Indian Journal of Fibre & Textile ResearchVol. 33, September 2008, pp. 253-257

Measurement of surface property using a special sensor developedfor pile materials

Takaka FujimotoTextile Material LaboratolY, Hokkaido University Education, Ainosato 5-3-1-5, Kitaku, Sapporo 002-8502 Japan

Matthew R Sunderland & Surinder K Tandona

Textile Science and Technology, AgResearch Limited, Lincoln Research Centre, Private Bag 4749,Christchurch 8140, New Zealand

Chie M Asano & Akira AsanoDepartment of Infonnation Engineering, Hiroshima University, Kagamiyama 1-7-1, Higashi-Hirosima 739-852 J Japan

and

Choji Murata & Hiroaki Fukuyama

Kato Tech Co, Ltd, Nishikujo Karatocho 26, Minamiku, 601-8447 Japan

A special sensor, like human finger tips, to measure the surface friction of various carpets with cut or loop pile hasbeen developed. The main body of the instrument is the KES multiple device and the attachments covered with the fake skinare appropriately attached to it. This instrument provides quick and easy testing for carpets and fabrics. This rapid methodwould be useful for quantifying friction and for designing high quality pile products.

Keywords: Carpet, Friction, Pile fabrics, Special sensor, Surface property

1 Introduction

The frictional behaviour of fibrous materialsgreatly affects their surface and mechanical propertiesand the performance of their end-products. Thesurface friction property of fabrics has been evaluatedby the coefficient of kinetic friction between fabricsurface and a piano wire contactor since 1970, whenthe Kawabata evaluation system for fabrics (KES-Fand FB) was developed. 1 The measured results haveprovided important information' in evaluating thefabric handle objectively. The coefficients of frictionof fabric surfaces have shown a strong correlationwith Numeri (smootlmess) of woven fabrics, which isone of the handle values representing a sense ofstickiness by human fingers. For carpets and thickmaterials, pilling test, compression recovery fromloading, trapped/tuft adhesion, flammability andabrasion testing have been well documented.2,3

Although a good touch and rub feeling is required for

'To whom all the correspondence should be addressed.E-mail: surinder.tandon@agresearch.co.nz

cut or loop pile materials and thick materials, thekinetic coefficient of friction has the problem ofbeing difficult to measure.4 In this study, the kineticcoefficient of friction of carpet and thick materialshas been investigated. For easy and rapidmeasurement, a special friction attaclm1ent isdeveloped for the loop and cut pile materials and forthe measurement of kinetic coefficients of frictionof various materials. The contactor of the attaclm1entis like a pair of finger tips, where the tip is covered bythe synthetic protein leather simulating human skin.Many researchers have studied the close relationshipbetween the friction of woven fabrics and theirobserved surface handle. It has been observed that thefabric handle is more closely related to the frictionbetween the fabric and the finger than the frictionbetween the fabric and the metal.s This new devicecan satisfy those demands and meet the expectationsin the textile field. Several researchers have studiedcarpets6

-8 with a focus on their properties such as

carpet shedding, shading, soiling and compressionrecovery, but not on the surface properties.

2.1 Measurement of Surface Properties

The surface propeliies of fabrics, woven andknitted, can bc measured easily by the KES-FB4contactor that consists of ten bent piano wiressimulating finger tips. For the pile materials likecarpets, fake furs, natural furs and other materialssuch as fabrics, the friction properties should bedetected similar to fingers stroking the pile or fur. Afinger-simulating sensor must rub the hairy surface ofa carpet while pushing down protruding fibres on thesurface. At least two fingers are required to simulatepushing down fibres or tufts between fingers. Theprobes require thc movement of pressing down amaterial's hair as it passes across the surface. Thespecial sensing probe and holder were designed tomeasure the surface property of pile materialsprecisely and consistently. The body of the devicewas developed by Kato Tech Co, Ltd. Figures land 2show the device and the special attachments formeasuring the friction. The spherical top surface ofthe attaelunent is covered by the synthctic proteinleather. Its brand name is Suppla[e.", and it is procuredfrom the Idemitsu Teelmofine Co., Ltd. It has morecomfortable and greater moisture-absorptionpropeliies than other artificial leathers. The contactormoves between 2cm intervals by a constant velocityof 0.1 cm/s on the material, which is placedhorizontally on the steel plate. The signal of surfacefriction must pass tlu'ough the high pass filter whereonly a wavelength smaller than 1mm can pass. Thepressure of the contactor against the specimen can beselected from 2.45 to 9.8N/finger. Data is given bythe distance-friction wave as shown in Fig. 3. Thekinetic coefficient of friction (MIU) and its deviation(MMD) have been derived.

