Luo Guang-Min, Liou Guang-Yen, Xiao Hong-Zhe
Department of Naval Architecture and Ocean Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 811532, Taiwan.
Polymers (Basel). 2022 Apr 1;14(7):1446. doi: 10.3390/polym14071446.
Vinyl ester (VE) resin has strong environmental tolerance and is the matrix commonly used in the composite materials of fiber-reinforced plastics (FRP). VE resin is often combined with glass fiber in different maritime structures, such as wind turbine blades, spinner cases, and nacelle cases. However, VE resin exhibits exothermic reactions and shrinkage during curing, which often generates residual strain in large structures and those with a high stacking number. This study explored the exothermic reaction and shrinkage of VE resin and glass fiber during the vacuum-assisted resin transfer molding process, as measured using a fiber Bragg grating sensor. The experiment results verified the relationship between the stacking number and residual strain shrinkage. In addition, the symmetric laminate method was used to prevent the bending-twisting coupling effect and subsequent warping deformation of the FRP laminated plate during curing. The experiment results also verified that the bottom layers of the FRP laminated plates produced using VE resin were closer to the mold, and exhibited more shrinkage as the stacking number increased. In addition, this study discovered that during the experiment, the symmetry layer of the FRP laminated plate had a higher exothermic temperature than the bottom layer as a result of the symmetry layer's ineffective heat dissipation. Therefore, the curing shrinkage of the symmetry layer resin was measured. The experiment results indicated that if the stacking number was between 10 and 30, the residual strain shrinkage of the symmetry layer was greater than that of the surface layer. However, because of the symmetric laminate, the residual strain of the symmetry layer did not increase when the temperature increased. Therefore, the greatest residual strain occurred at the surface of the bottom layer of the laminated plate with a stacking number of 40.
乙烯基酯（VE）树脂具有很强的环境耐受性，是纤维增强塑料（FRP）复合材料中常用的基体。VE树脂经常与玻璃纤维结合用于不同的海上结构，如风力涡轮机叶片、导流罩和机舱罩。然而，VE树脂在固化过程中会出现放热反应和收缩，这在大型结构和层数较高的结构中常常会产生残余应变。本研究探讨了在真空辅助树脂传递模塑过程中VE树脂和玻璃纤维的放热反应及收缩情况，采用光纤布拉格光栅传感器进行测量。实验结果验证了层数与残余应变收缩之间的关系。此外，采用对称层压板方法来防止FRP层压板在固化过程中出现弯曲 - 扭转耦合效应及随后的翘曲变形。实验结果还证实，使用VE树脂生产的FRP层压板的底层更靠近模具，并且随着层数增加收缩更大。此外，本研究发现，在实验过程中，由于对称层散热效率低，FRP层压板的对称层放热温度高于底层。因此，对对称层树脂的固化收缩进行了测量。实验结果表明，如果层数在10到30之间，对称层的残余应变收缩大于表层。然而，由于采用了对称层压板，对称层的残余应变在温度升高时并未增加。因此，最大残余应变出现在层数为40的层压板底层表面。
