Green Rubber Research Articles

Carbon nanodots as dual role of crosslinking and reinforcing chloroprene rubber

The environmental-friendly and sustainable development is a top concern of rubber industry. Here we report a green method to fabricate a class of mechanically robust chloroprene rubber (CR) by employing nitrogen doped carbon nanodots (N-CDs) as both crosslinker and reinforcing nanofillers. The N-CDs are prepared by a green bulk high-temperature carbonization method on large-scale and can crosslink CR by nucleophilic substitution. The vulcanization kinetics are studied by curemeter. Moreover, the covalent crosslinks result in strong interfacial interaction between N-CDs and CR, enabling exceptional reinforcement of the rubber matrix. Consequently, N-CDs crosslinked CR manifests excellent mechanical properties with a tensile stress up to 30 MPa and an elongation at break up to 1353%. With no carcinogenic and environmentally toxic additives included, this work provides a new strategy to prepare high-performance green rubber composites without pollution.

Lignin as Alternative Reinforcing Filler in the Rubber Industry: A Review

Lignin has a potential reinforcing filler and alternative to carbon black in rubber industry. This is due to cheaper materials, abundant with yearly renewable source, low weight, high biological efficiency and wide ecological adaptability. Utilization of bio-filler in rubber industry has increased more attention among the researchers due to increasing environmental concerns and toxicological effect of carbon black towards health and environment. This article is intended to summarize the current efforts in development of green and sustainable of rubber product. Instead of focused to silica and alternative rubber matrix like guayule and Russian dandelion, lignin also has potential as reinforcing filler and lead to development of competitive green rubber composites. Lignin has several special properties such as good mechanical, physico-chemical, biodegradability, antioxidant and excellent thermal stability. However, incorporation of lignin in rubber matrix is not a straightforward and needs to overcome with certain suitable solution because of the polarity of lignin molecules which contribute to strong self-interactions. Consequently, chemical modification of lignin is often used to improve the dispersion of lignin in elastomers, or compatibilizer is added to enhance interfacial of adhesion between lignin and rubber matrix. This review attempts to compile relevant knowledge about the performance of lignin-filled rubber composite from different approach such as mixing method, surface modification, hybrid filler etc. This study is expected to gain significance interest of researcher globally on the subject of lignin-based rubber composites and the advancement of development in green rubber product.

A Review on Recent Trends and Future Prospects of Lignin Based Green Rubber Composites

In the last two decades, the utilization of non-petroleum based renewable materials on the development of advanced rubber composites has attracted increasing attention of polymer researchers from both industrial and environmental viewpoints. Recently, lignin has emerged as promising non-petroleum based filler in the progress of green rubber technology. This review article aims to present the recent advances of lignin based natural and synthetic rubber composites. The potential of lignin as alternative reinforcing filler in rubber technology is critically evaluated in terms of cure, mechanical, dynamic mechanical and thermal properties. The dispersion of lignin within the rubber matrix is the key parameter that decides the overall performances of lignin based rubber composites. The last section of the review will emphasize the major challenges regarding the broad application of lignin as reinforcing filler in rubber industry. This study will be the part of huge interest of modern rubber researchers concerning the utilization of lignin for the development of non-petroleum based renewable and sustainable rubber composites.

Improving the Adhesion between Pineapple Leaf Fiber and Natural Rubber by Using Urea Formaldehyde Resin

Green composites, especially that are reinforced with natural fibers, have received a great deal of attention due to the problems of global warming and resources depletion. Pineapple leaf fiber (PALF) is an interesting choice because of its high mechanical properties and it is obtained from agricultural waste. In this work PALF is combined with natural rubber (NR) to produce green rubber composite with enhanced mechanical properties. Since the two materials are so different in their stiffness and polarity, poor interfacial adhesion and thus low stress transfer, between NR and PALF may be expected. Attempts were made to use urea formaldehyde (UF) resin to improve the adhesion between PALF and NR. PALF was coated with different amounts of UF resin in solution. The fiber was characterized with FTIR, XPS and SEM. Uniaxially aligned PALF reinforced rubber composites with a fixed amount of 10 parts per hundred of rubber (phr) PALF were prepared. The adhesion between PALF and NR was evaluated from the tensile stress-strain curve and fracture surface of the composite. It was found that UF resin had negligible effect in improving the stress transfer but rather reduced it as shown in the stress-strain curve. Thicker coating of UF resin led to lower reinforcement effect and, hence, lower modulus. Stress at break, on the other hand, increased with increasing the coating thickness.

