Characterisation and properties of bentonite/polypropylene composite
Loading...
Date
2007
Authors
Othman, Nadras
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
This project was concerned with the application of bentonite filler in thermoplastics composite. Thus, the first objective of this project was to study the effect of bentonite loading on properties of polypropylene (PP) matrix composites. Polypropylene composites at different bentonite loading (10-50 wt %) were compounded using a Polydrive Thermo Haake with Rheomix R600. The inclusion of bentonite into PP matrix improves the Young’s modulus, thermal stability and flammability. However, the use of bentonite reduces the mechanical properties and also increases the percentage of water absorption as increasing filler loading. The reduction in mechanical properties can be explained from the analysis of Scanning Electron Microscopy (SEM) micrograph of the tensile and impact fractured surfaces.
Secondly, the influences of compatibilisers or coupling agents on properties of bentonite filled PP composites have been investigated. Four types of compatibilisers or coupling agents were used in this project namely; polypropylene-graft-maleic anhydride (PPMAH), titanate (LICA 12), polyethylene-graft-acrylic acids (PEAA) and palm oil fatty acid additive (POFA). At similar filler loading bentonite filled PP composites with compatibilising or coupling agent exhibit lower peak and stabilization torques than the similar composites but without compatibilising or coupling agents. The highest tensile strength was recorded by the composites treated with PPMAH followed by composite treated with PEAA, LICA12 and POFA, respectively. The addition of PPMAH, PEAA, LICA12 and POFA improved the elongation at break as compared to uncompatibilised (PPBT) composite. The addition of compatibilisers or coupling agents into PP-bentonite composites further improved the Young’s modulus of the composites except for the composites with POFA treatment. At typical bentonite loading of 10-30 wt %, PPMAH treated composite recorded the highest impact strength followed by the composites treated with PEAA, LICA 12 and POFA, correspondingly. At higher filler loading, typically at 40-50 wt % of bentonite loading, the highest recorded impact strength was for composites treated with LICA 12 and followed by composites treated with PEAA, POFA and PPMAH, respectively. The incorporation of PPMAH into bentonite filled PP composites shows the lowest water absorption characteristic followed by composites treated with LICA 12, PEAA and POFA treatment respectively. However the presence of POFA in PP-bentonite composites demonstrates the highest thermal stability and the lowest was recorded by PPMAH treatment. Besides that the PPMAH treatment was capable of inducing crystallisation as indicated by increasing the percentage of crystallinity presence in the composites. The application of PPMAH, PEAA, LICA 12 and POFA improved the flammability of PP-bentonite composites. The lowest burning rate was achieved by LICA 12 treated PP-bentonite composites.
Grafting of maleic anhydride onto PP back bone was investigated in this project. 0.51 % of maleic anhydride (MAH) was successfully grafted onto the PP chain. It was determined by titration method and the evidences are supported by FTIR analysis which confirmed the existing of carbonyl anhydride group in the region of 1785-1795 cm-1 and 1865 cm-1, respectively. Maleic anhydride grafted PP (PPgMAH) was used as a matrix and filled with bentonite via in-situ method. The mechanical properties of bentonite filled PPgMAH composites were higher than bentonite filled pure PP except for elongation at break. PPgMAH/bentonite composites demonstrate lower percentage of water absorption than PP/bentonite composite and DSC results revealed the reduction in the percentage of crystallinity. However, the decomposition temperature has increased to 480°C and also improved the flammability.
Description
PhD
Keywords
Science Physic , bentonite composite , polypropylene composite