版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
MechanicalPropertiesofPolyurethane
CoatedKnittedFabricsIntroductionSamplesandworkingmethodResultsanddiscussionConclusionsPart1introduction
Polyurethane-coatedknittedfabricsare
ofinterestbecausetheyexhibitseveral
positiveproperties,andyettheyarelittle
studied,especiallythoseusedinthe
garmentindustry.Theadvantagesof
polyurethanecoatingsincomparisonto
otherpolymersaregreaterresistanceto
abrasionandsplitting,increasedstrength
anddurability.
Polyurethanesareformedbythepolyaddition
reactionofapolyisocyanate
withapolyalcohol(polyol)inthepresence
ofacatalystandotheradditives.
Polyisocyanateisamoleculewithtwo
ormoreisocyanatefunctionalgroups,R-(N=C=O)n≥2andapolyolisamolecule
withtwoormorehydroxylfunctional
groups,R’-(OH)n≥2.Thereaction
productisapolymercontainingtheurethane
linkage,-RNHCOOR’-[3].Thereisachancetodevelopcoatedknitted
fabricsasprotectiveclothing,work
clothing,sportswearandcasualwear
more
comfortablethanclothesmadeout
ofcoatedwovenfabricbecausemovements
arelessrestrictedifclothingis
madeofelasticknittedmaterial.Coatedknittedfabricsaregenerallymore
stretchableandelasticthanwovenfabrics.Part2SamplesandworkingmethodSamplesSevenknittedfabricswithdifferent
structures(designationsKF1-KF7)were
chosentocoverawideintervalofvalues
ofthecharacteristicsofelongationand
breakingforcestested(Tables1&2).Theywerecoatedunderthesameconditions,
onthesamecoatingline,withthree
differentpolyurethanecoatings(designated
PU1-PU3).Thepolyurethanecoatingshave
nearlyequalaveragethicknessesand
weights,butdifferentmechanicalproperties
(Table3).Asdescribedabove,thetotalnumberof
coatedknittedfabricswas21(7knitted
fabrics×3polyurethanecoatings).WorkingmethodThistimeweobservedmechanical
propertiesbeforeandaftercoating,and
formedconclusionsonthepredictionof
theirbehaviour.Thebehaviourofknittedandcoated
knittedfabricsinthelinearapplication
offorcewascomparedwiththatofthesamespecimensinthecaseofspherical
forceapplication.Thesampleswerestatisticallyanalysed
(descriptivestatistics,hypothesistesting-t-test,regressionanalysis).Part3ResultsanddiscussionElongationofcoatedknittedfabricsin
relationtotheknittedfabricElongationinthewaledirectionTheknittedfabricselongatedfrom46.41%to309.93%,whichisaconsequenceoftheirdifferentstructures.Thecoatedknittedfabricselongatedinthewaledirectionfrom44.41%to382.44%.Thecoatedknittedfabrichasaconsiderablyhigheraverageelongationinthewaledirectioninrelationtotheknittedfabric-onaverageabout16%,apartfromtheleaststretchableknittedfabric(KF3),whichwasnotaffectedbythecoating.NamelytheKF3samplewasknittedinapower-netstructure(Table1),whereelongationinthewaledirectiondependsdirectlyonelongationpropertiesoftheverticallylaidyarn(andnotformedintoloops).Thet-testshowsthatthereisnostatisticallyconsiderabledifferencebetweenthemeanvaluesofelongationofthegroupsofsamplestested(p=0.92)ortheycanbeobservedasthesametypeofpolyestercoatingforelongationinthewaledirection.Regressionanalysisindicatestherelationshipbetweentheelongationoftheknittedfabricandthatofthepolyurethane-coatedknittedfabric.