王盼 王朝暉
摘要:為促進(jìn)智能針織產(chǎn)品的設(shè)計(jì)與研發(fā),文章系統(tǒng)歸納了緯編導(dǎo)電織物及其類別,綜述了3種不同性能導(dǎo)電織物作用機(jī)理及應(yīng)用進(jìn)展,并對(duì)其制備要點(diǎn)進(jìn)行探討。電-力學(xué)性能織物對(duì)線圈結(jié)構(gòu)依賴性極強(qiáng),因其影響因素過(guò)多,無(wú)法形成統(tǒng)一的性能評(píng)判標(biāo)準(zhǔn);濕度傳感織物利用織物自身、濕敏材料或?qū)щ姴牧嫌H水性來(lái)實(shí)現(xiàn)電阻變化,因外力拉伸與濕度變化均能影響織物電阻,故制備時(shí)可增加復(fù)合層以防兩者產(chǎn)生耦合效應(yīng);電熱性能織物受導(dǎo)電材料、制備工藝及加載電壓影響,可采用鍍銀紗線或聚吡咯進(jìn)行制備且前者性能優(yōu)于后者。進(jìn)一步指出,加強(qiáng)高性能纖維材料研發(fā)、改善制備工藝、加快自供電技術(shù)應(yīng)用,以及建立完善的安全測(cè)試標(biāo)準(zhǔn)是智能針織產(chǎn)品未來(lái)的發(fā)展方向。
關(guān)鍵詞:緯編;導(dǎo)電織物;電-力學(xué)性能;濕度傳感;電熱性能;智能可穿戴;自供電技術(shù)
中圖分類號(hào):TS186.2文獻(xiàn)標(biāo)志碼:A文章編號(hào): 10017003(2022)06005008
引用頁(yè)碼: 061107
DOI: 10.3969/j.issn.1001-7003.2022.06.007(篇序)
基金項(xiàng)目: 中央高?;究蒲袠I(yè)務(wù)費(fèi)專項(xiàng)資金資助項(xiàng)目(2232020G-08);上海市科學(xué)技術(shù)委員會(huì)國(guó)際合作項(xiàng)目(21130750100)
作者簡(jiǎn)介:王盼(1991),女,博士研究生,研究方向?yàn)榉b先進(jìn)制造。通信作者:王朝暉,教授,wzh_sh2007@dhu.edu.cn。
近年來(lái),隨著科技的進(jìn)步與經(jīng)濟(jì)的發(fā)展,人們對(duì)現(xiàn)代紡織品的需求不再局限于防寒保暖,智能化設(shè)計(jì)已成為消費(fèi)者的新需求[1-2]。智能紡織品正受到各界人士的廣泛關(guān)注,其應(yīng)用領(lǐng)域也逐漸涉及到人們?nèi)粘I畹母鱾€(gè)方面。緯編導(dǎo)電織物因其獨(dú)特的組織結(jié)構(gòu)與服用性能[3],成為智能紡織領(lǐng)域的研究重點(diǎn)之一。針織線圈結(jié)構(gòu)不僅為導(dǎo)電織物提供了極好的全向拉伸性能[4],還使其具備了梭織、刺繡、無(wú)紡等其他織物無(wú)法比擬的彈性及柔軟貼體性[4]。目前研究的緯編導(dǎo)電織物主要利用外界刺激引起的電阻變化來(lái)實(shí)現(xiàn)智能化與功能化,具有結(jié)構(gòu)簡(jiǎn)單、易成形、質(zhì)地輕巧、柔韌性好且可設(shè)計(jì)性強(qiáng)等特點(diǎn)[5]。其中,電-力學(xué)性能導(dǎo)電針織物可通過(guò)監(jiān)測(cè)織物總電阻變化規(guī)律來(lái)了解織物外界受力情況,濕度傳感性能導(dǎo)電針織物可采用電阻率改變來(lái)表征環(huán)境濕度變化,電熱性能導(dǎo)電針織物可利用織物內(nèi)部電阻網(wǎng)絡(luò)將外部電源提供的電能直接轉(zhuǎn)化為熱能。各類緯編導(dǎo)電織物在醫(yī)療保健、汗液監(jiān)測(cè)及智能調(diào)溫等領(lǐng)域均具有廣泛的應(yīng)用前景。
鑒于緯編導(dǎo)電織物具有諸多優(yōu)點(diǎn)且應(yīng)用廣泛,本文歸納了緯編導(dǎo)電織物的定義及其分類,綜述了緯編導(dǎo)電織物的電-力學(xué)性能、濕度傳感性能與電熱性能的作用機(jī)理及應(yīng)用進(jìn)展,探討了不同性能導(dǎo)電織物的制備原則與要點(diǎn),并對(duì)智能針織產(chǎn)品未來(lái)的發(fā)展方向進(jìn)行了展望。
1 緯編導(dǎo)電織物及其分類
1.1 緯編導(dǎo)電織物
緯編導(dǎo)電織物是指具有一定導(dǎo)電性能的緯編針織物,其主要通過(guò)兩種方式進(jìn)行制備:一種是利用導(dǎo)電紗線在緯編針織機(jī)上直接編織而成[6],另一種則是在普通緯編針織物表面進(jìn)行特殊處理(涂覆、印刷、浸漬等),賦予其導(dǎo)電性,通常以前者為主。前者多采用針織圓緯機(jī)、電腦橫機(jī)等設(shè)備進(jìn)行制備,但要實(shí)現(xiàn)導(dǎo)電區(qū)域的局部定位編織時(shí),編織設(shè)備必須具備提花與剪線功能,因無(wú)縫圓緯機(jī)可實(shí)現(xiàn)多處局部定位編織,可作為首選設(shè)備;電腦橫機(jī)利用其紗嘴配置及嵌花功能可實(shí)現(xiàn)局部區(qū)域的精確定位編織,但因其織針偏粗,在編織輕薄貼體針織物時(shí)不如圓緯機(jī)應(yīng)用廣泛。后者是先將某些導(dǎo)電物質(zhì)與分散劑、還原劑及黏合劑等按照一定比例進(jìn)行混合[7],再采用涂層、浸漬等方法,將其均勻附著于針織物表面,形成連續(xù)穩(wěn)定的導(dǎo)電層。該制備方式生產(chǎn)的導(dǎo)電針織物較前者而言缺乏整體穩(wěn)定性,難以確保其附著導(dǎo)電物質(zhì)的均勻度及耐久性。
