【摘要】：聚乳酸是一種來源可再生、自身可降解、生物相容性好的環(huán)境友好型材料。因?yàn)镻LA的脆性大、沖擊性差和耐熱性差等缺點(diǎn)限制了PLA在應(yīng)用領(lǐng)域的進(jìn)一步擴(kuò)大。加入成核劑可以大大改變PLA的結(jié)晶性,進(jìn)而改變PLA的加工性、力學(xué)性能、熱性能和透光率等性能。因此,研究聚乳酸在不同成核劑作用下的結(jié)晶性能和結(jié)晶機(jī)理具有重要的意義。本文研究了科萊恩Nav101、納米凹凸棒粘土和吸附了山梨醇成核劑NX8000K的納米凹凸棒成核劑對(duì)PLA結(jié)晶性能和動(dòng)態(tài)熱機(jī)械性能的影響以及不同濃度成核促進(jìn)劑(CBT)對(duì)PLA/PPZn0.5結(jié)晶性能和其他性能的影響。首先,采用熔融共混的方法制備了PLA/Nav101復(fù)合物,研究了不同濃度的科萊恩Nav101成核劑對(duì)PLA的熱性能、結(jié)晶性、動(dòng)態(tài)力學(xué)性能和透光率等。結(jié)果表明,Nav101成核劑濃度為0.05%時(shí)對(duì)提高PLA的結(jié)晶性達(dá)到最佳狀態(tài)即結(jié)晶度和晶體密度均最大,繼續(xù)增加Nav101的濃度結(jié)晶性能趨于穩(wěn)定,Nav101不會(huì)改變PLA的晶型。DMA測試表明,在玻璃態(tài)區(qū),PLA/Nav1010.05的E’和Tg均達(dá)到最大值,當(dāng)Nav101的含量超過0.05%時(shí),E’反而逐漸下降。在整個(gè)可見光區(qū)域內(nèi),加入少量的Nav101成核劑后,PLA中透光率明顯下降。繼續(xù)增大Nav101的含量,PLA的平均透光率的下降趨勢有所減緩。其次,用溶劑澆鑄法制備了PLA/AT納米復(fù)合材料,研究了納米凹凸棒粘土(AT)的濃度效應(yīng)對(duì)PLA結(jié)晶性和透明性的影響。研究發(fā)現(xiàn)AT不會(huì)改變PLA的晶型。對(duì)于溶劑直接揮發(fā)所成的膜AT會(huì)降低PLA的結(jié)晶度,當(dāng)納米凹凸棒含量為3%時(shí),結(jié)晶度的降低程度最小;但是,消除熱歷史后的樣品,AT可以提高PLA的結(jié)晶性能。DMA測試發(fā)現(xiàn)極少量的AT(0.1%wt)會(huì)降低PLA的儲(chǔ)能模量和玻璃化轉(zhuǎn)變溫度,復(fù)合材料含3%的AT時(shí)PLA的E’和Tg值最大。加入AT后大大降低PLA的透光率,當(dāng)含3%的AT時(shí)復(fù)合物透光率幾乎降為零。再次,為了改善納米凹凸棒對(duì)PLA的結(jié)晶性和透明性的影響,用含不同濃度山梨醇成核劑的N,N-二甲基甲酰胺溶液處理納米凹凸棒,研究吸附了不同含量NX8000K的納米凹凸棒對(duì)PLA結(jié)晶性和透明性的影響。XRD測試表明,吸附了山梨醇成核劑后并沒有改變納米凹凸棒的晶體結(jié)構(gòu),但是檢測不到NX8000K的晶體特征峰。DSC測試表明,AT-NX8000K降低了溶劑澆鑄成膜的PLA復(fù)合材料的結(jié)晶性,其中PLA/AT1-NX3對(duì)PLA結(jié)晶度降低的影響最小;但是對(duì)于消除熱歷史后的復(fù)合材料,AT-NX8000K反而提高了PLA的熱結(jié)晶度,說明用山梨醇成核劑修飾納米凹凸棒有利于改善納米凹凸棒對(duì)PLA的結(jié)晶性能的影響。另外,修飾后的AT,可以改善復(fù)合材料的透明性,且隨著山梨醇成核劑比例的增大透明性逐漸增大,PLA/AT1-NX3出現(xiàn)的反�，F(xiàn)象,是因?yàn)樗慕Y(jié)晶度比PLA/AT1-NX1的結(jié)晶度大。最后,主要研究CBT對(duì)PLA/PPZn復(fù)合材料結(jié)晶性能的影響。研究發(fā)現(xiàn)寡聚物CBT可以促進(jìn)PLA/PPZn0.5的結(jié)晶性能,其中CBT濃度為0.4%時(shí)效果最佳,結(jié)晶度和結(jié)晶速率均是最大。POM發(fā)現(xiàn)CBT可以促進(jìn)PLA形成的球晶更加完善,在150℃等溫結(jié)晶時(shí),CBT含量超過0.4%后復(fù)合材料的晶體密度會(huì)降低。DMA測試表明,隨著CBT含量的增加儲(chǔ)能模量和Tg均增大,但在CBT含量為0.8%出現(xiàn)了反常。在PLA/PPZn0.5中加入CBT可以增大基體的熔融指數(shù),但是仍低于純PLA的熔融指數(shù),加入0.6%的CBT就已達(dá)到PLA/PPZn0.5材料熔體流動(dòng)性最佳狀態(tài)。對(duì)于透光率的研究發(fā)現(xiàn),在PLA/PPZn0.5中加入少量的CBT(≤0.4%)可以增大透光率且隨CBT含量的增加而增大;加入大量的CBT(≥0.6%)時(shí),復(fù)合材料的透光率反而隨CBT含量的增加而降低。
[Abstract]:Polylactic acid is a kind of environment-friendly material with renewable, self-degradable and good biocompatibility. Because of the large brittleness, poor impact and poor heat resistance of PLA, the further expansion of PLA in the field of application is limited. the addition of the nucleating agent can greatly change the crystallinity of the PLA, and further change the properties of the processability, the mechanical property, the thermal property and the light transmittance of the PLA. Therefore, it is of great significance to study the crystallization and crystallization mechanism of polylactic acid under different nucleating agents. The effects of the nano-attapulgite nucleating agent on the properties of PLA/ PPZn0. 5 and other properties of PLA/ PPZn0. 5 were studied in this paper. The effects of the nano-attapulgite nucleating agent on the properties of PLA/ PPZn0. 5 and the properties of the PLA/ PPZn0. 5 were studied. First, the PLA/ Nav101 complex was prepared by melt blending, and the thermal properties, crystallinity, dynamic mechanical properties and light transmittance of the PLA/ Nav101 nucleating agent for PLA were studied. The results show that when the concentration of the Na101 nucleating agent is 0. 