A novel TU derivative

N

-phenyl-

N

′-(

γ

-triethoxysilane)-propyl thiourea (STU)

is prepared and its binary accelerator system is investigated in detail. Compared to the control references

the optimum curing time of NR compounds with STU is the shortest

indicating a more nucleophilic reaction occurs. The Py-GC/MS results present that the phenyl iso-thiocyanate fragment still remains in the NR/STU compounds with or without extracting treatment

but no silane segment can be found in the vulcanizate with extracting treatment. Vibrations of C=S

NH and aromatic ring in FTIR experiments and a new methyne carbon peak

as well as the peaks of phenyl group of STU

in the solid state

13

C-NMR experiments are found in the NR/STU vulcanizate with extracting treatment. Moreover

the crosslinking density of vulcanizates with STU evolves to lower level

indicating the sulfur atom of STU does not contribute to the sulfur crosslinking. Therefore

a new vulcanization kinetic mechanism of STU is propounded that the thiourea groups can graft to the rubber main chains as pendant groups by chemical bonds during the vulcanization process

which is in accordance with the experimental observations quite well.