Copolyterephthalates containing tetramethylcyclobutane with impact and ballistic properties greater than bisphenol A polycarbonate

For the past 40 years bisphenol A polycarbonate has been the industry standard for lightweight transparent armor protection. More recently, researchers at the Shell Chemical Company developed a co-polyester derived from 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO), 1,3-propanediol (PDO), and dimethyl terephthalate (DMT). By varying the percent incorporation of the monomers, the thermal/mechanical properties of this copolyterephthalate are tunable. Shell found that interesting impact properties arose from the material when 40 mol% CBDO was incorporated into the polymer. This material displayed a notched Izod value of 1070 J/m while maintaining Tg near 100 °C. The work discussed here focuses on the mechanical, impact, and ballistic characterizations of this material. Tensile, notched Izod, and .22 FSP V50 data are reported. This new material shows improvement over bisphenol A polycarbonate in both notched Izod as well as ballistic impact values.