Preparation of Natural Rubber with Nanodiamond Nanomatrix Structure

Incorporation of nanoparticles into polymer forming nanomatrix structures opens a window to new pragmatic applications. In these matrices, micro sized polymer particles are embedded in a well connected nanoparticle matrices, introduces novel properties to the polymeric material. Physical and chemical robust nature and the highly tunable surface chemistry of nanodiamonds (ND) over other carbon based nanomaterial, makes it a potential candidate for nanomatrix formation with natural rubber. However there are no such reports to date. In present investigation ND was incorporated into urea deproteinized natural rubber. Commercial high ammonia natural rubber latex was deproteinized using urea in the presence of sodium dodecyl sulfate at room temperature (DPNR). Then the DPNR was reacted with shock wave synthesized ND (5%, SCM Fine Dia.) slurry in NH₄OH_, using 3.3×10^-5 mol/g- rubber tert-butylhydroperoxide / tetraethylenepentamine initiator at 303 K under N₂ saturated environment. Film of 1 mm thickness was prepared by casting ND/DPNR latex in petri dish and dried at 323 K for 24 hours in air.Then the film was further dried under reduced pressure for several days. The storage modulus of the resulting ND/DPNR was two times high as that of DPNR. However the DPNR with 5% ND film prepared by physical mixing in similar experimental conditions showed only a slight increase in storage modulus. In the morphology investigation by transmission electron microscope, the ND/DPNR shows formation of the nanomatrix structure. Further the gel content of the ND/ DPNR prepared with initiator, without the initiator and DPNR were 67.5%, 41.29% and 40% respectively.