In this study, we explored the possibility of partial devulcanizing or de-crosslinking and recycling of ground tire rubber (GTR), post-vulcanized flurorubber scraps and crosslinked polyethylene from cable scraps through high-shear mechanochemical milling in solid state by a modified solid-state mechanochemical reactor. Gel fraction of the scraps was remarkably reduced after milling, indicating the occurrence of stress induced breakage of crosslinking structures. The partially devulcanized or de-crosslinked polymer scraps can be reprocessed as virgin rubber or thermoplastics to obtain articles with high performance. The composites containing crosslinked polymer scraps were prepared by using solid state mechanochemical reactor. The foamed composites of low density polyethylene (LDPE) and ground tire rubber (GTR) mixture and blend of post-vulcanized flurorubber (FKM) and polyacrylate rubber (ACM) with better mechanical properties were obtained. The results indicated that the mechanochemical pretreatment of LDPE/GTR blends enhanced the dispersion state and thereby enhanced the foamability and mechanical properties of the blends. Blending of FKM with ACM might enhance the thermal resistance of ACM, and obtain the best compromise in compound processability and cost. Replacement of virgin FKM by reclaimed FKM is a potentially attractive way to combat its high cost. The ACM/devulcanized FKM blends have a curing rheology similar to that of virgin ACM compositions. The ACM/devulcanized FKM blends also exhibited better oil resistance than pure ACM. The experimental results indicated that the devulcanized FKM prepared by mechanochemical milling is a suitable filler of ACM vulcanizates overcoming the negative effects caused by rubber particles without devulcanizing. The results demonstrate that high-shear mechanochemical milling is a feasible technologic alternative for recycling of post-vulcanized or crosslinked polymer scraps.