Aluminium trihydroxide: Novel reinforcing filler in Polychloroprene rubber

Carbon black and chitin nanofibers for green tyres: Preparation and property evaluation

This research highlights the synergistic use of carbon black (CB) and chitin nanofibers (CHNFs) for developing green tyres for the first time. The CHNFs (12-30 nm) were prepared from chitin powder with the help of steam explosion and mild oxalic acid hydrolysis. The CHNFs were uniformly dispersed in natural rubber (NR) latex, dried, and mixed with CB in a two-roll mill to form NR/CB/CHNF composites. The NR/CB/CHNF composite at 1 phr CHNF loading exhibited tensile and tear strengths that were about 47 and 160 % greater than the NR-Neat, respectively. The dynamic mechanical analysis showed that the loss tangent (tan δ) at 60 °C was 50 % lower for the NR/CB/CHNF 1.0 composite than for the NR/CB50 composite. The study succeeded in developing a new green tyre tread formulation that would be helpful for attaining sustainability and a circular economy.

The Use of Copper Oxides as Cross-Linking Substances for Chloroprene Rubber and Study of the Vulcanizates Properties. Part II. The Effect of Filler Type on the Properties of CR Products

The properties of rubber materials are dependent on the characteristics of the elastomer matrix, the filler type, the cross-linking agent, the number of ingredients, and their interactions. In the previous article, we showed that chloroprene rubber can be efficiently cross-linked with copper(I) oxide or copper(II) oxide. During the processing of rubber compounds, the incorporation of a filler and a curing substance are two substantial parameters, such as the homogeneity of mixing and cross-linking that significantly affect the properties of the vulcanizates. Therefore, this work aimed to evaluate the curing characteristics, mechanical and dynamical properties, morphology, and flammability of the composites containing chloroprene rubber cross-linked with Cu₂O or CuO and filled with different fillers (silica, carbon black, montmorillonite, kaolin, chalk). It was found that the type of filler and curing agent had a significant impact on the degree of cross-linking of the chloroprene rubber and the properties of its vulcanizates. The degree and speed of the cross-linking of filled CR were higher when the CR was cured with copper(II) oxide. Among the fillers used, the presence of carbon black or silica ensured the highest degree of CR cross-linking and the most useful properties. The flammability tests indicated that all produced vulcanizates were characterized by a high oxygen index, which allows them to be classified as non-flammable materials.

Hybrid Silica-Based Fillers in Nanocomposites: Influence of Isotropic/Isotropic and Isotropic/Anisotropic Fillers on Mechanical Properties of Styrene-Butadiene (SBR)-Based Rubber

The improvement of mechanical properties of polymer-based nanocomposites is usually obtained through a strong polymer-silica interaction. Most often, precipitated silica nanoparticles are used as filler. In this work, we study the synergetic effect occurring between dual silica-based fillers in a styrene-butadiene rubber (SBR)/polybutadiene (PBD) rubber matrix. Precipitated Highly Dispersed Silica (HDS) nanoparticles (10 nm) have been associated with spherical Stöber silica nanoparticles (250 nm) and anisotropic nano-Sepiolite. By imaging filler at nano scale through Scanning Transmission Electron Microscopy, we have shown that anisotropic fillers align only in presence of a critical amount of HDS. The dynamic mechanical analysis of rubber compounds confirms that this alignment leads to a stiffer nanocomposite when compared to Sepiolite alone. On the contrary, spherical 250 nm nanoparticles inhibit percolation network and reduce the nanocomposite stiffness.

EFFECTS OF GRAFTED VINYL TRIETHOXY SILANE ON MOISTURE CROSSLINKED EPDM

An EPDM terpolymer grafted with silane vinyl triethoxysilane (EPDM-g-VTES) was prepared by melt grafting, with dicumyl peroxide (DCP) as an initiator. Next, dibutyl tin dilaurate was added as a catalyst to promote moisture crosslinking of EPDM-g-VTES. By means of the rheological response of the rubber compound, Fourier transform infrared spectroscopy, and moving die rheometer, the VTES graft ratio and DCP partial crosslinking (pre-crosslinking) of EDPM-g-VTES were characterized to show the feasibility of moisture crosslinking. The mechanical properties of moisture crosslinked EPDM-g-VTES specimens were tested by universal material tester. The results showed that when the weight ratio of VTES to DCP was fixed at 15:1, the VTES graft ratio and DCP partial crosslinking of EDPM-g-VTES increased with the increase of VTES content. But the torque in the moisture crosslinking curve of EPDM-g-VTES increased significantly with the extension of crosslinking time, which proved that EPDM grafted with VTES was cured by moisture successfully. The tensile strength and elongation at break of EPDM-g-VTES were improved by moisture cure. Furthermore, the moisture cured specimen with 3 wt% VTES had the best mechanical performance.

Effects of ionic liquid on cellulosic nanofiller filled natural rubber bionanocomposites

Cellulosic nanofillers are sustainable replacements of synthetic fillers while the agglomeration limits their potentials in high-performance rubber bionanocomposites. Herein, we investigate the effects of ionic liquid (IL) on cellulose nanocrystal and cellulose nanofibril filled natural rubber (NR) compounds and vulcanizates. The results indicate that IL improves the dispersion of cellulosic nanofillers, crosslinking density of NR matrix and mechanical strength of the vulcanizates. Invesigations of viscoelastic rheological behaviors show amplitude of Payne effect faints in compounds and raises relatively in vulcanizates with the increment of cellulosic nanofillers and IL.