Gudlin Schwarz I., Kovacevic S., Dimitrovski K.; Comparative Analysis of the Standard and Pre-wet Sizing Process. FIBRES & TEXTILES in Eastern Europe2011, Vol. 19, No.4 (87) pp. 135-141.135Comparative Analysis of the Standardand Pre-wet Sizing ProcessIvana Gudlin Schwarz, Stana Kovacevic, *Krste DimitrovskiUniversity of Zagreb, Faculty of Textile Technology, Prilaz baruna Filipovica 28a, 10000 Zagreb, Croatia, e-mail: ivana.schwarz@ttf.hr, *University of Ljubljana, Faculty of Natural Sciences and Engineering, Snezniska 5, 1000 Ljubljana, SloveniaAbstractThe aim of this paper is to show, usingcomparative analysis, all the differences, as well asexistingadvantagesanddisadvantagesoftwodifferentsizingprocedures.Materials used in the implementation of this extensive research are ring-spun cotton yarns, sized with PVA size. Test parameters of the yarn were analyzed, subjected tostatistical analysis and compared. All theknowledge obtained is supported by a detailed analysis ofmicroscopic cross-sectional images of unsized yarns and those sized with both processes, where differ-ences between the two sizing processes in the distribution of size pick-up on the yarn are distinctlyobservable.Thewholeresearch,whichisbasedonprovingthetechnological justifcation and optimisation of pre-wet sizing, lead to the conclusion that it is a really ex-ceptional technological process, which greatly contributes to large savings of sizing agents, water,energyandenvironmentalprotection,withoutanyconsequencesforthequalityof sized yarn.Key words: pre-wet sizing, standard sizing, ring-spun cotton yarn, mechanical properties, size pick-up.nIntroductionAs one of the most complex steps in fab-ric production, sizing plays a very impor-tantroleintheweavingprocess.Itim-provesthephysical-mechanicalparam-eters of warp threads, thus reducing warp breakage to a minimum, and achieves the maximumdegreeofweavingmachine effciency and energy savings. In order to fulflltheserequirements,thechoiceof sizingagentsisextremelyimportant,as wellasoptimisingandmaintainingsiz-ing process conditions and the size pick-up constant. Even today the optimisation ofsizepick-upappliedtoyarnpresents amajorprobleminthesizingprocess, despitethehighdegreeofautomation andhighqualitysizingagents.Infu-entialparametersintheoptimisationof size pick-up are defned by the substance balance that enters and exits the size box (Equation1).Usingcontinuousmeas-urements and maintenance of the temper-ature and sizing concentration in the size box,aswellasautomaticregulationof the squeezing strength and sizing speed, itispossibletodefneandmaintainthe sizepick-upconstant.Sizepick-upcan becontrolledbytheregulationofwarp moisture at the box exit, which can be af-fected by the pressure of the last squeez-ingrollers.Therequirementofmain-taining the size pick-up constant, except the substance balance, is to maintain the other parameters affecting the size pick-up constant, such as the size temperature, sizing speed, thread tension etc. [1 - 4].Sp ( ) %1001100 SpH SpWCW WSp = (1)where SP is the size pick-up, WH - warp moisture at the box entry in %, WSp - warp moisture at the box exit in %, and C is the size concentration in the box in %.Uniformsizingguaranteesveryhigh weavingmachineeffciencyandrea-sonablecostsoffabricmanufacturing. Toachievethisgoal,itisnecessaryto controlasmanyparametersaspossi-bleduringsizingandtoregulatethem automatically.Besidestheabove-listed parametersforoptimising andmaintain-ing the size pick-up constant, the viscos-ityofsize,levels and circulation ofsize inthebox,sizingagents,conditionsof sizepreparationandyarnpropertiesare alsoimportant.Itisbelievedthatthe optimalsizepick-upistheonethatwill allowminimumwarpthreadbreakson the weaving machine as well as satisfac-toryeffciencyoftheweavingmachine