THERMAL-DECOMPOSITION OF THE COPOLYMERS BASED ON LONG-CHAINED DIOL DIMETHACRYLATES AND BIS-GMA TEGDMA/

The process of thermal decomposition of copolymers based on six long-c hained diol dimethacrylates, namely 1,4-butane-, I,5-pentane-, 1,6-hex ane-, I,8-octane-, 1,10-decane- or 1,12-dodecanediol dimethacrylates ( 1,4-BDDM, I,5-PDDM, 1,6-HDDM, I,8-ODDM, I,10-DDDM or I,12-DDDDM, respe ctively), and 2-hydroxy-3-methacryloyl-oxypropoxy)phenyl]propane (BIS- GMA) or triethylene glycol dimethacrylate (TEGDMA), has been investiga ted by thermogravimetric analysis (TGA), TGA coupled with Fourier tran sform infra-red spectroscopy (TGA/FT-IR) and differential scanning cal orimetry (DSC). It has been found that the polymers under investigatio n are thermally stable up to approximate to 250 degrees C, as shown by the initial decomposition temperature (IDT) and that degradation prof iles are generally of a one-step type. No post-cure effects were found on the basis of DSC scans, thus indicating formation of an infusible three-dimensional network. The qualitative and quantitative analysis o f the main volatile products by TGA/FT-IR made it possible to confirm a polyesters' thermal degradation scheme with formation of CO2, olefin s and carbonyl-containing structures. (C) 1997 Elsevier Science B.V.