Natural fibers are seeing increased use in composite applications due to their reduced cost, low density, and environmental benefits (more sustainable and lower carbon footprint). Although many natural fiber systems have been examined over the last decade, there have been relatively few studies which have compared a variety of fiber types and processing methods directly in the same experimental set. In this study, natural fiber composites made from low density polyethylene (LDPE) and a variety of Canadian based fiber feedstocks were examined including hemp bast, flax bast, chemically pulped wood, wood chips, wheat straw, and mechanically pulped triticale. The effect of fiber type, fiber fraction and maleic anhydride polyethylene (MAPE) coupling agent on the mechanical properties and long-term moisture absorption behavior was quantified. In general, addition of natural fiber to LDPE results in an increase in modulus (stiffness) with a corresponding loss of material elongation and impact toughness. Of the fiber types tested, composites made from chemically pulped wood had the best mechanical properties and the least moisture absorption. However, the use of MAPE coupling agent was found to significantly increase the mechanical performance and reduce moisture absorption for all other natural fiber types. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 969-980, 2013
Over the past decade, there has been an increased demand for products manufactured using sustainable materials. Natural fiber composites are seen as an excellent replacement for synthetic fiber composites due to their low density, good mechanical properties (stiffness), good thermal/acoustic insulation properties and environmental benefits (waste stream utilization and low carbon footprint). While there has been a considerable number of studies examining the short-term behavior of natural fiber composites, very limited work has been done to characterize their long-term durability under cyclic loading. In this study, the fatigue behavior of a natural fiber reinforced thermoplastic composite material was investigated. Cyclic fatigue experiments were conducted on hemp fiber reinforced high density polyethylene (HDPE) at various fiber volume fractions, and under both dry and wet ambient conditions. Using a stress level concept, a generalized model was developed to predict the fatigue life of the various composite formulations tested. The concept of pseudo-plastic flow was incorporated in the fatigue model to form a new model, which is capable of simulating fatigue behavior at different frequencies, fatigue stress ratios and volume fractions.
The main goal of this research is maximizing the utilization of renewable materials in both the matrix and reinforcement, more importantly exploitation of waste material for biocomposite development and evaluating the mechanical, thermal and water resistance performances. Woven roving and chopped strand mat fiber glass, and hemp fiber mats are incorporated to an epoxy resin based matrix cured with novel hydrolyzed specified risk material (SRM) extracts. Aminophenyl sulphone (APS) is used as a control crosslinking agent for the epoxy resin. Results show that the biocomposites developed in this research exhibit promising flexural strength, tensile strength and tensile modulus; despite relatively poor moisture resistance. The use of waste protein hydrolyzate extracts, hydrolyzed proteins, as crosslinking agent of epoxy resins in making biocomposites is novel and promising and results can be extended to other proteinaceous biomasses as curing agent of epoxy resins.
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