andfabricquality,respectively. Accord-ingtoFigure1,theoptimalsizepick-upisslightlyhigherthantheminimum becausetheprecisionanduniformityof sizepick-upisveryhardtoachieve,es-peciallyonsinglecottonyarn,whichis mostly sized.A big unknown in size pick-up optimisa-tion is the sizing of wet warp, as well as theentirepre-wetsizingprocess,which differsfromthestandardsizingprocess intheconstructionofthesizingrange, whereanotherboxforpre-wettingwith hotwaterisaddedinfrontofthesize box.Theessenceoftheboxwithwa-ter is that before entering the size in the size box, the yarn is dipped in hot water (60 - 70 C), which enables the dissolu-tion and removal of grease as well as oth-er impurities and additives that are left on the raw yarn. Wetting the yarn allows to flltheinterspacesoftheyarnwithwa-ter,whereaftersqueezingoutexcessive water, the yarn remains wet and partially flled with water. By immersing such wet yarn in size, the water retained in the yarn comesintocontactwiththesize,which leads to a very quick mutual bonding, al-lowing faster and easier penetration of the size into the yarn compared to dry yarn, which is immersed directly into the size. However,thesizeconcentrationinthe yarn is lower than the size concentration because of the water retained in the yarn afterwetting,whichdilutesit.There-fore,alargerpartofthesizepick-upis retained on the yarn surface. When sizing iscarriedoutondryyarn,thesizealso penetratesintointerspacesintheyarn, but not with the same speed at which size penetrates during the sizing of wet yarn, hence the inner part of the yarn remains Figure1.Effectofsizepick-uponthe number of warp threads breaks on a weav-ingmachinewithoptimumsizepick-up; whereNbisthenumberofwarpthread breaks per machine and per hour, and Sp is the size pick-up.WSpWSpFIBRES & TEXTILES in Eastern Europe2011,Vol. 19, No.4 (87)136almostsize-free,whileontheperiphery asolidsizemantleiscreated. Allprevi-ousknowledgeofpre-wetsizingpoints to the obtainment of outstanding results, relevantphysical-mechanicalproperties, a consumption reduction in sizing agents andenergy,andanincreaseinweaving productivity [5 - 9]. Differentsizerecipesandsizeconcen-trations,respectively,areanimportant parameterintheoptimisationofthe standard sizing process and that with pre-wetting.Thisparameterrefectsgreater orsmallerdifferencesinthephysical-mechanicalpropertiesofyarnssizedby bothprocesses,whichisveryimportant for this study in terms of highlighting the advantages of the pre-wet sizing process (possibleadditionalsize,wateranden-ergycostreduction,aswellasalackof anegativeimpactonthesizingprocess and sized yarn).The aim of this research was proving the technical,economicandenvironmental justifcationforthepre-wetsizingproc-ess,whichisstillaratherunexplored areaandnotconfrmedbyscientifcre-search. The reason for such a poor repre-sentation of this topic in scientifc work is that laboratory work and the preparation ofsamplesisimpossible,respectively, whichisconsideredtobethemostim-portantreasonwhythisresearcharea hasremainedunexplored.Withtheop-timisationofthesizingprocess,exten-sive planned research and a comparative studyofstandardsizingprocessesand thepre-wetsizingprocess,onecanat-tempt to prove that there are many valid reasons for a non-standard technological process,emphasiseanumberofadvan-tages and disadvantages, as well as pos-sible improvements, and show the excep-tional beneft for factories and producers [10 - 12].nExperimentalSizing device Bothsizingprocesses(standardsizing andpre-wetsizing)werecarriedouton alaboratorysizingmachine(Figure2), constructed at the Faculty of Textile Tech-nology, University of Zagreb. It consists of a creel for cross wound bobbins, with the possibility of tension regulation, and twoboxesaboxforpre-wettingwith hot water and