Effect of plasma-polymerised acetylene-coated silica on the compound properties of natural rubber composites

Abstract

Silica-filled natural rubber (NR) encounters incompatibility problems, owing to the strong particle-particle interaction arising from the hydrogen bonds of hydroxyl groups, which generally leads to the formation of agglomerates. The addition of coupling agents, especially silane coupling agents, reduces the agglomeration. However, this has some disadvantages, such as toxicity, a risk of pre-curing, and the generation of ethanol during mixing. This work aims to focus on the effect of filling the plasma-polymerisation of polyacetylene-coated silica into natural rubber compounds. The deposition of plasma-polymerised acetylene applied to silica particles was firstly carried out using a radio frequency (RF) with an input power of 20 kW for 60 min and further incorporated into NR compounds. On the surface of the coated silica analysis, the formation of a polyacetylene layer on the silica surface was obviously confirmed that it exhibited more stability in water. The following polyacetylenecoated silica (PA-coated silica)-filled NR compound properties were analysed: mixing energy and temperature, Payne effect, complex viscosity, and cure characteristics. The NR compounds mixed with PA-coated silica showed a lower mixing torque, dumping temperature, Payne effect, and viscosity, when compared to NR compounds with unmodified silica and ordinary silane systems. However, the differences were insignificantly noticed in the cure characteristics of the compounds. Polyacetylene-coated silica developed from plasma polymerisation can be used to improve the uniformity of dispersion, as well as the compatibility of silica in a natural-rubber matrix, without changing its cure characteristics, compared to the one with a silane coupling agent.

Comparative Investigation of Nano-Sized Silica and Micrometer-Sized Calcium Carbonate on Structure and Properties of Natural Rubber Composites

“…This is due to the strongly acidic nature of silica, having a lot of chemically reactive silanol groups on the particle surfaces. These polar silanol groups adsorbed or otherwise reacted with the accelerator for the sulfur-based curing system, because the majority of accelerators are alkaline [ 5 , 17 , 29 ], reducing the quantity and efficiency of the accelerator in the vulcanization process and thereby decreasing the CRI.…”

Plasma Polymerization of Precipitated Silica for Tire Application

“…It is possible to coat the surface of the filler using different monomers, which tailor the characteristics in terms of surface energy and functionality. Various studies have been conducted on the effect of plasma modification of a filler [ 9 , 10 , 11 , 12 , 13 , 14 ], including silica and carbon black, with different precursors to investigate the property enhancements in several rubbers and their blends. Nah et al [ 9 ], improved the mechanical properties of SBR compounds by acetylene plasma-polymer deposition on silica.…”

New Modification Methods of the Silica Surface for Tire Applications

“…When preparing surface-treated silica, there are several surface-treatment techniques to consider. Instead of the traditional method of solution modification, alternative techniques like plasma polymerization [51][52][53][54][55][56][57] and vapor (gas) phase modification [58][59][60][61] have been investigated for surface treatment of silica. Both plasma polymerization and gas phase modification are environmentally friendly since they eliminate the need for organic solvents.…”