To Explore The Tensile Strength Performance of Dental PMMA

The tensile strength performance of dental PMMA is influenced by multiple factors, and its specific manifestations are as follows:

The basic tensile strength range: Generally speaking, the tensile strength of polymethyl methacrylate (PMMA) can reach the level of 50-77 mpa, and the flexural strength can reach 90-130 mpa. The upper limits of these performance data have reached or even exceeded those of some engineering plastics. However, the elongation at break of dental PMMA is only 2% to 3%, and its mechanical properties are basically those of hard and brittle plastics. It is notched sensitive and prone to cracking under stress.

The influence of reinforcing materials on tensile strength:

Natural powder enhancement: When the shell powder of Acacia (pistachio) was added to PMMA in different weight fractions and average particle sizes, the tensile strength decreased as the weight of the acacia shell powder increased. This might be due to the fact that pistachio shell powder cannot reduce the sliding of PMMA chains, and the high powder content leads to insufficient wettability of the particles, which reduces the adhesion between the matrix and the reinforcing powder, ultimately resulting in a decrease in tensile strength.

Other material enhancements: Researchers attempted to enhance the mechanical properties of denture base resin PMMA by adding Siwak powder with an average particle size of 75 microns. However, low concentrations (3% and 5%) of Siwak powder had little effect on the mechanical properties of thermally polymerized denture base acrylic resin, while the addition of 7% Siwak powder significantly reduced tensile strength.

The influence of chemical modification on tensile strength: By altering the structure of the ester group, the α -substituent, the main chain structure, or introducing chemical bonds for cross-linking between macromolecular chains, the tensile strength of PMMA can be enhanced. For instance, when methacrylic acid is copolymerized with MMA, with the increase of methacrylic acid content, some mechanical strengths of the copolymer are significantly improved. Acrylonitrile copolymerized with MMA, the impact strength and tensile strength of the copolymer are both higher than those of PMMA, and they increase with the increase of acrylonitrile content.