 [7 31] this takes placeat the interfaces [32] leading to improved adhesion Theless pronounced compatibilization efficiency observed in the2575 gPP blend (Figure 2(d)) in comparison with the othergPPPA12 compositions could be related to the fact thatthe amount of added PP-g-MA is relative to the PP phaseand thus its concentration is smaller increasing the PA12content In any case the dispersed particles of Figure 2 aredeeply embedded in the matrix This together with the finedispersed phase size proves that compatibilization occurredeffectively in these blends despite fast and easy mixing bydirect injection molding

33 Mechanical Properties Youngrsquos modulus-compositionplot of the compatibilized gPPPA12 blends as well as that ofthe uncompatibilized PPPA12 blends as a reference is shownin Figure 4 Both plots are very similar and for both theuncompatibilized and the compatibilized blends a positivedeviation from linearity can be clearly seen In the sameblends obtained by kneading-compression [8 9] negativedeviations appeared The positive deviations in Figure 4 ledto absolute synergism in some compositions with a highermodulus than in any of the neat components In order todiscuss the modulus behavior of the blends the molecularorientation a possible mixing-induced change in specificvolume and the crystallinity of the blend components mustbe considered As the modulus behavior is almost identicalfor both gPPPA12 and PPPA12 blends the discussion willonly be made for gPPPA12 blends

The molecular orientation of the blends needs to beexamined when attempting to explain the synergistic moduliso birefringencemeasurements were taken and the results are

1000

1200

1400

1600

1800

2000

0 20 40 60 80 100

Mod

ulus

(MPa

)

PA12 ()

Figure 4 Youngrsquos modulus of the uncompatibilized PPPA12 (I)and compatibilized gPPPA12 (e) blends as a function of the PA12content

0

10

20

30

40

50

0 20 40 60 80 100PA12 ()

Bire

frin

genc

e (times10minus3

)

Figure 5 Birefringence of the gPPPA12 blends as a function of thePA12 content

shown in Figure 5The plot is practically linear so a change inorientation on the blends was ruled out as an explanation forthe behavior of Youngrsquos modulus With respect to a mixing-induced change in specific volume the density-compositionplot was linear However further information about specificvolume changes could not be obtained due to the crystallinenature of both components on the one hand and on theother because changes on the crystalline content of eachcomponent occurred upon blending

Regarding the crystalline phases the crystallinity of thePA12 in the blends was fairly constant with composition andslightly lower than that of the pure PA12 The crystallinityof gPP was constant in the gPP rich blends but increasedin the PA12-rich compositions (Table 3) To discuss theseresults we will first refer to the possible effects of crys-tallinity in the whole composition range and then will addadditional considerations relative to the PA12-rich blendsConcerning the possible effects of the crystallinity in blendsof two crystallizable polymers the physical properties maybe altered not only by the blend composition and the phasemorphology but also by the crystallization behavior of each


of the two components [30] It is also known that (a) thecrystallization of a dispersed (or continuous) phase is verydifferent not only from that of the pure component but alsofrom the behavior of the continuous (or dispersed) phase(b) a nucleating activity of both components on each otheroften takes place this gives rise to smaller (and then largeramount of) crystals and may cause additional hinderingof the amorphous phase and (c) when the dispersion ofcrystalline particles becomes finer (by compatibilization forinstance) coincidental crystallization may occur [33] or beenhanced [34] Therefore the crystalline morphology ofthe components in this study very probably changes uponblending Even though the effects of these morphologicalchanges on the final properties are far frombeing understoodit is proposed that the behavior of the modulus of the blendsis a result of the change of morphology of the dispersedcrystalline phases

In the PA12-rich blends the previously observed newcrystallization peak points to the presence of a different crys-talline structure and this change in morphology is furthersupported by the effects set out in the paragraph aboveMore-over there was a marked increase in the crystallinity of thegPP phase It is known that marked changes in crystallinityusually influence themodulus values in polymers [35 36] dueto the greater presence of the amorphous phase The changefrom 45 to 65 for example is considerable enough toinfluence the modulus as the crystalline phase is expected toincrease its continuityThismakes the crystalline phase of thegPP themain contributor to themodulus which is consistentwith the modulus behavior observed

