Epoxy thermosets comprised of plant oils along with simple curing agents are sustainable and environmentally friendly polymers. The curing agent selected, and its compatibility with epoxy monomers, strongly affects the curing kinetics, the extent of curing, and the final properties of an epoxy polymers. The goal of this work is to expand the application of epoxidized oils in formulating biobased thermoset polymer systems. Epoxidized hemp oil (EHO) was produced with 8% oxirane oxygen content (OOC) after 24 hours using in situ generated performic acid. Two model curing agents—one aromatic (trimellitic anhydride, TMA) and one biobased nonaromatic (citric acid, CA)—with similar molecular weights were selected to study the cure behavior of EHO in acetone. Both curing agents are insoluble in EHO. The prepolymerization curing reaction behavior was monitored via the OOC, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, and gel permeation chromatography. It was demonstrated that at 50 °C, the reaction of EHO with TMA was extremely fast to form esters of TMA, while the reaction of EHO with CA was slower and followed different pathways. The cured EHO/TMA epoxy network is rigid and has a high alpha relaxation temperature (T _α) of 89 °C, which is associated with the glass transition temperature (T _g), while the cured EHO/CA network system is semirigid with a T _α of 40 °C. In addition, TGA analysis showed that the EHO/TMA resin system represents a more homogenous structure compared to the EHO/CA system, as indicated by the presence of lower‐temperature decompositions of citric acid derivatives.

中文翻译：

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用于热固性网络制备的环氧麻油预聚物的开发

由植物油和简单的固化剂组成的环氧树脂热固性材料是可持续的，环保的聚合物。所选择的固化剂及其与环氧单体的相容性会极大地影响固化动力学，固化程度和环氧聚合物的最终性能。这项工作的目的是扩大环氧化油在配制生物基热固性聚合物体系中的应用。使用原位生产24小时后，环氧乙烷油（EHO）的环氧乙烷含量为8％（OOC）生成过甲酸。选择了两种具有相似分子量的模型固化剂-一种芳香族（偏苯三酸酐，TMA）和一种生物基非芳香族（柠檬酸，CA）-来研究EHO在丙酮中的固化行为。两种固化剂均不溶于EHO。通过OOC，衰减全反射傅里叶变换红外（ATR-FTIR）光谱和凝胶渗透色谱法监测预聚合固化反应行为。结果表明，在50°C下，EHO与TMA的反应非常快，形成TMA的酯，而EHO与CA的反应较慢，并且遵循不同的途径。固化的EHO / TMA环氧网络是刚性的，并且具有高的α松弛温度（Ť _α的89℃，其与玻璃化转变温度相关联）（ Ť_克），而固化EHO / CA网络系统半刚性与Ť _α的40℃。此外，TGA分析表明，与EHO / CA系统相比，EHO / TMA树脂体系代表的结构更均一，柠檬酸衍生物在低温下会分解。