Predicting Useful Life of Green Tires through Different Methodologies

ABSTRACT One consideration when evaluating materials is the length of time over which they can be used, also called useful life. This is a complex question, especially for new green tire tread rubber compounds using silica as the main reinforcing filler that results in lower fuel consumption. The current work presents a critical approach of three methodologies used for predicting the useful life of different tire tread compositions. The methodologies considered were Arrhenius; Williams, Landel, and Ferry (WLF); and crack growth propagation. Different temperatures, strains, and mechanical properties were analyzed to evaluate the differences between the useful life of the new green tire tread and the carbon black reinforced reference one. Results showed different useful life for each evaluated property. Moreover, each tire tread composition presented a different useful life for the same property, while the silica reinforced composition presented a lower useful life when compared with the reference one.

SPECTROPHOTOMETRIC DETERMINATION OF COPPER COMPLEXES OF CHLOROPHYLLINS (E141ii)

In this study, the water-soluble green food colorant copper complexes of chlorophyllins, E141ii, as one of the most popular within the food industry was investigated. First, the spectroscopic parameters, absorbance maximum, λmax-vis, and molar absorptivities, ε, of E141ii dye were determined. The impact of the presence of aspartame, citric acid and vitamin C on the change in the positions of the absorbance maximum and change of its intensity in the visible range of the E141ii spectra also was investigated. Recorded absorption spectra was show that this dye had two absorbance maxima. The average molar absorptivities were calculated. These values of molar absorptivities were later used to quantify the unknown dye concentration in the analyzed food samples. It was found that the use of additives (vitamin C, citric acid and aspartame) does not cause a change in the positions of the absorbance maximum and change of its intensity in the visible range of the E141ii spectra. Therefore, it can be concluded that it is possible to quantify the E141ii by UV-Vis spectrophotometric method in the presence of these additives. Based on determined spectroscopic parameters, the dye concentration was calculated in green rubber candy colored with E141ii.

Covalent hybrid of graphene and silicon dioxide and reinforcing effect in rubber composites

For developing high performance graphene and silicon dioxide (SiO2)-based green rubber nanocomposites, dispersal of graphene nanosheets and SiO2 particles in rubber hosts and precise interface control are challenging due to their strong interlayer cohesive energy and surface inertia of graphene and the poor interaction with the organic matrix of SiO2. Here we report an efficient method to hybrid graphene nanosheets and SiO2 paticles. The SiO2 molecules were covalently bonded to the graphene surface via functionalized graphene, using plant polyphenol tannic acid (TA) as stabilizer and functional reagent, followed by further covalent derivatization through the Michael addition reaction between phenolic hydroxyl group on TA and primary amine on silane coupling agents modified SiO2. Through covalent hybridization, the SiO2 particles are uniformly decorated on the surface of graphene. The improved dispersion state of hybrid filler was attested by XRD, TEM and FTIR. SEM, DMA, mechanical analysis, thermal conductivity measurements and applied to characterize the hybrid nanocomposites. The results imply that the strategy of using hybrid fillers with covalent interactions has been established to be an efficient way to achieve high-performance rubber nanocomposites. The prominent confinement effect arising from nanosheets resulted in nearly 7.0% increase in the thermal conductivity of the highly synergistic hybridization graphene-SiO2 nanocomposites than that of the composite of graphene and SiO2 mixtures. The former possesses 45.4% increase in tensile strength and 32.6% in tear strength and 35.4% in compression set. The covalent hybridization nanocomposites exhibit excellent abrasive resistant capacity with nearly 36.6% increase than that of the composite of graphene and SiO2 mixtures. These results suggest that SiO2 and graphene covalent hybrid fillers have a high potential to be used in engineering composits.