The yield strength of the compatibilized gPPPA12 blendswas rather linear (Figure 6) This is consistent with the localnature of the yielding process that occurs in the structurallyless resistant zone of the specimenThe ductility values of thegPPPA12 blends are shown in Figure 7 together with thoseof the PP blends as ductility is a measure of compatibilityAs can be seen ductility drastically improved over the wholecomposition range when gPP was used The ductility ofthe 8515 gPP blend does not appear in Figure 7 becauseit was higher than the elongation limit of the machine Inprevious papers where PPPA12 blends were obtained bycompression molding [8 9] the addition of a compatibilizerdid not lead to an increase in ductility but rather to constantvalues or to a decrease It must be taken into account thatin reference [8] much larger particle sizes (4120583m in the 7030PPPA12 compatibilized blend) were present The increase inductility in this paper is most likely to be the result of andis indeed attributed to the decrease in the dispersed phasesize and the increase in interfacial adhesion both due to thecompatibilizing effect of the PP-g-PA12 copolymers formedin situ during processing

4 Conclusions

The addition of 20 PP-g-MA to the PP allowed gPPPA12compatible blends to be obtained by direct injection moldingthroughout the whole composition range No change wasobserved in the 119879

119892of the PA12 phase but that of gPP showed

a slight increase in PA12-rich blends Although no change

20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()

Figure 6 Yield strength of the compatibilized gPPPA12 blends asa function of the PA12 content

0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()

Figure 7 Ductility of the uncompatibilized PPPA12 (I) and com-patibilized gPPPA12 (e) blends as a function of the PA12 content

was observed in the two 119879119898119904 or the 119879

119888of the PA12 either a

nucleating effect of the PA12 took place during the coolingcrystallization of the gPP There was a second crystallizationpeak of gPP in the PA12-rich blends which indicates a changein the crystalline morphology of the gPP upon blending Thecrystallinity of the PA12 decreased slightly in the compatibleblends That of gPP was constant in gPP-rich blends but itincreased significantly in PA12-rich blends

The addition of the compatibilizer led to a clear reductionin the particle size (roughly from 2ndash5120583m to 05ndash1120583m) thanksto the formation of PP-g-PA12 copolymers at the interfacesThis resulted in a very considerable increase in ductility Thistogether with the decrease in the dispersed phase is a clearindication of compatibilization

Youngrsquos modulus of the blends showed synergistic behav-ior throughout the composition range This is believed tobe due to a change in the crystalline morphology of theblends and in the case of the PA12-rich blends it was alsodue to the significant increase (from 45 to 65) in thecrystallinity of the gPP phase which increases its continuityand its contribution to the modulus

Conflict of Interests

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


Acknowledgments

The financial support of the Basque Government (ProjectIT-611-13) and of the University of the Basque Country(UFI 1156) is gratefully acknowledged Nora Aranburu alsoacknowledges the Basque Government for the award of agrant for the development of this work

References

[1] D Wang Y Li X-M Xie and B-H Guo ldquoCompatibilizationand morphology development of immiscible ternary polymerblendsrdquo Polymer vol 52 no 1 pp 191ndash200 2011

[2] D R Paul and C B Bucknall Polymer Blends Wiley-Inter-science New York NY USA 2000

[3] S Datta and D J Lohse Polymeric Compatibilizers Usesand Benefits in Polymer Blends Hanser Publishers MunichGermany 1996

[4] G Jiang H Wu and S Guo ldquoReinforcement of adhesion anddevelopment of morphology at polymer-polymer interface viareactive compatibilization a reviewrdquo Polymer Engineering andScience vol 50 no 12 pp 2273ndash2286 2010

[5] A Sacchi L Di LandroM Pegoraro and F Severini ldquoMorphol-ogy of isotactic polypropylene-polyamide 66 blends and theirmechanical propertiesrdquo European Polymer Journal vol 40 no8 pp 1705ndash1713 2004