2.2 Compression Property

The thickness and compression properties ofspecimens are measured from the pressure-thicknesscurves. I Two steel plates compress the specimens.The velocity of the compression is 0.2 nmvs for thickmaterials and 20 micrOlvs for clothing fabrics. Whenthe pressure reaches 4900 Nm-2, the recovery processis measured by the same condition. Thecompressibility and energy to compress and torecover, and the thickness at any pressure are given.Thc measurement is carried out under the standardtesting laboratory temperature and relative humidity

Fig. 2-Special sensor simulating fingers

MIUMMDc

0

~ Mean deviation of MIU:E0CQ)'0

Mean of MIU~Q)00 0 Slide distance d

(20DC, 65% RH). Table 1 shows the basic propertiesof the specimen used.

3 Results and DiscussionThe new device was used to measure the above-

mentioned materials. The special sensor attached tothe device provi.des stable and clear infom1ation froma wide range of materials. Figure 4 shows the resultsof friction testing of various materials.

The values of the coefficient of kinetic friction ofmink: and pos~um furs show relatively low MJU. Theyare well known for their elegant touch and wannfeeling. Sponge has the highest MJU, which is usefulto clean up the surface of subjects. For wool wads,the wad of coarser fibres shows higher MJU than finewool wad.

Spccimcn Fibrc content Thickncss Weight% x I0.3, m kg/m2

Corduroy Cotton 0.991 0.172

Velvct Rayon 1.301 0.195

Velvetccn Cotton 1.31 0.230

Cashmcrc Cashmcre 2.02 0.329

Mink fur atural fur 9.72 0.668

Rum fur Natural fur 7.56 0.641

Possum fur Natural fur 12.2 0.933

Fakc fur(short) Acrylic 5.44 0.356

Fake fur(long) Acrylic 6.49 0.555

Siliconc rubbcr 3.00 3.938

Spongc Polyurethanc foam 14.5 0.214

Cut piIe carpct N Wool &jute 8.78 1.86

Cut pilc carpct Y Wool &jutc 12.5 2.52

wool'ivad A Mcrino 25 pm

Woolwadl3 Corriedale 35 pmWood A Sugi 10.0 3.88

Woodl3 White birch 10.0 6.95

Supplale Synthetic leathcr" 0.802 0.249

'Attachment top material (Top: Polyurethane including proteinpowdcr; l3asc: rayon 80%, nylon 20%).

Figure 5 shows the MIU surface frictional responseof a pile carpet, possum fur and acrylic fake furrespectively. The top curve of each data is for thefriction along the leaning direction of the fur or pile.The bottom curve is for the friction against theleaning direction of the fur or pile.

The results of measurement trials on some carpetsare described in the following section. Characteristicsurface friction of furs was observed. The leaningdirection of the fur is displayed in Fig. 5. Possum furshows a lower rubbing friction against the leaningdirection of fur (bottom curve). This result hasprobably come from the make-up of the animal's fur.For the acrylic fake fur, the friction along and againstthe leaning direction of fur is similar and large.

3.1 Frictional Behaviour of CarpetsFour kinds of wool carpets (Table 2) were

examined for the effect of treatment on the surf;lceprOpetiies. These carpet samples were made fromR750/2 tex yam with a stitch rate of 35 st./dm (35stitches per deeimetre along carpet) and in 1I8thgauge (8 rows of stitches per inch across carpet; 31.5needles/dm). The carpets were taken in pairs - onecontrol and the other treated with Lanasan NCfTM

Wood wad(Coakdale)

Wood(While hirch) r

Pile calVel

Fake Ill! (short)

Wood wi1d r I1__ .11

i(Marino)

