Microscopic mechanical properties and injection molding‐induced morphology on polypropylene rubber blend

Abstract

A microdeformation of a simple polymer blend of polypropylene (PP) and ethylene butene rubber (EBR) was investigated in this study. Injection moldinginduced morphology close to the surface was analyzed by transmission electron microscope, polarizing optical microscope, and Fourier transform IR spectroscopy. Breakup and coalescence of EBR particles scarcely occurred during the injection process. The EBR particles near the surface were observed as continuous fibers and were gradually changing to the ellipsoidal shape in the depth direction. The morphology in an injection molded specimen was related to depth profiles of mechanical factors, which were microhardness and shear stress measured by a Vickers and a Knoop microindenter and ''Surface and Interface Cutting Analysis System,'' respectively. Crystal structure of PP matrix affected to the microdeformation more strongly than that of EBR phase. The large oriented EBR domains disconnected continuity of the PP matrix and acted as a weak layer in the specimens. Finally, cohesive fracture occurred in the peel test of painted PP/EBR was discussed from a microdeformation point of view.

Effect of melt flow on morphology and linear thermal expansion of injection-molded ethylene-propylene-diene terpolymer/isotactic polypropylene blends

“…In the core portion, the polymer is less oriented. This phenomenon is the so‐called skin–core effect . In addition, Kobayashi et al reported that the morphologies of injection‐molded samples vary from the gate to the flow end.…”

“…Thus, morphology and properties should accordingly change with different positions. Researchers have carried out numerous simulations of the orientation in injection‐molded samples to investigate the relationship among flow, morphology and properties. However, in a considerable number of cases, morphological, performance and numerical studies were performed separately from experimental data obtained from various samples; thus, direct information about the relationships was inevitably lost …”

Viscoelastic flow analysis of surface morphology on injection‐molded polypropylene

“…Corresponding to such a change, morphology at the surface and mechanical properties should be changed in injection‐molded specimens. We have been dealing with the relationship between injection molding‐induced morphology and properties at the surface [1, 2]. The objective of this study is to understand the formation mechanism of frozen‐in orientation in injection‐molded PP.…”

Crystallization of polypropylene near the surface in injection‐molded plaques: A comparison of morphology and a numerical analysis

“…The skin morphology is different from that in other locations because moving molten PP is immediately frozen at the cold cavity wall. In our previous work [4,5], the microhardness and shear stress had their minima at the surface in the depth direction of the injection-molded plaques. Possible causes are low crystalllinity and anisotropy of morphology.…”

“…Our purpose in this study was to clarify the skin morphology formation in the [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] μm depth region by a WAXD analysis of three types of nucleated PP and by an original 2-D viscoelastic flow simulation program. Birefringence with a polarizing optical microscope (POM) and micro-beam synchrotron WAXD were utilized for evaluating injection-molding-induced morphology.…”