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旋轉流變儀如何選擇溫度控制單元?

發布時間:2022-10-17 13:26:42瀏覽次數:

  很多人都認為旋轉流變儀和有(you)一些簡(jian)單的(de)分析(xi)儀器一樣有(you)標(biao)準的(de)配置, 包括了所有(you)需要(yao)的(de)部件(jian)和配件(jian),只要(yao)買回(hui)去(qu)用就可以了。

  其實不然,旋(xuan)轉流變(bian)儀現在發展到了(le)一個比較(jiao)成(cheng)熟,同時也是很復(fu)雜的(de)分析儀器系統了(le)。由(you)于流變(bian)儀的(de)應用(yong)領域越來越廣,下面我先簡要說明一下目前可(ke)選的(de)常用(yong)四種溫(wen)控系統,然后(hou)再就一些典型(xing)的(de)應用(yong)推(tui)薦相(xiang)關的(de)配置:

  首先是廣受歡迎的半(ban)導體(ti)(Peltier)溫(wen)(wen)控(kong)單元。它是利用(yong)了半(ban)導體(ti)的一(yi)種特殊效應,通(tong)過本(ben)身溫(wen)(wen)度(du)(du)(du)的升高(gao)或降(jiang)低就能(neng)對平行板、錐板或同(tong)心圓筒的樣品控(kong)溫(wen)(wen),原理簡單,控(kong)制方(fang)便,已(yi)成為研究(jiu)精(jing)細(xi)化(hua)工、食品、化(hua)妝(zhuang)品、涂(tu)料、油墨(mo)等流變性能(neng)的首選溫(wen)(wen)控(kong)系統(tong)。Peltier半(ban)導體(ti)溫(wen)(wen)控(kong)方(fang)式的溫(wen)(wen)度(du)(du)(du)上限(xian)可(ke)以(yi)到(dao)200°C,基本(ben)滿足(zu)(zu)了上述(shu)領域(yu)對高(gao)溫(wen)(wen)測試范圍的需要(yao)。其溫(wen)(wen)度(du)(du)(du)的下限(xian)極限(xian)可(ke)以(yi)到(dao)達-60°C,也能(neng)滿足(zu)(zu)很(hen)多低溫(wen)(wen)測試的要(yao)求了。而且(qie)它最(zui)大(da)的優點是升降(jiang)溫(wen)(wen)速度(du)(du)(du)超快,最(zui)快可(ke)以(yi)實現60°C/分鐘(zhong)的變溫(wen)(wen)速度(du)(du)(du),溫(wen)(wen)控(kong)的精(jing)度(du)(du)(du)也能(neng)達到(dao)0.1~0.2°C。不過半(ban)導體(ti)溫(wen)(wen)控(kong)系統(tong)一(yi)定要(yao)接一(yi)個(ge)循環裝置,不管是水冷還是風冷,用(yong)于保(bao)護溫(wen)(wen)控(kong)系統(tong)不要(yao)過熱燒毀。另外要(yao)實現零度(du)(du)(du)以(yi)下的溫(wen)(wen)度(du)(du)(du)測試,外接循環裝置也要(yao)具有降(jiang)溫(wen)(wen)能(neng)力,這(zhe)樣才能(neng)輔助Peltier系統(tong)降(jiang)到(dao)更低的溫(wen)(wen)度(du)(du)(du)。比如說要(yao)Peltier系統(tong)降(jiang)到(dao)-40°C,那么(me)外接循環器(qi)也要(yao)能(neng)降(jiang)到(dao)-20°C。

