Influence of surface modification on the dispersion of nanoscale α-Al₂O₃ particles in a thermoplastic polyurethane matrix

• Published in: Journal of applied polymer science 2008-10, Vol.110 (1), p.237-243
• Main Authors: Chen, Cheng-Ho, Mao, Ching-Feng, Tsai, Ming-Shyong, Yen, Fu-Su, Lin, Jian-Min, Tseng, Ching-Hui, Chen, Heng-Yi
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Exact sciences and technology; Forms of application and semi-finished materials; nanocomposite; Polymer industry, paints, wood; Technology of polymers; TPU; α-Al2O3
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.28642

In this study, two types of nanoscale α-Al₂O₃ particles were used for preparation of α-Al₂O₃/thermoplastic polyurethane (TPU) composites. These α-Al₂O₃ particles were either coated or uncoated with stearic acid. For the uncoated α-Al₂O₃/TPU composite, the results of field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectrometry indicate that uncoated α-Al₂O₃ particles are significantly aggregated together. This aggregation is due to the poor compatibility between the inorganic filler (α-Al₂O₃) and the organic matrix (TPU). The size of clusters is in the range from 5 to 20 μm. For the coated α-Al₂O₃/TPU composite, FE-SEM results indicate that most coated α-Al₂O₃ particles are well dispersed in the TPU matrix. This phenomenon results from the effect of surface modifier (i.e., stearic acid) on α-Al₂O₃ particles. Stearic acid can act as a compatibilizer to bridge the boundary between the TPU matrix and the α-Al₂O₃ particle. Stearic acid is not only a suitable surface modifier for the nanoscale α-Al₂O₃ particle, but also a good dispersant for the dispersion of nanoscale α-Al₂O₃ particles in the TPU matrix.