ABS (arcylonitrile-butadiene-styrene) is one of the most common polymers in electrical and electronic equipment. In this thesis, ABS plastics from computer equipment housings have been investigated to find the effect of reprocessing upon chemical and physical properties. A torque rheometer was used to simulate the recycling process. Two ABS plastics were reprocessed at different temperatures and rotational speeds; the other one was multiply reprocessing for different number of cycles. After reprocessing, degradation levels of the reprocessed materials were investigated by FTIR (Fourier transform infrared spectrometry), GPC (gel permeation chromatography) and DMTA (dynamic mechanical thermal analysis); the change of additives was studied by GC/MS (gas chromatography/mass spectrometry); impact testing and tensile testing of reprocessed materials were carried out, and the fracture surfaces were examined using SEM (scanning electron microscopy). It was found that cross-linking of the rubber phase occurred at high reprocessing temperature. During multiple reprocessing, cross-linking of rubber might be accompanied by a slight increased thermo-oxidative degradation of ABS. Some additives were lost during processing. The impact strength of ABS plastic reduced after reprocessing, particularly at high temperature. During multiple reprocessing, impact strength of ABS plastic reduced continuously. Failure strain reduced after reprocessing. By SEM, the heterogeneity of reprocessed materials and the breakdown of microstructure of ABS polymer could be observed from the fracture surfaces of ‘after reprocessing’ samples. In this study, it was found that defects were possibly an important reason for the reduction of impact strength and failure strain after reprocessing at low temperature; at high reprocessing temperature, the reduction of impact strength was perhaps related to cross-linking of the rubber phase; the lack of adherence along SAN/rubber particles interface, which might be promoted by degradation of rubber, was an important reason for the reduction of impact strength of ABS plastic.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:636001 |
| Date | January 2006 |
| Creators | Bai, X. |
| Publisher | Swansea University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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