Effect of injection molding parameters on crystallinity and mechanical properties of isotactic polypropylene
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The effects of injection molding parameters namely mold temperature, melt temperature and injection speed on crystallization and mechanical properties of isotactic polypropylene were studied. The specimens were molded as per the Taguchi design of experiment and analyzed for signal to noise ratio and for analysis of variance test. The crystallinity and crystal sizes were determined by wide angle X-ray diffraction data. The specimens were tested for tensile, impact, flexural, stress relaxation and dynamic mechanical properties. It was observed that mold temperature was the most influential injection molding parameter governing the crystallinity and other mechanical properties. It was observed that increase in crystallinity is favorable from tensile and flexural strength point of view but impact properties deteriorate with increase in crystallinity. At high injection speed β-phase changes to α-phase due to shear induced orientation of polymer chains. It is interesting to notice that stress relaxation occurred in elastic as well as in plastic regions has the similar trends and can be modeled by the same decay model proposed in this paper.
KeywordsTaguchi design of experiment ANOVA α-PP β-PP Stress relaxation Wide angle X-ray diffraction
The author is thankful and acknowledge the extension of testing and characterization facilities by Prof. Alim Hussain Naqvi, Prof. Ameer Azam and Dr. Wasi A. Khan, Center of Excellence in Nanotechnology, Department of Applied Physics, Aligarh Muslim University, Aligarh, for this experimental study.
- 3.van der Meer DW (2003) Structure-property relationships in isotactic polypropylene. Twente University Press (TUP), EnschedeGoogle Scholar
- 12.van der Burgt FPTJ (2002) Crystallization of isotactic polypropylene, the influence of stereo-defects. Eindhoven Technische Universiteit, EindhovenGoogle Scholar
- 14.Dunk R, Bouvart D, Wright DGM, Autran M (1988) The effect of crystallinity on the properties of injection moulded polypropylene and polyacetal. Polymer 29(May):793–796Google Scholar
- 15.Weakley-Bollin SC (2010) The effect of injection molding conditions on the near surface rubber morphology, surface chemistry and adhesion performance of semi-crystalline and amorphous polymer. University of Michigan, Ann ArborGoogle Scholar
- 16.Selvakumar V, Manoharan N (2014) Thermal properties of polypropylene/montmorillonite nanocomposites. Indian J Sci Technol 7(November):136–139Google Scholar