a size box. The pre-wetting box consists of a pair of immersion roll-ers and a pair of rollers for squeezing out maintain the sizing speed constant using thewinderofsizedanddriedyarn,as well as the speed regulator.Inthesizingprocessalltheconditions mentioned,whicharenecessaryto achievemaximumsizingresults,were heldconstant,duetowhichitcanbe safely claimed that yarns were sized un-der the same conditions. Sizing was car-ried out using two recipes: the frst recipe withasizeconcentration(R1)of7.5%, andthesecondrecipe(R2)withacon-centrationof5%.Theconditionsofthe sizing process were not varied by chang-ing the recipe or size concentration. The water temperature in the pre-wetting box was 60 - 65 C, and the size temperature was75-85C. Threadtensionwasap-prox. 55 cN. The average moisture at the boxentrywas6.0%,betweenthetwo boxes-60.0%,attheboxexit-85.0% andafterthecontactdryeritwas5.5%. Thesizingspeedwas3m/min,andthe pressureonthelastpairofrollersfor excesswater. Thesizeboxconsistsofa workingboxwithtwopairsofimmer-sionrollersandtwopairsofrollersfor size squeezing, as well as a pre-box that allows to maintain constant size levels in the working box, namely continuous size circulationfromtheworkingboxtothe pre-boxwithnaturalfow,andfromthe pre-box to the working box using a pump. During the sizing process it is possible to maintainconstantwatertemperaturein the pre-wetting box and size temperature inthesizeboxwithembeddedheaters andthermostats,whichindirectlywarm thewaterandsizethroughthewallsof the boxes. Thread tension was measured during the sizing process at the box entry, while warp moisture was measured in all the important places: at the box entry, be-tweentwoboxesthepre-wettingbox andsizingbox,attheboxexitandafter contactdryer.Dryingthesizedyarnis preformedbycontact,movingitacross thetwoheatedcylindersofthecontact dryer.Itisalsopossibletoregulateand Table 1. Parameters of unsized yarns tested; CV - coeffcient of variation in %.Parameters Yarn 1 Yarn 2 Yarn 3Nominal yarn count - Ttn, tex 20.00 30.00 50.00Actual yarn count - Tta, tex 18.55 29.57 46.20Yarn twist - Tm, twist/maverage mean - x 913.04 707.44 537.60CV in % 5.20 5.93 2.61Unevenness - U, CV in % 16.01 18.43 14.08Figure2.Laboratorysizingmachine:1-creelforcrosswoundbobbins,2moisture measuring device, 3 - thread tension measuring device, 4 - pre-wetting box with hot wa-ter, 5 - size box, 6 - rollers for immersing yarn into size and water, 7 - rollers for size and squeezing out of water, 8 - regulation of the pressure of the last squeezing roller, 9 - contact dryer, 10 - winder of the sized yarn. Table 2. Characteristics of sizing agents and auxiliaries, and size recipes; * Brookfeld, sp2, at 85 C, 100 r.p.m., **at 85 C, 10 s.Sizing agent and auxiliaries Chemical nature Viscosity*, mPa Fluidity**, cmTUBOFLEX PVA 80 Polyvinilalcohol 82.2 13TUBOWAX 24Natural fats and waxes with a specifc emulsifer system2.1 -Recipe Compounds and amounts Concentration, %Recipe 1 - R11 l water100 g TUBOFLEX PVA 803.0 g TUBOWAX 247.5Recipe 2 - R21 l water70 g TUBOFLEX PVA 802.1 g TUBOWAX 245.0137FIBRES & TEXTILES in Eastern Europe2011, Vol. 19, No.4 (87)squeezingexcesssizewas19.1N/cm2. Thetemperatureonthecylindersofthe contact dryer was 140 C.Materials and test methodsThematerialsusedforthisinvestiga-tionwerethree100%ring-spuncotton yarnswithanominalcountof20,30 and 50 tex, certain features of which are shown in Table 1.Moreover, to treat the samples and to car-ryoutthesizingprocess,necessarysiz-ingagents(madebyBezemaCompany) wereused.Sizepreparationdependson theyarn(fbre)type,thesizingagents origin,differentsizingauxiliaries,and therequirementsofthesizingprocess itself.Basedontheseneeds,twodiffer-entrecipeswithdifferentconcentrations weredevelopedandthenusedinboth sizing processes, as shown