Journal of Applied Polymer Science, Vol.69, No.13, 2533-2540, 1998
Natural weathering of polypropylene films. II. Ultimate properties and exposure time
Changes in the ultimate properties brought about by outdoor weathering during the rainy season of polypropylene (PP) films were studied. The results obtained showed that the draw ratio hd, tensile stress ab, breaking ratio lambda(b), breaking factor (BF), work draw U-d, and work for rupture U-r all increased with increase in outdoor exposure time, attaining a maximum at about 240-h exposure time, before decreasing with further increases in exposure time. On the other hand, the draw ratio delta(s) remained practically constant up to about 100-h exposure time. The changes in the former set of properties were corroborated by the changes in the apparent crystallinity of the PP samples. In addition, it was shown that a 504-h exposure time was not enough to reduce the properties to damaging levels.
Keywords:THERMAL-OXIDATION