In this article, the physical-mechanical properties and processability of graft-modified highly chlorinated polyethylene (HCPE; chlorine contents: greater than or equal to 60%) with methyl methacrylate (MMA) by mechanochemistry reaction were studied. The results showed that the HCPE-g-MMA system is superior to unmodified HCPE in physical-mechanical properties, particularly in processability. In addition, the HCPE-g-MMA system, with about 62% chlorine content, was the same as PVC in its physical-mechanical properties. The HCPE-g-MMA system, with about 65.5% chlorine content, is the same as chlorinated poly(vinyl chloride) (CPVC) in its physical-mechanical properties, except that the Vicat softening temperature and processability of HCPE-g-MMA system are superior to PVC and CPVC. Compared with PVC and CPVC, the HCPE-g-MMA system proves better due to its lack of a toxic monomer. (C) 2003 Wiley Periodicals, Inc.