A degradation study of isotactic virgin and recycled polypropylene used in lead acid battery casings

Polypropylene has become a great concern with regards to environmental pollution since it is generally resistant to normal conditions of degradation. This factor has encouraged the industry to find ways to regenerate spent polypropylene. A good example of such a process is the recycling of lead acid batteries. The use of recycled polypropylene has cost saving implications, but does have a disadvantage in that the material starts to deteriorate after multiple processes. The comparative study investigated the use of various ratios of virgin and different grades of recycled PP in the manufacturing of lead acid battery cases and their influence on its physical and chemical properties. The degradation of PP was also investigated as the material was subjected to multiple manufacturing processes where the influence of stabilizers was considered. A common technique used for the analysis of PP, MFI was shown to be an effective technique to maintain a good quality control system within the battery case manufacturing process. The study further showed that it is important to maintain a compatible grade of PP for both the battery case and lid in order to allow for effective heat sealing of the two components.