Influence of the beta crystalline phase fraction on the mechanical behavior of polypropylene/calcium carbonate/polypropylene - graft - maleic anhydride composites

Abstract

Abstract:The formation of the crystalline phase of polypropylene in the presence of four different types of CaCO 3 was studied. All composites were prepared by melt mixing and extrusion and the concentration of CaCO 3 was maintained at 5 wt %. Furthermore, in another series of composites, 5 wt % of polypropylene-graft-maleic anhydride (PP-g-MA) was added for comparison. The tensile strength, flexural modulus and impact resistance of the composites were determined. The composites were also analyzed by DSC (differential scanning calorimetry) and WAXD (wide angle x-ray diffractometry) in order to understand and quantify the beta crystalline phase. The results indicated that the composite having the smallest CaCO 3 size and PP-g-MA presented the best combined mechanical properties, therefore, the highest impact resistance, flexural modulus and tensile strength were observed, which were attributed to the proportionally higher concentration of beta crystalline phase.

Filling and coloring effect of pearl shell powder and dye‐loaded pearl shell powder on polypropylene

“…Thus, the interfacial interaction between the fillers and PP matrix was strengthened, causing the improvement in the mechanical properties. Sakahara et al . found that calcium carbonate/PP composites compatibilized with PP‐g‐MAH showed higher tensile strength, flexural strength, and impact strength, as compared to untreated calcium carbonate/PP composites at corresponding filler content.…”

“…found that calcium carbonate/PP composites compatibilized with PP‐g‐MAH showed higher tensile strength, flexural strength, and impact strength, as compared to untreated calcium carbonate/PP composites at corresponding filler content. Sakahara et al . reported that the addition of 5 wt % calcium carbonate enhanced the tensile strength, flexural modulus, and impact resistance of PP compatibilized with PP‐g‐MAH.…”

“…As can be seen, with addition of the fillers, the crystallization peak temperatures and the corresponding melting peak temperatures move toward higher valves especially for the crystallization temperatures, which demonstrate the promoted crystallization with the filler incorporation. The main peaks are ascribed to the α‐phase crystal of PP, while in the case of high filling levels (≥10 wt %), the small melting peaks located at about 150 °C are due to the β‐phase PP . Li et al .…”

“…In addition, it can be observed that the intensity of β‐PP peaks is higher for DPSP/PP, as compared to PSP/PP. It has been reported that the presence of β‐phase in PP led to the better mechanical properties, particularly the impact strength . Thus, the superior impact strength of the DPSP/PP composites to that of PSP/PP was partially due to their higher β‐phase content.…”

“…Calcium carbonate (CaCO 3 ) is one of the most extensively adopted commercial fillers. In most cases, the filling of CaCO 3 particles significantly enhances the elastic modulus of PP but decreases its impact strength . Recently, it was reported that PP could be reinforced and toughened at the same time by the addition of surface‐modified CaCO 3 nanoparticles.…”