标题: | 液晶共聚酯与聚醯胺6,6掺合物之相容性与结晶性质的研究 Miscibility and Crystallization in Blends of Liquid Crystalline Copolyester and Polyamide 6,6 |
作者: | 汪信亨 Hsin-Heng Wang 韦光华 Kung-Hwa Wei 材料科学与工程学系 |
关键字: | 相容性;掺合;聚醯胺6,6;液晶高分子;Miscibility;Blend;PA66;lcp |
公开日期: | 2000 |
摘要: | 本论文为研究POB-PET莫耳比为60/40的杂式液晶共聚酯copoly (oxybenzoate-terephthalate) (简称为P64)与聚醯胺6,6 (polyamide 6,6,简称为PA66)掺合物的相容性与结晶性。由微差扫描式热分析仪(DSC)的结果得知不同组成的P64/PA66掺合物只有一个玻璃转移温度(Tg点),虽然P64与PA66的Tg点相近( 60.9oC与51.6oC),但进一步分析掺和物之熔点下降,可以得到掺合物之Flory-Huggins 作用参数为-0.19,因此我们可以得知在热熔态时掺合物中P64与PA66为部份相容。而由偏光显微镜(POM)的研究,当PA66含有7 wt %的P64时,呈现出最大的晶体。再由广角X-Ray的绕射图谱分析,经计算其Miller (002)和(010/110) 面的coherence length值在加入7 wt %的P64时为最大,表示少量的P64可使PA66分子链的排列更为有规则,使结晶变得更大,这与POM所观察出的结果一致。 在研究P64/PA66掺合物之等温结晶动力学(Isothermal crystallization kinetics)方面,在Avrami plot中掺合物呈现出一次和二结晶的行为,经分析一次结晶之Avrami exponent后,可得知其值随着P64的含量增加而下降,显示出球晶成长方式的改变,而其结晶速率常数k则显示出,当掺和物含有7 wt %的P64时,其结晶速率常数值最大,之后随着P64的含量增加而下降,此因P64/PA66掺合物的相容性,使得P64的含量增加时破坏PA66结晶的对称性,使结晶速率变小。而非等温结晶动力学(Non-isothermal crystallization kinetics)的研究中,由于P64/PA66掺和物存在着二次结晶的现象,使得一般常用的Ozawa方程式无法适用,因此我们选用另一种方程式来模拟,其结果与等温结晶动力学一致。 由于P64/PA66掺和物可能有酯-胺交换反应发生,而影响到掺和物之物性,因此我们利用13C 核磁共振光谱仪研究杂式液晶共聚酯P64与聚醯胺6,6 (PA66)的掺合物之酯-胺交换反应。我们可以发现在300oC持温10分钟才有酯-胺交换反应发生,因此可知在我们实验过程当中所进行的持温程序并不会发生酯-胺交换反应而影响到结果。而由掺合物极限黏度值的分析,我们可知由于P64与PA66分子之间的酯-胺交换反应及高分子链的裂解造成掺合物的极限黏度降低。 Miscibility in blends of random liquid crystalline copoly(oxybenzoate -ethylene terephthalate) at molar ratio 60/40 (P64) and spolyamide 6,6 (PA66) were investigated with differential scanning calorimetry, wide angle X-ray diffraction and polarized optical micrography. It was found that P64 and PA66 were partially miscible as evidenced from the appearance of a single glass transition temperature for each blend at different composition. At the melt state, the Flory-Huggins interaction parameter, □12, which was determined to be – 0.19 through the melting point depression analysis. The coherence lengths of PA66 in the presence of a small amount (around 7 wt%) of P64 were larger than that in pure PA66. The isothermal and non-isothermal crystallization behaviour in blends of P64 and PA66 were studied with differential scanning calorimetry. In isothermal crystallization experiment, the Avrami exponent were found to decrease with increase the concentrate of P64 and the crystallization rate coefficient had largest value in the small amount (7%) of P64. In non-isothermal crystallization experiment, we found that the Ozawa equation can not work on our case. We selected another one equation to discuss our results. The 13C nuclear magnetic resonance was found that the ester –amide exchange in the two polymers took place within 10 min when the blend was annealed at 300oC. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT890159056 http://hdl.handle.net/11536/66680 |
显示于类别: | Thesis |