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Up to now, rubber materials have been used in a wide range of applications, from automotive parts to special-design engineering pieces, as well as in the pharmaceutical, food, electronics, and military industries, among others. Since the discovery of the vulcanization of natural rubber (NR) in 1838, the continuous demand for this material has intensified the quest for a synthetic substitute with similar properties. In this regard, synthetic polyisoprene rubber (IR) emerged as an attractive alternative. However, despite the efforts made, some properties of natural rubber have been difficult to match (i.e., superior mechanical properties) due not only to its high content of cis-1,4-polyisoprene but also because its structure is considered a naturally occurring nanocomposite. In this sense, cutting-edge research has proposed the synthesis of nanocomposites with synthetic rubber, obtaining the same properties as natural rubber. This review focuses on the synthesis, structure, and properties of natural and synthetic rubber, with a special interest in the synthesis of IR nanocomposites, giving the reader a comprehensive reference on how to achieve a mimic of NR.

Many industries use synthetic rubber for various industrial purposes; thus, disposal of synthetic waste rubber into the environment causes huge environmental problems. A feasibility study to convert synthetic Nitrile Butadiene Rubber (NBR) waste into valuable products using batch-type slow pyrolysis will benefit small- to medium-scale industries in their waste handling. The main objective of this research was to find sustainable waste management and energy solutions for synthetic NBR waste using pyrolysis technology. This study employed a two-phase experimental approach where the first five preliminary experiments were conducted to assess the thermal decomposition behavior of NBR waste. In the second phase, three experiments were conducted to quantify the yields of pyrolysis products: pyrolysis oil, solid char, and syngas. The results reveal that the weight distribution of pyrolysis oil, solid char, and syngas was 39.00%, 42.91%, and 18.09%, respectively. Moreover, density, heating value, flash point, and viscosity were analyzed to investigate the quality of the pyrolysis oil, where it was found to be 972.50 kg/m3, 42.50 MJ/kg, 36.50 °C, and 25.44 cP, respectively. Analysis of the syngas composition revealed that carbon monoxide, carbon dioxide, methane, hydrogen, oxygen, and CnHm were 14.14%, 5.04%, 18.69%, 11.08%, 0.02%, and 10.00%, respectively. The heating value of syngas was 3873.70 Kcal/m3. The carbon footprint analysis indicated that a significant reduction is possible in greenhouse gas emissions compared to conventional incineration. Additionally, a cost benefit analysis highlighted the superior cost effectiveness of pyrolysis over incineration of NBR waste. These findings underscore the potential of pyrolysis as an effective tool for sustainable waste management and energy recovery solutions.

Polybutadiene (PB) and polyisoprene (PI) rubbers are indispensable synthetic elastomeric materials widely used in tires, footwear, hose, belts, sealants, electricity, construction, and other applications. Nowadays, PB and PI elastomers are produced from butadiene (BD) and isoprene (IP) monomers via transition-metal-mediated coordination polymerization. Transition metal catalytic systems consist of a precise characteristic structural unit at the molecular level: well known as “single-site catalysts” (SSCs). These have experienced a revolutionary advance in the recently developed conjugated dienes synthetic rubber method. Among the SSCs, a class of rare-earth, metal-centered half-sandwich molecule has been identified as a high-performance catalytic system for conjugated dienes polymerization. These novel half-sandwich rare-earth (HSRE) catalytic systems exhibit several irreplaceable advantages compared with the conventional Ziegler–Natta-type catalytic systems. These HSRE catalytic systems can create novel conjugated diene rubbers (CDRs) with high catalytic reactivity, high stereoselectivity, an adjustable polymer chain microstructure, and high molecular weights and are considered to be the next generation of ecofriendly and economic catalytic systems for industrial applications. This paper delivers a concise review of some important synthetic methods for representative HSRE complexes with characteristic structures and of the utilization of some HSRE catalytic systems for the preparation of high-performance CDRs, especially highly stereoregular PI and PB materials.