1.2 按照導(dǎo)電成分進(jìn)行分類
緯編導(dǎo)電織物根據(jù)所含導(dǎo)電成分不同,主要分為金屬系導(dǎo)電針織物、碳系導(dǎo)電針織物、金屬化合物型導(dǎo)電針織物及高分子型導(dǎo)電針織物四大類,如表1所示。
金屬系導(dǎo)電針織物具有良好的導(dǎo)熱性和導(dǎo)電性,其多采用金屬混紡紗線或外鍍金屬紗線直接編織而成,其中不銹鋼混紡與鍍銀導(dǎo)電針織物在紡織領(lǐng)域應(yīng)用最為廣泛;碳系導(dǎo)電針織物主要利用涂層法、摻雜法或碳化處理等獲得導(dǎo)電性,顏色通常為黑色,導(dǎo)電物質(zhì)容易脫落且手感較差;金屬化合物系導(dǎo)電針織物多采用吸附法、混合紡絲法或化學(xué)反應(yīng)法制備,其導(dǎo)電性不如碳黑系但牢度較好;高分子型導(dǎo)電針織物是利用導(dǎo)電高分子材料實(shí)現(xiàn)導(dǎo)電行為,由于高分子型導(dǎo)電纖維剛度過(guò)大、難溶、難熔且成型困難[8],故該類織物主要通過(guò)涂層法制備。
2 緯編導(dǎo)電織物多重性能及作用機(jī)理
隨著紡織品不斷地向智能化、功能化發(fā)展,導(dǎo)電針織物也逐漸被賦予多重性能,目前主要包括電-力學(xué)性能、濕度傳感性能及電熱性能,這三個(gè)性能均需設(shè)計(jì)外加電路才可實(shí)現(xiàn)。
2.1 電-力學(xué)性能及作用機(jī)理
導(dǎo)電針織物的電-力學(xué)性能是指具有大應(yīng)變和高彈回復(fù)性的導(dǎo)電針織物在承受各種外力作用時(shí),因發(fā)生形變而呈現(xiàn)
出相應(yīng)的電學(xué)特征。該類織物對(duì)針織線圈結(jié)構(gòu)的依賴性極強(qiáng),如圖1(a)所示,導(dǎo)電針織物在外力作用下線圈結(jié)構(gòu)發(fā)生形變導(dǎo)致電阻變化[9]。在整個(gè)受力過(guò)程中,線圈間接觸電阻與長(zhǎng)度電阻變化導(dǎo)致織物電信號(hào)發(fā)生改變,通過(guò)監(jiān)測(cè)織物總電阻變化規(guī)律即可了解織物外界受力情況。該性能可實(shí)現(xiàn)人體生理數(shù)據(jù)(運(yùn)動(dòng)、呼吸、心跳等)的實(shí)時(shí)、無(wú)感采集[10],多應(yīng)用于醫(yī)療保健及運(yùn)動(dòng)健身領(lǐng)域。B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
因?qū)щ娽樋椢锝?jīng)緯向組織結(jié)構(gòu)不同[11],其不同拉伸方向和橫縱尺寸所造成的電阻變化也存在一定差異。通常,同一導(dǎo)電針織物經(jīng)向拉伸電阻變化范圍大于緯向[12];導(dǎo)電針織物的橫列數(shù)與縱行數(shù)之比越大,其靈敏度越高、性能越好;當(dāng)橫縱列數(shù)相同時(shí),緯平針組織的靈敏度最佳,1×1羅紋組織次之,2×1羅紋組織最差;緯編導(dǎo)電織物在經(jīng)向拉伸時(shí),其電阻先隨織物伸長(zhǎng)呈線性上升,隨后呈緩慢上升至電阻值穩(wěn)定,再呈線性下降直至趨于穩(wěn)定。如圖1(b)所示,為了簡(jiǎn)化導(dǎo)電針織物的線圈電路分布[13],先將線圈單元簡(jiǎn)化為電阻六角模型(R1和R2為線圈自身長(zhǎng)度電阻,R3為線圈間接觸電阻),再將其看做一個(gè)電阻結(jié)構(gòu)單元并按照導(dǎo)電針織物組織結(jié)構(gòu)進(jìn)行橫、縱向排布,最終形成一個(gè)復(fù)雜的串并聯(lián)電路網(wǎng)。利用基爾霍夫電流定律(KCL)和電壓定律(KVL)對(duì)該非線性電路進(jìn)行分析求解,可得到固定橫縱列數(shù)導(dǎo)電針織物的等效電阻。
雖然緯編導(dǎo)電織物電-力學(xué)性能的相關(guān)研究很多,但因其受影響因素太多(紗線種類、織物密度、組織結(jié)構(gòu)、橫縱尺寸及編織工藝等),且其中任一因素發(fā)生改變均會(huì)影響現(xiàn)有電阻網(wǎng)絡(luò)模型,使得此性能織物靈敏度、線性度及應(yīng)變范圍等相關(guān)性能參數(shù)難以形成統(tǒng)一的評(píng)判標(biāo)準(zhǔn),因此,該類智能針織產(chǎn)品尚未實(shí)現(xiàn)大規(guī)模推廣。
2.2 濕度傳感性能及作用機(jī)理