Silanized silica compatibilization of NBR/gelatin blends for the production of green rubber products

In this study, acrylonitrile butadiene rubber (NBR)–gelatin blends were prepared by conventional melt blending process at 40°C processing temperature and 50 r min−1rotor speed in a Brabender-Plasticorder. Gelatin loading was varied from 10 to 50 phr. The extent of reinforcement was more prominent at 30 phr gelatin loading without compatibilization. Up to 30 phr gelatin loading, the tensile strength, abrasion resistance, and morphological properties of blends increased. After 30 phr gelatin loading, the toughness and abrasion resistance declined for samples containing 40 and 50 phr gelatin. However, cross-link density and hardness kept on increasing beyond 30 phr loading. At optimum loading of 30 phr of gelatin, 3, 3.5, and 4 phr of nano-silanized silica was added as a compatibilizer for further improvement in properties. After compatibilization of 30 phr gelatin sample with 4 phr of nano-silanized silica, the extent of reinforcement in terms of tensile strength was improved from 8.97 to 9.92 MPa.

Hybrid NBR/Chitosan/Nano-Silanised Silica Based Green Rubber Products

In the present study hybrid NBR/chitosan/nano-silanised silica blends were prepared by melt blending for utilisation of chitosan (the second most abundant biopolymer) in development of green rubber products. The non-reinforcing nature of chitosan was improved by addition of nano-silanised silica. The effect of nano-silanised silica loading on crosslink density, tensile properties, surface hardness, tear strength, abrasion resistance and morphology of blends was studied. Improvement in both mechanical and morphological properties of NBR-chitosan blends was observed upon addition of nano-silanised silica. FTIR analysis was also carried out to study the interaction between rubber phase and chitosan as a result of compatibilisation by nano-silanised silica.

1973, and: Outside Arcadia, and: Detasseling

1973, and: Outside Arcadia, and: Detasseling Jennifer Quinlan (bio) 1973 I dislike the adults who come to the Halloween party, hysterical in their assumed identities. The living room contains their drunken movements, from the couch, I watch ignored.My mother is twenty-six. My father is twenty-five. They move among the throng of ghoulsdancing far from each other & closer to others. They stare at each other from their distances. It feels heavy in the autumn night, like a body, or itscoffin. I feel a death and wonder why they want it.A television show teaches me how to subtract. It has to do with cookies. There are so many cookies and then there are fewer. I want all of the cookies. My mother digs through the sandbox in the morning & I helpher. We sift through the cat shit and grains looking for herwatch.We listen for its ticking & do not discuss how it flew fromher arm to be buried here. The television show also taught me about time. It changes things. [End Page 40] Outside Arcadia I was born another daughter in afamily overripe with girls, our Iowafarm begged for the boys I denied it. I was born a sickly runt amidstbellowing cattle we called home. I was born among a clutch of chickenscackling and cracking corn with wornbeaks until their heads were twisted. I was born an unhappiness. I was born with a gift for vanishing andvapor early to a woman with eyesas empty as the endless sky. I was born an insignificant weed in the fieldof my father's producing mind. I was born a pair of pedal pushersmy boyfriend peeled from mybody tending tenderly to myflesh and our daughter's wild spiritimplanted a tick engorging itself onmy bloodbaby emerging. You'll never outlive this sinmy father whispered. Hiswords a weight stunting mygrowth. [End Page 41] Detasseling At fourteen, it was a good job paying $10 an hourbut how to put a price on the way corn leaves can cutthe long sleeves and green rubber kitchen gloves my only protectionthe metal of the machine's bucket bruising my narrow hips. Bruiseshis thick thumbs would press into at nightwhen not even exhaustion kept me from him.He was the landlord's son who had spent the day in a field making hay."You smell like summer," he said that first night as he pulled me into the shadows. Everything interesting to me that summer involved himin the dark cool grass of the night. I never saw him otherwise.I wrapped my long legs around him trying that motion for the first timeI wanted to bury him into me or set something loosewith our sun-soaked bodies and yet we were careful with each other. We hardly spoke.That was before I understood how overripe desire can become.One of our last nights, it began to rain."It's washing it all away," he said, "as though it never happened." [End Page 42] Jennifer Quinlan Jennifer Quinlan is a poet and librarian living in St. Cloud, Minnesota, where she works at St. Cloud State University. This is her first publication. Copyright © 2018 University of Nebraska Press

