【摘 要】
：
Extensional fields(processing temperature,shear flow,drawing and annealing,etc)play crucial roles in crystallization mediation of polymers.Since Ikade et al.reported that equimolar mixing of poly(L-la
【机 构】
：
Beijing National Laboratory for Molecular Sciences,Key Laboratory of Engineering Plastic,Institute o
【出 处】
：
The 11th International Symposium on Polymer Physics(PP2014)(
论文部分内容阅读
Extensional fields(processing temperature,shear flow,drawing and annealing,etc)play crucial roles in crystallization mediation of polymers.Since Ikade et al.reported that equimolar mixing of poly(L-lactic acid)(PLLA)/poly(D-lactic acid)(PDLA)produces stereocomplex(sc)crystals with Tm around 230℃,1 crystallization behavior of PLLA/PDLA under different extensional fields has attracted widely interest.2-5 However,preparation of PLLA/PDLA materials with high content of sc-crystals still has many issues due to a competition between homo-polymer crystals(α-crystals)and sc-crystals.In the present work,effect of melting temperature,cooling rate and drawing on the crystallization behavior of PLLA/PDLA blends were investigated.The results showed that PLLA/PDLA(weight ratio: 1:1)blends cooling from different melting temperatures had different crystallization behaviors(Figure 1).With the increase of melting temperature,the crystallization peaks of sc-crystals and α-crystals shifted to lower temperature and the crystallization rate decreases.At the same melting temperature,the crystallization abilities of blends were depressed due to the fast cooling rates(Figure 2).Highly oriented sc-crystals were obtained by drawing PLLA/PDLA(1/1)blends at around Tg and then annealing at a temperature between the melting point of α-crystals and sc-crystals(Figure 3).The above results provide a basis understanding for the crystallization behavior of PLLA/PDLA blends.
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