Enhancing Thermomechanical Properties and Heat Distortion Resistance of Poly(L-lactide) with High Crystallinity under High Cooling Rate
Enhancing Thermomechanical Properties and Heat Distortion Resistance of Poly(L-lactide) with High Crystallinity under High Cooling Rate
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高冷却速率下提高高结晶度聚L-丙交酯的热机械性能和耐热变形性能
DOI：
10.1021/sc500783s
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发表时间：
2015
影响因子：
8.4
通讯作者：
Yang Ming-Bo
中科院分区：
文献类型：
--
作者：
Yin Hai-Yan;Wei Xin-Feng;Bao Rui-Ying;Dong Quan-Xiao;Liu Zheng-Ying;Yang Wei;Xie Bang-Hu;Yang Ming-Bo
本论文采用一种新型的成核剂（NA），报道了自身高熔点的同辛内酯（hPLLA微晶）。特别地，将具有187 °C的熔融温度（Tm）的hPLLA微晶引入具有较低Tm的PLLA基质中，即，通过在170 °C下简单地熔融共混（其在两种PLLA的Tm之间），可以在168 °C下制备聚乳酸。非等温和等温结晶结果表明，PLLA微晶是PLLA的有效成核剂.此外，与两种广泛报道的用于PLLA的NA、滑石和立构复合物微晶相比，hPLLA微晶对PLLA的结晶速率显示出显著得多的促进作用。最重要的是，这种促进作用在非常高的冷却速率下仍然有效，导致在100 °C/min的冷却速率下结晶度为39.1%，这有助于在常规制造工艺中获得高结晶度PLLA产品。光学显微镜观察表明，由于hPLLA微晶与PLLA基体具有相同的化学组成和晶格组成，从而产生了显著的异相成核效应，从而显著促进了PLLA的结晶。进一步的表征表明，通过使用这种新型高效NA来提高PLLA的结晶度，可以显著提高PLLA的热机械性能和耐热变形性能。例如，在80 °C（高于PLLA的Tg）下，在掺入5wt%hPLLA的情况下，弹性模量从8增加到477 MPa，增加了60倍。
In this work, a novel, effective and simple approach to largely improve the thermomechanical properties and heat distortion resistance of biodegradable poly(l-lactide) (PLLA) by using a new nucleating agent (NA), i.e., itself high-melting-point homocrystallites (hPLLA crystallites) is reported. Specially,hPLLA crystallites with a melting temperature (Tm) of 187 °C were introduced into the PLLA matrix with a lowerTm, i.e., 168 °C via simply melt blending at 170 °C which is between theTms of the two PLLAs. Nonisothermal and isothermal crystallization results reveal thathPLLA crystallite is an efficient nucleating agent for PLLA. Also,hPLLA crystallites show much more prominently promoting effect on the crystallization rate of PLLA in comparison with two widely reported NAs for PLLA, talc and stereocomplex crystallites. Most importantly, this promoting effect is still efficient at very high cooling rate, leading to a crystallinity of 39.1% at a cooling rate of 100 °C/min, which can help to obtain high-crystallinity PLLA products in conventional manufacturing processes. The optical microscopic observation reveals that the remarkable crystallization promotion can be attributed to the outstanding heterogeneous nucleation effect, as a result of both identical chemical constitution and lattice constitution betweenhPLLA crystallites and PLLA matrix. Further characterizations indicate that the enhancement of PLLA crystallinity by using such a new efficient NA can enhance the thermomechanical properties and heat distortion resistance of PLLA remarkably. For instance, at 80 °C (aboveTgof PLLA), the elastic modulus increases by 60 times from 8 to 477 MPa with the incorporation of 5 wt %hPLLA.