[6] J Nagel D Scheidler B Hupfer et al ldquoInvestigations on theformation of composites by injection molding of PA6 anddifferent grafted polypropylenes and their blendsrdquo Journal ofApplied Polymer Science vol 100 no 4 pp 2992ndash2999 2006

[7] N Abacha and S Fellahi ldquoSynthesis of polypropylene-graft-maleic anhydride compatibilizer and evaluation of nylon6polypropylene blend propertiesrdquo Polymer International vol54 no 6 pp 909ndash916 2005

[8] S Jose B Francis S Thomas and J Karger-Kocsis ldquoMorphol-ogy and mechanical properties of polyamide 12polypropyleneblends in presence and absence of reactive compatibiliserrdquoPolymer vol 47 no 11 pp 3874ndash3888 2006

[9] S Jose S V Nair S Thomas and J Karger-Kocsis ldquoEffect ofreactive compatibilisation on the phase morphology and tensileproperties of PA12PP blendsrdquo Journal of Applied PolymerScience vol 99 no 5 pp 2640ndash2660 2006

[10] J Zhang P J Cole U Nagpal C W Macosko and T PLodge ldquoDirect correlation between adhesion promotion andcoupling reaction at immiscible polymer-polymer interfacesrdquoThe Journal of Adhesion vol 82 no 9 pp 887ndash902 2006

[11] M Jaziri N Barhoumi V Massardier and F Melis ldquoBlendingPPwith PA6 industrial wastes effect of the composition and thecompatibilizationrdquo Journal of Applied Polymer Science vol 107no 6 pp 3451ndash3458 2008

[12] D Li D Jia and P Zhou ldquoCompatibilization of polypropy-lenenylon 6 blends with a polypropylene solid-phase graftrdquoJournal of Applied Polymer Science vol 93 no 1 pp 420ndash4272004

[13] C-H Jung J-H Choi Y-M Lim et al ldquoPreparation of poly-propylene compatibilizer by radiation grafting and its effect onPPNylon 6 blendrdquoMacromolecular Symposia vol 249-250 pp573ndash579 2007

[14] S Jose S Thomas P K Biju P Koshy and J Karger-KocsisldquoThermal degradation and crystallisation studies of reactivelycompatibilised polymer blendsrdquo Polymer Degradation and Sta-bility vol 93 no 6 pp 1176ndash1187 2008

[15] A Tedesco R V Barbosa S M B Nachtigall and R S MaulerldquoComparative study of PP-MA and PP-GMA as compatibilizingagents on polypropylenenylon 6 blendsrdquo Polymer Testing vol21 no 1 pp 11ndash15 2002

[16] P Agrawal S I Oliveira E M Araujo and T J A MeloldquoEffect of different polypropylenes and compatibilizers on therheological mechanical and morphological properties of nylon6PP blendsrdquo Journal of Materials Science vol 42 no 13 pp5007ndash5012 2007

[17] A Valenza and D Acierno ldquoTernary blends of nylon 12poly-propylenemodified polypropylene influence of functionalgroups of the modified polypropylenerdquo European PolymerJournal vol 30 no 10 pp 1121ndash1126 1994

[18] G M Shashidhara D Biswas B S Pai A K Kadiyala G SW Feroze andM Ganesh ldquoEffect of PP-g-MAH compatibilizercontent in polypropylenenylon-6 blendsrdquoPolymer Bulletin vol63 no 1 pp 147ndash157 2009

[19] A Tedesco P F Krey R V Barbosa and R S Mauler ldquoEffect ofthe type of nylon chain-end on the compatibilization of PPPP-GMAnylon 6 blendsrdquo Polymer International vol 51 no 2 pp105ndash110 2002

[20] I Y Phang T Liu A Mohamed et al ldquoMorphology thermaland mechanical properties of nylon 12organoclay nanocom-posites prepared by melt compoundingrdquo Polymer Internationalvol 54 no 2 pp 456ndash464 2005

[21] T Tang Z Lei X Zhang H Chen and B Huang ldquoStudies onsimultaneous crystallization of polypropylenenylon 12 blendsrdquoPolymer vol 36 no 26 pp 5061ndash5063 1995