旋轉流變儀

  第二種溫(wen)(wen)(wen)(wen)控(kong)方(fang)式就是電(dian)(dian)(dian)加(jia)熱(re)(re)(re)溫(wen)(wen)(wen)(wen)控(kong)系(xi)統(tong)。說簡單些,就是電(dian)(dian)(dian)熱(re)(re)(re)毯(tan)的(de)(de)(de)(de)加(jia)熱(re)(re)(re)方(fang)式,可(ke)以(yi)實(shi)現平行(xing)板(ban)、錐(zhui)(zhui)板(ban)或同(tong)心(xin)圓(yuan)(yuan)筒的(de)(de)(de)(de)控(kong)溫(wen)(wen)(wen)(wen)。與第一種Peltier方(fang)式相比,電(dian)(dian)(dian)加(jia)熱(re)(re)(re)方(fang)式的(de)(de)(de)(de)溫(wen)(wen)(wen)(wen)度(du)(du)上限可(ke)以(yi)提高(gao)到400°C(平行(xing)板(ban)、錐(zhui)(zhui)板(ban))或者是300°C(同(tong)心(xin)圓(yuan)(yuan)筒),滿足(zu)(zu)相關高(gao)分(fen)子熔體和其它高(gao)溫(wen)(wen)(wen)(wen)測試的(de)(de)(de)(de)需要(yao)。由于加(jia)熱(re)(re)(re)體本身的(de)(de)(de)(de)熱(re)(re)(re)慣量較大,所(suo)以(yi)一旦到達設定(ding)溫(wen)(wen)(wen)(wen)度(du)(du)后,溫(wen)(wen)(wen)(wen)度(du)(du)波動(dong)小。特別是平行(xing)板(ban)、錐(zhui)(zhui)板(ban)測試樣品時(shi),不會(hui)出現在(zai)裝樣過程中(zhong)(zhong)溫(wen)(wen)(wen)(wen)度(du)(du)大幅波動(dong)的(de)(de)(de)(de)問題。但同(tong)時(shi)帶(dai)來的(de)(de)(de)(de)不足(zu)(zu)就是電(dian)(dian)(dian)加(jia)熱(re)(re)(re)系(xi)統(tong)升溫(wen)(wen)(wen)(wen)速(su)度(du)(du)慢,視溫(wen)(wen)(wen)(wen)度(du)(du)范圍(wei)的(de)(de)(de)(de)不同(tong),升溫(wen)(wen)(wen)(wen)速(su)度(du)(du)在(zai)3~5°C/分(fen)鐘不等。好在(zai)可(ke)以(yi)在(zai)電(dian)(dian)(dian)加(jia)熱(re)(re)(re)溫(wen)(wen)(wen)(wen)控(kong)系(xi)統(tong)中(zhong)(zhong)接入一套液(ye)體控(kong)溫(wen)(wen)(wen)(wen)的(de)(de)(de)(de)循環(huan)器,加(jia)速(su)降溫(wen)(wen)(wen)(wen),同(tong)時(shi)還(huan)能實(shi)現一些低于室溫(wen)(wen)(wen)(wen)的(de)(de)(de)(de)實(shi)驗。

  第(di)三種(zhong)(zhong)溫控方(fang)式(shi)是直接(jie)接(jie)入液(ye)體控溫循(xun)(xun)環(huan)(huan)器(qi)的(de)方(fang)法,俗稱水(shui)浴控溫。當然循(xun)(xun)環(huan)(huan)液(ye)既(ji)可(ke)以(yi)是水(shui),也可(ke)以(yi)是溫度(du)(du)范圍更寬的(de)硅(gui)油或水(shui)/乙二醇的(de)混合液(ye)。這種(zhong)(zhong)控溫系統的(de)溫度(du)(du)范圍就依賴與(yu)所接(jie)循(xun)(xun)環(huan)(huan)器(qi)的(de)能力了,有溫度(du)(du)范圍窄(zhai)的(de),也有從-40°C ~ 150 °C的(de),不一而足。

  最(zui)后一種溫(wen)(wen)(wen)(wen)控(kong)方式(shi)是(shi)(shi)輻射對流(liu)爐。從名字上看(kan)就是(shi)(shi)相對較新的(de)溫(wen)(wen)(wen)(wen)控(kong)方式(shi),你猜的(de)沒錯(cuo),溫(wen)(wen)(wen)(wen)控(kong)范圍從-150°C 到(dao) 600°C,是(shi)(shi)溫(wen)(wen)(wen)(wen)控(kong)范圍最(zui)寬的(de)方式(shi)。簡單(dan)說就是(shi)(shi)電吹風+電熱毯雙系(xi)統(tong),配(pei)合(he)液氮低溫(wen)(wen)(wen)(wen)系(xi)統(tong),是(shi)(shi)最(zui)無敵的(de)方式(shi),也(ye)是(shi)(shi)最(zui)昂(ang)貴的(de)溫(wen)(wen)(wen)(wen)控(kong)方式(shi)。適用(yong)于平行板(ban)、錐板(ban)、固(gu)體扭轉(DMA功能)、熔體拉伸、紫外固(gu)化等(deng)等(deng),也(ye)是(shi)(shi)聚(ju)合(he)物流(liu)變學通(tong)常選的(de)方式(shi)。

  旋轉流變儀鼓勵客戶(hu)根(gen)據自己(ji)的(de)確實需(xu)要選配一種或幾種最(zui)適合于(yu)研究(jiu)內容和(he)方向的(de)溫控系統,沒有(you)最(zui)好的(de)溫控,只有(you)最(zui)合適的(de)溫控。

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