in Table 2.To test the samples before and after siz-ing,standardisedmethodswereused. Thusthebreakingforce,elongationat break,worktoraptureandstrengthof yarns,madebyTextechno,Germany, were tested on a Statimat M tensile tester accordingtoISO2062.Yarnhairiness wastestedbeforeandaftersizingby recordingthefbresprotrudingfromthe yarnstructureusingaZweigleG565 hairinessmeter,accordingtoASTMD 5674-01;twistsweretestedbymeans ofaMesdanLabTwisttesteraccording toISO17202,whileyarnunevenness wAS tested on an Unevenness tester 80, typeB-tt.Keisokki.Abrasionresist-ancetestswereperformedonaZweigle G551abrasiontesterbeforeandafter sizing, where each of 20 types of thread loadedwithaweightof20gweresub-jected to the abrasion process until thread breakage. The movement of the cylinder coatedwithemerypaper(fneness600): left, right and its rotation around its axis achievesacertainabrasionintensityin theyarnandemerypaper.Duringthe process the yarn weakens, and at the mo-ment when the mass of the weights hung on the yarn overcomes the yarn strength, a break occurs, with the number of roller movementsuntilthebreakhavingbeen recorded.nResults and discussionTheresultsofextensivetestsarerepre-sented graphically (Figure 3 - 5) in order toclearlyshowthedifferencebetween a)YFS = -1858 + 41.390X1 + 1.588X2 + + 5.648X3YFP = -2344 + 47.760X1 + 2.040X2 +-3.715X3b)YES = 14.44 - 0.075X1 - 0.010X2 +- 0.104X3YEP = -8.53 + 0.203X1 + 0.010X2 + - 0.189X3c)YWS = - 2642 + 62.650X1 + 2.037X2 + - 8.221)X3YWP = - 5926 + 102.400X1 + 4.920X2 + - 27.420X3d)YTS = - 21.62 + 0.458X1 + 0.036X2 + + 0.053X3YTP = - 32.19 + 0.633X1 + 0.047X2 + - 0.449X3Figure3.Diagramsofthebreakingpropertiesofunsizedyarnsandyarnssizedwith recipesR1andR2withthestandardsizingprocessandpre-wetsizingprocess:a)Fin cN-breakingforce,b)Ein%-elongationatbreak,c)WincNcm-worktorupture, d) in cN/tex - strength (where: U - unsized yarn, R1S - yarn sized with the standard sizing process and recipe 1, R2S - yarn sized with the standard sizing process and recipe 2, R1P - yarn sized with the pre-wet sizing process and recipe 1, R2P - yarn sized with the pre-wet sizing process and recipe 2).FIBRES & TEXTILES in Eastern Europe2011,Vol. 19, No.4 (87)138Figure 5. Diagram of a) hairiness b) abrasion resistance of yarn sized with recipes R1 and R2 using the standard sizing and pre-wet sizing processes.a) b)yarns sized with the two recipes and two different sizing processes.Using the results obtained and their mul-tiple regression analysis, we arrive at the conclusion that there is a strong infuence of the large number of existing independ-ent variables (predictors) on the depend-ent variance (criterion), between which it is possible to achieve a high correlation. Thegoaloftheregressionanalysiscon-ducted is to determine the extent to which alinearcombinationofpredictorsex-plains variations in criteria, and what the contributionorimportanceofindividual predictors is [13]. Predictors that are very importanttoachieveamaximumcorre-lationwiththecriteriondependonthe criterion (YS - a criterion for dry yarn in astandardsizingprocess,YP-criteria forwetyarninasizingprocedurewith pre-wetting), and in our case they are pa-rameters: yarn count before sizing (X1), twistsbeforesizing(X2),andthesize concentration in recipes (X3).Figure 3 (see page 137) shows a graphi-calrepresentationoftestresultsforthe breaking properties - the breaking force, elongationatbreak,worktorupture andstrengthofunsizedyarnsandyarns sized with size recipes R1 and R2 using thestandardsizingprocessandpre-wet sizing process. Moreover, graphical rep-resentationsofthemultipleregression analysis of the results obtained are given, withcorrespondingmultipleregression equations, as well as the high correlation between criteria obtained through testing and statistical