本文選題：溫度梯度 + 橫晶�。� 參考：《大連理工大學(xué)》2015年碩士論文

【摘要】：結(jié)晶溫度是影響聚合物及其復(fù)合材料聚集態(tài)結(jié)構(gòu)的重要因素。因此,結(jié)晶溫度對聚合物結(jié)晶形態(tài)及結(jié)構(gòu)影響的研究具有十分重要的理論和應(yīng)用意義。溫度梯度場是一種高通量的研究手段,提高實(shí)驗(yàn)效率的同時(shí)降低了實(shí)驗(yàn)誤差。將樣品置于溫度梯度場中等溫結(jié)晶,一次實(shí)驗(yàn)即可獲得連續(xù)變化的結(jié)晶溫度對結(jié)晶形態(tài)及結(jié)構(gòu)的影響。近年來,橫晶結(jié)構(gòu)成為提高復(fù)合材料界面粘結(jié)性能的新方法。本文第二章以環(huán)保型材料聚乳酸(PLLA)為基體,以高比強(qiáng)度、優(yōu)異導(dǎo)電性及導(dǎo)熱性的碳纖維(CF)為填料,采用溶液澆鑄法制備了CF/PLLA復(fù)合材料薄膜。通過溫度梯度場中等溫結(jié)晶的方法研究了橫晶的結(jié)晶形態(tài)隨結(jié)晶溫度的變化。結(jié)果表明,隨著結(jié)晶溫度從132℃不斷降低至111℃,CF/PLLA復(fù)合材料中CF表面的成核密度不斷增大,橫晶層的厚度不斷減小。偏光顯微鏡法對橫晶的等溫結(jié)晶動力學(xué)的分析結(jié)果表明,當(dāng)結(jié)晶溫度從126℃不斷降低至114℃時(shí),單纖上的成核潛伏時(shí)間逐漸縮短,橫晶的徑向生長速率逐漸降低。研究發(fā)現(xiàn),橫晶的生長與周圍球晶的生長相互競爭,并影響橫晶層的厚度。聚偏氟乙烯(PVDF)因其β晶型所呈現(xiàn)的壓電性得到了廣泛的關(guān)注。PVDF熔融結(jié)晶可得到α和γ晶型,兩種晶型可在一定條件下轉(zhuǎn)化為p晶型。本文第三章對PVDF熔融結(jié)晶過程中α和γ晶型結(jié)晶行為進(jìn)行了研究。110～180℃的溫度梯度場中等溫結(jié)晶8h的結(jié)果表明Y晶相在高溫下的成核能力高于α晶相,但γ晶相的徑向生長速率低于α晶相。T。164℃時(shí)得到單一的γ晶相；FTIR和DSC測試表明：隨著T。的降低,γ/α晶相含量比不斷降低。此外,首次發(fā)現(xiàn)了γ晶相對α晶相成核的誘導(dǎo)作用。隨后研究了CF/PVDF復(fù)合材料中橫晶的結(jié)晶行為,結(jié)果表明橫晶的晶相組成對Tc具有強(qiáng)烈的依賴性。Tc164℃時(shí),橫晶由單一的Y晶相構(gòu)成；150℃Tc160℃時(shí),CF表面出現(xiàn)了少量的α晶核,但Y晶相的異相成核仍占主要優(yōu)勢。Tc140℃時(shí),CF表面γ晶核的生長受到α晶的抑制,橫晶主要由α晶相構(gòu)成。144℃CTc156℃時(shí),CF表面的γ晶相橫晶能夠誘導(dǎo)α晶相成核,最終發(fā)展為橫晶結(jié)構(gòu),在界面處形成了雙層橫晶。第四章研究了少量PVDF的引入對PLLA結(jié)晶行為的影響。采用溶液共混法和熔融共混法分別制備了5/95和10/90 PVDF/PLLA共混物薄膜。溫度梯度場中等溫結(jié)晶的結(jié)果表明,PVDF可以提高PLLA的晶核密度,降低結(jié)晶尺寸。POM, DSC和WAXD證明PVDF可在共混物熔體中在較高溫度優(yōu)先結(jié)晶,成為PLLA的異相成核劑,提高PLLA的結(jié)晶溫度和成核速率。
[Abstract]:Crystallization temperature is an important factor affecting the aggregation structure of polymer and its composites. Therefore, the effect of crystallization temperature on the crystalline morphology and structure of polymers is of great theoretical and practical significance. The temperature gradient field is a high flux research method, which improves the experimental efficiency and reduces the experimental error. After the samples were subjected to isothermal crystallization in a temperature gradient field, the effect of continuously varying crystallization temperature on the morphology and structure of the crystal could be obtained in one experiment. In recent years, transgranular structure has become a new method to improve the interfacial bond properties of composites. In the second chapter, CF/PLLA composite films were prepared by solution casting method, using poly (lactic acid) (PLLA) as substrate and carbon fiber (CF) with high specific strength, excellent electrical conductivity and thermal conductivity as filler. The change of crystal morphology with crystallization temperature was studied by means of isothermal crystallization in temperature gradient field. The results show that with the decreasing of crystallization temperature from 132 鈩，

本文編號：1973213