Cream concentrated latex for foam rubber products

Fresh natural latex (around 40% rubber and 60% water) can be transformed to concentrated natural latex (around 60% rubber and 40% water) in order to realise economical transportation and easier latex product’s preparation. The concentrated natural latex is an extremely valuable material. It can be applied for many types of products, for example, foam rubber as pillow and mattress, elastic band, etc. Industrially, the concentrated natural latex can be prepared by centrifugation which requires an enormous expensive machine. From the eco-friendly products point of view, most of rubber entrepreneurs in the world try to develop a green rubber product. So, the main objective of this study is to prepare the cream concentrated latex without any sophisticated machine. Thus, we work on a simple, cheap and green method that does not use any expensive machine but uses water-based chemical as sodium alginate to prepare the cream concentrated latex. The optimal amount of sodium alginate in the latex was studied. The main characteristics of the cream concentrated latex were tested by various technics, such as alkalinity, total solid content (TSC), dry rubber content (DRC), etc. We found that there are no significant differences of results between fresh natural latex and cream concentrated latex, except for the TSC and DRC. The TSC and DRC of cream latex are higher than those of fresh natural latex. Finally, we propose a model of natural rubber particle and sodium alginate to form the cream concentrated latex.

Micro-sphere based viscoplastic constitutive model for uncured green rubber

Uncured rubber exhibits strong viscoplastic flow without a distinct yield point accompanied by hardening. Classical hyperelastic models developed for crosslinked rubber do not apply to uncured rubber due to the lack of crosslinks which endow the material its elasticity. This paper presents a new constitutive model for the isothermal response of uncured green rubber. The kinematic structure of the proposed approach is based on the affine micro-sphere model. The computation of the stretch in the orientation direction follows the Cauchy-Born rule. The micro-sphere enables numerical integration over the unit sphere via finite summation over the orientation directions corresponding to the integration points over the sphere. This structure replaces the complex three-dimensional formulations of finite inelasticity based on the multiplicative split of the deformation gradient by a simpler and more attractive one-dimensional rheological representation at the orientation directions. The rheology of the model consists of two parts: (i) a part responsible for the rate-independent reponse and (ii) a part responsible for the rate-dependent response, respectively. The first branch consists of a spring connected to a modified Kelvin element, where the latter spring models the kinematic hardening. The dashpot describes a time-independent endochronic flow rule based solely on the deformation history. The second branch consists of a spring connected to a Maxwell element in parallel to a dashpot. The two dashpots in the latter branch model the ground-state viscoelasticity and rate-dependent hardening phenomenon. Albeit its apparent complexity, the proposed rheology and its numerical implementation are straightforward. The proposed model shows favorable results suitable for large scale finite element based simulations for forming process of uncured rubber components.

Carbon Nanotubes in Tyre Rubbers. Part 2: A Study of the Effect of Nanotubes on the Properties of Carbon-black-filled Tread Rubbers

The processing and mechanical properties of green and vulcanised tread rubbers based on a blend of two types of styrene butadiene rubber filled with carbon black and containing single-layer carbon nanotubes (SCNTs) were studied. Three types of rubber mix were prepared: one containing untreated SCNTs and stearic acid, and two with SCNTs treated by different methods. The properties of these composites were compared. In all cases, the introduction of SCNTs leads to an increase in the cohesion strength of green rubber mixes, to an improvement in their vulcanisation properties, and to an increase in the Mooney viscosity, and also to an improvement in the dynamic properties of the vulcanisates, and here the Payne effect increases. There is also an improvement in the wear resistance, especially in the case of introducing untreated SCNTs and stearic acid which ensures the presence of –COOH groups.