Volatile Organic Compounds (VOCs) are prevalent emissions from a plethora of industries, known for their role in the formation of atmospheric ozone, thus contributing to secondary pollution. Both the United States and the European Union have presented various regulatory measures to mitigate VOC emissions. Nevertheless, the diversity of VOCs, some exhibiting carcinogenic properties, pose substantial challenges in devising comprehensive mitigation strategies. In light of this, the current study focuses on the synthetic rubber manufacturing industry, specifically analyzing VOCs with high emission volumes and elevated Photochemical Ozone Creation Potentials (POCPs). A total of 88 compounds, including PM-57 and TO-14A, were examined in this study. The Active and Passive monitoring methods, two out of the six recommended by the Environmental Protection Agency (EPA) for Fenceline monitoring, were employed. For business entity ‘A’, the Active method revealed the highest emission rates of n-butane (13.5%) and n-Pentane (12.8%). In contrast, the Passive method indicated styrene (9.4%) and toluene (8.1%) as the most prominently emitted compounds. Benzene, though detected at all points ranging from 1~3 µg/m³, is not manipulated in this industry, suggesting potential influence from neighboring enterprises. Compounds such as benzene, toluene, ethylbenzene, xylene, and styrene demonstrated convertible concentrations using both Active and Passive methods, detected within the range of 0~3 µg/m³. Notably, the average concentrations determined by both methods exhibited remarkable similarity. For business entity ‘B’, the Active method detected significant levels of n-hexane (45.0%) and methylcyclopentane (14.4%), whereas the Passive method identified high concentrations of n-hexane (37.7%) and isopentane (8.8%). A general pattern emerged where high concentrations were exhibited at points 9, 10, and 11, located within the production area, while points 1, 2, and 3 displayed lower concentrations, likely due to the influence of eastward wind patterns. In terms of compounds with high POCPs, business entity ‘A’ demonstrated substantial emission of n-butane (38.80%) and n-hexane (27.15%) using the Active method, and toluene (28.62%) and n-hexane (25.23%) via the Passive method. For business entity ‘B’, n-hexane emerged dominantly, detected at 84.57% using the Active method and 68.85% via the Passive method. This suggests that in the synthetic rubber manufacturing industry, n-hexane should be prioritized in formulating effective emission reduction strategies.

We describe a sliding mode controller design for an artificial rubber muscle driven by tap-water pressure. The hysteretic characteristics of this water-hydraulic artificial rubber muscle (WARM) often deteriorate its control accuracy. To cope with this complicated hysteresis, a modeling approach based on the least squares support vector machine (LS-SVM) with nonlinear kernel functions is first applied to a WARM. By employing this LS-SVM-based WARM model, a sliding mode controller is then derived for the WARM drive system. We verify the control performance of the proposed controller and compare its tracking accuracy with our previously developed controller through experiments.

Natural rubber is a kind of indispensable biopolymers with great use and strategic importance in human society. However, its production relies almost exclusively on rubber-producing plants Hevea brasiliensis, which have high requirements for growth conditions, and the mechanism of natural rubber biosynthesis remains largely unknown. In the past two decades, details of the rubber chain polymerization and proteins involved in natural rubber biosynthesis have been investigated intensively. Meanwhile, omics and other advanced biotechnologies bring new insight into rubber production and development of new rubber-producing plants. This review summarizes the achievements of the past two decades in understanding the biosynthesis of natural rubber, especially the massive information obtained from the omics analyses. Possibilities of natural rubber biosynthesis in vitro or in genetically engineered microorganisms are also discussed.

