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Chain structure, linear viscoelasticity and extensional rheology of poly(4‐vinyl biphenyl‐stat‐styrene) statistical copolymers
Polymer Engineering and Science ( IF 3.2 ) Pub Date : 2021-01-18 , DOI: 10.1002/pen.25641 Carlos R. López‐Barrón 1
Polymer Engineering and Science ( IF 3.2 ) Pub Date : 2021-01-18 , DOI: 10.1002/pen.25641 Carlos R. López‐Barrón 1
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A series of statistical copolymers of 4‐vinylbiphenyl and styrene were prepared via free radical polymerization to investigate the effect of the comonomer ratio on their microstructure and rheological properties. The glass transition temperature of the copolymers follows a nonlinear monotonic decreasing dependence with increasing styrene content which is well described by the Gordon‐Taylor equation. WAXS measurements reveal that both the backbone to backbone and the inter‐phenyl distances (d1 and d2, respectively) are decreasing functions of the styrene content in the copolymers. The apparent monomeric friction coefficient, calculated from dynamic frequency sweeps in the linear viscoelastic regime, decreases exponentially with the styrene content in the copolymer. We postulate that the strong effect of the copolymer composition on the friction coefficient is due to the larger overlapping distance between phenyl rings of adjacent polymer chains (doverlap), giving rise to stronger aromatic π–π interactions, which in turn results in stronger friction between adjacent chains. The increase in doverlap and monomeric friction coefficient also leads to a significant increase in the extensional strain hardening measured during extensional startup flow measurements.
中文翻译：
聚（4-乙烯基联苯-静态-苯乙烯）统计共聚物的链结构，线性粘弹性和延伸流变性
通过自由基聚合制备了一系列4-乙烯基联苯和苯乙烯的统计共聚物，以研究共聚单体比例对它们的微观结构和流变性能的影响。共聚物的玻璃化转变温度随苯乙烯含量的增加而呈非线性单调递减依赖性，这可以通过Gordon-Taylor方程很好地描述。WAXS测量显示，主链到主链以及苯间距离（d 1和d 2分别是共聚物中苯乙烯含量的递减函数。由线性粘弹性状态下的动态频率扫描计算得出的表观单体摩擦系数随共聚物中苯乙烯含量的增加呈指数下降。我们假设共聚物组合物对摩擦系数的强烈影响是由于相邻聚合物链的苯环之间的重叠距离更大（d重叠），从而导致更强的芳族π - π相互作用，进而导致更强的摩擦力。在相邻链之间。d重叠的增加 单体摩擦系数也导致在拉伸启动流量测量期间测得的拉伸应变硬化显着增加。
更新日期：2021-01-18
中文翻译：
聚（4-乙烯基联苯-静态-苯乙烯）统计共聚物的链结构，线性粘弹性和延伸流变性
通过自由基聚合制备了一系列4-乙烯基联苯和苯乙烯的统计共聚物，以研究共聚单体比例对它们的微观结构和流变性能的影响。共聚物的玻璃化转变温度随苯乙烯含量的增加而呈非线性单调递减依赖性，这可以通过Gordon-Taylor方程很好地描述。WAXS测量显示，主链到主链以及苯间距离（d 1和d 2分别是共聚物中苯乙烯含量的递减函数。由线性粘弹性状态下的动态频率扫描计算得出的表观单体摩擦系数随共聚物中苯乙烯含量的增加呈指数下降。我们假设共聚物组合物对摩擦系数的强烈影响是由于相邻聚合物链的苯环之间的重叠距离更大（d重叠），从而导致更强的芳族π - π相互作用，进而导致更强的摩擦力。在相邻链之间。d重叠的增加 单体摩擦系数也导致在拉伸启动流量测量期间测得的拉伸应变硬化显着增加。
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