導(dǎo)電針織物的濕度傳感性能是指具有一定吸水性的導(dǎo)電針織物在周圍濕度發(fā)生變化時(shí),其電阻也會(huì)產(chǎn)生相應(yīng)改變。該性能對(duì)針織結(jié)構(gòu)不具依賴性,主要依靠織物自身、濕敏材料或?qū)щ姴牧系挠H水性來(lái)實(shí)現(xiàn)濕度傳感。該類織物主要通過(guò)電阻率改變來(lái)表征環(huán)境濕度變化[14-15],可用于監(jiān)測(cè)尿失禁、傷口愈合、出汗量或服裝微氣候等方面。
導(dǎo)電針織物所含導(dǎo)電成分不同,其作用機(jī)理亦不相同。針對(duì)大多數(shù)導(dǎo)電針織物而言,通常濕度越大,導(dǎo)電性能越好,其電阻越小,但存在少數(shù)導(dǎo)電針織物隨濕度增加,導(dǎo)電性能變差,其電阻愈來(lái)愈大。例如,用碳納米管(SWCNT)與聚乙烯醇(PVA)長(zhǎng)絲制備的導(dǎo)電針織物,SWCNT具有極好導(dǎo)電性,而PVA長(zhǎng)絲不導(dǎo)電但容易吸水膨脹[16],兩者結(jié)合后,可利用PVA在潮濕環(huán)境下發(fā)生溶脹來(lái)增加碳納米管間隙,從而使織物電阻增大。另外,經(jīng)新型二維類石墨烯結(jié)構(gòu)MXene處理制備的導(dǎo)電針織物同樣可利用MXene的導(dǎo)電性和親水性來(lái)實(shí)現(xiàn)濕度傳感[17],其作用機(jī)理如圖2所示。MXene未接觸水分子時(shí),其上下層結(jié)構(gòu)間距由—OH之間的鍵能決定;當(dāng)MXene與水接觸后,水分子進(jìn)入其結(jié)構(gòu)層中間,與MXene的含氧官能團(tuán)形成新的—OH,使得MXene結(jié)構(gòu)層間的距離增加,且周圍環(huán)境濕度越大,其距離越大,從而導(dǎo)致含MXene導(dǎo)電針織物電阻增大。在潮濕條件下,導(dǎo)電針織物的經(jīng)向和緯向表現(xiàn)出不同的電學(xué)行為,鑒于其緯向靈敏度和線性度更佳,故多采用導(dǎo)電針織物的緯向來(lái)監(jiān)測(cè)電阻變化[18]。
目前緯編導(dǎo)電織物濕度傳感性能的研究相對(duì)較少,仍處于起步階段。因針織結(jié)構(gòu)的柔軟貼體性,未來(lái)可考慮將其集成于服裝上或者利用針織全成形技術(shù)實(shí)現(xiàn)一體成形,以代替?zhèn)鹘y(tǒng)測(cè)試方法,實(shí)現(xiàn)皮膚表面濕度與出汗量的實(shí)時(shí)測(cè)量。另外,若能在該性能織物表面增加一層離子選擇性薄膜或生物分子酶膜,甚至可以實(shí)現(xiàn)汗液成分的檢測(cè)。
2.3 電熱性能及作用機(jī)理
導(dǎo)電針織物的電熱性能是指導(dǎo)電針織物在外加電路作用下,由于電阻存在而產(chǎn)生通電發(fā)熱現(xiàn)象。該性能是利用織物內(nèi)部電阻網(wǎng)絡(luò)將外部電源提供的電能直接轉(zhuǎn)化為熱能[19],其多應(yīng)用于極地防寒服、智能家居及體育防護(hù)等領(lǐng)域。
若將導(dǎo)電針織物視作純電阻電路,由焦耳定律(式(1))可知,電流通過(guò)織物產(chǎn)生的熱量與電流的平方、織物電阻均成正比,這說(shuō)明可通過(guò)改變電流或織物電阻來(lái)控制織物的產(chǎn)熱量,電流大小依靠外接電源控制,織物電阻由導(dǎo)電材料和制備工藝共同決定。以鍍銀紗線導(dǎo)電針織物為例,可采用鍍銀紗線與非導(dǎo)電紗線橫列間隔編織方式[20],來(lái)增加織物內(nèi)部電阻,其織物結(jié)構(gòu)及等效電阻如圖3所示。由熱傳遞相關(guān)理論(式(2))可知[21],電加熱導(dǎo)電針織物可達(dá)到的平衡溫度與其表面積、電阻成反比,而與加載電壓成正比,這表明可通過(guò)適當(dāng)增大加載電壓、減小織物電阻及表面積的方式,提高導(dǎo)電針織物的平衡溫度。另外,導(dǎo)電針織物電熱性能還與其最大負(fù)載電流、熱穩(wěn)定性、電熱溫升及發(fā)熱均勻性等指標(biāo)相關(guān)。最大負(fù)載電流是導(dǎo)電針織物允許通過(guò)的最大電流[22],該值越大則織物能達(dá)到平衡溫度越高;熱穩(wěn)定性可通過(guò)導(dǎo)電針織物達(dá)到平衡溫度時(shí)電阻變化率進(jìn)行表征(式(3)),可反映織物電阻受溫度影響程度,該值越小代表織物熱穩(wěn)定性越好;電熱溫升是導(dǎo)電針織物平衡溫度與環(huán)境溫度的差值[23],用于反映導(dǎo)電針織物的調(diào)溫幅度大小;發(fā)熱均勻性是衡量導(dǎo)電針織物電熱性能的重要指標(biāo),可通過(guò)觀測(cè)導(dǎo)電針織物表面溫度分布情況進(jìn)行評(píng)價(jià)。
Q=I2Rt??? (1)
式中:Q為熱量;I為電流;R為導(dǎo)電針織物電阻;t為通電時(shí)間。
T=PhS+Ta=U2hSR+Ta(2)
式中:T為平衡溫度;P為消耗功率;S為導(dǎo)電針織物表面積;U為加載電壓;h為對(duì)流傳感系數(shù);Ta為環(huán)境溫度。B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
