Effect of Clay, Mixing Speed, and Time on Mechanical Properties of Glass Fiber/Clay Reinforced Unsaturated Polyester Prepared by Vacuum Bag Technique

Modification of the properties of GFRP composites is mostly done because of its wide application, one of which is to increase its thermal resistance properties. Adding clay as a filler can increase flame retardant but affects changing mechanical properties. Clay mixed with resin with a magnetic stirrer with speed and mixing time parameters was studied to see the effect on changes in mechanical properties (flexural, tensile, and impact) which were analyzed using the CCD method. Variations of clay 1, 2, and 3% with stirring speeds of 100, 150, and 200 rpm and mixing times of 60, 90, and 120 min resulted in changes in flexural strength and modulus between −12 and 8% and −10% to 15% compared to pure resin. The highest increase in flexural strength and modulus occurred with the addition of 1% clay stirred at 200 rpm for 60 min was 306 MPa and 12,055 MPa. The same trend also occurs in Tensile strength and modulus, with the highest being 193 MPa and 6,258 MPa and the highest impact being 153 kJ/m2. The maximum strength and modulus were produced at low clay level, high mixing speed, and short mixing time. Maximum mechanical properties are produced at low clay content, high mixing speed, and short mixing time. High shear resulting from rapid stirring causes the clay to split and spread so that clay agglomeration does not occur. Short stirring time reduces the evaporation of the styrene so that more crosslinking occurs. Clay has a maximum function as a filler because of low agglomeration and there is a lot of crosslinking causing better mechanical properties.