Influence of silica loading on the mechanical properties and resistance to oil and thermal aging of CR/NR blends

Abstract

Blends of 75/25 chloroprene rubber(CR)/ natural rubber (NR) filled with various loadings of precipitated silica were prepared and their processability and mechanical properties as well as their resistance to thermal aging and oil were determined. The blend morphology was also studied using the atomic force microscopy technique. The results reveal that the mixing energy and the Mooney viscosity of the compound are increased continuously with increasing silica loading. It is also found that both scorch and optimum curing times are shortened while the total crosslink density is increased with increasing silica loading. The positive effect on cure could be explained by the chemical reaction between the allylic chlorine atom of CR and the silanol group on silica surface. The tensile strength, modulus, and hardness of the blend vulcanizate are noticeably improved while the compression set at elevated temperature is impaired with increasing silica loading. The results also reveal that both thermal aging resistance and oil resistance of the blend vulcanizates, as represented by the relative properties, are enhanced with the addition of silica. The resistance enhancement is believed to arise from the combination of the dilution effect, the increased crosslink density and also the reduction of NR dispersed phase size.

Compatibilization of natural rubber/nitrile rubber blends by sol–gel nano-silica generated by in situ method

“…In this case T g of NBR remains almost unaffected, while that of NR shows slight negative shift in case of filled composites compared to that of unfilled one. One interesting point is noted here regarding peak height reduction [36,37]. The tan d peak height decreases consistently in NR phase as silica content increases for the filled composites (2)(3)(4)(5), while that in NBR phase shows inconsistent variation within small range.…”

“…It is well established in literature that silane can link with the silica via its hydroxyl group that is resulted upon hydrolysis of ethoxy group present at one end. On the other hand, the sulfur bridges present at the other side can be broken and connect to rubber chains during vulcanization (both NR and NBR) [4,[36][37][38][39][40][41]. In addition to this, processing conditions might also influence the silica distribution.…”

“…The curve that best fits with experimental data corresponds to volume fraction, / * 1.3. Hence, it can be concluded that not only the amount of filler but certainly there are other factors such as shape, size, dispersion of filler as well as their interaction with rubber chain and crosslinking density that can strongly influence the reinforcement effect [36,37].…”

Filler Wetting in Miscible ESBR/SSBR Blends and Its Effect on Mechanical Properties

“…c F is the mass concentration of silica in the single rubber mixture or binary blends. For ESBR/SSBR blend the rubber layer L B(ESBR/ SSBR) is the rubber part in the rubber-fi ller gel and consists of two contributions according to Equation ( 2) .…”

Influence of aging medium on recovery behaviors of CR/NR composite from circular deformation

“…CR/NR blends have displayed good weather resistance in several studies. [13][14][15][16][17][18] was changed into a circular form by fixing both ends of the sample with a pin. Third, the circularly deformed samples were aged at 70, 80, 90, and 95 o C for 1, 3, 7, 14, 21, and 30 days in a convection oven.…”