05%, the crystallinity and the crystal density of the PLA are the best, the crystallinity and the crystal density are the largest, the concentration and crystallization performance of the Nav101 is continued to be stabilized, and the Nav101 does not change the crystal type of the PLA. The DMA test shows that in the glass-state area, the E of the PLA/ Nav1010.05 'and Tg all reach the maximum value, when the content of the Nav101 exceeds 0.05%, E' Instead, it's getting down. After the addition of a small amount of the Nav101 nucleating agent throughout the visible region, the light transmittance in the PLA was significantly reduced. Continuing to increase the content of the Nav101, the decrease in the average light transmittance of the PLA is slowed. Secondly, the PLA/ AT nanocomposite was prepared by the method of solvent casting, and the effect of the concentration of the nano-attapulgite clay (AT) on the crystallinity and transparency of PLA was studied. The study found that AT does not change the crystalline form of PLA. The film AT directly volatilizes the solvent can lower the crystallinity of the PLA, and when the content of the nano-attapulgite is 3%, the degree of crystallinity is minimized; however, the AT can improve the crystallization property of the PLA when the sample after the heat history is eliminated. The DMA test found that a very small amount of AT (0.1% wt) would reduce the storage modulus and the glass transition temperature of the PLA, and the E of PLA when the composite contains 3% AT The value of 'and Tg' is the maximum. After the addition of the AT, the light transmittance of the PLA is greatly reduced, and the light transmittance of the composite is almost zero when the AT is contained in 3%. Thirdly, in order to improve the effect of nano-attapulgite on the crystallinity and transparency of PLA, the effect of nano-attapulgite on the crystallinity and transparency of PLA was studied by using N, N-dimethylamino-amine solution with different concentration of sorbitol nucleating agent to treat the nano-attapulgite. The XRD test shows that the crystal structure of the nano-attapulgite is not changed after the sorbitol nucleating agent is adsorbed, but the crystal characteristic peak of the NX8000K is not detected. The DSC test shows that AT-NX8000K reduces the crystallinity of the PLA composite film formed by solvent casting, wherein the effect of PLA/ AT1-NX3 on the reduction of the crystallinity of PLA is the least; however, the AT-NX8000K improves the thermal crystallinity of the PLA, The effect of modifying the nano-attapulgite with a sorbitol nucleating agent is beneficial to the improvement of the crystallization property of the nano-attapulgite on the PLA. In addition, the modified AT can improve the transparency of the composite material and gradually increase the transparency with the increase of the proportion of the sorbitol nucleating agent, as the degree of crystallinity of the PLA/ AT1-NX3 is larger than that of the PLA/ AT1-NX1. Finally, the effect of CBT on the crystallization behavior of PLA/ PPZn composite was studied. It was found that the oligomer CBT can promote the crystallization of PLA/ PPZn 0.5, with the CBT concentration of 0.4%, the best effect, the crystallinity and the crystallization rate being the largest. POM has found that CBT can promote the improvement of the spherulites formed by PLA, and at the temperature of 150 鈩，

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