Two new methods to obtain crosslinking plasticized poly(vinyl chloride) (PVC) are shown. One is by the substitution reaction of PVC with the sodium salt of gamma-mercaptopropyl trimetoxysilane and the other is by the free-radical reaction of azide-modified PVC with gamma-acryloxypropyltrimetoxysilane and vinyltri(2-metoxyetoxy)silane. The content of gel and the number average molecular weight between crosslinking (M(c)) were determined by Soxhlet extraction and by using the Flory-Rehner equation. The reactions of PVC with the above organosilanes under normal processing conditions of the polymer lead to high gel contents and, therefore, low M(c). The ultimate tensile strength and elongation at break at 110 degrees C of these polymers are greatly enhanced over those of the uncrosslinked polymer. The results are improved compared to those taken from literature for similar systems.