Differences in Properties of Pro-degradant Added PP and Gamma-Irradiated PP Under Environmental Aging
Polypropylene (PP) is used for different sectors of the industry and in consequence produces a large amount of waste discarded at landfills causing serious environmental impacts. Controlled degradation of PP can be achieved by exposing the polymers to defined parameters, such as absorbed radiation dose, weather, oxygen, etc. The aim of this study was to compare two methods of accelerated degradation: gamma irradiation of PP 20 kGy and the incorporation of the commercial pro-degradant d2w® (1 wt%) in PP. Dumbbell samples were manufactured by the injection process and exposed to the environment aging for 90 days. Structural changes in PP macromolecules are created upon exposure to ionizing radiation such as main chain scission, crosslinking and peroxidation (in presence of air). Differential scanning calorimetry (DSC), thermogravimetric analysis (TG), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), X-ray fluorescence, Fourier-transformed infrared spectroscopy (FTIR) and mechanical tests characterized the samples. The samples previously irradiated, PP 20 kGy, after natural aging showed higher oxidation and presence of surface cracks than the PP d2w®. They also showed presence of carbonyl groups and decrease of melting temperature corroborating with oxo-degradation.
KeywordsIonizing radiation Polypropylene Pro-degradant Environmental aging
The authors thank CAPES for supporting the Project Electronuclear 012/2013, Centre of Science and Technology of Materials—CCTM–IPEN for microscopy analysis (SEM), the technicians Eleosmar Gasparin and M.Sc. Djalma B. Dias for technical support and multipurpose gamma irradiation facility at the CTR–IPEN.
- 1.Karger-Kocsis J (1999) Polypropylene Polymer Science and Technology. In Mulhsupt R (Ed) Ziegler-Natta catalysis and propylene polymerization. Dordrecht, Kluwer Academic Publishers, The NetherlandsGoogle Scholar
- 5.Makuuchi K, Cheng S (2012) John Wiley & SonsGoogle Scholar
- 8.Romano RSG, Oliani WL, Parra DF, Lugao AB (2016) Evaluation of environmental aging of polypropylene irradiated versus pristine. TMS—Characterization of Minerals and Materials. http://dx.doi.org/10.1002/9781119263722.ch92
- 13.ASTM D 638-2014—Standard teste method for tensile properties of plasticsGoogle Scholar
- 14.ASTM D 1435-2013—Standard practice for outdoor weathering of plasticsGoogle Scholar
- 15.ASTM D 3418-2015—Standard test method for transition temperature of polymers by differential scanning calorimetry (DSC)Google Scholar
- 16.Mark JE (2007) Physical properties of polymers handbook, 2nd edn. SpringerGoogle Scholar
- 29.Roe-Sosa A (2015) J Appl Polym Sci 42721:1–11Google Scholar
- 33.Schnabel W (1981) Polymer degradation: principles and practical applications. Hanser International, MunchenGoogle Scholar