estimation. Figure3.ashowsthebreakingforceof all the samples tested. The values of sized yarn samples of counts of 20 and 50 tex, whichweresizedwithbothprocesses and recipes, are almost the same, with an averageincrease,comparedtounsized yarns, of almost 38% for 20 tex yarn and 33% for 50 tex yarn. For 30 tex yarn, dif-ferences in sized yarns are more visible, thebestresultsofwhichwereachieved foryarnsizedwiththestandardprocess and R1, and yarn sized with recipe R2 us-ingthepre-wetsizingprocess.Multiple regressionequationsarealsoshownin Figure3.aforthestandardsizingproc-ess and pre-wet sizing process separately, aswellaslinearregressionequations andthecorrelationbetweenthevalues of breaking force obtained by testing and those of the breaking force estimated by analysis. Valuesoftheelongationatbreakofthe yarns tested are shown in Figure 3.b. For 20texyarntheresultsaredividedinto two groups with almost identical values: the yarn sized with the standard process, andthosesizedwiththepre-wetsizing process,withadifferencebetweenthe groupsofalmost7%infavourofyarn sizedwiththestandardprocess. Asimi-larsituationiswith50texyarn,where onegrouprepresentsyarnsizedwith bothprocessesandR1,andthesecond group-yarnsizedwithR2,withadif-ference between the groups of almost 9% infavourofyarnsizedwithR2.Asin the case of the breaking force, the values forayarncountof30texaredifferent, where the smallest decrease in elongation at break was recorded for yarn sized with R2andR1usingthestandardprocess. Furthermore,thediagramshowsmulti-pleregressionequations,linearregres-sion equations, and correlations between thevaluesobtainedbytestingandthose oftheelongationatbreakestimatedby analysis.InFigure3.ctheuniformvaluesof 20texsizedyarncanbeobserved;they varywithin15%withoutmajordevia-tionsfromthoseofunsizedyarn,which isalsothecaseforthevaluesof50tex sized yarn, varying within 6% only, with an average increase in sizing yarn of 14% compared to unsized yarns. In the case of 30 tex yarn, case differences are discern-ible, where the maximum deviation, as in case of the breaking force and elongation at break, is observable in yarn sized with R1usingthepre-wetsizingprocess.By analysingthepredictorsthatinfuence thecriteria-worktorupture,multiple regressionequationsareobtained,and throughthelinearregressionoftheval-uesobtainedandbyanalysisoftheval-uesofworktoraptureestimated,ahigh degreeofcorrelationwiththestandard sizingandpre-wetsizingprocessesis obtained. Breakingstrengthisaparameterthat bringsintorelationyarnfnessesand force,thevaluesofwhichobtainedare showninFigure3.d.Thevaluesof 20texsizedyarnareperfectlyconsist-ent with an increase of almost 33% com-pared to unsized yarn, as is the case with 50texyarn,wheretheaveragevalueof equal values of the samples increased by 28%comparedtounsizedyarn.30tex yarnshowsdifferencesamongtheval-ues, where once again the maximum de-viationisobservableinyarnsizedwith Figure 4. Diagram of the size pick-up (Sp in %) of yarn sized with recipes R1 and R2 using the standard and pre-wet sizing processes.YSpS = - 35.65 + 0.440X1 + 0.033X2 ++ 0.668X3YSpP = - 39.29 + 0.387X1 + 0.031X2 ++ 1.539X3139FIBRES & TEXTILES in Eastern Europe2011, Vol. 19, No.4 (87)R1 using the pre-wet sizing process. The coeffcient of the correlation between the valuesobtainedbytestingandthosees-timatedbymultipleregressionanalysis for the breaking strength for the pre-wet sizingprocessisquitelow(only0.76), while it is very high for the standard siz-ing process.What can be observed is that in all tests of breaking properties 30 tex yarn shows the greatest deviations between both siz-ingprocesses.Thesedifferencescanbe explained by the occurrence of high yarn stretchduringpre-wetsizing,whichoc-curs due to the higher yarn unevenness.Figure 4 shows the value