Journal of Rubber Research最新文献

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.

Understanding and managing the generation of odour nuisances throughout the raw rubber processing industry are vital to reduce the impact on the community. This paper aims to review literature on odour studies and management in the raw rubber processing industry. The generation of odour is typically associated with microbial reactions occurring in non-rubber components. The most offensive compound groups commonly discussed in the literature are sulfur derivatives and volatile fatty acids due to their unpleasant characteristics and low-odour threshold. Major sources of these odorants are from effluent treatment of the latex processing plant and exhaust gas from the drying process at the block rubber processing plant, respectively. However, studies performed on the composition of rubber emissions also reported the presence of other compound groups such as aldehyde, ester, amine and aromatic, which could potentially contribute to the odour emissions. Single or multiple odour assessment methods can be applied based on the objective of the odour assessment. Olfactory and chemical testings were generally applied to evaluate the odour concentration, offensiveness and identification of potential odorants, while odour wheel and dispersion modelling were employed to assess the impact on the community. Odour legislations mainly used olfactory techniques and dispersion modelling to control the odour emissions by limiting the odour release at a tolerable limit. Numerous mitigation measures have been studied and performed upstream and downstream of rubber processing, such as utilising biological methods and aerated effluent treatment that produces less odour, chemical substitution and installation of wet scrubber to reduce the odour emissions from drying process. Nevertheless, the literature is lacking studies conducted at the industrial scale on odour generation and mitigation where knowledge can be applied to develop an appropriate odour management strategy in the current industrial scenario to mitigate the odour effectively.

Chitosan is considered one of the most promising materials for polymer electrolyte membrane fuel cells (PEMFC) due to the high manufacturing cost of the commercial polymer electrolyte membrane (PEM). In this study, chitosan (C-1), chloroacetate chitosan (CCS-21), epoxidized natural rubber (ENR-41), chitosan blended with ENR (CE-6 and CE-7), and chloroacetate chitosan blended with ENR (CCE-26 and CCE-27) based membranes were prepared by solution casting technique and crosslinked with acid and base. The Fourier transform infrared (FTIR) spectroscopy results showed improvements in their peaks, and the atomic force microscopy revealed that the blended membranes had a higher surface roughness than the other membranes. The optical contact angle (OCA) showed that the C-1 had the highest contact angle, while the ENR-41 had the least contact angle. From the electrical measurements, the CCS-21 gave the highest capacitance, conductance, and conductivity. The CE-7 showed the highest resistance and resistivity while ENR-41 showed the highest dissipation factor and dielectric constant. Taken together, CE-7 showed the most suitable characteristics which makes it suitable for use as a PEM.

Carbon black (CB) has been used for over one-hundred years as a reinforcing filler in rubber matrix. In order to reduce our dependence on fossil resources, attempts have been made to develop renewable biofillers such as starch in the rubber industry. In this study, NR/SBR blends (50/50) were prepared with different loading of wheat starch (5, 10, 20, 35 and 50 phr). A semi-efficient sulphur vulcanization system (semi-EV) was employed. The curing characteristics of the compounds were determined with a Monsanto Rheometer at 130, 140 and 150 °C. The properties of unfilled and filled NR/SBR blends prepared at 150 °C were evaluated by swelling measurements, tensile tester, dynamic mechanical analyser (DMA) and scanning electron microscope (SEM). The results showed that the optimal cure time, minimum torque, and maximum torque of filled NR/SBR blends were improved. It was found that the tensile strength and the elongation at break of wheat starch filled NR/SBR blends were maximal with the incorporation of 20 phr of wheat starch. The chemical crosslink densities were found to follow the mechanical properties. The results of DMA indicated that incorporation of wheat starch led to an increase in the glass transition temperature whilst reducing the mobility of macromolecular chains of NR/SBR mixtures, and on the other hand improved their slip resistance on wet surfaces, thus indicating its potential application in the manufacture of tyre tread.