Parulekar Yashodhan, Mohanty Amar K, Imam Syed H
School of Packaging, Michigan State University, 130 Packaging Building, East Lansing, Ml 48824, USA.
J Nanosci Nanotechnol. 2007 Oct;7(10):3580-9. doi: 10.1166/jnn.2007.852.
Montmorillonite clay treated with neopentyl (diallyl)oxy tri(dioctyl) pyrophosphato titanate was used as a reinforcement for toughened bacterial bioplastic, Polyhydroxybutyrate (PHB) in order to develop novel biodegradable nanocomposites. The modified clay, PHB, toughening partner and specific compatibilizer were processed by extrusion followed by injection molding. Different microscopy and goniometry techniques, rheology analysis, X-ray diffraction and thermo-mechanical testing were used to characterize the nanocomposites. Results showed that the nanocomposites with 5 wt% titanate-modified clay loading exhibited about 400% improvement in impact properties and 40% reduction in modulus in comparison with virgin PHB. The novel aspect of the titanate-based modification was that the nanocomposites still maintained nearly the same impact strength value as that of toughened PHB. The diffraction patterns suggest exfoliation of the organically modified clays and this was further supported by transmission electron microscopy and melt rheological analysis. The mechanical properties of the nanocomposites were correlated with a modified Halpin-Tsai theoretical model and the predictions matched significantly with the experimental results. Toughened and compatibilized PHB showed significantly lower biodegradation rate than virgin PHB and most significantly the addition of the titanate-modified clay in the same formulation enhanced the biodegradation several fold.
用新戊基（二烯丙基）氧基三（二辛基）焦磷酸钛酸酯处理的蒙脱石粘土被用作增强剂，用于增韧细菌生物塑料聚羟基丁酸酯（PHB），以开发新型可生物降解纳米复合材料。将改性粘土、PHB、增韧剂和特定的相容剂通过挤出然后注塑成型进行加工。使用不同的显微镜和测角技术、流变学分析、X射线衍射和热机械测试来表征纳米复合材料。结果表明，与纯PHB相比，含有5 wt%钛酸酯改性粘土的纳米复合材料的冲击性能提高了约400%，模量降低了40%。基于钛酸酯的改性的新颖之处在于，纳米复合材料仍保持与增韧PHB几乎相同的冲击强度值。衍射图谱表明有机改性粘土发生了剥离，这进一步得到了透射电子显微镜和熔体流变学分析的支持。纳米复合材料的力学性能与改进的Halpin-Tsai理论模型相关，预测结果与实验结果显著匹配。增韧和相容的PHB的生物降解率明显低于纯PHB，最显著的是在相同配方中添加钛酸酯改性粘土使生物降解增强了几倍。
