Influence of reactant concentration and reaction time in the chemical modification process of polypropylene by p-phenylen-bis-maleamic acid in the melt

Following earlier studies on chemical modification processes of polypropyle nes by polar monomers, a new study by grafting p-phenylen-bis-maleamic acid in the molten state has been carried out. In a previous a work a four inde pendent variable Box-Wilson experimental design lets us conclude the adequa cy of working at a certain gear rate and low times of reaction. This is the reason why, in this work, a two independent variable design (reactant conc entrations) has been used and applied to four different times of reaction i n order to check those findings. Besides, it is also confirmed that the pro cess follows an oscillating evolution of grafting level with the reaction t ime, and the existence of critical points for the reactant concentrations ( p-phenylen-bis-maleamic acid and dycumile peroxide). These facts seem to ag ree with a chemisorption mechanism, governing the reaction yields in this k ind of reactive systems, where the main and limiting role is played by the macromolecular substrate. (C) 2000 Elsevier Science Ltd. All rights reserve d.