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Abstract. In this study, the interfacial and mechanical properties of cellulose nanocrystals (CNC) coated glass fiber/epoxy composites were investigated as a function of the CNC content on the surface of glass fibers (GF). Chopped GF rovings were coated with CNC by immersing the GF in CNC (0-5 wt%) aqueous suspensions. Single fiber fragmentation (SFF) tests showed that the interfacial shear strength (IFSS) increased by ~69% in composites produced with CNC coated GF as compared to uncoated GF, suggesting an enhancement of stress transfer across the GF/matrix interface. The role of CNC coatings on the tensile, flexural, and thermo-mechanical properties of the CNC-coated GF/epoxy composites was investigated. Incorporation of 0.17 wt% CNC in the composite resulted in increases of ~10% in both elastic modulus and tensile strength, and 40 and 43 % in flexural modulus and strength respectively. In conclusion CNC coatings on GF alter the GF/matrix interface resulting in improvement of the mechanical performance of the corresponding composites.
Keywords: polymer composites, nanomaterials, coatings, mechanical properties
1.Introduction
Short glass fiber (GF) polymer matrix composites (PMC) with 30-50 wt% fiber loading have been widely used in automotive and marine industries as structural components due to their high specific strength and stiffness. Continued development in light-weighted PMC with higher mechanical performance has been fueled by the premise that 10% reduction in the vehicle weight can result in 6-8% increase in fuel efficiency [1]. One approach towards light weighting is the incorporation of nanoparticles either as a reinforcement phase within the matrix polymer, or at the fiber/matrix interface [2-5]. The high surface area per unit volume of nanoparticles enhances the interactions with the other constituents in the composite and subsequently enhances the mechanical properties compared to larger dimension particles of the same composition [6]. However, issues such as inhomogeneous dispersion and agglomerate formation should be addressed before using these materials in large scale production of composites.
Alternative nanoparticles that have potential for increasing GF-polymer matrix composites properties are cellulose nanomaterials (CNs). CNs are cellulose-based nanoparticles that are obtained from plants, algae, bacteria and marine animals [7-9]. CN particles are generally grouped based on the cellulose source and the extraction methods, leading to various CN types, including: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), algae cellulose (AC), bacterial cellulose (BC),...