φ/%=ΔRR0×100??? (3)
式中:φ為電阻變化率;ΔR為電阻變化量;R0為導(dǎo)電針織物的初始電阻。
目前緯編電加熱針織物的研究較多且一些較為成熟的電加熱針織產(chǎn)品已經(jīng)投入市場(chǎng),但現(xiàn)有產(chǎn)品仍存在一些不足之處。比如,電加熱針織產(chǎn)品的溫控系統(tǒng)不夠智能化,產(chǎn)品多采用分檔手動(dòng)調(diào)溫模式,無(wú)法根據(jù)溫度變化自動(dòng)調(diào)節(jié)加熱量;電加熱針織產(chǎn)品主要使用充電寶進(jìn)行能源供應(yīng),存在便攜性差、工作時(shí)間較短等問(wèn)題。因此,未來(lái)電加熱針織產(chǎn)品可在全自動(dòng)溫控系統(tǒng)設(shè)計(jì)和無(wú)線電能傳輸方面進(jìn)行研究,以提升產(chǎn)品性能和用戶體驗(yàn)。
3 緯編導(dǎo)電織物的制備要點(diǎn)
緯編導(dǎo)電織物性能不同,其制備工藝、原則及側(cè)重點(diǎn)各不相同,要根據(jù)實(shí)際應(yīng)用需求,進(jìn)行合理設(shè)計(jì),以生產(chǎn)出性能優(yōu)良的緯編導(dǎo)電針織產(chǎn)品。
3.1 電-力學(xué)性能導(dǎo)電針織物的制備要點(diǎn)
紗線原料選擇、組織結(jié)構(gòu)設(shè)計(jì)、編織工藝及電壓加載方式均對(duì)導(dǎo)電針織物的電-力學(xué)性能具有重要影響,故其制備原則主要圍繞以下幾點(diǎn)展開(kāi)。
1) 在紗線原料選擇方面,因該性能導(dǎo)電針織物需要具備優(yōu)良的導(dǎo)電性、彈性及高度回復(fù)性[24-25],故在實(shí)際生產(chǎn)中,通常采用鍍銀導(dǎo)電紗線或不銹鋼混紡導(dǎo)電紗線加入氨綸彈性紗、滌綸紗等普通紗線共同執(zhí)行編織,不但能增加導(dǎo)電織物的保形性,還能改善其電-力學(xué)性能。
2) 在織物組織結(jié)構(gòu)設(shè)計(jì)方面,由于當(dāng)前現(xiàn)有的電力學(xué)模型較為單一[26-27],故導(dǎo)電針織物的組織結(jié)構(gòu)設(shè)計(jì)不宜過(guò)于復(fù)雜,一般采用常見(jiàn)的基本組織,如緯平針組織、羅紋組織及正反針組織等。
3) 在編織工藝選擇上,主要采用提花添紗和嵌花添紗兩種工藝,采用工藝不同,電壓加載方式亦不相同,如圖4所示。因采用嵌花添紗工藝編織的導(dǎo)電針織物,背面不存在浮線[28],故提高了導(dǎo)電針織物的靈敏度、穩(wěn)定性與美觀性。
3.2 濕度傳感導(dǎo)電針織物的制備要點(diǎn)
與電-力性能導(dǎo)電針織物相比,濕度傳感導(dǎo)電針織物除了要具備良好的導(dǎo)電性外,還要具備一定吸水性、耐腐蝕性及尺寸穩(wěn)定性,在其制備過(guò)程中需注意以下幾點(diǎn)。
1) 為避免導(dǎo)電針織物因長(zhǎng)期處于潮濕環(huán)境下生銹或被氧化導(dǎo)致靈敏度降低[29],要選擇化學(xué)性能穩(wěn)定的原料進(jìn)行制備。
2) 為提高導(dǎo)電針織物的吸水性,要對(duì)導(dǎo)電針織物進(jìn)行親水處理,但在選擇親水助劑時(shí)要保證其不會(huì)與導(dǎo)電物質(zhì)產(chǎn)生化學(xué)反應(yīng),還要具備良好的耐久性。
3) 由于外力拉伸變形與濕度變化均能影響導(dǎo)電針織物電阻變化規(guī)律,故在進(jìn)行織物結(jié)構(gòu)設(shè)計(jì)時(shí),可在導(dǎo)電針織物背面增加復(fù)合層,以限制織物橫縱向拉伸變形,防止兩者產(chǎn)生耦合效應(yīng)。
當(dāng)利用金屬導(dǎo)電紗線制備濕度傳感織物時(shí),可選用不銹鋼滌綸混紡紗線以質(zhì)地緊密厚實(shí)的組織結(jié)構(gòu)(羅紋組織、毛圈組織等)進(jìn)行制備,織片下機(jī)后將其浸入溫度為25 ℃、質(zhì)量分?jǐn)?shù)為20%的聚酯聚醚型親水整理劑溶液中進(jìn)行親水處理[18],隨后在160 ℃的高溫下進(jìn)行干燥處理,最后可獲得具有良好吸水性與導(dǎo)電性的濕度傳感針織物;當(dāng)采用MXene制備濕度傳感織物時(shí),先將針織物樣片置于蒸餾水中用超聲波清洗半小時(shí)進(jìn)行除雜處理[30],然后將織物放入65 ℃的烘箱中烘干,隨后將其放入質(zhì)量濃度為5 mg/mL的MXene溶液中,待織物表面完全被MXene顆粒包覆[31],顏色變?yōu)楹谏?,將其撈出并置?5 ℃烘箱中再次烘干,取出即可得到基于MXene的濕度傳感針織物。
3.3 電熱性能導(dǎo)電針織物的制備要點(diǎn)
導(dǎo)電針織物發(fā)熱效果主要受導(dǎo)電材料、制備工藝及加載電壓影響。在導(dǎo)電材料選擇上,多采用鍍銀紗線或聚吡咯來(lái)進(jìn)行制備,兩種導(dǎo)電加熱織物對(duì)比如表2所示。聚吡咯涂層加熱織物在制備難易、熱穩(wěn)定性方面較優(yōu),但在耐水洗性、服用性能及平衡溫度方面較差,故兩者綜合比較,鍍銀紗線制備的電加熱織物具有更大優(yōu)勢(shì)。