for the amount of size pick-up on yarns. Yarn size pick-up on yarns sized with the standard sizing process is higher than on those sized with the pre-wet process. According to the dif-ferencesobtained,itcanbenotedthat duringstandardsizing,sizepenetrates intotheinterspacesoffbresflledwith air,becomingdenserwiththeincreas-ingconcentrationandmorediffcultto besqueezedoutoftheyarnpassingbe-tween the squeezing rollers. A small dif-ferencebetweenyarnssizedwithR1in both sizing processes can be easily seen, which is present at all three yarn counts. Signifcantdifferencesareobservablein yarn sized with R2 using both processes at all three yarn counts, where an almost equal difference in reducing size pick-up (onaverage50%)betweenthestandard sizing process (R2S) and pre-wet process (R2P) is maintained. For size pick-up val-ues as dependent variables, a multiple re-gression analysis was also conducted. On the basis of estimated values of the linear regression analysis together with the test-ing value obtained, a correlation value of 0.8153 is obtained for the standard sizing process, and even a higher correlation of 0.9141 for the pre-wet process.Figure 5 shows diagrams of two param-eterswhichareextremelyimportantfor theweavingprocess,whicharegreatly improved by a successful sizing process. Hairiness,i.e.thenumberofprotrud-ingfbres,isreducedbysizing,andthe abrasionresistanceisincreased,which affects the reduction in friction resulting from the thread passing through the met-al elements of the weaving machine and, therefore, the number of thread breaks in the weaving process. Figure5.ashowsvaluesoftestsonthe hairinessofunsizedyarnsandyarns sized with both recipes using both sizing processes.Thelargesthairinessreduc-tion was recorded for yarn sized with R1 using the pre-wet process, by even 84%, followedbytheyarnsizedwithR1us-ingthestandardprocess-82%.Asfor R1, the same is the case for R2, where a greater hairiness reduction was recorded foryarnsizedwiththepre-wetprocess (77%),comparedtoyarnsizedwiththe standard process (76%).Adiagramofabrasionresistancevalues of the unsized yarns and yarns sized test-ed with both recipes using both processes is shown in Figure 5.b. For more refned yarns (20 and 30 tex), there is an observa-ble decrease in the abrasion resistance of yarns sized with R2 using both processes, compared to unsized yarn. The size pick-upstrengthensandreinforcestheyarn, whichisattributedtotheextensionthat occursduringthesizingprocess,which islargerinyarnsizedwithalowersize concentration. For 50 tex yarn, this phe-nomenon is not present, but the increase in abrasion resistance for all sized yarns isseveraltimeslargerthanforunsized yarn.Theprocedureofdistributingsizepick-upovertheyarn,whichdiffersforyarn sized with the standard process and pre-wet process, is also very interesting (Fig-ures6,7).Foryarnsizedwiththepre-wet process, the process of wetting yarn inhotwaterallowstofllinterspacesof yarn with water. Immersing the wet yarn in size leads to the diffusion of water re-tained in the yarn with size, as well as to very quick mutual coupling, which allows fasterandeasierpenetrationofsizeinto theyarn,whereitisvisible(Figure7). However, the concentration of size in the interior of the yarn is less than that of the size,becausethewaterretainedinthe interioroftheyarndilutesit. Therefore, mostofthesizepick-upremainsonthe surfaceoftheyarn.Usingthestandard process,thesizingpenetratesthrough thedryyarnandthickens,passingwith more and more diffcultly and at a lower speedthroughdryyarninterspaces,and thereforeinsidetheyarnitalmostdoes Figure6.Microscopiccross-sectionalimageofyarnsizedwiththestandardprocess (A - view of the entire yarn, B & B1 - enlarged representation of the periphery of the yarn, C - enlarged representation of the centre