Study of the weathering of high melt strength polypropylene (HMS-PP)
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2007
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INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE; MEETING ON NUCLEAR APPLICATIONS, 8th/ MEETING ON REACTOR PHYSICS AND THERMAL HYDRAULICS, 15th
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Resumo
One of the reasons for the good acceptance of the commercial PP is the fact that market requires products with
features of “engineering plastics” with prices in the range of commodities. High melt strength polypropylene
(HMSPP) grades are produced by radiation process and have improved rheology for melt blow processes. The
melt strength (MS) properties of a polymer increase with molecular weight and with long chain branching due
to the increase in the entanglement level. The main scope of this study was to evaluate the stability of HMS-PP
prepared by gamma radiation with doses of 12.5, 20 kGy in comparison with virgin PP. Many variables
influence the rate of degradation of polymers by photo-oxidation. The irradiance and permeability to oxygen are
the most important factors but other factors such as temperature and moisture have also influenced the
degradation rates. Polypropylenes are sensitive to oxidation due to the presence of the tertiary carbon atom.
Therefore, effective stabilization against oxidation (thermo and photo oxidation) is required. The samples
submitted to the natural aging for a period of six months were characterized by: tensile test, thermogravimetry
analysis (TGA), optical microscopy, scanning electronic microscopy (SEM) and infrared spectroscopy (FTIR).
SEM analysis showed particular aspects of cracks on the surface. The loss of tensile strength is associated to the
presence of fractures. The results showed that pronounced oxidation followed by chain scission occur at the
initial periods of weathering exposition of the HMS-PP.
Como referenciar
OLIANI, WASHINGTON L.; PARRA, DUCLERC F.; OTAGURO, HARUMI; LIMA, LUIS F.C.P.; LUGAO, ADEMAR B. Study of the weathering of high melt strength polypropylene (HMS-PP). In: INTERNATIONAL NUCLEAR ATLANTIC CONFERENCE; MEETING ON NUCLEAR APPLICATIONS, 8th/ MEETING ON REACTOR PHYSICS AND THERMAL HYDRAULICS, 15th, Sept. 30 - Oct. 5, 2007, Santos, SP. Proceedings... Disponível em: http://repositorio.ipen.br/handle/123456789/15723. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.