Morphology evolution and crystalline structure of controlled‐rheology polypropylene in micro‐injection molding1. (8th December 2015)

• Record Type: Journal Article
• Authors: Li, Mengjue; Qi, Yang; Zhao, Zhongguo; Xiang, Zhang; Liao, Xia; Niu, Yanhua; Kong, Miqiu
• Is Part Of: Polymers for advanced technologies. Volume 27:Number 4(2016)
• Page Start: 494
• Page End: 503
• Publication Date: 2015-12-08
• Subjects: micro‐injection molding -- morphology evolution -- controlled‐rheology polypropylene -- crystallization; Polymers -- Periodicals; 668.9
• DOI: 10.1002/pat.3696
• Languages: English
• ISSNs: 1042-7147

Abstract

Abstract : In this paper, the microstructural evolution of controlled‐rheology polypropylene (CRPP) with different melt viscoelasticities was investigated by polarized optical microscopy, scanning electronic microscopy, differential scanning calorimeter, and wide‐angle X‐ray diffraction. It is found that a typical "skin‐core" structure formed in CRPP microparts and the thickness of oriented layer of CRPP microparts decreases notably with the addition of peroxide. The thickness of oriented layer and the distribution of different layers strongly depend on the melt flow properties and the corresponding relaxation time ( λ ). Furthermore, the mechanisms of the suppressed formation of oriented layers during the micro‐injection molding process are discussed mainly from the viewpoint of rheology and thermodynamics. It is revealed that the shear‐induced orientation is one of the key factors for the formation of oriented molecular structure (row nuclei). The final thickness of the oriented layer is the result of the competition between the orientation behavior and the disorientation behavior. Copyright © 2015 John Wiley & Sons, Ltd.