Effects of titanate coupling agent on the mechanical, thermal, and morphological properties of poly(methyl methacrylate)/hydroxyapatite denture base composites

Abstract

Poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) denture base composites were prepared using heat-processing polymers powder–liquid method, according to dental laboratory practice. The HA was pre-treated by isopropyl triisostearoyl titanate coupling agent (TCA) in order to improve the interfacial bonding between HA and PMMA. The effects of different concentration of titanate coupling agent (i.e., 2–8%) on the mechanical and morphological properties of PMMA were investigated. It was found that PMMA/2% TCA-treated HA composites exhibited higher flexural modulus and strength compared to PMMA/untreated HA composites. This is attributed to the enhanced interfacial interaction between PMMA and HA by the titanate coupling agent. However, for the PMMA/HA treated with 6% and 8% of TCA, the flexural properties was slightly reduced, which may associated to the plasticizing effects caused by excessive concentration of coupling agent. In addition, the fracture toughness properties of PMMA/5HA composites were influenced by the different concentration of TCA. The thermal properties of the PMMA/HA composites were enhanced by the treatment of titanate coupling agent.