| Fluororubber can be long-term used in rigorous conditions,but it cannot be used widely due to its high price. There are fewer researches on regeneration of fluororubber. The fluororubber regeneration technology can help to alleviate the shortage of rubber resources and reduce the costs.In this paper,the effect of the amount of different reclaiming agents,process conditions (mill shear number),the variety and content of plasticizers on waste reclaimed fluororubber were studied. The structure and properties of vulcanizate rubber of reclaimed fluororubber/fluororubber and reclaimed fluororubber/nitrile-butadiene Rubber (NBR) blends were investigated. The properties and structures of reclaimed fluororubber and its vulcanizate blends were characterized by scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), thermal gravimetric analyzer (TGA) and curing instrument. The main experimental work and results were listed as follows:(1) When the amount of reclaiming agents were 0～5phr,the maximum and minimum torque were decreased as increasing of the reclaiming agents content. Comparing with phenylhydrazine/FeCl2 and commercial reclaiming agents,the maximum equilibrium swelling of vulcanizate reclaimed fluororubber was obtained by adding 2-mercaptobenzothiazole at the 3phr.(2) Due to the higher Shore A hardness of vulcanized reclaimed fluororubber, cashew nut shell oil (CNSL) modified by maleic anhydride and butyl acrylate was used to plasticize reclaimed fluororubber. Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry analysis results showed that maleic anhydride and butyl acrylate were successfully grafted on CNSL.(3) When the amount of plasticizers were 0～5 phr, maximum and minimum torque of reclaimed fluororubber were decreased and the scorch time and optimum curing time increased by adding the plasticizers. After post curing,it was found that bis(2-ethylhexyl) terephthalate had little effect on plasticization. Compared with tri-octyl tri-meta-benzoate,the vulcanized rubber had higher mechanical properties and low shore A hardness by using modified CNSL as a plasticizer.(4) With the mill shear number increase,the scorch time and optimum curing time of reclaimed fluororubber increased first and then kept constant. There was the highest tensile strength of vulcanize rubber when the mill run at 30 times. And the hardness value increased as mill shear number increasing. When the amount of curing agent bisphenol AF increased,the scorch time of reclaimed fluororubber increased and the optimum curing time decreased.(5) To the tluororubber/reclaimed fluororubber blends system,as the proportion of reclaimed fluororubber between 0 to 50%,the minimum torque of blends was showed gradually increasing,and the maximum torque was decreased first and then increased. The scorch time was changed little,but the optimum curing time gradually decreased with the increasing of the content of reclaimed fluororubber. The tensile strength and the elongation at break of vulcanized rubber blend were decreased with adding reclaimed fluororubber. After aging in thermal air or oil,the tensile strength of the blends was increased whereas the elongation at break was decreased.(6) To the NBR/reclaimed fluororubber composites,as the proportion of reclaimed fluororubber increasing to 50%,the maximum and minimum torque of vulcanized blends were first decreased and then increased,and the scorch time decreased gradually. The optimum curing time was decreased first and then kept constant with the increasing of the content of reclaimed fluororubber. The tensile strength and the break elongation of vulcanized blends were decreased as the content of reclaimed fluororubber increasing,but the compression set was turned lower. As the proportion of reclaimed fluororubber was 30%,the thermal oxidative aging resistance and oil resistance of vulcanized blends were better. The TG result showed that blending with reclaimed fluororubber could slightly increase the thermostability of NBR. |
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