of the yarn).B1 CB AFIBRES & TEXTILES in Eastern Europe2011,Vol. 19, No.4 (87)140not exist (Figure 6). However, this is the reason why the size is mostly retained on theperipheryoftheyarn,whereitcre-ates a mantle, as opposed to yarn sized with the pre-wet process, where the size applied on the periphery of the yarn does not form such an intense and rigid layer. These assertions are easily observable in microscopic images. For example, an im-ageofyarnwithacountof20tex-un-sizedandsizedwithrecipe1usingboth processes,wastakenwithanSEMmi-croscope JSM - 6060LV.nConclusionsTheprocessingofsamples,theim-plementationofstandardisedtesting methodsandtheanalysisoftheresults obtainedallowtomakeacomparative analysisofthestandardsizingprocess and pre-wet sizing process. Each of these processesbringscertainadvantagesand disadvantages. The standard sizing proc-B1 CB AC2 C1Figure7.Microscopiccross-sectionalimageofyarnsizedwiththepre-wetprocess(A- view of the entire yarn, B & B1 - enlarged representation of the periphery of the yarn, C, C1 & C2 - enlarged representation of the centre of the yarn).essisagenerallywell-known,accepted andubiquitousprocessinthetextilein-dustry.Butofgreatsignifcanceisthe fact that the replacement of the standard process in terms of upgrading and install-ingapartofthesizingrangenecessary fortheimplementationofthepre-wet sizingprocessdoesnotrequirecomplex procedures or large fnancial expenditure. On the other hand, based on the research conducted, it can be concluded that there is no drastic difference in the results ob-tainedforthetwoprocesses,withonly somepropertiesofyarnsizedwiththe pre-wetsizingprocessbeingnoticeably better. This is the reason why this process is preferred due to the economical effects -theconsumptionofsizingagentsand power is lower.Atthesametime,thankstoprocessing with two different size recipes using both sizingprocesses,aninsightintoeventual differencesinthisparameterisprovided. The properties of yarn sized with recipes of a lower size concentration (5%) showed very good results in terms of insignifcant deviations (despite a much smaller amount of size pick-up on the yarn) as compared to the recipe with a higher size concentra-tion (7.5%), especially in the pre-wet siz-ing process, in which some properties are evenbetter. Theseindicatorsareofgreat importanceforthepre-wetsizingproc-essinviewofthepossibilitytoreduce additionalsize,waterandenergycosts (bothforthesizingprocessanddesizing process),withnonegativeimpactonthe properties of the sizing process nor on the quality of the sized yarn, including excep-tionalsignifcancefortheenvironmental aspect of the overall process. Moreover,theimportantconclusion drawnfromthisstudy(concerningthe pre-wet sizing process) is that yarn with ahigherunevennessoffneness,dueto a high sensitivity to stress in a wet state, whichcausesyarnstretchinganddefor-mation,isnecessarytominimiseyarn tension,notonlyinthepre-wettingand sizingpartoftheprocess,butalsoafter exiting the dryer. This phenomenon is not so pronounced in case of the standard siz-ing of dry yarn.This research was based on the process-ing,testingandcomparisonoftwosiz-ingprocessesforrawyarns;however,it is assumed that similar research of dyed warpi.e.yarnsdyedwithdifferentcol-our shades, could lead to very interesting fndings.Thesefndingsareexpectedin differences between the two sizing proc-essesanddifferencesinpropertiesbe-tweentheshadesofdyedyarns,which alsorepresentsagreatunknownanda problem for the sizing process.Alloftheindicatorsmentionedabove and the results obtained from the investi-gations conducted indicate the exception-al importance and justifcation of a non-standardtechnologicalprocess(pre-wet sizing process), which, with much lower costs(sizingagents,waterandenergy savings),givesexcellentresults,having a positive impact on reducing the number ofyarnbreaks,machineeffciency,and, thus, on the quality of fnished fabrics. Theaimofthestudywastoprovethe technical,economicandenvironmental justifcationforthepre-wetsizingproc-ess, which was achieved by extensive in-vestigations. 