Influence of morphology and surface preparation on the weatherability of polypropylene

• Published in: Journal of materials science 1995-05, Vol.30 (9), p.2364-2376
• Main Authors: OGIER, L, RABELLO, M. S, WHITE, J. R
• Format: Article
• Language: English
• Subjects: Ageing; Applied sciences; Exact sciences and technology; Physical properties; Polymer industry, paints, wood; Properties and testing; Technology of polymers
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/bf01184588

Regions with injection moulded polypropylene bars having different morphologies have been exposed by milling away material from the surface then illuminating them with ultraviolet radiation (uv) for periods up to 18 weeks. The crystal morphology prior to uv exposure was determined using x-ray diffraction. The effects of the uv were investigated using tensile tests and differential scanning calorimetry. Examples of bars broken in the tensile tests were examined in the scanning electron microscope. When tensile tests were conducted on samples that were exposed for a short while to uv after removing the surface, cracks formed that followed the machining marks and failure occurred at a fairly low extension. Some of the ductility was restored if the machine marks were polished away before conducting the uv exposure. The results appeared to be insensitive to surface finish at longer exposure times. The severity of the damage caused by photo-oxidation increases as the crystallinity increases.