εcw=1.2312εkw-8.4717ThecoefficientofdeterminationR2=0.9915Itispossibletousetheregressionmodelobtainedforeasypredictionofthebehaviourofthecoatedknittedfabricandthechoiceofanappropriateknittedfabricsubstrate.ElongationinthecoursedirectionTheknittedfabricselongatedfrom34.96%to157.93%,whichisaconsequenceofthedifferentstructuresofknittedfabricsandyarnsused.Thecoatedknittedfabricselongatedinthecoursedirectionfrom96.15%to358.75%.Thecoatedknittedfabrichasaconsiderablyhigheraverageelongationinthecoursedirectioninrelationtotheknittedfabric-onaverageabout102%.Thet-testshowsthatthereisnostatisticallyconsiderabledifferencebetweenthemeanvaluesofelongationoftheknittedfabricscoatedwiththreedifferenttypesofPUcoating(p=0.72)fortheelongationinthecoursedirection.Regressionanalysisshowedthattherelationshipbetweentheelongationoftheknittedfabricandthecoatedknittedfabricinthecoursedirectionhaveonlyamediumcorrelation(r=0.79).Therelationshipbetweenvariablesisnotlinear.Exponentialregressionmodelεcc=103.53××e0.0064εkcwithacoefficientofdeterminationR2=0.6262,isthebestexplanationofelongationvarianceinthecoursedirectionofthesamplesofcoatedknittedfabrics(ecc)studiedwithregardtotheelongationofthesamplesofthesameknittedfabrics(ekc)examined.Itisinterestingtoinvestigatewhichelementstogetherwiththeelongationoftheknittedfabricaffecttheelongationofthecoatedknittedfabricinthecoursedirection.ThesamplesofcoatedfabricKF3,KF4andKF5showagreaterdifferenceintheelongationofthecoatedfabricanduncoatedfabric(Figure4,Table5)andmoresignificantlydeviatefromtheadaptedtheoreticalcurveoftheexponentialmodel.Theywereproducedfromalowthicknessknittedfabric(Table1).Theratiobetweenknittedfabricthicknessandcoatingthicknessincomparisonwithotherknittedfabricsislower(Table5)Thereisrelativelymorecoating,makingagreatercontributiontoelongationinsuchcoatedfabrics.Therelationshipbetweentheratioofthicknesses(Tr)andthatofelongation(er)clearlyshows(r=0.89)εtheelongationdecreasesifthereisrelativelylesscoatingonthecoatedfabric.Byusingmultiplelinearregression,amuchbetterrelationshipbetweentheelongationofthecoatedfabricinthecoursedirectionandbothvariables(elongationoftheknittedfabricandratioofknittedfabricthicknessandcoating)εcc=149.3042+2.032309εkc-44.866TrThecoefficientofmultiplecorrelation(R=0.91)indicatesastrongrelationshipbetweentheelongationofthecoatedknittedfabricinthecoursedirectionandthetwovariablesobserved.Inadditiontotheelongationoftheknittedfabric,theratiooftheknittedfabricthicknessandcoatingshouldbeconsidered.Technologicallythesefindingsshowhowextremelysensitiveitistopredictthebehaviourofcoatedknittedfabricswithaverythinsubstrate(thickness>0.4mm).ComparisonoftheelongationoftheknittedfabricandcoatedknittedfabricduringsphericalelongationTheknittedfabricselongatedfrom26to68mmuntilballbursting.Thecoatedknittedfabricselongatedfrom25to66mm.Thet-testshowsagainthatthereisnostatisticallysignificantdifferencebetweenthearithmeticmeansofthethreetypes(PU1-PU3)ofsamplestested(p=0.8372),andtheycanbeobservedasonegroupofsamples.Thelowerelongationofthecoatedknittedfabricduringsphericalelongation,onaverage8%.Itispossibletoconcludethatcoatingfixestheyarnandtheknittedfabricstructure,i.e.thepolyurethaneadhesivegluestheyarnwhichformsloops,henceitcannotmovefreelyanddeformthefabricstructurenoradapttosphericalelongation,causinganearlyburstofthecoatedknittedfabric.Thesamecoatedknittedfabric,whichwillshowbettercharacteristicsthantheknittedfabricitselfduringelongationinthecourseorwaledirection,exposedtosphericalelongationwillshowpoorercharacteristics.Themodeloflinearregressionεcb=0.7468εkb+6.1557withcoefficientofdeterminationR2=0.9292BreakingforceofthecoatedanduncoatedknittedfabricsBreakingforceinthewaledirectionBreakingforcesfrom104.6Nto907.5Nweremeasuredintheknittedfabricofdifferentstructures.Breakingforcesfrom136.7Nto1053Nweremeasuredinthecoatedknittedfabrics.Thecoatingcausedslightlyhigherbreakingforces–onaverage24%.Thet-testshowsagainthatthereisnostatisticallysignificantdifferencebetweenbetweenthebreakingforcesofthethreepolyurethane-coatedgroupsofsamplestested(p=0.93).LinearregressionmodelFcw=1.098Fkw+48.736,withthecoefficientofdeterminationR2=0.9802BreakingforceinthecoursedirectionoftheknittedfabricBreakingforcesfrom66.27Nto501.8Nweremeasuredintheknittedfabric.Theburstingofthecoatedknittedfabricsinthecoursedirectionoccurredatbreakingforcesfrom108.1Nto672.2N.Thecoatingcausedanincreaseinbreakingforcesinthecoursedirectionoftheknittedfabric-onaverageabout27%.Thet-testshowsagainthatthereisnostatisticallysignificantdifferencebetweenthebreakingforcesofthethreepolyurethane-coatedgroupsofsamplestested(p=0.88).RegressionmodelFcc=99.51×1,0039Fkc,withthecoefficientofdeterminationR2=0.9367BreakingforceofthesphericalburstoftheknittedfabricandcoatedknittedfabricBreakingforcesfrom73Nto1058Nweremeasuredintheknittedfabricsandfrom91Nto1228NinthecoatedknittedfabricsCoatingcausedanincreaseintheresistancetosphericalbursting-onaverageabout13%.thet-testshowsagainthatthereisnostatisticallysignificantdifferencebetweenthebreakingforcesofthethreepolyurethane-coatedgroupsofsamplestested(p=0.989).LinearregressionmodelFcb=1,1214Fkb+4,0992explainstherelationshipbetweentheoccurrencesobserved(Figure13).ThecoefficientofdeterminationR2=0.9956Part4ConclusionsAlthoughcoatingsignificantlychangesthemechanicalpropertiesofknittedfabrics,thepropertiesofcoatedknittedfabricsareprimarilydeterminedbythepropertiesoftheknittedsubstrate.Elongationinthecoursedirectionoftheknittedfabricsignificantlyincreasesaftercoating-onaveragebyabout102%,whiletheincreaseinelongationbycoatinginthewaledirectionislower,amountingtoabout16%.Elongationinthewaledirectionofcoatedknittedfabricscanbepredictedwithgreatcertaintyknowingthatoftheknittedfabric.Alinearregressionmodelexplains99.15%oftherelationshipbetweentheelongationoftheknittedfabricandcoatedknittedfabric.Elongationinthecoursedirectionofcoatedknittedfabricscanbepredictedwithgreatcertaintyknowingt
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 古诗词鉴赏 专题练习 统编版语文八年级下册
- 香火接续:传统社会的招赘婚姻研究
- 教育投资与教育消费
- 写景作文开头结尾
- 高数考研知识点总结
- 正规自愿离婚协议书格式
- 心血管科护士长工作总结
- 医疗资源管理和利用情况总结
- 2024-2029年中国信息管理系统行业发展分析及发展前景与投资研究报告
- 2024-2029年中国促进生长类保健品行业市场现状分析及竞争格局与投资发展研究报告
- 西藏自治区拉萨市2024届高三下学期5月月考语文试题(解析版)
- 营养专科护士进修汇报
- MOOC 英语跨文化交际-郑州大学 中国大学慕课答案
- 中国红色文化精神智慧树知到期末考试答案章节答案2024年西安交通大学
- MOOC 学术英语写作-东南大学 中国大学慕课答案
- 工程变更通知单ECN模板-20220213
- 幸福在哪里智慧树知到期末考试答案2024年
- 2024届江苏省镇江市丹阳市中考三模英语试题含答案
- 江苏省苏南五市联考2024届中考一模数学试题含解析
- 2023年山东中国海洋大学财务处会计人员招聘考试真题及答案
- 施工现场管理与文明施工-文明施工
评论
0/150
提交评论