Preparation of fixed length carbon fiber reinforced plastic composite sheets with isotropic mechanical properties

The sheet molding compounds (SMCs) with different fiber volume ratios were prepared by dispersing the fixed length carbon fiber with length of 30 mm in the vinyl resin matrix, the as-prepared SMCs were further processed into carbon fiber reinforced polymer (CFRP) composites by a vacuum hot-pressing process. The influence of different fiber volume fraction (15%-40% vol) on the tensile and bending strength and the transverse isotropic characteristics of mechanical property of the CFRP composites were investigated. The mechanical property and fracture surface analysis show that the CFRP composites with 25%-30% vol carbon fibers have 2% dispersion coefficient of tensile strength in various directions. It indicates that the carbon fibers are dispersed homogeneously in vinyl resin matrix, resulting in better transverse isotropic mechanical property of the prepared CFRP composites. In comparison with the composite with 15% vol carbon fibers, the tensile and bending strength of the CFRP composites containing 25% and 30% vol carbon fibers possessing the maximum of 141.4 MPa and 549.0 MPa, increase about 112.8% and 129.6%, respectively.