Reinforced chloroprene rubber byin situgenerated silica particles: Evidence of bound rubber on the silica surface

Flame retardant chloroprene rubbers with high tensile strength and elongation at break via dual cross-linked networks

The tensile strength and elongation at break of rubbers are mutually restrictive factors. Design and preparation of chloroprene rubber (CR) with high tensile strength, high elongation at break and excellent flame retardancy at the same time is challenging. Melamine cyanurate (MCA) is for the first time discovered to be a reactive flame retardant for CR. The tensile strength of C-M36 (with 3 wt% ZnO and 36 wt% MCA) vulcanizate is 2.5 times that of C-M0 (only with 3 wt% ZnO) vulcanizate, while the elongation at break of C-M36 vulcanizate is 1.3 times that of ZnO cross-linked C-M0 vulcanizate. At the same time, the limiting oxygen index of C-M36 (39%) is 1.22 times that of C-M0 (32%). FTIR and the vulcanization tests confirm that the reaction between CR and cyanuric acid occurs under the catalysis of a base (melamine), and the cyanuric acid molecules are grafted onto the molecular chain of CR. Two types of crosslinking networks are formed in CR vulcanizate, namely the traditional covalent bond crosslinks and the triple hydrogen crosslinks formed between cyanuric acid and melamine. Thus, the flame-retardant CR/MCA vulcanizate with high strength and high elongation at break is obtained. This research will strongly promote the industrial application of CR.

Melamine cyanurate served as a reactive flame retardant crosslinker for chloroprene rubbers.

EMERGING ADVANCES IN RUBBER TECHNOLOGY BY THE SUITABLE APPLICATION OF SOL-GEL SCIENCE AND TECHNOLOGY

In recent years, the application of sol-gel science to industrial polymer research has offered advancements in rubber technology. The use of sol-gel–synthesized materials for the development of highly reinforced rubber composites is the most commonly adopted and popular method exercised by rubber scientists. This article comprehensively reviews the recent progress regarding preparation and properties of sol-gel–synthesized nanoparticles-based rubber composites. The pragmatic consequences of sol-gel–synthesized nanoparticles in rubber compounds are systematically described through rheological, mechanical, and thermal properties. Emphatic focus is given to understanding the reinforcement mechanism of rubber composites by the use of sol-gel–derived alkoxide silica as filler. The properties of rubber nanocomposites are usually dependent on the dispersion of sol-gel–synthesized nanoparticles into the rubber matrix. The results reviewed from prolific studies suggested that sol-gel science has tremendous potential to develop high performance rubber nanocomposites for future industrial application.

Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Organoclay nanoparticles (Cloisite^® C10A, Cloisite^® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

All-Waste Hybrid Composites with Waste Silicon Photovoltaic Module

Nowadays, global warming, energy issues and environmental concern have forced energy production stakeholders to find new low carbon solutions. Photovoltaic technologies as renewable energy resources represent a competitive way for the transition from conventional fossil fuels towards a renewable energy economy. The highest renewable energy systems (RES) market share is based on silicon photovoltaic (Si-PV). The installed RES have rapidly increased over the last two decades, but, after the end of their service life, they will be disposed of. Therefore, the constant increase of the installed RES has attracted the global concern due to their impact on the environment and, most of all, due to the content of their valuable resources. However, the rational management of RES waste has not been addressed so far. The paper represents an extension of a previous work focused on Si-PV recycling by developing all waste hybrid composites. The extension research conducted in this paper is related to the influence of Si-PV characteristics on the mechanical performances and water stability of the hybrid composites. All waste hybrid composites developed by embedding different Si-PV grain sizes were tested before and after water immersion in terms of mechanical strength, interfacial adhesion, crystallinity and morphology by scanning electron microscopy (SEM) analyses. The results revealed the better performance of such Si-PV composites compared to that of sieved composites even after long term water immersion. Therefore, high-content Si-PV hybrid composites could be developed without Si-PV powder sieving. Further on, all waste hybrid composites could be used as paving slabs, protective barriers for outdoor applications.

Effects of octamethylcyclotetrasiloxane grafting and in situ silica particle generation on the curing and mechanical properties of a styrene butadiene rubber composite

The reinforcement of octamethylcyclotetrasiloxane (D₄) grafted styrene butadiene rubber (SBR-g-D₄) with in situ generated silica was performed using the sol–gel reaction of tetraethoxysilane (TEOS) in latex. The characterization of SBR-g-D₄ and in situ generated silica reinforced SBR-g-D₄ was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The grafting efficiency of the styrene butadiene rubber (SBR) was determined by a gravimetric method. It was found that the constant silicon content and the grafting efficiency of SBR were 1.72% and 0.13 wt% when the weight ratio of D₄ to SBR was 0.20. The effects of the D₄ and in situ generated silica content on the curing characteristics, mechanical properties and morphology of SBR latex were investigated. The mechanical properties of in situ generated silica reinforced SBR-g-D₄ vulcanizates were improved significantly compared to raw SBR vulcanizate when the in situ generated silica content was 18.05%. Compared with silica reinforced SBR-g-D₄, the tensile strength, wet skid resistance and rolling resistance of the in situ generated silica reinforced SBR-g-D₄ were better. This is because of the higher crosslinking degree in the SBR-g-D₄ matrix and the strong chemical bond between SBR-g-D₄ molecular chains and in situ generated silica. Scanning electron microscopy analysis revealed good silica filler dispersion in all the reinforced SBR-g-D₄ vulcanizates.

The reinforcement of octamethylcyclotetrasiloxane (D₄) grafted styrene butadiene rubber (SBR-g-D₄) with in situ generated silica was performed using the sol–gel reaction of tetraethoxysilane (TEOS) in latex.

Entrapped Styrene Butadiene Polymer Chains by Sol-Gel-Derived Silica Nanoparticles with Hierarchical Raspberry Structures

A sol-gel transformation of liquid silica precursor to solid silica particles was carried out in a one-pot synthesis way, where a solution of styrene butadiene elastomer was present. The composites, thus produced, offered remarkable improvements of mechanical and dynamic mechanical performances compared to precipitated silica. The morphological analysis reveals that the alkoxy-based silica particles resemble a raspberry structure when the synthesis of the silica was carried out in the presence of polymer molecules and represent a much more open silica-network structure. However, in the absence of the polymer, the morphology of the silica particles is found to be different. It is envisaged that the special morphology of the in situ synthesized silica particles contributes to the superior reinforcement effects, which are associated with a strong silica-rubber interaction by rubber chains trapped inside the raspberry-like silica aggregates. Therefore, the interfaces are characterized in detail by low-field solid-state ¹H NMR spectroscopy, ²⁹Si solid-state NMR spectroscopy, and energy-dispersive X-ray spectroscopy. Low-field ¹H NMR-based double-quantum experiments provide a quantitative information about the cross-link density of the silica-filled rubber composites and about the influence of silane coupling agent on the chemical cross-link density of the network and correlates well with equilibrium swelling measurements. The special microstructure of the alkoxy-based silica was found to be associated with the interaction between alkoxy-based silica and rubber chains as a consequence of particle growth in the presence of rubber chains.

The effect of bound rubber on vulcanization kinetics in silica filled silicone rubber

Different filler networks mediated by bound rubber show obviously different effects on vulcanization kinetics.