Micromechanical modeling, thermal, and dielectric studies of poly (methyl methacrylate)-barium titanate composites

Polymer composites containing poly (methyl methacrylate) (PMMA) and barium titanate (BaTiO₃) were synthesized using the solution mixing method. The electrical conductivity of PMMA is 6 × 10⁻⁹ S/cm, and adding 2% fillers reduces to 5 × 10⁻⁹ S/cm. The melting point of PMMA is 373 °C, and adding 2% and 4% fillers increased it to 376 °C and 379 °C, respectively. The polymer chains become less mobile and block macromolecules on the filler surface. The modulus of elasticity and mechanical tensile stress of the polymer composites with a 5-wt% of BaTiO₃ are 759.3 MPa and 75.6 MPa, respectively. The breakdown strength of PMMA is 203 KV and reduces with the addition of 5% filler to 144 KV. The values of E c/E m evaluated using the Tsai-Pagano, Christensen-Waals, ROM, Mori-Tanaka, and Halpin-Tsai models underpredict the modulus compared to experimental E c/E m values. Fourier spectroscopy confirmed the presence of Ti-O and BaTiO₃ bonds in the polymer composite. Scanning electron microscope images reveal spherical aggregates of BaTiO₃ coated with PMMA and an interparticle network. The dielectric constant of PMMA is 3 and increased with the addition of 2% and 4% fillers to 4 and 4.3, respectively.