I II !Rnmfilf Ir I I

Silicon mbher I

!~- 1 -'1=Cntlhmere I

1r Tll I I

I IVel\'Ct . U I I_·....··-1.. I

I IPo',.sum flU - ...JJ IT I I

Mink nIl' I II0.1 0.2 0.3 0,4 0.5 0.6 0.7

MIU

2.00 [ Pile carpet

100:-1.00 [

-2.00 L, , ,~em 0 1 2

0- 0.80 t Possum fur

I.:o:~r-~~------------7·0.80 ~~! ~ ~

L. em 0 2

0'8o~Ae~

OM =00 --DAD

·0.80 ~ '--' --' ---'~cm 0

= ,;;'1Fig. 5-Recorded surface properties for pile carpet, possum furand acrylic fake fur

(silicon dioxide).9 The specimens of the latter groupwere treated with nanoparticle silica with anoptimised particle size. It has been commercialised asLanasan NCF.

The change in kinetic coefficient of friction ofcarpets before and after the treatment is shown in Fig.6. The MIU is significantly (p< 0.05) higher fortreated specimens. Among the cut-pile carpet

~ 0.3::?:

N 0Specimen

Property P N 0 Y

Type Loop Cut pile Cut pile Cut pile

Fibre Pile: wool, Backing: jute

Pile length, mm 4 6 10 10

P, N, 0, and Yare the specimen codes (P-Purple, N-Navy,O-Orange, and Y-Yellow)

specimens, the MIU is highest for treated pile carpet"N" because of its shorter pile height (6mm). It hasbeen found that the treatment of test carpetssignificantly reduces the soiling & fibre-sheddingrate, and improves both yarn strength & abrasionresistance.9 From this study, the trends of the changesin the kinetic friction coefficients of the surface ofcarpets correlate wi those effects. The loop pilecarpet shows some different change from the cut pilecarpets. The loop carpet specimens didn't show muchdifference compared to the cut pile carpet specimens.The surface yarns of loop carpets seem to change lessthan those of the cut pile carpet because thealignment of fibres is quite different between the twotypes. Treated carpets show higher EMC(compressibility) which correlates with the resultsfrom carpet wear testing, where the pile thickness lossis greater for treated specimens. The loop pile carpetdoes not show this, may be because with loop pile itis harder to change this property. The RC (resilience)is lower for treated carpets, except for the carpet "Y",where the difference is very small. The treatedcarpets would show lower resilience (recovery)because of greater frictional restraint and losses dueto increased friction. The marks left on the carpetafter compression would be bigger if the resilience islower, resulting in bigger compression marks fortreated carpets.

Table 3 shows the coefficient of friction (MJU)averaged, the standard deviation of MIU, meandeviation of MIU, the compression resilience RC andthe compressibility EMC for four carpet specimensbefore and after the treatment.

Table 3 - Results of surface and compression tests for carpets

Specimen Condition Surface properties Compression propertiesMIU SD ofMIU MMD RC% EMC

P Control 0.355 0.0165 0.003 35.78 0.132

Treated 0.358 0.0328 0.004 32.25 0.152

N Control 0.398 0.0173 0.002 29.71 0.306

Treated 0.542 0.0505 0.003 13.48 0.226

0 Control 0.383 0.0208 0.002 31.54 0.160

Treated 0.503 0.0227 0.003 26.83 0.128

Y Control 0.362 0.0051 0.002 31.79 0.172

Treated 0.449 0.0491 0.003 31.19 0.140

4 ConclusionsThe newly developed device provides impOliant

information on the surface friction properties of thicktextiles, with physical and chemical treatments. Theeffect of treatment on the coefficient of kineticfriction was also verified for cut pile carpets. A rapidmethod to quantify the surface friction of thick textilematerials as presented in this study would be usefulfor quantifying friction that has previously beendifficult to measure, and for designing high qualitypile products.

AcknowledgementThe authors are thankful to Dr Satoru Oya of

Hokkaido University of Education, for providingwood samples. Thanks are also due to the Kato TechCo. Ltd, for their support with the instrumentationduring this work. The partial support by the JapanSociety for the Promotion of Science USPS) forproviding the Grant-in-Aid for scientific research (B)is also acknowledged.

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