PROCEDE DE PREPARATION D'HOMOPOLYMERES D'HALOGENURES DE VINYLE AYANT DES CARACTERISTIQUES AMELIOREES DE MISE EN OEUVRE

摘要

The stages are:- (1) free radical initiation of polymerisation of vinyl halides using appropriate catalyst at a temp. sufficient to give 10-60% conversion. (2) Increase in temp. above that of stage 1 during the remainder of the polymerisation. (1) is vinyl chloride. Temp. of stage 1 is 35-55 degrees C and of stage 2 is 60-80 degrees C. A chain transfer agent (aliphatic halogenated hydrocarbon) may be included at the start of stage 2. The polymerisation may take place in aq. suspension. The polymers are used for films, containers, and moulding materials. The polymer has good flow properties with improved strength and is free from unmelted high mol. wt. polymer which causes "fish eyes" in mixtures of high and low mol.wt. PVC.