聚乳酸结晶性能的调控及其机理的研究
发布时间：2018-11-09 17:46
【摘要】：聚乳酸是一种来源可再生、自身可降解、生物相容性好的环境友好型材料。因为PLA的脆性大、冲击性差和耐热性差等缺点限制了PLA在应用领域的进一步扩大。加入成核剂可以大大改变PLA的结晶性,进而改变PLA的加工性、力学性能、热性能和透光率等性能。因此,研究聚乳酸在不同成核剂作用下的结晶性能和结晶机理具有重要的意义。本文研究了科莱恩Nav101、纳米凹凸棒粘土和吸附了山梨醇成核剂NX8000K的纳米凹凸棒成核剂对PLA结晶性能和动态热机械性能的影响以及不同浓度成核促进剂(CBT)对PLA/PPZn0.5结晶性能和其他性能的影响。首先,采用熔融共混的方法制备了PLA/Nav101复合物,研究了不同浓度的科莱恩Nav101成核剂对PLA的热性能、结晶性、动态力学性能和透光率等。结果表明,Nav101成核剂浓度为0.05%时对提高PLA的结晶性达到最佳状态即结晶度和晶体密度均最大,继续增加Nav101的浓度结晶性能趋于稳定,Nav101不会改变PLA的晶型。DMA测试表明,在玻璃态区,PLA/Nav1010.05的E’和Tg均达到最大值,当Nav101的含量超过0.05%时,E’反而逐渐下降。在整个可见光区域内,加入少量的Nav101成核剂后,PLA中透光率明显下降。继续增大Nav101的含量,PLA的平均透光率的下降趋势有所减缓。其次,用溶剂浇铸法制备了PLA/AT纳米复合材料,研究了纳米凹凸棒粘土(AT)的浓度效应对PLA结晶性和透明性的影响。研究发现AT不会改变PLA的晶型。对于溶剂直接挥发所成的膜AT会降低PLA的结晶度,当纳米凹凸棒含量为3%时,结晶度的降低程度最小;但是,消除热历史后的样品,AT可以提高PLA的结晶性能。DMA测试发现极少量的AT(0.1%wt)会降低PLA的储能模量和玻璃化转变温度,复合材料含3%的AT时PLA的E’和Tg值最大。加入AT后大大降低PLA的透光率,当含3%的AT时复合物透光率几乎降为零。再次,为了改善纳米凹凸棒对PLA的结晶性和透明性的影响,用含不同浓度山梨醇成核剂的N,N-二甲基甲酰胺溶液处理纳米凹凸棒,研究吸附了不同含量NX8000K的纳米凹凸棒对PLA结晶性和透明性的影响。XRD测试表明,吸附了山梨醇成核剂后并没有改变纳米凹凸棒的晶体结构,但是检测不到NX8000K的晶体特征峰。DSC测试表明,AT-NX8000K降低了溶剂浇铸成膜的PLA复合材料的结晶性,其中PLA/AT1-NX3对PLA结晶度降低的影响最小;但是对于消除热历史后的复合材料,AT-NX8000K反而提高了PLA的热结晶度,说明用山梨醇成核剂修饰纳米凹凸棒有利于改善纳米凹凸棒对PLA的结晶性能的影响。另外,修饰后的AT,可以改善复合材料的透明性,且随着山梨醇成核剂比例的增大透明性逐渐增大,PLA/AT1-NX3出现的反常现象,是因为它的结晶度比PLA/AT1-NX1的结晶度大。最后,主要研究CBT对PLA/PPZn复合材料结晶性能的影响。研究发现寡聚物CBT可以促进PLA/PPZn0.5的结晶性能,其中CBT浓度为0.4%时效果最佳,结晶度和结晶速率均是最大。POM发现CBT可以促进PLA形成的球晶更加完善,在150℃等温结晶时,CBT含量超过0.4%后复合材料的晶体密度会降低。DMA测试表明,随着CBT含量的增加储能模量和Tg均增大,但在CBT含量为0.8%出现了反常。在PLA/PPZn0.5中加入CBT可以增大基体的熔融指数,但是仍低于纯PLA的熔融指数,加入0.6%的CBT就已达到PLA/PPZn0.5材料熔体流动性最佳状态。对于透光率的研究发现,在PLA/PPZn0.5中加入少量的CBT(≤0.4%)可以增大透光率且随CBT含量的增加而增大;加入大量的CBT(≥0.6%)时,复合材料的透光率反而随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，
本文编号：2321123
[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，
本文编号：2321123
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