[22] T Tang Z Lei and B Huang ldquoStudies on morphology andcrystallization of polypropylenepolyamide 12 blendsrdquo Polymervol 37 no 15 pp 3219ndash3226 1996

[23] T McNally W R Murphy C Y Lew R J Turner and GP Brennan ldquoPolyamide-12 layered silicate nanocomposites bymelt blendingrdquo Polymer vol 44 no 9 pp 2761ndash2772 2003

[24] YWu Y Yang B Li andYHan ldquoReactive blending ofmodifiedpolypropylene and polyamide 12 effects of compatibilizercontent on crystallization and blend morphologyrdquo Journal ofApplied Polymer Science vol 100 no 4 pp 3187ndash3192 2006

[25] N Torres J J Robin and B Boutevin ldquoStudy of compatibi-lization of HDPE-PET blends by adding grafted or statisticalcopolymersrdquo Journal of Applied Polymer Science vol 81 no 10pp 2377ndash2386 2001

[26] SM BNachtigall AHO Felix andR SMauler ldquoBlend com-patibilizers based on silane- and maleic anhydride-modifiedpolyolefinsrdquo Journal of Applied Polymer Science vol 88 no 10pp 2492ndash2498 2003

[27] N Aranburu and J I Eguiazabal ldquoCompatible blends ofpolypropylene with an amorphous polyamiderdquo Journal ofApplied Polymer Science vol 127 no 6 pp 5007ndash5013 2013

[28] Q Wei D Chionna and M Pracella ldquoReactive compatibiliza-tion of PA6LDPE blends with glycidyl methacrylate function-alized polyolefinsrdquoMacromolecular Chemistry and Physics vol206 no 7 pp 777ndash786 2005

[29] J Piglowski I GancarzMWlazlak andH-W Kammer ldquoCrys-tallization inmodified blends of polyamide and polypropylenerdquoPolymer vol 41 no 18 pp 6813ndash6824 2000

[30] L A Utracki Polymer Blends Handbook Kluwer AcademicPublishers Dordrecht The Netherlands 2002

[31] H Liu T Xie Y Zhang YOu andG Yang ldquoPhasemorphologydevelopment in PPPA6 blends induced by a maleated thermo-plastic elastomerrdquo Journal of Polymer Science Part B PolymerPhysics vol 44 no 7 pp 1050ndash1061 2006


[32] J Duvall C Sellitti V Topolkaraev A Hiltner E Baer and CMyers ldquoEffect of compatibilization on the properties of poly-amide 66polypropylene (7525wtwt) blendsrdquoPolymer vol 35no 18 pp 3948ndash3957 1994

[33] S J Park B K Kim and H M Jeong ldquoMorphological thermaland rheological properties of the blends polypropylenenylon-6 polypropylenenylon-6(maleic anhydride-g-polypropylene)and (maleic anhydride-g-polypropylene)nylon-6rdquo EuropeanPolymer Journal vol 26 no 2 pp 131ndash136 1990

[34] H-S Moon B-K Ryoo and J-K Park ldquoConcurrent crystal-lization in polypropylenenylon-6 blends using maleic anhy-dride grafted polypropylene as a compatibilizing agentrdquo Journalof Polymer Science Part B Polymer Physics vol 32 no 8 pp1427ndash1435 1994

[35] A Arzak J I Eguiazabal and J Nazabal ldquoBiphasic compatibleblends from injection-molded poly(ether ether ketone)poly-sulfonerdquo Journal of Applied Polymer Science vol 65 no 8 pp1503ndash1510 1997

[36] L E Sanchez-Cadena B Alvarado-Tenorio A Romo-Uribe BCampillo O Flores and H Yao ldquoHot-pressed boards based onrecycled high-density polyethylene tetrapack mechanical pro-perties and fracture behaviorrdquo Journal of Reinforced Plastics andComposites vol 32 no 23 pp 1779ndash1792 2013

