Abdoulhossien Massoudi - Department of Chemistry, Payame Noor University, P. O. BOX ۱۹۳۹۵-۴۶۹۷ Tehran, Iran
Azam Louie - Department of Chemistry, Payame Noor University, P. O. BOX ۱۹۳۹۵-۴۶۹۷ Tehran, Iran
Omid Louie - Department of Chemistry, Payame Noor University, P. O. BOX ۱۹۳۹۵-۴۶۹۷ Tehran, Iran

Poly methyl methacrylate (PMMA) is the most common material used in Prosthodontics. Severalstudies indicate a breakdown of the number of very high resin bases after 2 to 3 years to avoidbreaking bass, and several attempts have been made such as altering the chemical structure ofresin by adding causes cross linking or copolymerization. As an innovative method forimproving the physical properties of the prosthesis and increasing its strength, a copolymer ofstyrene-methyl methacrylate was proposed. Tensile strength was increased with the increase ofstyrene with methyl methacrylate in an amount determined to be the most resistant. Polystyreneand poly methyl methacrylate and copolymers characterized by FTIR, CNMR and Tg and tensilestrength were measured according to ISO1567 standard.

Copolymer; poly methyl methacrylate (PMMA); poly styrene(PSt); tensile strength