Zhang Xiaohu, Li Xiaofan, Zhu Wenbin, Xie Xinzheng, Ji Huan, Bi Jifu
Huangpu Institute of Materials, Centers for Aircraft Science, Guangzhou 510700, China.
Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130102, China.
Polymers (Basel). 2023 Dec 21;16(1):35. doi: 10.3390/polym16010035.
The crystallization behavior of neodymium-based rare earth polybutadiene rubber (Nd-BR) is studied in the presence of small-molecule treated distillate aromatic extract (TDAE) and high-molecular-weight polybutadiene-isoprene copolymer rubber (BIR). Pronounced inhibitory effects on the crystallization of Nd-BR are exhibited by both materials, as evidenced by reductions in the crystallization temperature (), melting point (), and corresponding enthalpy change. It is found that, at equal concentrations, a greater influence on the crystallization rate is exerted by TDAE oils, whereas nucleation inhibition is more potently affected by BIR. Incomplete crystallization during cooling is exhibited by Nd-BR when the TDAE oil concentration reaches 40 parts per hundreds of rubber (PHR) (31 wt.%), or BIR achieves a 60 wt.% concentration; subsequently, a noticeable cold crystallization phenomenon is observed upon heating. Insights into the isothermal crystallization kinetics are offered by the data, which reveal that the Avrami index value for Nd-BR predominantly ranges between 2.5 and 3.0. A decrease in the value is induced by a small amount of TDAE oil, while a noticeable decline in the value is observed only when the BIR concentration is 60 wt.%. A correlation between the crystallization activation energy, the concentration of TDAE oil and BIR, and the crystallization temperature is established; a negative activation energy is recorded, and a decrease in the crystallization rate is noted when both concentrations are low and the crystallization temperature exceeds -50 °C. In contrast, positive activation energy and an increase in the crystallization rate are observed when the BIR concentration reaches 60%, and the crystallization temperature resides between -50 °C and -70 °C.
在小分子处理的馏分芳烃抽提物（TDAE）和高分子量聚丁二烯-异戊二烯共聚物橡胶（BIR）存在的情况下，研究了钕基稀土聚丁二烯橡胶（Nd-BR）的结晶行为。两种材料均对Nd-BR的结晶表现出明显的抑制作用，结晶温度（）、熔点（）和相应的焓变降低证明了这一点。研究发现，在浓度相等时，TDAE油对结晶速率的影响更大，而BIR对成核抑制的影响更显著。当TDAE油浓度达到40份每百份橡胶（PHR）（31 wt.%）或BIR浓度达到60 wt.%时，Nd-BR在冷却过程中出现不完全结晶；随后，加热时观察到明显的冷结晶现象。这些数据提供了对等温结晶动力学的深入了解，结果表明Nd-BR的Avrami指数值主要在2.5至3.0之间。少量TDAE油会导致该值降低，而只有当BIR浓度为60 wt.%时，该值才会明显下降。建立了结晶活化能、TDAE油和BIR浓度与结晶温度之间的相关性；记录到负的活化能，当两种浓度都较低且结晶温度超过-50°C时，结晶速率下降。相反，当BIR浓度达到60%且结晶温度在-50°C至-70°C之间时，观察到正的活化能和结晶速率增加。