Now there is not a single area of industry that can do without adhesive elastomer materials. Composites based on synthetic rubbers comprise 75% of the total volume of adhesive materials produced, which is due to the combination of unique properties typical of the elastomer base of the adhesive. The base of many imported adhesives for the bonding of rubber to metal is chlorinated natural rubber. As an alternative, chlorinated synthetic isoprene rubber has been proposed, developed at the Scientific Research Institute for Synthetic Rubber in St Petersburg. The chlorinated isoprene rubber was compared with imported chlorinated natural rubber in adhesive composites, and the physicomechanical properties of mixes based on a blend of chlorinated rubber and nitrile butadiene rubber were investigated. The investigation was conducted on chlorinated natural rubber of grade Pergut S20, chlorinated isoprene rubber SKI-3, and nitrile butadiene rubbers of grades BNKS-28AMN and SKN-26S. The influence of the ratio of chlorinated rubber to nitrile butadiene rubber and the technological factors of mix preparation on the properties of films produced from them was established. It was shown that, in terms of the level of properties, home-produced chlorinated rubber can be used as the base for adhesives for hot bonding of rubber to metal instead of imported Pergut S20.

Antioxidants are prevalently used during rubber production to improve rubber performance, delay aging, and extend service life. However, recent studies have revealed that their transformation products (TPs) could adversely affect environmental organisms and even lead to environmental events, which led to great public concern about environmental occurrence and potential impacts of rubber antioxidants and their TPs. In this review, we first summarize the category and application of rubber antioxidants in the world, and then demonstrate the formation mechanism of their TPs in the environment, emphasizing their influence on the ozone oxidative degradation. The potential toxic effects of antioxidants and their TPs are further reviewed to improve understanding of their biological health impact and environmental risks. Finally, the environmental occurrences of antioxidants and their TPs are summarized and their environmental impacts are demonstrated based on the recent studies. Due to the currently limited understanding on the toxic and biological effects of these compounds, further studies are required in order to better assess various TPs of these antioxidants and their environmental impact. To our knowledge, this is the first review on antioxidants and their TPs in the environment, which may elevate the environmental risk awareness of rubber products and their TPs in the near future.

Annually, approximately 3 billion tires are commercially transacted worldwide each year and an equivalent amount is disposed of by the end of their life. Despite the increase in the life of tires and the global economic and pandemic crisis, the number of discarded tires is going to rise further due to the increasing demand for vehicles worldwide (approximately 5 billion tires by the end of 2030). The obsolete methods of tire disposal, including landfill, burning, etc., are a responsible for environmental issues (harmful substances production, air and soil pollution) and for the transmission of various diseases. Nowadays, approximately 70% of the total tires at the end of their life (ELTs) is recovered. The largest percentage of the recovered ELTs is intended for energy production or recovery as a fuel in cement industries or can be used for the production of various materials. A significant amount (approximately 95%) of the discarded ELTs can be reused. The products from the processing of ELTs can be fragments of different sizes and types, including: Trimmed rubber (70% by weight), steel wire (5–30% by weight), and fluff or textile fibers (up to 15% by weight). From the aforementioned materials, rubber and steel wires are mainly recovered and used for numerous applications. However, current ways of utilizing these materials will have to adapt or change in the near future, in order to comply with stricter regulations. The purpose of the current study is to sufficiently review recent progress on the management of ELTs, focusing on alternative uses of textile fibers such as additive for sound absorbing materials, bituminous conglomerates, concrete production, plastic materials, soil reinforcement, etc.

Rubber is an essential part of our daily lives with thousands of rubber-based products being made and used. Natural rubber undergoes chemical processes and structural modifications, while synthetic rubber, mainly synthetized from petroleum by-products are difficult to degrade safely and sustainably. The most prominent group of biological rubber degraders are Actinobacteria. Rubber degrading Actinobacteria contain rubber degrading genes or rubber oxygenase known as latex clearing protein (lcp). Rubber is a polymer consisting of isoprene, each containing one double bond. The degradation of rubber first takes place when lcp enzyme cleaves the isoprene double bond, breaking them down into the sole carbon and energy source to be utilized by the bacteria. Actinobacteria grow in diverse environments, and lcp gene containing strains have been detected from various sources including soil, water, human, animal, and plant samples. This review entails the occurrence, physiology, biochemistry, and molecular characteristics of Actinobacteria with respect to its rubber degrading ability, and discusses possible technological applications based on the activity of Actinobacteria for treating rubber waste in a more environmentally responsible manner.