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 range of basic tensile strength: 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 certain engineering plastics. However, the elongation at break of dental PMMA is only 2%-3%, and its mechanical property characteristics are basically those of a hard and brittle plastic, with notch sensitivity and prone to cracking under stress.

The influence of reinforcing materials on tensile strength:

Natural powder reinforcement: When the shell powder of the pistachio (also known as "Moon Nut") is added to PMMA in different weight fractions and average particle sizes, the tensile strength decreases as the weight of the shell powder of the pistachio increases. 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, reducing the adhesion between the matrix and the reinforcing powder, and 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 thermopolymerized denture base acrylic resin, while adding 7% of Siwak powder significantly reduced the tensile strength.

The influence of chemical modification on tensile strength: By altering the structure of ester groups, α -position substituents, main chain structure, or introducing chemical bonds for cross-linking between macromolecular chains, the tensile strength of PMMA can be enhanced. For example, when methacrylic acid copolymerizes with MMA, with the increase of methacrylic acid content, some mechanical strengths of the copolymer are significantly improved; Acrylonitrile copolymerizes 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.