Kalin Dragnevski,*1 Athene Donald,1 Phil Taylor,2 Martin Murray,3 Simon Davies,3 Elizabeth Bone3
Summary: Environmental scanning electron microscopy (ESEM) was used to study the film formation mechanisms and extent of coalescence of three acrylic latex com- positions with different glass transition temperatures (Tg), here defined as standard- low Tg, standard-high Tg (both carboxymethyl cellulose- stabilised) and novel (stabilised with a novel polysaccharide derived from agricultural waste). The ESEM analysis revealed that the microstructure of the standard – low-Tg system consisted of individual particles in dispersion and upon evaporation a continuous film formed, whereas in the case of the standard - high Tg latex particle deformation was not observed, but particle aggregation resulted in the formation of crystal-like structures that have formed via the formation of stacking faults. However, in the case of the novel system the microstructure consisted of individual particles and clusters and during evaporation a discontinuous film formed with voids present within its structure and some of the clusters accumulating on the surface of the specimens.
Keywords: ESEM; film formation; polymer latex
Introduction
摘要：環(huán)境掃描電子顯微鏡（ESEM）被用來(lái)研究三丙烯酸乳膠組合物在不同玻璃轉(zhuǎn)變溫度（Tg）下的成膜機(jī)理和凝聚程度，這里的轉(zhuǎn)變溫度定義為標(biāo)準(zhǔn)低溫轉(zhuǎn)變溫度，標(biāo)準(zhǔn)高溫轉(zhuǎn)變溫度（兩者溫度下都是羧甲基纖維素穩(wěn)定的）和新型的轉(zhuǎn)變溫度（用一種從農(nóng)業(yè)廢棄物中提取的新型多糖穩(wěn)定）。環(huán)境掃描電鏡分析表明標(biāo)準(zhǔn)低玻璃轉(zhuǎn)變溫度下的系統(tǒng)的微觀結(jié)構(gòu)由單個(gè)粒子在分散蒸發(fā)后形成連續(xù)膜，而在標(biāo)準(zhǔn)高玻璃轉(zhuǎn)變溫度的情況下，沒(méi)有觀察到乳膠粒子變形，但是粒子聚集通過(guò)堆垛層錯(cuò)結(jié)構(gòu)的形成形成了晶體狀結(jié)構(gòu)。然而在新系統(tǒng)下，微觀結(jié)構(gòu)由單個(gè)粒子和集團(tuán)組成，并且在蒸發(fā)過(guò)程中，形成一個(gè)不連續(xù)薄膜，并且在其組織結(jié)構(gòu)內(nèi)有空洞，一些集團(tuán)積累在試樣表面。
關(guān)鍵詞：環(huán)境掃描電子顯微鏡，成膜，聚合乳膠。
簡(jiǎn)介
聚合物乳膠，由于其廣泛的用途，已經(jīng)成為許多理論和實(shí)驗(yàn)研究的課題。傳統(tǒng)用作油漆或粘合劑時(shí)，乳膠以潮濕的狀態(tài)用于物體表面，并且可以在室溫條件下干燥成膜。因此，傳統(tǒng)的電子顯微鏡由于其極端干燥的觀測(cè)條件和樣品制備的要求，將不適合在潮濕的狀態(tài)下的乳膠觀察。另一方面，環(huán)境掃描電子顯微鏡使得觀察潮濕和絕緣樣品成為可能，已經(jīng)成功用于包括乳膠成膜的研究的大量系統(tǒng)和動(dòng)態(tài)過(guò)程的研究。