Karbhari Vistasp M
Department of Civil Engineering, University of Texas, Arlington, TX 76006, USA.
Department of Mechanical and Aerospace Engineering, University of Texas, Arlington, TX 76006, USA.
Polymers (Basel). 2024 Jul 29;16(15):2157. doi: 10.3390/polym16152157.
Pultruded fiber reinforced polymer composites used in civil, power, and offshore/marine applications use fillers as resin extenders and for process efficiency. Although the primary use of fillers is in the form of an extender and processing aid, the appropriate selection of filler can result in enhancing mechanical performance characteristics, durability, and multifunctionality. This is of special interest in structural and high voltage applications where the previous use of specific fillers has been at levels that are too low to provide these enhancements. This study investigates the use of montmorillonite organoclay fillers of three different particle sizes as substitutes for conventional CaCO fillers with the intent of enhancing mechanical performance and hygrothermal durability. The study investigates moisture uptake and kinetics and reveals that uptake is well described by a two-stage process that incorporates both a diffusion dominated initial phase and a second slower phase representing relaxation and deterioration. The incorporation of the organoclay particles substantially decreases uptake levels in comparison to the use of CaCO fillers while also enhancing stage I, diffusion, dominated stability, with the use of the 1.5 mm organoclay fillers showing as much as a 41.5% reduction in peak uptake as compared to the CaCO fillers at the same 20% loading level (by weight of resin). The mechanical performance was characterized using tension, flexure, and short beam shear tests. The organoclay fillers showed a significant improvement in each, albeit with differences due to particle size. Overall, the best performance after exposure to four different temperatures of immersion in deionized water was shown by the 4.8 mm organoclay filler-based E-glass/vinylester composite system, which was the only one to have less than a 50% deterioration over all characteristics after immersion for a year in deionized water at the highest temperature investigated (70 °C). The fillers not only enhance resistance to uptake but also increase tortuosity in the path, thereby decreasing the overall effect of uptake. The observations demonstrate that the use of the exfoliated organoclay particles with intercalation, which have been previously used in very low amounts, and which are known to be beneficial in relation to enhanced thermal stability, flame retardancy, and decreased flammability, provide enhanced mechanical characteristics, decreased moisture uptake, and increased hygrothermal durability when used at particle loading levels comparable to those of conventional fillers, suggesting that these novel systems could be considered for critical structural applications.
用于土木、电力和海上/海洋应用的拉挤纤维增强聚合物复合材料使用填料作为树脂增量剂并提高加工效率。尽管填料的主要用途是作为增量剂和加工助剂，但适当选择填料可以提高机械性能、耐久性和多功能性。这在结构和高压应用中尤为重要，因为之前特定填料的使用量过低，无法提供这些性能提升。本研究调查了三种不同粒径的蒙脱石有机粘土填料作为传统碳酸钙填料替代品的使用情况，目的是提高机械性能和湿热耐久性。该研究调查了吸湿情况及其动力学，并表明吸湿过程可以很好地用两阶段过程来描述，该过程包括一个以扩散为主的初始阶段和一个代表松弛和劣化的较慢的第二阶段。与使用碳酸钙填料相比，加入有机粘土颗粒可大幅降低吸湿水平，同时还能提高第一阶段（扩散主导阶段）的稳定性，在相同的20%（按树脂重量计）加载水平下，使用1.5毫米的有机粘土填料时，峰值吸湿量比碳酸钙填料减少了41.5%。使用拉伸、弯曲和短梁剪切试验对机械性能进行了表征。有机粘土填料在各项性能上均有显著改善，尽管因粒径不同存在差异。总体而言，基于4.8毫米有机粘土填料的E玻璃/乙烯基酯复合体系在浸入去离子水的四种不同温度下表现出最佳性能，它是在研究的最高温度（70°C）下在去离子水中浸泡一年后所有性能劣化小于50%的唯一体系。填料不仅增强了吸湿抗性，还增加了路径的曲折度，从而降低了吸湿的总体影响。这些观察结果表明，以前使用量极少的具有插层作用的剥离型有机粘土颗粒，已知在提高热稳定性、阻燃性和降低可燃性方面有益，当以与传统填料相当的颗粒加载水平使用时，可提供增强的机械性能、降低吸湿量并提高湿热耐久性，这表明这些新型体系可考虑用于关键的结构应用。
