Zhu Jinjian, Wang Xiaojun, Chen Minzhuang
Department of Composite Materials, College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China.
Materials (Basel). 2023 Jun 28;16(13):4677. doi: 10.3390/ma16134677.
Dual-initiation is a new orientation of many studies in the curing of unsaturated polyester resin and the manufacture of low-density unsaturated polyester resin (LDUPR) composite materials. In our research, two kinds of low-temperature (40-70 °C) initiators (cyclohexanone peroxide (CYHP) and methyl ethyl ketone peroxide (MEKP)), one kind of medium-temperature (70-130 °C) initiator (tert-butyl peroxy-2-ethylhexanoate (TBPO)), and three kinds of high-temperature (≥130 °C) initiators (tert-butyl benzoate peroxide (TBPB), tert-amyl carbonate peroxide-2-ethylhexanoate (TAEC), and tert-butyl carbonate peroxide-2-ethylhexanoate (TBEC)) were applied to constitute different dual-initiators. Those dual-initiators were a low-temperature dual-initiator (CYHP/MEKP), medium-low-temperature dual-initiators (CYHP/TBPO and MEKP/TBPO), and high-temperature dual-initiators (TAEC/TBPB, TAEC/TBEC, and TBEC/TBPB). In the low-temperature and medium-low-temperature ranges, the LDUPR sample displayed the highest specific compression strength () of 42.08 ± 0.26 MPa·g·cm in the presence of the MEKP/TBPO dual-initiator. In the high-temperature range, the LDUPR sample exhibited the highest specific compression strength () of 43.32 ± 0.45 MPa·g·cm for the existence of the TAEC/TBPB dual-initiator. It is pointed out that the dual-initiator released more active free radicals, accelerating the initial curing time and the peak time of UPR. More active free radicals caused both high-activity (short-chain) molecules and low-activity (long-chain or intertwined) molecules in resin to cross-link, prolonging UPR's curing process by approximately two minutes and resulting in an improvement of UPR's cross-linking. In the presence of a dual-initiator, the integrated and planar microstructure of LDUPR samples performed uniformly distributed dimples, dispersed external forces, and enhanced samples' specific compressive strength.
双引发是不饱和聚酯树脂固化及低密度不饱和聚酯树脂（LDUPR）复合材料制造领域众多研究的新方向。在我们的研究中，应用了两种低温（40 - 70°C）引发剂（过氧化环己酮（CYHP）和过氧化甲乙酮（MEKP））、一种中温（70 - 130°C）引发剂（叔丁基过氧 - 2 - 乙基己酸酯（TBPO））以及三种高温（≥130°C）引发剂（过氧化苯甲酸叔丁酯（TBPB）、2 - 乙基己酸叔戊酯过氧化物（TAEC）和2 - 乙基己酸叔丁酯过氧化物（TBEC））来构成不同的双引发剂。这些双引发剂包括低温双引发剂（CYHP/MEKP）、中低温双引发剂（CYHP/TBPO和MEKP/TBPO）以及高温双引发剂（TAEC/TBPB、TAEC/TBEC和TBEC/TBPB）。在低温和中低温范围内，LDUPR样品在MEKP/TBPO双引发剂存在下显示出最高的比压缩强度（），为42.08 ± 0.26 MPa·g·cm。在高温范围内，LDUPR样品在TAEC/TBPB双引发剂存在时表现出最高的比压缩强度（），为43.32 ± 0.45 MPa·g·cm。研究指出，双引发剂释放出更多活性自由基，加快了不饱和聚酯树脂（UPR）的初始固化时间和峰值时间。更多的活性自由基促使树脂中的高活性（短链）分子和低活性（长链或缠结）分子交联，使UPR的固化过程延长约两分钟，并导致UPR交联度提高。在双引发剂存在的情况下，LDUPR样品的整体平面微观结构呈现出均匀分布的凹坑，分散了外力，增强了样品的比压缩强度。
