Significantly improved performance of rubber/silica composites by addition of sorbic acid

Abstract

Sorbic acid (SA) was used to improve the performance of styrene-butadiene rubber (SBR)/silica composites by direct blending. The mechanisms for the significantly improved performance were studied by X-ray photoelectron spectroscopy, X-ray diffraction and by the determinations of bound rubber content and crosslink density. The strong interfacial bonding between silica and the rubber matrix resulted from SA-intermediated linkages. Significantly improved dispersion of silica by virtue of the interactions between silica and SA was found. Formation of zinc disorbate during compounding of composites was confirmed. The effects of SA content on vulcanization behavior, morphology, mechanical properties and abrasion loss of composites were studied. Significantly improved mechanical properties of SA-modified SBR/silica composites were demonstrated. Changes in vulcanization behavior, morphology and performance were correlated with the interactions between silica and SA and the largely improved dispersion of silica. Polymer Journal ( Keywords: interface; SA; SBR; silica; zinc disorbate INTRODUCTION Silica is one of the most important reinforcing fillers in the rubber industry. As a reinforcing filler, silica provides a unique combination of high tear strength, high modulus and fatigue resistance, particularly low rolling resistance and superior wet traction for 'green' tire tread applications. 1-5 However, numerous hydrophilic silanols exist on the silica surface, resulting in strong filler-filler interactions and poor affinity toward hydrocarbon rubbers, such as styrene-butadiene rubber (SBR). [6][7][8] It is well accepted that dispersion and interfacial bonding are two crucial factors in determining the ultimate performance of rubber/silica composites. 6 Owing to unsatisfactory dispersion and interfacial interactions, the performance of pristine silica-filled SBR compounds in areas such as strength and abrasion resistance hardly meets the requirements for high-performance rubber products. Numerous routes for improving the performance of silicareinforced rubber compounds have been attempted, and some success has been achieved. Incorporation of silanes, especially those containing polysulfides such as Si69 and Si75, during the processing of rubber/silica compounds is the most common practice for improving the overall performance. These modifications establish chemical linkages between the rubber network and the silica surface. [9][10][11][12] Alternatively, grafting techniques also render better dispersion and interfacial bonding in rubber/silica systems. [13][14][15][16][17] For example, Inoubli et al. 14 investigated polybutylacrylate (PBA) filled with Stöber silica particles grafted with PBA chains; their small-angle neutron scattering and transmission electron microscopy results showed well-dispersed grafted silica particles in the PBA matrix. Other methods such as

SBR/silica composites modified by a polymerizable protic ionic liquid

“…When the elastic sample (T4Tg) is loaded with dynamic strain, the rubber chains in the interfacial region may readily be deformed due to a weakened filler network and altered interfacial structures. 27,54 Aggravated interfacial chain motion then leads to higher loss at temperatures above the glass transition.…”

“…[45][46][47] Reactivity of MimS on SBR and the interaction between poly(MimS) and silica Many researchers, including us, have confirmed the polymerizability of sorbyl substances such as sorbic acid and sorbates. [25][26][27][48][49][50] Although the reactivity of sorbyl in MimS should be different from sorbic acid, it is believed that it can undergo polymerization via the free radical mechanism. The polymerization of MimS was characterized by FTIR spectroscopy (Figure 4).…”

“…[22][23][24] Functional and compatible ILs should be specifically designed for rubber compounds. In the present work, based on the reactivities of sorbic acid and its salt towards diene rubber, [25][26][27] a functional IL, MimS, was synthesized and verified by 1 H nuclear magnetic resonance and Fourier transform infrared (FTIR) spectroscopy. MimS was investigated as a modifier for improving the performance of silicafilled styrene butadiene rubber (SBR) composites.…”

Reinforcement of nitrile rubber by in situ formed zinc disorbate

“…In view of the high cost of metal (meth)acrylates and the corrosive nature of (meth)acrylic acid, exploring alternative reactive metal carboxylates was still necessary. Recently, we demonstrated that sorbic acid (SA), a common food preservative, was very effective in promoting the interfacial properties of silica or halloysite reinforced rubber and it is revealed that zinc disorbate (ZDS) was in situ formed in those systems [19][20][21]. In the present work, we attempted to use the in situ formed ZDS as the sole reinforcing agent for nitrile rubber (NBR).…”

Hybrid SiO2@POSS nanofiller: a promising reinforcing system for rubber nanocomposites

“…[1][2][3][4][5][6] In this context, we reported that the fine tuning of size and shape in silica nanoparticles (NPs), along with their surface organic functionalization, favors filler interaction with the polymer and allows the formation of a homogeneous and continuous percolative filler network which enhances the mechanical properties of the ensuing composites. 7,8 Recently, we also demonstrated that particles having an anisotropic shape are able to self-assemble in nanostructures inside the rubber matrix, providing an increase of the rubber immobilized at the filler/rubber interface and a consequent improvement of the mechanical properties.…”