Journal of Rubber Research最新文献

In this paper, walnut shell filler of 75–150 µm and 45–75 µm size was used in rubber compound with different loadings (2,3, and 5 phr). At 2, 3, and 5 phr loading, small-size WNS powder (45–75 µm) has higher modulus at 300%, tensile strength and elongation at break than larger-size powder (75–150 µm); however, modulus at 300% is lower than blank compound. As the amount of WNS filler increases, the elongation at break with modulus at 300% and tensile strength decrease. The goal of using silane is to improve the interfacial interaction between WNS filler and the rubber matrix. Larger-size WNS filler using Si69 compound demonstrated higher modulus at 300% with higher elongation at break and tensile strength compared to non-silanised compound; however, modulus at 300% remained lower than blank compound. The silanised compound with both WNS fillers demonstrated slightly higher rebound resilience at 100 °C, slightly lower heat build-up, and slightly lower tan delta at 60 °C than the blank compound. It was demonstrated that small-size WNS filler with silane could partially replace N330 carbon black (3 phr) in natural rubber-based tire tread compound due to its bio-based, biodegradable, renewable and sustainable properties.

Due to continuous progress in science and technology and the pressure to seek low cost, green materials for electrochemical devices have led to discover the possibility to use natural rubber (NR) as a polymer for electrolytes. This study reports about modifying Sri Lankan NR and using it for a solid polymer electrolyte in fabricating super capacitors with natural graphite electrodes. Solid polymer electrolyte was prepared using methyl grafted NR as the polymer and magnesiumtrifluoromethanesulfonate as the salt. The composition, 1 NR: 0.80 magnesiumtrifluoromethanesulfonate showed the maximum room temperature conductivity of 3.36 × 10^–3 Scm⁻¹. Capacitive features were dominant at low frequencies. Initial single electrode specific capacitance was about 32 Fg⁻¹ whereas the initial single electrode specific discharge capacitance was about 12.8 Fg⁻¹. Even though the values are not very high, they are highlighting the suitability to launch further studies to enhance performance of super capacitors with NR based electrolytes.

Silicone rubber foam (SRF) is a kind of polymer material with excellent performance but flammable. The flame-retardant SRF was prepared with diatomite (Dia) and hexaphenoxycyclotriphosphazene (HPCTP) as flame retardants. Cone calorimetry tests (CCT), scanning electron microscopes (SEM) and mechanical tests were used to investigate the effects of Dia and HPCTP on the flame retardancy, smoke suppression and mechanical properties of SRF. The results showed that Dia and HPCTP had a synergistic effect on flame retardancy and smoke suppression. With the addition of 5 wt% Dia and 5 wt% HPCTP, the peak heat release rate (PHRR), the total heat release rate (THR), the peak smoke release rate (PSPR) and the total smoke production (TSP) of SRF decreased by 54.43, 37.64, 62.3 and 58%, respectively. With the addition of Dia and HPCTP, the thickness of the carbon layer became thicker, the cracks became smaller and the microstructure became denser. In addition, when the contents of 5 wt% Dia and 5 wt% HPCTP were added, the mechanical properties of SRF were the best; the tensile strength increased to 0.195 MPa, and the elongation at break increased by 109.85%. It provided a new flame-retardant method for SRF.

Room temperature vulcanised (RTV) silicone rubber is widely used in daily life. Ordinary and traditional flame-retarding RTV silicone rubber are easy to turn into brittle char layer or ashes without any self-supporting and bonding ability after experiencing a combustion process, which could not inhibit the secondary disasters after fire. To improve the fire-resistance performances of RTV silicone rubber, a new single component ceramifiable RTV silicone rubber was prepared in this work. The tack-free time, mechanical properties and thermal properties of different formulations were tested. The flexural strength and adhesion strength of the ceramic residues were studied by orthogonal designed experiments, which exhibited the maximum of 8.80 and 0.300 MPa after sintering at 1000 °C, respectively. The ceramifying process of the single component ceramifiable RTV silicone rubber at high temperatures was also investigated. These results will provide a basis for the development of fire-resistant silicone adhesive with better performance that can meet the actual needs.

Natural Rubber Serum (NRS), the aqueous portion of natural rubber (NR) latex contains proteins that can be extracted to be used in animal feed although, in the conventional rubber processing scenario, it is discarded in the effluent. The NRS protein has strong potential as an alternative protein source for animal feeds. However, studies on its palatability in the animal diet and its effect on growth performance remain scarce. This study aimed to explore the feasibility of adding NRS protein to the broiler chicken basal diet with a focus on nutritional composition and its growth performance using 160 day-0 broiler (Ross) chickens. The study observed that when NRS protein was included at varying levels in the basal diet, changes were observed in all nutritional contents (crude protein, carbohydrate, crude fat and energy). The live body weight of broiler chicken fed with different levels of NRS protein increased when the chickens reached 35 days old and achieved the live weight of market standard of more than 2000 g per chicken on the 42nd day. The highest mortality among treatments recorded was 1.25%; lower than the commercial mortality standard of 5 to 7%. The broiler chicken treated with the addition of 2.0% NRS protein showed better feed conversion ratio (FCR) values compared with that of the control chicken. Similarly, the chickens also showed increased digestive tract development and nutrient capacity. The composition percentage of E. coli over total caecal bacteria was also lower in broiler chickens fed with diets supplemented with NRS protein when compared to the control diet. In general, dietary supplementation with 4.0% NRS protein in chicken feed was optimal for growth performance with no deteriorating effect on intestinal morphology and caecal bacteria. The results demonstrated that NRS protein is a viable substitute as a feed ingredient for broiler chickens and may be a worthwhile avenue to pursue in sourcing local ingredients for the Malaysian feed industry.