采用鍍銀紗線與滌綸紗線制備導(dǎo)電發(fā)熱織物時(shí),織物發(fā)熱均勻度跟鍍銀紗線與滌綸紗線橫列間隔排布方式相關(guān)[32],兩橫列間隔越小,發(fā)熱均勻性越好,但間隔過(guò)小會(huì)降低織物整體電阻,使其發(fā)熱效率降低,經(jīng)研究發(fā)現(xiàn)兩者橫列比為1︰2時(shí)發(fā)熱均勻性最佳。在組織結(jié)構(gòu)設(shè)計(jì)時(shí),多采用緯平針組織、羅紋或雙羅紋組織,較少使用提花組織、襯緯組織,因襯緯組織將導(dǎo)電紗線作為緯紗直接襯入[33],其發(fā)熱效率較低,可根據(jù)實(shí)際需要,確定具體組織結(jié)構(gòu)類型。在進(jìn)行加載電壓設(shè)計(jì)時(shí),主要考慮兩點(diǎn):一是要注意不能超過(guò)導(dǎo)電紗線的最大負(fù)載電流[34];二是要找到最佳電壓加載位置,因電壓加載位置不同,會(huì)影響織物平衡溫度與升溫速率,所以要經(jīng)過(guò)多次嘗試來(lái)確定最佳電壓加載位置。
利用液相原位聚合法進(jìn)行聚吡咯涂層織物制備時(shí)[35],其基本制備步驟如下:先將針織物樣片(純棉或黏膠纖維織物)進(jìn)行除雜晾曬,再將其置于一定摩爾濃度的吡咯單體溶液中進(jìn)行預(yù)濕,半小時(shí)后加入適量FeCl3·6H2O溶液,使溶液中FeCl3與吡咯單體摩爾質(zhì)量比為1︰2并不斷攪拌,等充分反應(yīng)后,將樣布取出放入2%乙醇溶液中進(jìn)行洗滌,最后將樣布撈出控干[36]。在整個(gè)制備過(guò)程中,聚吡咯涂層織物電阻隨吡咯單體溶液摩爾濃度增大而減小;隨反應(yīng)時(shí)間的增加先減小后增大;隨反應(yīng)溫度升高而增大,但反應(yīng)溫度過(guò)高會(huì)阻礙聚合反應(yīng)的進(jìn)行。實(shí)踐證明,當(dāng)采用0.4 mol/L的吡咯溶液、反應(yīng)時(shí)間為2 h、反應(yīng)溫度為室溫時(shí),即可制備出發(fā)熱效果良好的聚吡咯涂層織物。B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
4 結(jié) 語(yǔ)
本文綜述了緯編導(dǎo)電織物電-力學(xué)性能、濕度傳感性能及電熱性能的作用機(jī)理與應(yīng)用進(jìn)展,并探討了不同性能緯編導(dǎo)電織物的制備原則及要點(diǎn),為導(dǎo)電針織產(chǎn)品后續(xù)的設(shè)計(jì)研發(fā)提供了理論依據(jù)與技術(shù)指導(dǎo)。
緯編導(dǎo)電織物的諸多優(yōu)點(diǎn)使其在智能可穿戴領(lǐng)域占有絕對(duì)優(yōu)勢(shì),智能針織品的普及與應(yīng)用已成為必然趨勢(shì)。隨著智能針織產(chǎn)品應(yīng)用領(lǐng)域的拓展與大規(guī)模市場(chǎng)化,其在材料耐久性、結(jié)構(gòu)穩(wěn)定性、能源供應(yīng)及產(chǎn)品安全性等方面的問(wèn)題日益顯著,針對(duì)這些問(wèn)題,本文指出了解決途徑。
1) 加強(qiáng)高性能纖維材料的研發(fā)。纖維材料是導(dǎo)電針織物的基礎(chǔ),對(duì)智能針織產(chǎn)品的各項(xiàng)性能具有直接影響,研發(fā)高性能纖維材料不僅能解決材料耐久性問(wèn)題,還能提高產(chǎn)品的其他性能,如高導(dǎo)電性、高彈性、耐高溫性及抗輻射性等。
2) 改善現(xiàn)有的制備工藝。導(dǎo)電針織物因其線圈結(jié)構(gòu)的特殊性,經(jīng)反復(fù)拉伸、洗滌會(huì)發(fā)生一定程度變形而影響自身性能,因此要采取一系列的改革措施對(duì)現(xiàn)有的制備工藝進(jìn)行優(yōu)化,以提高產(chǎn)品的結(jié)構(gòu)穩(wěn)定性。
3) 加快自供電技術(shù)應(yīng)用。自供電技術(shù)可利用特殊織物將周圍環(huán)境中的各種能量(人體運(yùn)動(dòng)、摩擦、光能或太陽(yáng)能等)收集起來(lái)并將其轉(zhuǎn)化成電能,為低功耗電子元件供電。如果將其與智能針織產(chǎn)品結(jié)合,既能實(shí)現(xiàn)零電能消耗,又能節(jié)約成本、保護(hù)環(huán)境。
4) 建立完善的安全測(cè)試標(biāo)準(zhǔn)。智能針織產(chǎn)品的安全性主要包括化學(xué)成分安全性、電路安全性、信息安全性、阻燃性及電磁輻射等,通過(guò)制定出相應(yīng)的測(cè)試標(biāo)準(zhǔn),以規(guī)范智能針織產(chǎn)品市場(chǎng)。
參考文獻(xiàn):
[1]蔡倩文, 王金鳳, 陳慰來(lái). 緯編針織柔性傳感器結(jié)構(gòu)及其導(dǎo)電性能[J]. 紡織學(xué)報(bào), 2016, 37(6): 48-53.
