Preparation and properties of the aramid pulp/nitrile butadiene rubber composites with compatibilization of ionic liquids

To improve the uniformity and the mechanical/wear performances of the aramid pulp (AP)/nitrile butadiene rubber (NBR) composites, two types of ionic liquids (ILs), that is, 1-carboxymethyl-3-methylimidazolium chloride ([CmMIM]Cl) and 1-allyl-3-vinylimidazolium chloride ([AVIM]Cl) were applied on the AP surface, respectively. The ILs partially disrupted the hydrogen-bonds between the aramid chains to mitigate the fiber entanglement, and connected the AP to the rubber matrix by hydrogen-bond interaction or the crosslinking reaction during the vulcanization. The test results showed that, the IL treatments effectively improved the tensile and tear strengths without obviously affecting the physical characteristics of the composites. The wear properties of the AP/NBR composites also improved due to the enhancements of the tear strength and the connection between the AP and NBR matrix. Compared to the [CmMIM]Cl, the [AVIM]Cl was more efficient to improve the properties attributed to its better compatibilization for the AP/NBR system. For example, the specific wear rate under 20-N load of the composite with 15-phr [AVIM]Cl-AP was 1.1 x 10(-7) mm(3) N-1 mm(-1), which was approximately 25% and 35% lower than that of the composites reinforced with 15-phr [CmMIM]Cl-AP and untreated AP, respectively.