Synthesis and characterization of cardanol‐grafted natural rubber—The solution technique

Abstract

Cardanol, a by-product of the cashew industry, has been recently proven to be a multifunctional additive (MFA) in rubbers. It is expected that grafting of cardanol onto natural rubber (NR) would impart inherent MFA characteristics to the rubber. Grafting has been carried out in solution using toluene as the solvent and a peroxide initiator. Optimized conditions of grafting reaction could be arrived at using a statistical tool namely orthogonal array testing strategy, keeping the maximum percentage of grafting as the selection criteria. Further studies were conducted to study the influence of monomer concentration and initiator concentrations. The effect of the reaction temperature and reaction time were also investigated. Characterization of grafted rubber was carried out with the help of infrared spectroscopy, nuclear magnetic resonance spectroscopy and thermal analysis. IR spectrum of cardanol exhibited the characteristic peak of cardanol at 3356 cm À1. Percent grafting (PG) of cardanol onto NR was determined by residual weight method. PG increased with increasing cardanol quantity reached an optimum and then decreased. The increase in reaction time and reaction temperature also caused increasing levels of the grafted cardanol. However, PG continuously increased with increasing initiator concentrations. Differential scanning calorimetry studies of the grafted NR showed a lower glass transition temperature than that of the raw NR, which is indicative of the plasticization effect of cardanol. The thermogravimetric analysis showed a higher thermo oxidative stability for cardanol-grafted NR.

Petro‐based and bio‐based plasticizers: Chemical structures to plasticizing properties

“…It includes more than one compound because the composition of the side chain varies in its degree of unsaturation . Cardanol components are 48% mono‐unsaturated, 16% bi‐unsaturated, and 29% tri‐unsaturated which represents 2 average double bonds per chain. Chemical and physical properties of cardanol are very close to those of DEHP.…”

A renewable waste material for the synthesis of a novel non-halogenated flame retardant polymer

“…It has been reported that cardanol can also be used along with ligninbased compounds for the synthesis of polyurethanes that exhibit good thermal and mechanical properties (Minh Tan, 1996). The unsaturated chains of cardanol have been grafted with natural rubber to increase heat stability and the resulting compounds were reported to exhibit much better thermo-oxidative stability (Vikram and Nando, 2007). Derivatives of cardanol have also shown promise as anti-oxidants in the stabilization of gasoline (Dantas et al, 2003).…”

Horseradish Peroxidase Catalyzed Synthesis of Polycardanol Microcapsules

“…An important attribute of cardanol is that it is a biodegradable monomer and degrades to 96% of its original weight within 28 days (2). Cardanol and its derivatives have been utilized for a variety of applications such as resins (2), friction lining materials (3), and surface coatings (4). Cardanol has been polymerized using oxidative catalysts such as iron salen (5).…”