靜電紡絲纖維後處理與混摻4032D對左旋聚乳酸結晶行為的影響

Abstract

本研究分為兩部分，第一部分探討靜電紡絲纖維後處理的影響，第二部分討論混摻含有3~4%右旋單元(D-form)的左旋聚乳酸(此後稱4032D)，對於左旋聚乳酸(PLLA)結晶行為以及型態學上之變化。 電紡絲中討論聚乳酸/氯仿/四氫呋喃系統，在剛紡完的纖維會殘留水與溶劑在纖維皮層以及內部，且電紡絲過程會造成高分子非晶質的有序排列結構，利用不同後處理方式(例如真空乾燥、浸泡非溶劑)，觀察殘留溶劑改變以及有序結構影響的程度。從TGA與DSC結果發現，纖維浸泡在非溶劑會較有效去除殘留溶劑，但也改變非晶質有序結構，認為是非溶劑會澎潤皮層與殘留溶劑交換，同時造成分子鏈鬆弛運動，我們也觀察浸泡不同非溶劑對於分子鏈鬆弛運動的影響。 在混摻系統中主要利用POM討論混摻不同比例4032D對PLLA結晶行為與形態學的影響。從球晶成長速度得知，D-form單元的加入會改變鏈的規整度、鏈運動的活化能與折疊自由能，綜合因素使球晶成長速度下降。從型態學得知，混摻物與4032D的球晶會出現環狀結構，來自D-form單元改變晶體的折疊鏈方式。也觀察結晶形態得知D-form單元比例的提高，影響晶核的形成機制，使晶核密度下降。最後利用DSC觀察熱性質，並輔佐說明POM觀察到的結晶行為知道D-form的加入使結晶速度的降低。

This study is divided into two parts. The first part discusses the effect of electrospun post-processing. The second part studies the effect of crystallization behavior and crystal morphology of PLLA when blending poly(L-lactic acid) containing 3~4% D-form(hereinafter referred to as 4032D). The PLA/Chloroform/THF ternary system is discussed in electrospinning. The electrospinning fibers will remain water on the surface of the fiber, the solvent of the skin layer, and the water and solvent inside the fiber after electrospinning. Also, the electrospinning process will result in ordered structure in amorphous area. We use different post-processing methods (vacuum drying or soaking in non-solvent) to observe the degree of residual solvent and the ordered structure. From the results of TGA and DSC, it is found that soaking the electrospun into non-solvent will remove the residual solvent more effectively, and it also change the order structure of the amorphous. Simultaneously, we observe the influence of soaking fibers in different non-solvents on the molecular relaxation. In blending system, POM is mainly used to discuss the influence of crystallization behavior and crystal morphology after blending 4032D into PLLA. It is known from the spherulites growth rate that the addition of D-form units will change the regularity of the chain, the activation energy of molecular motion and the free energy of folding, and the combined factors will reduce the growth of spherulites. From the crystal morphology, we know that the 4032D and blending system show a ring structure on spherulite, and it comes from the D-form units change the way of crystal folded. Also from the morphology, it is known that the increase in the proportion of 4032D affects the formation mechanism of crystal nucleus and reduces the density of crystal nucleus. We use DSC to observe the thermal properties, and DSC analysis assist in explaining the crystallization behavior by POM, knowing that the blending of 4032D reduces the crystallization rate.