Effect of bentonite addition on the optical properties of different polymeric composites materials

ABSTRACT In this work, composite materials were obtained by the incorporation of bentonite to biodegradable and synthetic polymeric matrices. Commercial (BE) and natural (BM) bentonite samples were employed, as well as three different polymeric matrices: thermoplastic corn starch (TPS), high density polyethylene (HDPE) and a poly(styrene-b-butadiene-b-styrene) triblock copolymer (SBS). Composite materials were obtained by incorporating 5 % w/w filler by melt mixing. Films were obtained by thermo-compression in a hydraulic press. By Scanning Electron Microscopy (SEM) it were examined the homogeneity and appearance of films. Opacity and UV barrier capacity were determined from the UV-vis spectra recorded in a spectrophotometer. Film color measurements were performed using a colorimeter in the transmittance mode, recording parameters L, a, and b. From SEM micrographs, a good filler distribution in the three different matrices were observed. The addition of bentonite modified the optical properties of films due to their blocking effect, evidenced in an increase in both UV barrier capacity and opacity.

摘要 本研究通过将膨润土引入可生物降解与合成聚合物基体中，制备得到复合材料。实验采用商用（BE）及天然（BM）两种膨润土样品，同时选用三种不同的聚合物基体：热塑性玉米淀粉（TPS）、高密度聚乙烯（HDPE）以及聚（苯乙烯-丁二烯-苯乙烯）三嵌段共聚物（SBS）。以5%质量分数添加填料，通过熔融共混法制备复合材料，再经液压机热压成型得到薄膜。采用扫描电子显微镜（SEM）对薄膜的均匀性与形貌进行表征；通过分光光度计采集紫外-可见光谱，测定薄膜的不透明度与紫外阻隔性能；采用色差仪的透射模式开展颜色参数测试，记录L、a、b三个颜色空间参数。扫描电子显微镜观测结果显示，膨润土在三种聚合物基体中均实现了良好的分散。由于膨润土的阻隔作用，添加膨润土后薄膜的光学性能发生改变，具体表现为紫外阻隔性能与不透明度均得到提升。