Abstract
The formation of the crystalline phase of polypropylene in the presence of four different types of CaCO3 was studied. All composites were prepared by melt mixing and extrusion and the concentration of CaCO3 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 CaCO3 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.
Highlights
Particulate filled isotactic polypropyleneIt is well known that isotactic polypropyleneis widely used for automotive interior and exterior applications, for instance the instrument panel, interior exhibit four different crystalline forms[8,9,10,11,12,13,14,15,16,17]: alpha, beta, gama and smectic forms
The results indicated that the composite having the smallest CaCO3 size and polypropylene-graft-maleic anhydride (PP-g-MA) presented the best combined mechanical properties, the highest impact resistance, flexural modulus and tensile strength were observed, which were attributed to the proportionally higher concentration of beta crystalline phase
Isotactic polypropylene and the composites 1, 1S, 2 and 3 presented similar results (Figure 1a), 33 MPa, after PP-g-MA addition, all composites have shown improvement independent of the particle size of the calcium carbonate, higher resistances were observed for those having smaller particle sizes
Summary
Particulate filled isotactic polypropylene (iPP)It is well known that isotactic polypropylene (iPP)is widely used for automotive interior and exterior applications, for instance the instrument panel, interior exhibit four different crystalline forms[8,9,10,11,12,13,14,15,16,17]: alpha (more common), beta, gama and smectic forms. The results indicated that the composite having the smallest CaCO3 size and PP-g-MA presented the best combined mechanical properties, the highest impact resistance, flexural modulus and tensile strength were observed, which were attributed to the proportionally higher concentration of beta crystalline phase.
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