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


For this study the PP was first modified by a PP-g-MA copolymer to obtain gPP and the gPPPA12 blendswere prepared directly during the plasticization step of aninjection molding process through the whole compositionrange Next they were characterized by dynamic-mechanicalthermal analysis (DMTA) and differential scanning calorime-try (DSC)The compatibilization level reachedwas tested anddiscussed by themorphology (scanning electronmicroscopySEM) and the tensile properties before and after compatibi-lization

2 Experimental

The polymers used in this work were an isotactic polypropy-lene (PP) Isplen PP070 G2M by Repsol YPF and apolyamide-12 (PA12) Rilsan AMNO TLD by ArkemaThe maleated polypropylene (PP-g-MA) was FusabondPMZ203D supplied byDuPont with 074maleic anhydridecontent (min 055 max 115) Drying before processingwas performed at 50∘C in an air circulation oven for 4 h forPP-g-MA and at 80∘C in a vacuum oven for 24 h in the caseof PA12

To obtain the compatibilized blends first PP and PP-g-MA were mixed by extrusion in an 8020 proportionas explained below Then the PPPP-g-MA blend (gPPhereafter) was directly mixed-injection molded with PA12

The mixing of PP and PP-g-MA to obtain gPP wasperformed in a Collin ZK25 corotating twin screw extruder-kneader The screw diameter and the LD ratio were 25mmand 30 respectively A melt temperature of 200∘C and ascrew rotation speed of 200 rpm were used The extrudateswere cooled in a water bath and pelletized The compatibi-lized gPPPA12 and uncompatibilized PPPA12 blends as areference were obtained by direct mixing-injection moldingof the components Blending was carried out during theplasticization step of the injection molding process devel-oped in a Battenfeld BA-230E reciprocating screw injectionmolding machine to obtain tensile (ASTM D638 type IVthickness 184mm) and impact (ASTM D256 thickness31mm) specimens The neat polymers were also molded asreference materialsThe screw of the plasticization unit was astandard screw with a diameter of 18mm an LD ratio of 178and a compression ratio of 4Themelt temperaturewas 200∘Cand the mold temperature was 15∘C The injection speedand pressure were 102 cm3sdotsminus1 and 2750 bar respectivelyThespecimenswere left to condition for 24 h in a dessicator beforeanalysis or testing

Dynamic mechanical analysis was carried out in a TAInstruments DMA Q800 apparatus that provided the plot ofthe loss modulus (11986410158401015840) against temperature The scans werecarried out from minus100 to 140∘C at a constant heating rate of4∘Cmin and at a frequency of 1Hz The melting behaviorwas studied by DSC using a Perkin-Elmer DSC-7 calorimetercalibrated with an Indium standard A heating scanwasmadefrom 30∘C to 200∘C at a heating rate of 20∘Cmin and thesubsequent cooling scan was made in the same conditionsThemelting temperature (119879

119898) and enthalpy (Δ119867

119898) of PP and

PA12 were determined from the heating scans using the peak

maximum and area respectively As the melting peaks ofthe PP and PA12 in the blends partially overlapped thepartial areas were used in order to estimate the crystallinityof each component of the blend To do this the total areawas first calculated and then a separating line was drawnfrom theminimumbetween themelting peaks to the baselinein order to calculate the partial area belonging to eachcomponent of the blend The crystallization temperatures(119879119888) were determined from the cooling scans using the

minimum temperatures of the crystallization exothermsThecrystallinity of PP and PA12 was calculated assuming amelting enthalpy of 209 Jg for 100 crystalline PP [11] and2092 Jg for 100 crystalline PA12 [23] respectively XRDpatterns were recorded in an Xrsquopert X-ray diffractometeroperating at 40 kV and 40mA using a Ni-filtered K

120572Cu

radiation sourceCryogenically broken surfaces of the tensile specimens

of the blends were observed after gold-coating by scanningelectron microscopy (SEM) using a Hitachi S-2700 electronmicroscope operated at an accelerating voltage of 15 kV

