This study emphasizes the reactivity of (R)-(+)- limonene, a major byproduct of the citrus industry, and its potential to be used as a biobased thermoset precursor. We separated the cis and trans limonene epoxides and synthesized limonene dioxide (LDO) monomers using an environmentally friendly epoxidation. Their crosslinking reactivity with glutaric anhydride, a biobased hardener, to obtain fully biobased thermosets was studied. The influence of the stereochemistry of limonene epoxide monomers on the copolymerization, the crosslinking density, and the resulting material properties were investigated. By comparing the cis- and trans-LDO reactivity, for the first time, we found that cis-LDO generates thermosets with high mechanical properties (σ = 43 MPa; ε = 4.56%; E = 1.36 GPa; E′ = 1.68 GPa, Shore D hardness = 81), thus establishing this isomer as a very promising biobased epoxy monomer.

中文翻译：

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柠檬烯的顺式/反式立体化学对酸酐交联合成生物基热固性材料的影响

本研究强调了柑橘产业的主要副产品 ( R )-(+)- 柠檬烯的反应性，以及其用作生物基热固性前体的潜力。我们分离了顺式和反式柠檬烯环氧化物，并使用环保的环氧化合成了二氧化柠檬烯 (LDO) 单体。研究了它们与戊二酸酐（一种生物基硬化剂）的交联反应，以获得完全生物基热固性材料。研究了柠檬烯环氧化物单体的立体化学对共聚、交联密度和所得材料性能的影响。通过比较顺式和反式LDO 的反应性，我们首次发现顺式和反式 LDO-LDO 产生具有高机械性能的热固性材料（σ​​ = 43 MPa；ε = 4.56%；E = 1.36 GPa；E ' = 1.68 GPa，肖氏 D 硬度 = 81），因此将该异构体确立为非常有前途的生物基环氧单体。