Photopolymerization of dendritic methacrylated polyesters. II. Characteristics and kinetics

✍ Scribed by Wenfang Shi; Bengt Rånby

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 434 KB
• Volume: 59
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960321)59:12<1945::aid-app17>3.0.co;2-q

✦ Synopsis

The starburst dendritic polyester with about eight double bonds was found to polymerize rapidly in the presence of a 3% photofragmenting initiator, benzildimethylketal, at room temperature in air, reaching 75% conversion after 0.15 s UV irradiation of a pm film. The effects of a photoinitiator and comonomer on the photopolymerization process for methacrylated polyester resins were investigated by measuring the conversion of the unsaturation and physical properties. The degree of copolymerization of the unsaturation decreases in the case of resins with high functionality. A kinetic study of the UV-induced curing of the dendritic polyesters by evaluating gel content and belt speed has shown that the photopolymerization rate increases rapidly with increasing acrylic functionality of the dendritic polyesters, which is in favor of the theory of radical-chain polymerization. High pendulum hardness is obtained with dendritic polyesters of high functionality. However, the addition of 10-40 w t % multifunctional monomer trimethylolpropane triacrylate has a small effect on the curing efficiency after prolonged UV irradiation, which is different from conventional linear acrylated oligomers.