Tensile testing was carried out using an Instron 4301machine at a cross-head speed of 10mmmin and at 23 plusmn 2∘Cand 50 plusmn 5 relative humidity The mechanical properties(yield strength and ductility measured as the elongation atbreak) were determined from the load-displacement curvesYoungrsquos modulus was determined bymeans of an extensome-ter at a cross-head speed of 1mmmin A minimum of fivespecimens were tested for each reported value

The orientation of the injection molded specimens wasestimated by means of birefringence measurements carriedout using a Metricon Model 2010 equipped with an infraredlaser with a wavelength of 1550 nm The samples were pre-pared by sectioning the central part of the specimens with aLeica 1600 microtome

The density of the blends was determined by the displace-ment method in a Mirage SD-120L electronic densitometerusing butyl alcohol as the immersion liquid The estimatedresolution was 00003 gcm3

3 Results and Discussion

31 Phase Behavior The amorphous phase behavior ofthe gPPPA12 blends was studied by dynamic mechanical-thermal analysis (DMTA)The plots of selected compositionsare shown in Figure 1 and the corresponding 119879

119892values are

shown on Table 1 The 119879119892values of the PP blends showed

similar trends Figure 1 shows that irrespective of the com-position of the blend two glass transitions always appearedclose to those of pure gPP and PA12 indicating the existenceof two phases No significant trend is observed in the 119879

119892of

the PA12 in the blends but a slight increase is observed in the119879

119892of gPP in the PA12-rich blends This slight increase also

occurred in the PP blends which makes it more significantThis increase will be discussed later and is unlikely to be dueto the presence of slight amounts of PA12 resulting from acompatibilization reaction because it also appeared in the PPblends and besides it is known that the different polarity ofboth components causes full immiscibility [8]



Composition 119879

119892


10 30 50 70 90

Loss

mod

ulus

100085157525

604050504060

2575

1585

0100

minus30 minus10

T (∘C)






119888 As expected [11 14 25]







119888




Composition 119879

119898

(∘C) 119879

119888











(a) (b)

(c) (d)


(a) (b)

(c) (d)








1000

1200

1400

1600

1800

2000

0 20 40 60 80 100

Mod

ulus

(MPa

)

PA12 ()


0

10

20

30

40

50

0 20 40 60 80 100PA12 ()

Bire

frin

genc

e (times10minus3

)








4 Conclusions




20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()


0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()










Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Composition 119879

119892


10 30 50 70 90

Loss

mod

ulus

100085157525

604050504060

2575

1585

0100

minus30 minus10

T (∘C)






119888 As expected [11 14 25]







119888




Composition 119879

119898

(∘C) 119879

119888











(a) (b)

(c) (d)


(a) (b)

(c) (d)








1000

1200

1400

1600

1800

2000

0 20 40 60 80 100

Mod

ulus

(MPa

)

PA12 ()


0

10

20

30

40

50

0 20 40 60 80 100PA12 ()

Bire

frin

genc

e (times10minus3

)








4 Conclusions




20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()


0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()










Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a) (b)

(c) (d)


(a) (b)

(c) (d)








1000

1200

1400

1600

1800

2000

0 20 40 60 80 100

Mod

ulus

(MPa

)

PA12 ()


0

10

20

30

40

50

0 20 40 60 80 100PA12 ()

Bire

frin

genc

e (times10minus3

)








4 Conclusions




20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()


0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()










Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials









1000

1200

1400

1600

1800

2000

0 20 40 60 80 100

Mod

ulus

(MPa

)

PA12 ()


0

10

20

30

40

50

0 20 40 60 80 100PA12 ()

Bire

frin

genc

e (times10minus3

)








4 Conclusions




20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()


0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()










Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







4 Conclusions




20

25

30

35

40

45

50

0 20 40 60 80 100

Yiel

d str

engt

h (M

Pa)

PA12 ()


0

50

100

150

200

250

300

350

400

0 20 40 60 80 100

Duc

tility

()

PA12 ()










Acknowledgments


References













































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Acknowledgments


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 Improved Mechanical Properties of ...downloads.hindawi.com/journals/ijps/2015/742540.pdf · Improved Mechanical Properties of Compatibilized Polypropylene/Polyamide-12