Morphological aspects of injected polypropylene/clay nanocomposite materials

Abstract

Polypropylene (PP) clay nanocomposites were injection‐molded using two different coupling agents based on maleic anhydride‐grafted PP (MA‐g‐PP) and two clay loadings. The morphological aspects of these materials were studied by depth profiling. Molecular chain and clay orientations were characterized using attenuated total reflectance‐infrared analysis and transmission electron microscopy (TEM). Both clay platelets and PP molecular chain orientations were found to decrease from the surface toward the core of the injection–molded specimens. Clay intercalation, characterized by both complementary X‐ray diffraction and TEM, was found to be significantly influenced by both the characteristics of the coupling agent used and the type of residual stresses generated at each layer across the thickness of the injection‐molded parts. The use of low‐molecular weight (Mw) MA‐g‐PP led to a uniform intercalation but with no further exfoliation. The use of higher molecular weight MA‐g‐PP led to a heterogeneous intercalation with some signs of exfoliation. The crystallization behavior of PP clay nanocomposites studied by differential scanning calorimetry showed an increase in the level of crystallinity from the surface to the core of the specimens; these results were also confirmed by scanning electron microscopy. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Microstructure, Tensile Property, and Surface Quality of Glass Fiber-Reinforced Polypropylene Parts Molded by Rapid Heat Cycle Molding

“…ey attributed this high gloss surface to the amorphous phase, which completely wrapped all crystalline phases on the surface; finally, the surface presented a pure and uniform amorphous phase. However, this conclusion differs from the observations of other researchers [17,21,31] who indicated that the surface of the PP sample is composed of both crystalline and amorphous phases. Another researcher (Wang et al [35]) pointed out that, for the virgin PP, the surface gloss exhibited a different trend: instead of increasing, it tended to decrease as the cavity surface temperature continued to rise after reaching 110°C.…”

“…e statistical results of crystallinity in each layer in all samples are shown in Figure 8. e inner crystallization variation trend in the CIM sample is the same as the study result obtained by Salah et al [31]. And the crystallinity in each layer in the RHCM samples is higher than that in the CIM sample; furthermore, the crystallinity in all layers increases continuously as the cavity surface temperature increases.…”

Polipropilen ambalajın eş-enjeksiyon dolum karakteristiğinin 3-B simülasyonu

“…Around 0.2 mm virgin PP from the walls nucleated and it is interpreted that it solidified virgin PP tends to adhere on the wall during 3.06 s injection period. It is mentioned that the cooling rate, temperature gradient, shear condition, pressure distribution, and many other injection parameters strongly affect the distribution of crystallization behaviour of PP, frozen, and the surface quality and mechanical properties of plastic parts [17].…”