Considering that the rubber isolation bearing of buildings is exposed to the air will be, respectively, subjected to the freeze–thaw cycles in the wintertime period, the isolation effect of the bearing is very likely to be affected. To this end, the freeze–thaw cycle tests of natural rubber (NR) materials were carried out, with the aim of investigating how the performances of NR bearings in northern China change under freeze–thaw cycles in winter and the mechanical properties of NR materials with time were studied. The results show that after the freeze–thaw cycle test, the appearance of the rubber sheet did not have an obvious change. However, the sealing plate and steel plate layer of the rubber bearing had brown rust spots and the colour of the rubber layer was still dark. After the freeze–thaw cycle, the vertical compression stiffness and the horizontal equivalent stiffness of the rubber isolation bearing showed a decreasing trend. After freeze–thawing cycles, the Mooney–Rivlin constitutive model constant C₁₀ of rubber material showed a decreasing trend with the test time while C₀₁ showed an increasing trend. Under the action of freeze–thawing cycles, the stiffness of basic mechanical properties of rubber isolation bearings will decrease as time increases. Among them, the vertical compression stiffness has decreased by 10.24% and the horizontal equivalent stiffness has decreased by 2% after 50 years under the freeze–thaw cycles based on the prediction equation of the test values, while the vertical compression stiffness has decreased by 5.73%, and the horizontal equivalent stiffness has decreased by 8.7% after 50 years under the freeze–thaw cycles based on the prediction equation of the simulation value. The above research results can provide a basis for the study of the degradation law of the rubber isolation bearing and the evaluation of the life cycle performance of the isolation projects.

Post-vulcanised latex curing method was adapted in this study to develop nitrile butadiene rubber/graphene oxide (NBR/GO) membranes for oily wastewater filtration. This is a comparatively new method for solvent-free membrane preparation. Due to the fact that the oily wastewater could be discharged at different pH in industry, the pH reading of the oily wastewater in this study was varied from 4 to 10 to investigate its effect on the membrane performance in terms of tensile strength, permeation flux, and oil rejection efficiency. Performance of latex-based membranes over a range of pH has yet to be reported in literature. Thus, the knowledge from this work has significant impact on future applications of latex-based membranes to treat wastewater discharged at different ranges of pH. NBR/GO membranes were found to have good retention of tensile properties at all pH ranges. This feature is attributed to the crosslinks in the NBR matrix which provides a strong and stable three-dimensional network between the polymeric macromolecules. Moreover, with incorporation of 2 wt% GO, the NBR/GO membrane was able to achieve permeation flux of more than 500 L/m².hr and oil rejection of more than 50% at all pH ranges. This can be attributed to the membrane's average pore size of 0.2810 µm and a water contact angle of 75°, both of which concurrently manifest oil rejection and water flux characteristics. The highest permeation flux and oil rejection of 2720.53 L/m².hr and 91.88%, respectively, were achieved at a pH range of 6–7.

Inositols are a class of biologically active compounds which can be used as precursors for the synthesis of a wide range of bioactive products. Lately, there is growing awareness on the importance of developing chiral compounds in the pharmaceutical and nutraceutical industries. This new emphasis on chiral compounds boils down to safety matters, with an aim to select the right enantiomer for desired biological activities. Natural rubber serum (NRS) has the advantage as it possesses a significant percentage of naturally occurring bioactive inositol compounds. For this study, considerable amounts of quebrachitol (2-O-methyl-l-chiro-inositol) were isolated from NRS using membrane separation technology and converted to l-chiro-inositol crystals. Characterisations of the resulting inositol compounds were performed using Fourier transform infrared spectroscopy (FTIR), high-performance liquid chromatography–mass spectrometry (LCMS) and liquid-state nuclear magnetic resonance (NMR) spectroscopy methods. FTIR and NMR results for the l-chiro-inositol compound obtained showed similar spectrums as the commercial control, while LCMS mass spectra was demonstrated to be at m/z 179.03 (M–H)⁻ in the negative ionisation mode, confirming the compound to be l-chiro-inositol. Thus, it can be concluded that quebrachitol from NRS obtained via membrane separation technology and its modified inositol derivatives have high potential market value to be used as building blocks for pharmaceutical and nutraceutical applications. Quebrachitol already exists naturally as an enantiomer and chiral compound in the rubber tree, and instead of being treated as a waste product, its usage can actively contribute to tackling environmental pollution from rubber processing effluents.

Epoxidized Natural Rubber (ENR) is a specialty rubber produced by modification of natural rubber (NR) latex. In this study, the effects of vulcanisation temperature on the vulcanisation characteristics and vulcanisation kinetics of ENR compounds were studied. A Monsanto Moving Die Rheometer (MDR2000) was used, with vulcanisation temperatures ranging from 140 to 180 °C considered. Unfilled ENR and NR compounds were compared to filled compounds, in which carbon black and silica fillers were used. All compounds' optimal vulcanisation time (t₉₅), curing rate index (CRI), percentage of reversal (R₃₀₀) and vulcanisation kinetics were investigated. It can be shown that for both filled and unfilled compounds, ENR has a shorter t₉₅, a higher CRI, and a higher R₃₀₀ than NR. Furthermore, higher vulcanisation temperatures decreased the t₉₅, with increased CRI and enhanced R₃₀₀ for all compounds. It was observed that ENR tended to have lower activation energy, E_a than NR for both filled and unfilled compounds and among the compounds examined, silica-filled ENR showed the highest activation energy value.