Ultraviolet (UV) curing kinetics of hyperbranched polysiloxane (HBP) initiated by 2-
Hydroxy-2-methyl-1-[(4-isobutyl)phenyl]-1-propanone (Trade name: IHT-PI 185)
was studied by using Differential Photo Calorimeter (DPC). The effects of
photoinitiator concentration, UV irradiation intensity, environment temperature and
atmosphere on curing behaviors were investigated. It was found that both curing rate
(R) and ultimate vinyl conversion percentage (C) first increase and then tend to
stabilize within 3 wt% of photoinitiator concentration. Higher UV irradiation intensity
can lead to higher values of R and C. Particularly, R is proportional to the square root
of irradiation intensity at initial stage. Although raising temperature could raise the
values of R and C, the effect of temperature on R is not marked. Oxygen possesses
a notable inhibition effect on curing, however, induction period can be reduced by
enhancing irradiation intensity. Curing kinetics was studied using Ameliorated
Autocatalytic Model attaching a diffusion term. It is found that the model is suitable to
describe the autocatalysis effect at the initial stage and the termination stage controlled
by diffusion process. The kinetic parameters including total apparent curing exponent
and apparent activation energy calculated by model above are c.a. 6 and 13.15
KJ/mol, respectively.
