Study on the Polymerization, Curing, and Mechanical Properties of Unsaturated Polyester Nanocomposite: Effect of Monomers Ratio and Nanosilicate Concentration

In this study, after the preparation of unsaturated polyester with various ratios of anhydride monomers, the effects of nanosilicate on the polymerization, curing behavior, and mechanical properties were investigated. The unsaturated polyester resin was synthesized at various molar ratios of anhydride monomers (maleic/phthalic: 10 to 90%) and propylene glycol. Acid number measurement was used to evaluate polymerization. With an increase in the molar maleic content, the time of polymerization reaction and the acidic number increased. In the next step, the resin was cured with an accelerator and initiator, and styrene monomer. curing behavior was determined using a curing curve and gelation time measurement. The curing curve showed that by increasing the maleic anhydride monomer ratio from 10% to 90%, the curing time decreased by 77%, and the maximum thermogenic temperature increased by 24%. Increasing the maleic content from 10 to 90% resulted in tensile strength changes from 11 to 70 MPa and tensile modulus from 60 to 359 MPa. The impact strength and the heat distortion temperature increased and became plateaued at higher maleic percentages. The nanocomposites were prepared with 50 mol% maleic anhydrides, containing 2, 4, 6, and 8 wt.% of nanosilicate. By increasing the amount of nanoclay, the curing time decreased and the maximum exothermic temperature increased. Mechanical properties were evaluated by using Heat Deflection Temperature (HDT), tensile properties, impact strength, and surface hardness tests. The impact strength and the heat distortion temperature also showed an upward trend with an increase in the amount of nano, even in small quantities. By adding 8% nanoclay to the matrix, the impact strength and heat deflection temperature increased by 11% and 13%.