Optimization of UV-Induced Graft Polymerization of Acrylic Acid on Polypropylene Films Using CdS as Light Sensor

Photoconductive cell of CdS was used to optimize the photograft polymerization of acrylic acid (AA) onto polypropylene film surface. Effect of UV-light intensity on the performance of this reaction in the three-dimensional space inside the reactor was researched. A relationship between light intensity measured as conductance and performance of the AA graft reaction was found. In addition, a linear relationship (r(2) = 0.98) between the grafting degree (G) and conductance (G/wt% = (2.2 +/- 0.1) 10(4)c - (0.3 +/- 0.4)) was determined in the range of 5 to 20% G, where a minimum stabilization time, such as 5 min, was required. Standard deviation of the G value and the conductance decreased when a longer distance between the film and the lamp was used, leading to a more homogeneous surface modification. Therefore, we propose this system as a new method to monitor and predict the performance of UV-induced reactions.