Evaluation of fiber surfaces treatment and sizing on the shear and transverse tensile strengths of carbon fiber‐reinforced thermoset and thermoplastic matrix composites

Abstract

The mechanical performance of advanced composite materials depends to a large extent on the adhesion between the fiber and matrix. This is especially true for maximizing the strength of unidirectional composites in off-axis directions. The materials of interest in this study were PAN-based carbon fibers (XA and A4) used in combination with a thermoset (EPON 828 epoxy) and a thermoplastic (liquid crystal polymer) matrix. The effect of surface treatment and sizing were evaluated by measuring the short-beam shear (SBS) and transverse flexural (TF) tensile strengths of unidirectional composites. Results indicated that fiber surface treatment improves the shear and transverse tensile strengths for both thermosetting and thermoplastic matrix/carbon fiber-reinforced unidirectional composites. A small additional improvement in strengths was observed as the result of sizingtreated fibers for the epoxy composites. Scanning electron microscope photomicre graphs were used to determine the location of composite failure, relative to the fiber-matrix interface. Finally, the epoxy composites SBS and TF strengths appear to be limited to the maximum transverse tensile strength of the epoxy matrix, while the thermoplastic composite SBS and TF strengths are limited by the LCP matrix shear and transverse tensile strengths, respectively.

In situ polymerization and nano‐templating phenomenon in nylon fiber/PMMA composite laminates

“…Therefore, regardless of the composite fabrication technique employed, superior composite strength cannot be attained without excellent adhesion between fiber and matrix. 4 Without this adhesion, load cannot be efficiently transferred from matrix to fiber, and poor composite properties will result. Given that fiber and matrix are generally incompatible, fibers are always pretreated with compatibalizers called sizings to ensure adhesion between fiber and matrix.…”

Effects of silica surface treatment on the impregnation process of silica fiber/phenolics composites

“…Because the interphase couples the stress transfer between the reinforcement and the matrix, the characteristics of the interphase are directly responsible for determining the static and dynamic properties of composite materials, as well as their environmental stability. [2][3][4]6 After surface treatment, the fibers are generally sized or coated with a thin polymer layer. 5,[7][8][9][10][11] The purpose of sizing is to insert a polymer interlayer between the silica fiber and the polymer matrix and to use the properties of the sizing to control the level of fiber/matrix adhesion.…”

Short‐beam three‐point bend tests in syntactic foams. Part II: Effect of microballoons content on shear strength

“…Blackketter et al 15 studied the evaluation of fiber surface treatment and sizing on the shear and transverse tensile strengths of carbon fiber-reinforced thermoset and thermoplastic matrix composites. Cui et al 19 studied the failure mechanism in the three-and four-point bending tests.…”