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Mechanical behavior of CaCO 3 particulate‐filled β‐crystalline phase polypropylene composites
Author(s) -
Tjong S. C.,
Li R. K. Y.,
Cheung T.
Publication year - 1997
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11657
Subject(s) - materials science , composite material , ultimate tensile strength , polypropylene , scanning electron microscope , composite number , filler (materials) , calcium carbonate , calcium stearate , izod impact strength test , lamellar structure , polymer , charpy impact test , raw material , chemistry , organic chemistry
Abstract β‐crystalline phase polypropylene (PP) composites containing 5, 10, 20, 30, and 40% (by weight) of CaCO 3 filler were prepared by injection molding. The β‐form PP was produced by adding a bicomponent β‐nucleator consisting of equal amounts of pimelic acid and calcium stearate. The morphology, static tensile, and impact properties of these composites were investigated in this study. Scanning electron microscopy (SEM) observations revealed that the β‐spherulites of the polymer matrix of the composites exhibit curved lamellae and sheaf‐like structures. The fillers were observed to disperse within the inter‐lamellar spacings of the β‐PP composite containing 10% calcium carbonate addition. However, the filler particles tend to link together to form larger aggregates when the filler content reaches 20%. Static tensile measurements showed that the elastic modulus of the composites increases with increasing filler content but the yield strength decreases with increasing filler addition. The falling weight Charpy impact test indicated that the β‐PP polymer exhibits the highest critical strain energy release rate ( G c ) value. However, there was a drastic drop in G c of the β‐PP composites with increasing filler content. The results are discussed and explained in terms of materials morphology.