Fabrication and evaluation of mechanical properties of Sisal and glass microfibers reinforced novolac phenolic composites

This study aims to evaluate the enhancement of tensile strength and hardness in phenolic matrix composites reinforced with either glass fibers or natural sisal fibers, with each type added at a 40% weight fraction. The study explores the potential of cost-effective, eco-friendly fibers for a wide range of industrial and engineering applications, particularly where thermal insulation and fire resistance are critical. Novolac phenolic resin was mixed with fiber powder and a hardener (hexamine) at 14% of the resin’s weight, then molded and compressed with a hot press. The resulting composite sheets were then cut into test specimens using CNC water jet cutting. Initially, each fiber type was manually cut, dried in an oven, and ground using a high-speed industrial grinder, then sieved to achieve a uniform particle size of 150-300 microns. Novolac resin was also ground and sieved to ensure optimal homogeneity. Three formulations were prepared and thoroughly mixed for even distribution as follows: the total mass for each formulation is 300g. Pure Novolac Resin: Contains only resin, without any fibers. Glass Fiber-Reinforced Composite: Contains 40%, or 120g, of glass fibers, with the remaining being resin. Sisal Fiber-Reinforced Composite: Contains 40%, or 120g, of natural fibers, with the remaining being resin. Each formulation was placed into a mold cavity, producing the three composite sheets, which were subsequently cut into tensile specimens using CNC water jet cutting. The results demonstrated significant improvements in mechanical properties: glass fiber reinforcement led to a 278.2% improvement in tensile strength compared to pure Novolac, while sisal fiber reinforcement showed a 106.98% improvement. Hardness testing revealed an 8.43% increase with glass fiber addition and a 2.27% increase with sisal fiber reinforcement, confirming the suitability of these materials for diverse applications requiring enhanced performance.