CAI Qianwen, WANG Jinfeng, CHEN Weilai. Structures and electrical properties of weft-knitted flexible sensors[J]. Journal of Textile Research, 2016, 37(6): 48-53.
[2]陳斌, 李娜娜, 蔡璐, 等. 導(dǎo)電針織物結(jié)構(gòu)設(shè)計(jì)及性能研究[J]. 針織工業(yè), 2015(6): 23-25.
CHEN Bin, LI Nana, CAI Lu, et al. Structure design of conductive fiber knitted fabric and its property analysis[J]. Knitting Industries, 2015(6): 23-25.
[3]錢鑫, 蘇萌, 李風(fēng)煜, 等. 柔性可穿戴電子傳感器研究進(jìn)展[J]. 化學(xué)學(xué)報(bào), 2016, 74(7): 565-575.
QIAN Xin, SU Meng, LI Fengyu, et al. Research progress of flexible wearable electronic sensors[J]. Acta Chemica Sinica, 2016, 74(7): 565-575.
[4]SEYEDIN S, ZHANG P, NAEBE M, et al. Textile strain sensors: A review of the fabrication technologies, performance evaluation and applications[J]. Materials Horizons, 2019, 6(2): 219-249.
[5]王棟, 卿星, 蔣海青, 等. 纖維材料與可穿戴技術(shù)的融合與創(chuàng)新[J]. 紡織學(xué)報(bào), 2018, 39(5): 150-154.
WANG Dong, QING Xing, JIANG Haiqing, et al. Integration and innovation of fiber materials and wearable technology[J]. Journal of Textile Research, 2018, 39(5): 150-154.
[6]KADIR O, OAGUR A, ASLI A, et al. Textile based sensing system for lower limb motion monitoring[J]. Biosystems & Biorobotics, 2019, 21(1): 395-399.
[7]CHEN Z F, WANG Z, LI X M, et al. Flexible piezoelectric-induced pressure sensors for static measurements based on nanowires/graphene heterostructures[J]. ACS Nano, 2017(11): 4507-4513.
[8]ZHAO C, SHU K, WANG C, et al. Reduced graphene oxide and polypyrrole /reduced graphene oxide composite coated stretchable fabric electrodes for super capacitor application[J]. Electrochimica Acta, 2015, 172(1): 12-19.
[9]田明偉, 李增慶, 盧韻靜, 等. 紡織基柔性力學(xué)傳感器研究進(jìn)展[J]. 紡織學(xué)報(bào), 2018, 39(5): 170-176.
TIAN Mingwei, LI Zengqing, LU Yunjing, et al. Recent progress of textile-based flexible mechanical sensors[J]. Journal of Textile Research, 2018, 39(5): 170-176.B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
[10]韓曉雪, 繆旭紅. 氨綸緯編導(dǎo)電織物縱向電力學(xué)性能[J]. 紡織學(xué)報(bào), 2019, 40(4): 60-65.
HAN Xiaoxue, MIAO Xuhong. Longitudinal electrical physical properties of spandex weft-knitted conductive fabric[J]. Journal of Textile Research, 2019, 40(4): 60-65.
[11]HANG Y J, LONG H R. Resistive network model of the weft-knitted strain sensor with the plating stitch-Part 2: Resistive network model during the elongation along course direction[J]. Journal of Engineered Fibers and Fabrics, 2020, 15(35): 1-16.
[12]SEYEDIN S, MORADI S, SINGH C, et al. Continuous production of stretchable conductive multi-filaments in kilometer scale enables facile knitting of wearable strain sensing textiles[J]. Applied Materials Today, 2018, 11: 255-263.
[13]謝娟. 針織物傳感器雙向延伸電-力學(xué)性能及肢體動(dòng)作監(jiān)測(cè)研究[D]. 上海: 東華大學(xué), 2015.
XIE Juan. Research into Electro-Mechanical Properties of Knitted Sensor under Strip Biaxial Elongation and Application in Monitoring Body Movements[D]. Shanghai: Donghua University, 2015.
[14]吳雪顏, 盛斌, 黃元申. 石墨烯濕度傳感器研究進(jìn)展[J]. 傳感器與微系統(tǒng), 2020(9): 1-3.
