Meaning
Inorganic filamentary reinforcements added to polymer matrices increase the structural performance of thermoplastic composites. Incorporating glass fiber into a resin shifts the material behavior from ductile to rigid, enhancing both load capacity and thermal resistance. This additive is widely utilized in structural automotive and industrial components.
Reinforcement Effect
Load transfer from the compliant polymer matrix to the high-modulus glass fiber requires strong interfacial adhesion. Coupling agents are applied to the fibers to create covalent bonds with the polymer chains. Without this chemical bonding, the fibers act as stress concentrators rather than reinforcing agents.
Flow Orientation
Melt flow behavior during the injection stage determines the spatial distribution of the reinforcements. When glass fiber flows through a gate, the shear forces align the filaments parallel to the flow direction. This alignment creates highly anisotropic properties in the solid part.
Shrinkage varies significantly between the flow and cross-flow directions.
Mechanical Consequence
High concentrations of these fibers dramatically increase the tensile strength and heat deflection temperature of the moulded component. However, the presence of glass fiber accelerates tool wear through abrasion on the screw and barrel surfaces of the injection moulding machine. The reduced ductility of the composite also lowers the impact toughness of the final part under high-rate loading.
High viscosity in the filled resin necessitates elevated melt temperatures and increased injection pressures to achieve complete cavity filling.
