The influence of monomer ratios on the properties of copolymers of 3,3′-spirobiphthalide and bisphenol A diglycidyl ether

Summary A spirobislactone, 3,3-spirobiphthalide (SBP), has been copolymerized with the diglycidyl ether of bisphenol A (DGEBA), and the properties of the products have been evaluated and related to the proportion (1–15%) of SBP monomer used. Polymers were characterized by infrared spectral analysis,¹³C NMR, thermal analysis, and mechanical testing. Polymers containing SBP have lower glass transition temperatures and higher decomposition temperatures than DGEBA polymers cured with phthalic anhydride (PA). Materials with higher SBP content have higher T_alpha values. Mechanical properties of the SBP copolymers are similar to those of DGEBA-PA polymers.