Separators for lead–acid batteries have traditionally been manufactured from the extrusion and subsequent extraction of a calendered sheet formed from a mixture of process oil, ultrahigh molecular weight polyethylene (UHMWPE), and precipitated silica. A small amount of anti-oxidant is commonly used to prevent chain scission during the extrusion process, and some of it will remain in the final separator. The SiO2/PE ratio, amount of residual oil, oil composition, and speciality additives can all play a role in the oxidation resistance of the separator. This study examines the change in chemical composition and properties of battery separators when exposed to an oxidizing environment in standard laboratory tests and throughout the life of a lead–acid battery.


Richard Pekala
ENTEK International LLC
Vice President - Research & Development

Biography: Dr Pekala is Vice-President of Research & Development for ENTEK International LLC. He has a Bachelor of Science in Biomedical Engineering from Duke University (1981) and a Doctor of Science in Polymeric Materials from the Massachusetts Institute of Technology (1984). Dr Pekala began his career at Lawrence Livermore National Laboratory where he worked for 11 years in the Materials Science Department on aerogels and other low density, microcellular materials. In 1996, Dr Pekala joined PPG Industries as a scientist working in the Silica Products business unit. At PPG, he managed the Microporous Materials Group and was responsible for precipitated silica used in battery separators and synthetic printing media. In 1999, Dr Pekala joined ENTEK where he helped to commercialize new products such as lithium-ion battery separators, waterproof breathable membranes, and golf car separators. Dr Pekala has over 100 technical publications, 2 R&D 100 awards, and 33 patents.


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