Rate dependencies and energy absorption characteristics of nanoreinforced, biofiber, and microcellular polymer composites

Abstract The effects of loading rate on bio‐, nano‐, and microcellular composite systems have been studied. Fiber–resin systems have been manufactured and dynamically tested at various speeds to assess their strain‐rate dependencies (rate hardening) and energy‐dissipation characteristics compared to conventional materials. The following composite systems have been fabricated and studied: polypropylene/sisal fiber biocomposite, hemp/vinyl ester biocomposite, thermoplastic olefin/nanoclay composite, microcellular polypropylene/sisal fiber biocomposite, and microcellular thermoplastic olefin/nanoclay composite. It has been determined that the biocomposite systems studied possess unique energy dissipation characteristics and muted rate dependence, while the nanocomposite system did not. In addition, microcellular foaming of these materials further enhanced the effects. Though the exact mechanisms at play are not fully understood at this point, it has been found that in addition to the microcellular voids, the anatomical vasculature of the natural fibers may play a role in energy dissipation processes in these hybrid materials. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers