Effects of Petroleum-Based Oils as Dispersing Aids on Physicochemical Characteristics of Magnetorheological Elastomers

This paper investigated the effects of petroleum-based oils (PBOs) as a dispersing aid on the physicochemical characteristics of natural rubber (NR)-based magnetorheological elastomers (MREs). The addition of PBOs was expected to overcome the low performance of magnetorheological (MR) elastomers due to their inhomogeneous dispersion and the mobility of magnetic particles within the elastomer matrix. The NR-based MREs were firstly fabricated by mixing the NR compounds homogeneously with different ratios of naphthenic oil (NO), light mineral oil (LMO), and paraffin oil (PO) to aromatic oil (AO), with weight percentage ratios of 100:0, 70:30, 50:50, and 30:70, respectively. From the obtained results, the ratios of NO mixed with low amounts of AO improved the material physicochemical characteristics, such as thermal properties. Meanwhile, LMO mixed the AO led to the best results for curing characteristics, microstructure observation, and magnetic properties of the MREs. We found that the LMO mixed with a high content of AO could provide good compatibility between the rubber molecular and magnetic particles due to similar chemical structures, which apparently enhance the physicochemical characteristics of MREs. In conclusion, the 30:70 ratio of LMO:AO is considered the preferable dispersing aid for MREs due to structural compounds present in the oil that enhance the physicochemical characteristics of the NR-based MREs.

The use of illite in function of filler applied in rubber blend

The presented work was dealing with the study of the commercial filler influence change in rubber blend by an alternative filler based on the clay mineral - illite. The focus of the presented work was aimed at the study of selected curing characteristics of rubber blend with addition of clay mineral filler and physico-mechanical properties of prepared vulcanizates. Curing characteristics, the processing safety, minimum and maximum torque, optimal curing time and curing rate coefficient were determined during the curing experiment phase. Selected physico-mechanical properties were given by the determination of hardness, tensibility and tensile strength. The obtained results proved the possibility of partial commercial filler replacement by an alternative filler and the positive effect of clay mineral on resulting important properties in rubber industry.

Application of biowaste in rubber blend

Submitted paper deals with the incorporation of biological waste into the rubber blend and moreover, it is mainly connected with the determination of the influence of this biowaste on the basic properties of the blends and vulcanizate. Wood flour, which comes from the production of wood pellets, was used as the biowaste. Biowaste was used as a filler but also as a plasticizer. The effect of the mentioned biowaste (wood flour) in rubber blend was determined from the aspect of curing characteristics and physical-mechanical properties. In addition, Payne effect was also determined. Achieved results show the possibilities of partial use of biowaste in the rubber blend and provide other research possibilities.

The influence of liquid rubber on selected properties of rubber compound and its vulcanizates

The aim of the work was to determine the influence of liquid rubber on selected properties of rubber compound and its vulcanizates. Due to the liquid form of this rubber, it is not possible to completely replace the conventional solid rubber used in the mixture because of problems in further processing. In four experimental tests, we used different amounts of liquid rubber in the recipe together with butadiene-styrene rubber and the compounds we mixed according to the general conditions. We studied the curing characteristics of prepared mixture and we measuremend physical and mechanical properties of study vulcanizates and summarized the individual measured values for each parameter and suggested the greatest importance of the recipe for rubber practice.

Curing characteristics and rheological properties of bentonite- filled rubber blends

The study deals with the examination of the rheological behaviour of rubber blends which were filled with bentonite. The filler - polymer as well as the filler - filler interactions were studied and determined from the frequency sweep and strain sweep rheological measurements. The used natural bentonite was extracted from the locality called Jelsovy Potok. The natural bentonite had a fine fraction with a particle size of 15μm a 45 μm and it was added into rubber blends as a partial replacement of commonly used filler. The rubber blends were characterised on the basis of curing characteristics (minimum torque ML, maximum torque MH, optimum time of cure t(c90), processing safety of blend ts,). Moreover, the complex viscosity and Payne effect were also specified. The required measurements were done by using PRPA 2000.

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.

GTR/NBR/Silica Composites Performance Properties as a Function of Curing System: Sulfur versus Peroxides

In this work, conventional sulfur and two types of organic peroxides (dicumyl peroxide (DCP) and di-(2-tert-butyl-peroxyisopropyl)-benzene (BIB)) curing systems were used to investigate the possibility for tailoring of the performance properties of GTR/NBR blends reinforced with a variable content of highly dispersive silica (0–30 phr). The curing characteristics, static mechanical and acoustical properties, swelling behavior, thermal stability, and microstructure of the prepared composites were investigated. The results show that regardless of the curing system used, increasing the content of highly dispersive silica resulted in the improvement of the mechanical properties of the studied materials. It was observed that sulfur-based systems are the best choice in terms of cross-linking efficiency determined based on torque increment and cross-link density parameters. However, further analysis of the physico-mechanical properties indicated that the cross-linking efficiency does not match the performance of specimens, and the materials obtained using organic peroxides show higher tensile properties. This is due to the improved physical interactions between the GTR/NBR matrix and highly dispersive silica when using peroxide systems. It was confirmed using the analysis of the Wolff activity coefficient, indicating the enhanced synergy.

Production and properties of natural rubber glove using sustainable benign accelerator

In natural polyisoprene glove manufacturing industries, the selection of accelerators in the curing system is mainly determined by the curing characteristics, maturation time required, cross-link density and mechanical properties of gloves. In this study, a new accelerator replacing conventional ones in a typical glove manufacturing process, was studied in order to produce free carcinogen dipped article. The glove properties and performance prepared by using both conventional and new proposed accelerators were studied and compared. The use of a conventional accelerator tends to release carcinogenic chemicals namely N-nitrosamine and N-nitrosatable substances. These chemicals are restrained on dipped articles under the requirement of EN 71-12:2013. Xanthogen accelerators promote the reduction of carcinogenic chemicals, but they are associated with prolonged maturation hour, which is unfavourable in the manufacturing industry. This study used a mixture of a benign accelerator, namely, diisononyldithiocarbamate and diisopropyl xanthogen polysulfide, to substitute the usage of conventional accelerators zinc dibutyl dithiocarbamate and zinc diethyl dithiocarbamate. The effects of benign accelerator loading in latex compounds were studied by focusing on the swelling index, maturation hour, carcinogenic chemical released and mechanical properties, thermal degradation and stability. Results showed no presence of N-nitrosamines and N-nitrosatable substances in the final dipped products by using 0.3 and 0.5 phr of benign accelerator. This study showed that 0.5 phr of benign accelerator achieved a moderate pre-vulcanising rate and improved the pre-ageing tensile strength and elongation by 11% and 7.0%, respectively. Moreover, its thermal stability was higher and discolouration intensity was lower as compared with the conventional accelerator.