141FIBRES & TEXTILES in Eastern Europe2011, Vol. 19, No.4 (87)AcknowledgmentsTheresultsshowninthepapercamefrom investigationsoftheprojectAdvanced Technical Textiles and Processes, code: 117-0000000-1376, Faculty of Textile Technology, University of Zagreb, Croatia, conducted with the support of the Ministry of Science, Educa-tion and Sports of the Republic of Croatia.References1. GoswamiB.C.,AnandjiwalaR.D.,Hall D.M.: Textile Sizing, Marcel Dekker, Inc., NewYork,Basel,2004,ISBN:0-8247-5053-5.2. Kovaevi S., Penava .: Impact of Siz-ing on Physico-mechanical Properties of Yarn, Fibres & textiles in Eastern Europe, Vol. 12, No. 48 (4), 2004, pp. 32-36. 3. SolimanH.A.:EvaluationofSizingas ConntrollingParameterintheTen-dency to Yarn Entangling, ITB Garn-und Flachenherstellung, Vol. 41 (2), 1995, pp. 42-44.4. 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RozelleW.N.:Pre-wet:NewMoney Maker in Warp Sizing Operations, Textile World, Vol. 149 (5), 1999, pp. 73-79.12. Sherrer A.: Benninger: SaveSize Pre-Wet Warp Sizing, Textile World, Vol. 150 (4), 2000, pp. 42-43.13. Bernstein S., Bernstein R.: Elements of statistics II: Inferential Statistics, McGraw-Hill, New York, 1999, ISBN: 0-07-005023-6.Received 19.04.2010 Reviewed 03.09.2010Technical University of LodzFaculty of Material Technologiesand Textile DesignDepartmentof Physical Chemistry of PolymersThe research activity of the Department is focused on areas related to the chemistry and physical chemistry of polymers. The main di-rections of scientifc activity are as follows: ninvestigation of the polyreaction process, in particularmatrix polymerisation, nphysico-chemical characteristics of polymers and copolymers, nstudy of the relationship between their structure and properties, nsynthesis of multimonomers, nchemical modifcation of synthetic and natural polymers in order to obtain products with specifc properties, ncopolyesters of chitin a new bioactive materials for medical appli-cations, nsurface modifcation of textile materials by deposition of poly-electrolyte nanolayers.The Department has at its disposal the following modern measuring techniques for the physical and chemical analysis of polymers: ngel permeation chromatography equipment, consisting of a Wa-ters Alliance separation module and multiple detector system: refractive index, UV-VIS, intrinsic viscosity and right angle laser light scattering; nFTIR spectrometer system 2000 from Perkin-Elmer with data col-lection and processing software; nUV-VIS spectrometer Lambda 2 from Perkin-Elmer; ndifferential scanning calorimeter DSC7 from Perkin-Elmer; nthermoballance coupled with an infrared spectrometer from Per-kin-Elmer.Theme cooperation: research of the surface modifcation of textiles using polyelectrolyte nanolayers(Lebiniz Institut fr Polymerforsc-hung, Dresden, Germany); chitin derivatives and their applications (National Institute of Agrobiological Sciences + NIAS, Tsukuba, Ja-pan).The Departments staff conduct classes on a variety of topics at all levels of education at the Faculty of Material Technologies and Textile Design. These classes cover subjects such as chemistry, the physical chemistry of polymers, instrumental methods in the physi-co-chemical characterisation of polymers, polymer materials, etc. For more information please contact:Department of Physical Chemistry of PolymersTechnical Universiy of Lodzul. Zeromskiego 116, 90-924 Lodz, Polandtel.: (48)(42) 631-33-60 e-mail:rojan@p.lodz.plweb site: http://www.k41.p.lodz.pl/