The effect of fibre and coupling agent content on the mechanical properties of hemp/polypropylene composites

Composites made from hemp and polypropylene were prepared in order to determine the effect of fibre and coupling agent content on their mechanical properties. The samples were prepared by compression molding after an initial melt blending and homogenization step in an internal batch mixer. Different fibre contents (0, 10, 20 and 30 wt%) and sizes (355 and 500 μm) were used with two coupling agents: maleic anhydride polypropylene (MAPP) pellets and wax. For each case, MAPP concentrations between 0 and 7 wt% (fibre basis) were added to determine the optimum amount maximizing mechanical properties. The fractured surfaces of these composites were investigated by scanning electron microscopic technique (SEM) to investigate the fibre/matrix interfacial bonding. The mechanical properties of the composites were characterized in tensile, torsion, and flexion and the results showed that coupling agent addition has a positive effect on all moduli with an optimum content ranging between 2 and 4 wt%. It was also found that the coupling agent wax was more effective that the pellets.

[1]  M. Misra,et al.  Natural, Fibers, Biopolymers and Biocomposites , 2009 .

[2]  M. Vallejos,et al.  Full exploitation of Cannabis sativa as reinforcement/filler of thermoplastic composite materials , 2007 .

[3]  M. Vallejos,et al.  Effect of maleated polypropylene as coupling agent for polypropylene composites reinforced with hemp strands , 2006 .

[4]  M. Sain,et al.  Surface characteristics of untreated and modified hemp fibers , 2006 .

[5]  Qinglin Wu,et al.  Wood‐fiber/high‐density‐polyethylene composites: Coupling agent performance , 2005 .

[6]  Harriëtte L. Bos,et al.  Reinforcement of polypropylene by annual plant fibers: optimisation of the coupling agent efficiency , 2000 .

[7]  A. Błędzki,et al.  Composites reinforced with cellulose based fibres , 1999 .

[8]  M. Snijder,et al.  Polyolefines and Engineering Plastics Reinforced with Annual Plant Fibers , 1997 .

[9]  A. Błędzki,et al.  The influence of fiber-surface treatment on the mechanical properties of jute-polypropylene composites , 1997 .

[10]  K. Mieck,et al.  Faser-Matrix-Haftung in Kunststoffverbunden aus thermoplastischer Matrix und Flachs, 2. Die anwendung von funktionalisiertem polypropylen† , 1995 .

[11]  J. Keurentjes,et al.  A simple experimental method for the measurement of the surface tension of cellulosic fibres and its relation with chemical composition. , 1993 .

[12]  B. Kokta,et al.  Reinforcing high density polyethylene with cellulosic fibers. I: The effect of additives on fiber dispersion and mechanical properties , 1991 .

[13]  B. Kokta,et al.  A comparative study on the effect of aging on mechanical properties of LLDPE- glass fiber, mica, and wood fiber composites , 1990 .

[14]  B. Kokta,et al.  Composites of Polyvinyl Chloride-Wood Fibers. I. Effect of Isocyanate as a Bonding Agent , 1990 .

[15]  B. Kokta,et al.  Compounding of cellulose fibers with polypropylene: Effect of fiber treatment on dispersion in the polymer matirx , 1989 .

[16]  B. Kokta,et al.  Composites of polyvinyl chloride—wood fibers: IV. Effect of the nature of fibers , 1989 .

[17]  B. Kokta,et al.  Influence of coupling agents and treatments on the mechanical properties of cellulose fiber–polystyrene composites , 1989 .

[18]  G. Thomas,et al.  Wood fibers as reinforcing fillers for polyolefins , 1984 .

[19]  J. Valade,et al.  Use of wood fibers in thermoplastic composites , 1983 .