WU Xueyan, SHENG Bin, HUANG Yuanshen. Research progress on graphene-based humidity sensor[J]. Transducer and Microsystem Technologies, 2020(9): 1-3.
[15]熊瑩, 陶肖明. 智能傳感紡織品研究進(jìn)展[J]. 針織工業(yè), 2019(7): 8-12.
XIONG Ying, TAO Xiaoming. Research progress of smart sensing textiles[J]. Knitting Industries, 2019(7): 8-12.
[16]ANABEl R, LUISA F G, JORGE A D, et al. Fabrication of bulk alumina structures with humidity sensing capabilities using direct ink write technique[J]. Rapid Prototyping Journal, 2021, 27(4): 11-20.
[17]王麗紅. 基于柔性包芯紗的應(yīng)變/濕度傳感器制備及其智能可穿戴應(yīng)用研究[D]. 青島: 青島大學(xué), 2020.
WANG Lihong. Preparation of Strain/Humidity Sensor Composed by Flexible Core-Sheath Yarn and its Application in Smart Wearable Clothing[D]. Qingdao: Qingdao University, 2020.
[18]CHEN Q, SHU L, FU B L, et al. Electrical resistance of stainless steel/polyester blended knitted fabrics for application to measure sweat quantity[J]. Polymers, 2021, 13(7): 1-20.
[19]李雅芳. 基于鍍銀紗線的加熱織物制備及其熱力學(xué)性能研究與仿真[D]. 天津: 天津工業(yè)大學(xué), 2017.
LI Yafang. Research and Simulation of Heating Fabric Preparation Based on Silver-Plated Yarn and its Thermodynamic Properties[D]. Tianjin: Tiangong University, 2017.
[20]李潔瓊, 馬大力. 鍍銀導(dǎo)電紗線智能電加熱針織毛衫的設(shè)計(jì)開(kāi)發(fā)[J]. 針織工業(yè), 2020(10): 62-65.
LI Jieqiong, MA Dali. Development of intelligent electric heating knitted sweater with silver plated conductive yarn[J]. Knitting Industries, 2020(10): 62-65.B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
[21]HAMDANI S T A, POTLURI P, FERNANDO A. Thermo-mechanical behavior of textile heating fabric based on silver coated polymeric yarn[J]. Materials, 2013, 6(3): 1-8.
[22]張阿真, 鄭瑞平, 劉皓. 電加熱服裝服飾的研究進(jìn)展[J]. 材料科學(xué)與工程學(xué)報(bào), 2020, 38(6): 1032-1040.
ZHANG Azhen, ZHENG Ruiping, LIU Hao. Research progress of flexible heating element and its application in wearables[J]. Journal of Materials Science and Engineering, 2020, 38(6): 1032-1040.
[23]KIM H, LEE S. Characterization of electrical heating performance of CFDM 3D-printed graphene/polylactic acid (PLA) horseshoe pattern with different 3D printing directions[J]. Polymers, 2020, 12(12): 2955.
[24]TOGNETTI A, LORUSSI F, MURAG D, et al. New generation of wearable goniometers for motion capture systems[J]. Journal of Neuro Engineering and Rehabilitation, 2014, 11(1): 56-73.
[25]RAJI R K, MIAO X H, WAN A L, et al. Knitted piezoresistive smart chest band and its application for respiration patterns assessment[J]. Journal of Engineered Fibers and Fabrics, 2019, 14(4): 1-14.
[26]QIU Q, ZHU M M, LI Z L, et al. Highly flexible, breathable, tailorable and washable power generation fabrics for wearable electronics[J]. Nano Energy, 2019, 58(1): 750-758.
[27]劉嬋嬋, 繆旭紅, 李煜天. 基于針織的肘部彎曲傳感器傳感性能研究[J]. 絲綢, 2019, 56(12): 16-21.
LIU Chanchan, MIAO Xuhong, LI Yutian. Research on sensing performance of knitted elbow bending sensor[J]. Journal of Silk, 2019, 56(12): 16-21.
[28]張佳慧, 王建萍. 圓形緯編針織物電極導(dǎo)電性能及電阻理論模型構(gòu)建[J]. 紡織學(xué)報(bào), 2020, 41(3): 56-61.
ZHANG Jiahui, WANG Jianping. Electric conduction and resistance theory model of circular weft knitted electrodes[J]. Journal of Textile Research, 2020, 41(3): 56-61.
[29]BI S Y, HOU L, LU Y X. An integrated wearable strain, temperature and humidity sensor for multifunctional monitoring[J]. Composites Part A, 2021, 149(5): 99-103.
[30]GIUSEPPE R, VALENTIAN T, CLAUDIO C, et al. Structural and morphological characterizations of MWCNTs hybrid coating onto cotton fabric as potential humidity and temperature wearable sensor[J]. Sensors & Actuators B: Chemical, 2017, 252: 428-439.
[31]ZHANG X H, CHAO X J, LOU L, et al. Personal thermal management by thermally conductive composites: A review[J]. Composites Communications, 2021, 23(1): 100585-100595.
[32]李雅芳, 劉皓, 趙義俠. 基于鍍銀紗線的電加熱織物溫度場(chǎng)模擬與電熱性能[J]. 材料工程, 2019, 47(2): 68-75.
LI Yafang, LIU Hao, ZHAO Yixia. Electric heating fabrics based on silver plated yarn and simulation of temperature field[J]. Journal of Materials Engineering, 2019, 47(2): 68-75.B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
[33]盧俊宇, 陳莉, 劉皓. 針織加熱織物的設(shè)計(jì)及其電熱性能測(cè)試[J]. 上海紡織科技, 2017, 45(3): 31-34.
