Su Bei, Zhou Ying-Guo
School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China.
Materials (Basel). 2019 Feb 14;12(4):563. doi: 10.3390/ma12040563.
Poly(cyclohexylene dimethylene cyclohexanedicarboxylate) (PCCE) is a kind of copolyester polymer with excellent toughness and outstanding flexibility. However, the opacity caused by crystallization limits the widespread application of PCCE in products that have transparency requirements. The effects of 1,3:2,4-Di-p-methylbenzylidene sorbitol (MDBS) on the crystallization behavior, transparency, and mechanical properties of a PCCE melt were investigated via differential scanning calorimetry (DSC), spectrophotometry, and tensile testing. The results suggest that the transparency and mechanical properties of PCCE drastically improve and that its crystallization behaviors are obviously influenced by the addition of MDBS. PCCE with 0.6 wt% MDBS was then selected as a representative sample, and its thermal behavior and crystal morphology were further investigated by DSC, hot-staged polarizing microscopy (HSPLM), and scanning electron microscopy (SEM). The quantitative results suggest that, compared to neat PCCE resin, PCCE/MDBS has a lower isothermal and nonisothermal crystallization activation energy, which indicates a rapid crystallization process. The results also show that, compared to the pure PCCE melt, the PCCE/MDBS melt experiences a greater increase in the number of crystals and a greater decrease in the crystal size during cooling. The acceleration of the crystallization process and reduction in crystal size can be both attributed to the nucleation effect of the MDBS. In conclusion, because the addition of the nucleating agent improves the transparency and tensile properties of PCCE by adjusting and controlling its thermal and crystallization behaviors, the proposed technique of using a compounding nucleating agent to control crystallization is therefore suitable for PCCE.
聚（环己烷二甲醇环己烷二甲酸酯）（PCCE）是一种具有优异韧性和出色柔韧性的共聚酯聚合物。然而，结晶引起的不透明性限制了PCCE在有透明度要求的产品中的广泛应用。通过差示扫描量热法（DSC）、分光光度法和拉伸试验研究了1,3:2,4-二对甲基亚苄基山梨醇（MDBS）对PCCE熔体结晶行为、透明度和力学性能的影响。结果表明，添加MDBS后，PCCE的透明度和力学性能大幅提高，其结晶行为也受到明显影响。然后选择含有0.6 wt% MDBS的PCCE作为代表性样品，通过DSC、热台偏光显微镜（HSPLM）和扫描电子显微镜（SEM）进一步研究其热行为和晶体形态。定量结果表明，与纯PCCE树脂相比，PCCE/MDBS具有较低的等温结晶和非等温结晶活化能，这表明其结晶过程较快。结果还表明，与纯PCCE熔体相比，PCCE/MDBS熔体在冷却过程中晶体数量增加更多，晶体尺寸减小更多。结晶过程的加速和晶体尺寸的减小都可归因于MDBS的成核作用。总之，由于添加成核剂通过调节和控制PCCE的热行为和结晶行为提高了其透明度和拉伸性能，因此所提出的使用复合成核剂控制结晶的技术适用于PCCE。
