| Because of the special macromolecular structure of coal, ultrafine coal powder can replace the carbon black partly or completely using as reinforcing filler in the rubber. In order to enhance the reinforcing performance of the ultrafine coal powder on polymers, the alcamines, coupling reagents and polymers formed by insitu polymerization, etc were usually used to modify the surface of the ultrafine coal powder. The linear phenol-formaldehyde resin (LPF or PF) is also used as an organic reinforcing filler of some certain rubber. The investigations on the preparation of reinforcing filler of ultrafine coal powder modified with the PF have seldom seen in literature.In this paper, the surface modification of LPF on different rank ultrafine coal powders (Yunnan brown coal, Shenfu 3-1coal and Tongchuan coal) was investigated by the mechanochemistry method on the planetary ball mill, and a novel reinforcing filler-coal powder modified with the PF (Coal-g-PF) with both properties of coal and LPF, was prepared by using this method. The reinforcing effect of the reinforcing fillers on NBR was further conducted.Firstly, the influence of the ratio of ball to coal (ball/coal), ball grinding time and the PF adding amount on the rate of the PF grafting on the Yunnan brown coal surface was studied under the conditions of the ratio of steel ball (Φ16,Φ10, Φ6) is 3:2:1, the rotational speed of ball mill is 300 rpm and PF adding amount is 4%.The result indicated that the rate of the PF grafting on Yunnan brown coal is highest when the ball/coal is 15:1 and ball grinding time is 4.5hr. Based on these results, the effect of PF adding amount on the rate of the PF conversion and grafting onto different rank the ultrafine coal powders was further investigated.It was found that with increase of PF adding amount, the rate of the PF grafting onto the ultrafine coal powder take on increasing trend, and the PF conversion rate rises quickly at the...
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