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LessonTwoCottonPropertiesandUsesArelativelyhighlevelofmoistureabsorptionandgoodwickingpropertieshelpmakecottononeofthemorecomfortablefibers.Becauseofthehydroxylgroupsinthecellulose,cottonhasahighattractionforwater.Aswaterentersthefiber,cottonswellsanditscrosssectionbecomesmorerounded.Thehighaffinityformoistureandtheabilitytoswellwhenwetallowcottontoabsorbaboutone-fourthofitsweightinwater.Thismeansthatinhotweatherperspirationfromthebodywillbeabsorbedincottonfabrics,transportedalongtheyarnstotheoutersurfaceoftheclothandevaporatedintotheair.Thus,thebodywillbeaidedinmaintainingitstemperature.相对较好的吸湿性和良好的芯吸性使棉纤维成为最舒适的纤维之一。因为纤维素的羟基基团，使得棉花对水有很强的吸引力。当水进入纤维棉，棉开始膨胀，其截面变得更圆。这种高度的亲水性和潮湿时溶胀的性能使棉花可吸水达到其重量的1/4左右。这意味着，在炎热的天气里，身体的汗液会被棉织物吸收，沿着纱线输送到衣物外表面并蒸发到空气中。因此，这对维持体温有帮助。Unfortunately,thehydrophilicnatureofcottonmakesitsusceptibletowater-bornestains.Water-solublecolorantssuchasthoseincoffeeorgrapejuicewillpenetratethefiberalongwiththewater;whenthewaterevaporates,thecolorantistrappedinthefiber.Perhapsthemajordisadvantagetocottongoodsistheirtendencytowrinkleandthedifficultyofremovingwrinkles.Therigidityofcottonfiberreducestheabilityofyarnstoresistwrinkling.Whenthefibersarebenttoanewconfiguration,thehydrogenbondswhichholdthecellulosechainstogetherarerupturedandthemoleculesslideinordertominimizethestresswithinthefiber.Thehydrogenbondsreforminthenewpositions,sothatwhenthecrushingforceisremovedthefibersstayinthenewpositions.Itistheruptureandreformationofthehydrogenbondsthathelpstomaintainwrinkles,sothatcottongoodsmustbeironed.遗憾的是，棉纤维的亲水性使得它容易受到水渍。如咖啡或葡萄汁的水溶性色素会随着水分渗入纤维；当水分蒸发后，着色剂会停留在纤维上。也许棉产品主要的缺点就是其会起皱以及难以抗皱。棉纤维的刚性使得纱线抗皱性能降低。当纤维弯曲成新的结构时，将纤维素链连结起来的氢键断裂，同时分子滑移以减少纤维中的应力。氢键在新的位置重键，因而挤压的外力去除，纤维停留在新的位置。正是氢键的断裂与重键使得织物保持褶皱，所以棉织物需要熨烫。Cottonisamoderatelystrongfiberwithgoodabrasionresistanceandgooddimensionalstability.Itisresistanttotheacids,alkalies,andorganicsolventsnormallyavailabletoconsumers.Butsinceitisanaturalmaterial,itissubjecttoattackbyinsects,moldsandfungus.Mostprominentisthetendencyforcottontomildewifallowedtoremaindamp.棉纤维是具有良好的耐磨性和尺寸稳定性，强度适中的纤维。它耐酸，耐碱以及有机溶剂，消费者普遍接纳。但由于它是一种天然物质，它受昆虫，霉菌和真菌攻击。最突出的是棉一旦放在持续潮湿的环境下会发霉。Cottonresistssunlightandheatwell,althoughdirectexposuretoconstantstrongsunlightwillcauseyellowingandeventualdegradationofthefiber.Yellowingmayalsooccurwhencottongoodsaredriedingasdryers.Thecolorchangeistheresultofachemicalreactionbetweencelluloseandoxygenornitrogenoxidesinthehotairinthedryer.Cottonswillretaintheirwhitenesslongerwhenline-driedordriedintheelectricdryer.