Evolution of crosslinking structure in vulcanized natural rubber during thermal aging in the presence of a constant compressive stress

•Constant compressive stress promoted the fracture of polysulfide and disulfide bonds.•Reactive sulfur-containing side (RSS) groups were formed under compressive stress.•RSS groups could participate in re-crosslinking reactions in the presence of heat.•RSS groups increased the hysteresis loss of NR under deformation.