Synthesis of novel compatibilizers and their application in PP/nylon-66 blends. I. Synthesis and characterization

A series of novel compatibilizers with different length of oligocaprolacton e branch chains, which are capped with one, two or three carboxyl groups at one of these branch chains' extremities, were synthesized by a three-step approach involving: (1) the oligomerization of epsilon-caprolactone initiat ed by various of hydroxy acids (glycollic acid, DL-malic acid, or citric ac id); (2) the reaction of acryloyl chloride with alpha-hydroxyl-w-carboxyl ( 1,2,3)-oligocaprolactone (HCPCL); and (3) the graft copolymerization of alp ha-acryloyl-w-carboxyl (1,2,3)-oligocaprolactone (ACPCL) with polypropylene . Effects of various parameters such as monomer ACPCL and initiator benzoyl p eroxide concentration, reaction time, and ACPCL kinds on the grafting perce ntage of ACPCL onto polypropylene (PP) in xylene solution were studied. The grafting of ACPCL onto PP in a laboratorial single screw extruder was also investigated. The maximum extents of grafting achieved in solution and mel t were about 10.2 and 12.3%, respectively. The intermediate products, HCPCL and ACPCL were characterized by acid-base titration, hydroxyl value titration, Fourier transform infrared spectroscop y (FTIR),H-1- and C-13-nuclear magnetic resonance analyses, respectively. T he grafting copolymers were also characterized by electrometric titration, FTIR analysis, and differential scanning calorimetric, respectively. (C) 20 00 Elsevier Science Ltd. All rights reserved.