棉纤维耐光，耐热，尽管直接暴晒在持续的强光下会引起发黄，并最终引起纤维的降解。变黄也可能出现在棉产品被气体干燥剂干燥时。颜色的变化是纤维素和氧或二氧化氮在热空气中干燥的化学反应的结果。棉花自然挂干或烘干机烘干会长时间保持其白度。Ofmajorinterestisthefactthatcottonyarnisstrongerwhenwetthanwhendry.Thispropertyisaconsequenceofthemacro-andmicro-structuralfeaturesofthefiber.Aswaterisabsorbed,thefiberswellsanditscrosssectionbecomesmorerounded.Usuallytheabsorptionofsuchalargeamountofforeignmaterialwouldcauseahighdegreeofinternalstressandleadtoweakeningofthefiber.Incotton,however,theabsorptionofwatercausesadecreaseintheinternalstresses.Thus,withlessinternalstressestoovercome,theswollenfiberbecomesstronger.Atthesametime,theswollenfiberswithintheyarnspressuponeachothermorestrongly.Theinternalfrictionstrengthenstheyarns.Inaddition,theabsorbedwateractsasaninternallubricantwhichimpartsahigherlevelofflexibilitytothefibers.Thisaccountsforthefactthatcottongarmentsaremoreeasilyironedwhendamp.Cottonfabricsaresusceptibletoshrinkageuponlaundering.值得关注的是，棉纱线在潮湿环境下比在干燥环境下强度更大。这种性质是棉纤维宏观和微观结构特征的结果。当水被吸收，纤维膨胀，其截面变得更圆。通常这种大量的外来物质的吸收会导致内部应力较高，导致纤维弱化。然而，棉纤维吸水导致内部应力减少。因此，减少克服内部应力，肿胀的纤维变得强度更大。同时，纱线中的溶胀纤维之间的互相挤压更强烈，内部的摩擦力增强了纱线强度。此外，所吸收的水作为一种内部润滑剂，赋予纤维较高水平的灵活性。这解释了棉衣物潮湿时更容易熨烫，棉织物洗水时易收缩。Perhapsmorethananyotherfiber,cottonsatisfiestherequirementsofapparel,homefurnishings,recreational,andindustrialuses.Itprovidesfabricsthatarestrong,lightweight,pliable,easilydried,andreadilylaundered.Inapparel,cottonprovidesgarmentsthatarecomfortable,readilydriedinbright,long-lastingcolors,andeasytocarefor.Themajordrawbacksareapropensityforcottonyamstoshrinkandforcottonclothtowrinkle.Shrinkagemaybecontrolledbytheapplicationofshrink-resistantfinishes.Durable-presspropertiesmaybeimpartedbychemicaltreatmentorbyblendingcottonwithmorewrinkle-resistantfibers,suchaspolyester.棉也许比其他任何纤维更能满足服装，家居家具，休闲和工业用途的要求。它提供了强度大，轻薄，柔软，快干，易清洗功能的织物。在衣物方面，棉带来了舒适、在光下快干、色彩持久、容易打理的服饰。它主要的缺点是棉纱线会缩水和棉布会起皱。缩水可以应用防缩后整理来控制。耐用性能可以通过化学处理或在棉纤维混纺中使用抗皱纤维，如涤纶来实现。Inhomefurnishings,cottonservesindurable,general-servicefabrics.Althoughtheymaylacktheformalappearanceofmaterialsmadefromotherfibers,cottongoodsprovideacomfortable,homeyenvironment.Cottonfabricshavebeenthemainstayofbedlinensandtowelsfordecades,becausetheyarecomfortable,durable,andmoisture-absorbent.Polyester/cottonblendsprovidethemodernconsumerwithno-ironsheetsandpillowcasesthatretainacrisp,freshfeel.在家居用品中，棉产品担当了实用而全方位服务的织物。虽然他们可能没有其他纤维材质的美观，但棉织品（为我们）提供了一个舒适，温馨的环境。棉织物一直是几十年来的床单和毛巾的主要材质，因为他们非常舒适，耐用且具有吸湿性。涤/棉混纺织物为现代顾客提供了无须熨烫的床单和枕套，保持织物清新。Forrecreationaluse,cottonhastraditionallybeenusedfortentingand