LU Junyu, CHEN Li, LIU Hao. Design and electrothermal performance of knitted heating fabric[J]. Shanghai Textile Science & Technology, 2017, 45(3): 31-34.
[34]王宏付, 張海棠, 柯瑩. 智能防寒服裝研究進(jìn)展[J]. 服裝學(xué)報(bào), 2021, 6(1): 29-35.
WANG Hongfu, ZHANG Haitang, KE Ying. Research progress on intelligent cold protective clothing[J]. Journal of Clothing Research, 2021, 6(1): 29-35.
[35]李萍, 蔣曉文. 智能電加熱服的研究進(jìn)展[J]. 棉紡織技術(shù), 2019, 47(9): 79-84.
LI Ping, JIANG Xiaowen. Research progress of intelligent electric heating clothing[J]. Cotton Textile Technology, 2019, 47(9): 79-84.
[36]KIM H, LEE S, KIM H. Electrical heating performance of electro-conductive para-aramid knit manufactured by dip-coating in a graphene/waterborne polyurethane composite[J]. Scientific Reports, 2019, 9(1): 2-11.
Research progress on multiple properties and preparation of weft-knitted conductive fabrics
WANG Pan, WANG Zhaohui
(a.College of Fashion and Design; b.Key Laboratory of Clothing Design and Technology, Ministry of Education; c.Shanghai Belt andRoad Joint Laboratory of Textile Intelligent Manufacturing, Donghua University, Shanghai 200051, China)
Abstract:Weft-knitted conductive fabrics have become one of the research focuses in the field of smart textiles due to their unique organizational structure and wearability. The knitted loop structure not only provides the conductive fabric with excellent omnidirectional stretch properties, but also provides elasticity, softness and fit that other fabrics cannot match. In recent years, the researched weft-knitted conductive fabrics, which mainly use resistance changes caused by external stimuli to achieve intelligence and functionalization, have the characteristics of simple structure, easiness to form, light texture, good flexibility and strong designability. They have broad application prospects in fields such as healthcare, sweat monitoring, and smart temperature regulation.
At present, weft-knitted conductive fabrics are endowed with multiple properties. Among them, conductive knitted fabrics with electro-mechanical properties can help us understand the external force by monitoring the change law of the total resistance of the fabric. The selection of yarn raw materials, the design of weave structure, the weaving process and the way of voltage loading have important effects on the electro-mechanical properties during preparation. This type of fabric can realize real-time, non-inductive acquisition of human physiological data, and is mostly used in the fields of medical care and sports and fitness. Conductive fabrics with humidity sensing properties do not depend on the knitted structure, but mainly rely on the hydrophilicity of the fabric itself, humidity sensitive materials or conductive materials to achieve humidity sensing. This type of fabric mainly characterizes environmental humidity changes through resistivity changes. Since both external stretching and humidity changes can affect fabric resistance, a composite layer to prevent coupling effects between the two can be added during preparation. This type of fabric can be used for monitoring incontinence, wound healing, sweating or microclimate of garments and other related fields. Conductive knitted fabrics with electrothermal properties can directly convert electrical energy provided by external power sources into thermal energy by using the internal resistance network of the fabric, and are mainly affected by conductive materials, preparation processes and loading voltage during preparation. Silver-coated yarn or polypyrrole can be used as the conductive material, and the former has better performance than the latter. This type of fabric is mostly used in such fields as polar winter clothing, smart home and sports protection.B48DEDB0-EFB8-41B5-B6E2-27DDC842923C
Weft-knitted conductive fabrics with electro-mechanical properties are a hot research topic because of many factors (such as yarn type, fabric density, weave structure, horizontal and vertical dimensions, and weaving process, etc.). Any change of any of these factors will affect the existing resistance network model, so there is no unified evaluation standard for the related performance parameters such as sensitivity, linearity and strain range of this kind of fabrics. There are relatively few studies on weft-knitted conductive fabrics with moisture sensing properties. However, due to the softness and fit of the knitted structure, it is expected to replace the traditional test method and realize the real-time measurement of skin surface humidity and sweat amount. In addition, if a layer of ion-selective film or biomolecular enzyme film can be added to the surface of fabrics with such properties, the detection of sweat components can even be realized. At present, some relatively mature electric heating knitted products have been put into the market, but there are still some deficiencies in the existing products. For example, the temperature control system of electric heating knitted products is not intelligent enough, and the electric heating knitted products have problems of poor portability and short working time. Therefore, the future research direction of such products mainly lies in the design of automatic temperature control system and wireless power transmission to improve product performance and user experience.
The multiple advantages of the weft-knitted conductive fabric make it an absolute advantage in the field of smart wearables, and the popularization and application of smart knitwear have become an inevitable trend. With the expansion and large-scale marketization of the application field of smart knitted products, the problems of material durability, structural stability, energy supply and product safety have become increasingly prominent. The key to solving these problems lies in the following points: First, the research and development of high-performance fiber materials should be strengthened. The development of high-performance fiber materials can not only solve the problem of material durability, but also improve other properties of the products. Second, the existing preparation process should be improved. Due to its structural characteristics, conductive knitted fabrics will deform and the performance will be affected after repeated stretching and washing. Therefore, the preparation process should be optimized to improve its stability. Third, the application of self-powered technology should be accelerated. If the self-powered technology is combined with smart knitted products, it can not only achieve zero power consumption, but also save costs and protect the environment. Finally, a sound security testing standard should be established. The market of smart knitted products should be regulated by developing corresponding test standards.
Key words:weft-knitted; conductive fabrics; electro-mechanical properties; humidity sensor; electrothermal property; smart wearables; self-powered technologyB48DEDB0-EFB8-41B5-B6E2-27DDC842923C