Effects of rubber curing ingredients and phenolic‐resin on mechanical, thermal, and morphological characteristics of rubber/phenolic‐resin blends

Abstract

This article examines the physical and mechanical characteristics of mixtures of two different synthetic rubbers, namely styrene-butadiene rubber (SBR) and nitril-butadiene rubber (NBR), with novolac type phenolicresin (PH). According to Taguchi experimental design method, it is shown that the addition of PH increases the crosslinking density of rubber phase probably due to its curative effects. Thermal analysis of the blends indicates that, contrary to NBR/PH blend, thermal stability of SBR/ PH blend is dependent on sulfur content due to predominant polysulfidic crosslinks formed in SBR. Slight shift in glass-transition temperature (T g ) of pure SBR and NBR vulcanizates by the addition of PH suggests that both SBR/PH and NBR/PH are incompatible blends with a partially soluble PH in the rubber phase. Two-phase morphology of the mixtures is also evidenced by scanning electron microscopy. Correlation of the rubber/PH modulus versus PH concentration by Halpin-Tsai model shows a deviation from the model. Presence of PH in the rubber phase is thought to vary the mechanical properties of the rubber phase by changing both the crosslinking density and rigidity of the molecular network of the rubber, leading to misuse of modulus of pure rubber in Halpin-Tsai equation.

Properties of poly(vinyl alcohol)—Bentonite clay nanocomposite films in relation to polymer–clay interactions

“…51 Concerning the mechanical properties, Halpin-Tsai equation is one of the most versatile and widely used semiempirical equations for the polymeric composites and blends. 52,53 Figure 9 presents the experimental data and the prediction using the abovementioned model, with clay particle aspect ratio equal to 8. At higher relative humidity, due to the samples' different degree of swelling, the model can not be effectively applied.…”

Taguchi analysis of extrusion variables and composition effects on the morphology and mechanical properties of EPR-g-MA toughened polyamide 6 and its composite with short glass fiber

“…Furthermore, it can make possible to investigate the interaction effect of the parameters. The Taguchi method has also been applied successfully for parametric analysis of various polymeric systems [32][33][34][35].…”

Tribological Characteristics of Rubber-Based Friction Materials

“…This behavior for organic matrix friction materials (mainly for thermosetting resins) has been attributed to a decrease in mechanical strength, thermal degradation of organic matrix at the interface and the formation of load-carrying friction film causing an effective increase in the true contact area and consequently reduction in applied pressure on the friction material [26][27][28]. However, due to lower thermal stability of rubber material compared with thermosetting resin [11,25], thermal degradation of rubber binder for RBFM is expected to be more prominent. Figure 4 shows the influence of sliding velocity and temperature history on the fade behavior of RM.…”

“…Thus rubber-based friction materials (RBFMs), comprising rubber as primary binder incorporated with various fillers and additives, can be used as suitable friction materials in the braking system of railroad vehicles [5,[7][8][9]. In RBFM, phenolic resin can also be added to some extent to strengthen and stiffen the rubber matrix; however, the rubber often forms the continuous polymer matrix [11].…”

“…For the polymer-based composite friction materials, the conformability can be achieved greatly by the polymeric binder used. Among the polymers, rubber materials, having the glass transition temperature (T g ) much lower than the ambient temperature, can be the best candidate to obtain such conformable characteristic [5,[8][9][10][11]. Thus rubber-based friction materials (RBFMs), comprising rubber as primary binder incorporated with various fillers and additives, can be used as suitable friction materials in the braking system of railroad vehicles [5,[7][8][9].…”