Mechanical properties of polypropylene composites based on natural fibers subjected to multiple extrusion cycles

Abstract

The influence of multiple extrusion cycles on the behavior of natural fibers-reinforced polypropylene was studied. Composites were fabricated with 20 wt % of flax fibers. Final fibers dimensions (length and diameter) were measured by means of optical microscopy. Mechanical properties of matrix and composites were measured after each extrusion cycle. It was observed that the elastic modulus increased by fibers incorporation. The elastic modulus of the matrix was higher after the first process cycle than that of the virgin material, mainly because of chain scission. In the next cycles, the modulus kept constant. On the other hand the elastic modulus of the composite after a single extrusion step was lower than that predicted by the Halpin-Tsai model probably because of a poor mixing and to low adhesion at the fiber-matrix interface. In the following two steps, modulus increased because the better fiber dispersion was observed. For the final two extrusion cycles, the slow decrease in this property was correlated with the darkening and poor organoleptic properties observed as a result of thermal degradation.

The effect of reprocessing on the mechanical properties of the waste fabric reinforced composites

“…In this study, tensile properties of composites remained quite stable until the third injection step however in further recycling steps significant drop in tensile properties were observed because of the matrix degradation and shortening of fibers. Moran et al (2007) reported that shortening of fiber lengths as a result of reprocessing steps had a certain effect on the mechanical properties of the composite materials. Migneault et al (2008) explored that there was a linear relationship between fiber length and mechanical properties of the composites.…”

Effects of Multiple Extrusions on Structure-property Performance of Natural Fiber High-density Polyethylene Biocomposites

“…16,[19][20][21][22][23] The archival publications indicate that water absorption and thickness swelling behavior of reprocessed natural fiber plastic composites depend on a numerous factors including interface quality, chemical composition, fiber length and distribution, and density. The results confirmed that generally the recycling process boosted water resistance and dimensional stability in the studied formulations.…”

Postconsumer high‐density polyethylene/agave fiber foamed composites coated with chitosan for the removal of heavy metals

“…Among other desirable properties, the composites should possess enhanced biodegradability and should be reusable. [2][3][4] The removal of heavy metals from wastewaters is an important industrial challenge and is a concern to human health. Several solid adsorbents have been proposed for the removal of heavy metals from aqueous streams, for example, ion-exchange resins, 5 membrane filters, 6 metal hydroxide, 7 activated carbons, 8 and porous polymer beads.…”