High cis-polybutadiene (HCBR) was epoxidized by using in situ formed formic acid and hydrogen peroxide in the absence and presence of Tween 20 at 50 °C at different reaction times. Epoxidized HCBR (EHCBR) with degree of epoxidation from 3.7 to 38.8% was obtained. Low degree epoxidation EHCBR are semi-crystalline rubbers presenting lower crystallization temperatures than the non-epoxidized rubber on cooling and a cold crystallization and melting temperature on heating, differently from high epoxidation content rubbers (over 10%) which are amorphous materials. Epoxidation increases the glass transition temperature and decreases the melting temperature and the degree of crystallinity of the polybutadiene. The increase of epoxidation also decreases its thermal stability, which drops about 28 °C when the content of epoxidation is increased about 30%. Non-isothermal crystallization experiments of HCBR and EHCBR were systematically carried out at cooling rates of 5, 10, 20, and 30 °C/min to evaluate the crystallinity developed upon cooling. By increasing the cooling rate, the crystallization enthalpy increases for HCBR while it decreases for EHCBR.

中文翻译：

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环氧化高顺式聚丁二烯橡胶的热和结晶行为

高顺式在不存在和存在Tween 20的情况下，于50℃在不同的反应时间下，通过使用原位形成的甲酸和过氧化氢对-聚丁二烯（HCBR）进行环氧化。得到环氧化度为3.7至38.8％的环氧化HCBR（EHCBR）。低度环氧化EHCBR是半结晶橡胶，在冷却时的结晶温度低于非环氧化橡胶，在加热时的结晶结晶和熔融温度较低，这与非晶态材料的高环氧化含量的橡胶（超过10％）不同。环氧化增加了玻璃化转变温度并降低了熔融温度和聚丁二烯的结晶度。环氧化的增加也会降低其热稳定性，当环氧化的含量增加约30％时，热稳定性会下降约28°C。HCBR和EHCBR的非等温结晶实验是在5、10、20和30°C / min的冷却速率下系统进行的，以评估冷却时产生的结晶度。通过增加冷却速率，HCBR的结晶焓增加，而EHCBR则降低。