Silica‐reinforced natural rubber prepared by the sol–gel process of ethoxysilanes in rubber latex

Abstract

Silica-reinforced natural rubber (NR) composite was prepared by using tetraethoxysilane (TEOS) as a precursor to generate silica particles inside the rubber. The silica was generated in situ by the sol-gel process of TEOS that was mixed directly into commercial-graded NR latex having 60% dry rubber content and 0.7% ammonia. The conversions of TEOS to silica inside the rubber were ranging from 90 to 97%. The silica particles dispersed evenly without extensive aggregation with sizes between 100 and 500 nm, as determined by scanning electron microscopy (SEM). An experimental design methodology, namely ''two-level factorial design,'' was used to evaluate the influence of the amounts of TEOS, ammonia, and gelation time on the tensile modulus, tensile strength, and tear strength of the vulcanizates. The mechanical properties were significantly affected by the amount of TEOS added into the latex. Ammonia in the amount of 0.7% (w/w) present in the commercial latex was found to be sufficient for the conversion reaction of TEOS to silica. Bis-(3-triethoxysilylpropyl)tetrasulfide or TESPT, a coupling agent regularly used in rubber industry, was also added with TEOS to prepare the silica-filled composite. The presence of TESPT resulted in an increase of the mechanical properties and the rate of sulfur cure.

Effect of silane integrated sol–gel derived in situ silica on the properties of nitrile rubber

“…The amount of organosilane has been varied to assess its influence on the properties of the composites. Similar approaches of in situ silica generation along with different organosilanes in NR latex and aminopropylsilane in epoxidized SBR solution were reported . Properties of all the synthesized composites were evaluated in terms of curing characteristics, morphology, mechanical and dynamic mechanical properties.…”

Silica nanoparticles reinforced natural rubber latex composites: The effects of silica dimension and polydispersity on performance

“…Meanwhile, the t s2 of PS filled NR compounds were lower compared with AS/NR compounds, which indicated that this kind of compounds was easier to scorch. This can be explained that PS has smaller exposed surface area and lower absorption of curatives, while more left in the rubber matrix . In the preparation of silica/NR masterbatches, all of the silica was moisture‐treated and the moisture existed on the silica surface promoted the hydrolysis of nitrogen‐sulfur bonds of the accelerator NS, which then reacted to the formation of 2‐mercaptobenzothiazole (MBT) and resulted in faster scorch .…”

“…First, the in situ silica particles prepared by in situ sol–gel method with silica precursor, and then co‐flocculated with rubber latex has been reported . Meanwhile, many efforts have been carried out focusing on the silica reinforce rubber in latex system by sol–gel method as well . Second, various types of commercial silica were used to prepare the silica slurry, which was blended with NR latex to prepare the masterbatches directly .…”

The preparation and structural characterization of ambient-dried porous methylsilicone matrix doped with SiO2 powder

“…SiO 2 is frequently used as filler to reinforce the polymer matrix due to its low cost and high melting point. SiO 2 -filled polymer composites could be achieved by in-situ formation of SiO 2 via sol-gel process or incorporating SiO 2 powder in polymer matrix [11][12][13][14]. The former process is used for formation of nanosized hybrid composite in which careful control over the synthesis parameters is crucial.…”