Fatigue crack propagation in mica‐filled polyolefins

Abstract

Edge notched samples of polypropylene (PP) and high-density polyethylene (HDPE) containing different mica concentrations were tested in mode I tensile loading. Crack growth was approximated by a non-linear regression of exponential form using statistical software (SAS). Characterization of fatigue crack propagation (FCP) was made using the Paris-Erdogan law. The crack front in PP was preceded by a wide plastic zone in which craze developed, leading to a discontinuous crack growth. Using spline functions, a margin between maximum and minimum FCP rates, recorded during the crack progression, is presented along with the average FCP rates. It is shown that mica-reinforced PP samples exhibit higher FCP rates than unfilled PP. In HDPE, mica reduces FCP rates resulting in a higher resistance to fatigue crack propagation. Effect of test frequency is presented for unfilled polymers and 10 percent mica concentration by weight in both matrices. An increase in the test frequency has no significant effect on FCP rates for both raw and mica-reinforced PP. Unfilled and mica-filled HDPE show noticeable decrease in FCP rates with increasing frequency.

Polymer micro and nanocomposites: Structure, interactions, properties

“…The consequence of this change is decreased yield stress and strength as well as improved deformability [93]. Strong interaction, however, is not always necessary or advantageous for the preparation of composites with desired properties; the plastic deformation of the matrix is the main energy absorbing process in impact, which increases with decreasing strength of adhesion [131,152,153].…”

Particulate Fillers in Thermoplastics

“…The consequence of this change is decreased yield stress and strength as well as improved deformability [135,215]. Strong interaction, however, is not always necessary or advantageous for the preparation of composites with desired properties; the plastic deformation of the matrix is the main energy absorbing process in impact, which increases with decreasing strength of adhesion [182,[223][224][225].…”

Effect of pimelic acid treatment on the crystallization, morphology, and mechanical properties of isotactic polypropylene/mica composites

“…Therefore, MC‐reinforced PP composites possess several excellent properties, among them are improved strength, high stiffness, good dimensional stability, enhanced heat resistance and electrical resistivity, and reduced cost [1–3]. In the literature, the mechanical properties [4–22], fracture mechanisms [23–28], dynamic mechanical behaviors [29–31], rheological behaviors [4, 21, 32–35], crystallization behaviors [14, 30, 31, 36–39], surface texture [40], mechanical degradation of MC during processing [41], ultrasonic weld strength [42], heat transmission behavior [43], coupling mechanisms of chlorinated paraffins [44, 45] in PP/MC composites, and the mechanical properties of PP/poly(vinyl butyral)/MC [46], PP/ethylene vinylalcohol copolymer/MC [47], and PP–MC–glass mat‐reinforced thermoplastics composites [48] were reported.…”