Carbon Nanotubes in Tyre Rubbers. Part 3: Study of the Effect of Nanotubes in Silica-filled Tread Rubbers

The processing and mechanical properties of green and vulcanised tread rubbers based on styrene butadiene rubber and polybutadiene with the addition of natural rubbers filled with silica and containing single-walled carbon nanotubes (SCNTs) were studied. Two types of rubber were manufactured: one containing untreated SCNTs and stearic acid, ensuring the presence of – COOH groups, and the other with treated SCNTs. The properties of these composites were compared. In both cases, the introduction of SCNTs leads to an increase in the cohesion strength of the green rubber mixes, to an improvement in their vulcanisation properties, and to an increase in their Mooney viscosity. In contrast to tread rubbers filled with carbon black, in the case of filling with silica the Payne effect decreases. The dynamic and other mechanical properties of the vulcanisates change in different ways. The wear resistance, like other service properties, is improved.

Scaling green rubber cultivation in Southwest China—An integrative analysis of stakeholder perspectives

The rubber boom across much of Southeast Asia has led to environmental destruction, and the resultant crash in the price of rubber has destabilised livelihoods. We investigated the necessary factors required to enable a transition towards a more sustainable model for rubber cultivation in Southwest China (i.e. the 'greening' of rubber cultivation), using a framework for the integrative study of multiple aspects in complex land use issues. We present findings from stakeholder interviews and a stakeholder workshop, and discuss their relevance within and beyond Southwest China. The current focus of researchers and development practitioners tends to be on finding technical solutions to address unsustainable rubber cultivation practices. However, stakeholder consultations revealed that the key barriers were more social: low levels of trust and knowledge exchange between stakeholder groups and fragmented visions about the future of the landscape. It is very important to continue the economic prosperity initially brought by rubber, but, without improved communication between government and researchers and smallholder farmers, this will be very difficult to achieve. A wider landscape perspective is needed to address issues in rubber cultivation to avoid repeating the same problems of cash crop boom and bust experienced with other crops, most notably bananas. We conclude that more effort should be put into developing mechanisms that integrate technical knowledge, enhance social relationships, and present a forum for reconciling - or at least acknowledging - the differing needs, knowledge, and objectives of different groups, and transcending the power dynamics between smallholder farmers and government and researchers.

Making a green rubber stamp: emerging dynamics of natural rubber eco-certification

ABSTRACTThe recent expansion and intensification of natural rubber cultivation has been associated with widespread forest conversion, habitat and biodiversity loss, increased livelihood vulnerabilities and, in some cases, dispossession of land. While these issues have attracted considerable attention from scientific and academic communities, public awareness – particularly in terms of consumer demand for standards and certification – has been slow to develop in comparison to other agro-commodity crops. Drawing on the concepts of global value chain analysis, management swing potential and issue attention cycle, this article examines the relatively slow uptake of natural rubber eco-certification through a comparison of three case studies in Jambi (Indonesia), Xishuangbanna (China) and Kerala (India). This study finds that natural rubber certification has taken a path of least resistance, emerging in relatively short value chains characterized by high degrees of vertical integration where existing production practices require minimal adjustment to achieve certification. Although certification programmes often position themselves as transparent and accountable alternatives to government regulation, the success of these programmes is dependent on the continued presence of the state to establish the necessary institutional and social foundations for private regulation to operate successfully. Consumer pressure plays an important role in evoking sustainability initiatives and influencing standards, yet when disconnected from the specific issues associated with a particular commodity, public concerns may produce standards and forms of certification that need to be complemented by sub-national and national policy and programmes in providing solutions for ecosystem service and social problems.EDITED BY Meine van Noordwijk

Research on Mechanical Properties of Steel Fiber Reinforced Rubber Concrete

The purpose of this paper is to research on the mechanical properties of steel fiber reinforced rubber concrete in this paper. Cracks, deformation and other issues often exist in the process of using concrete, a commonly used building material. Adding a certain amount of powder or rubber particles in concrete can be a good solution to these problems. This work studied construction technology of green rubber concrete. It is found that only by emphasizing the selection of tire and rubber particles as well as fabrication and application of rubber concrete can the quality of construction engineering be improved to the highest extent, based on the concept and characteristics of rubber concrete and combining them with the status of their applications in building construction.

Morphology and mechanical properties of sisal fiber and nano cellulose green rubber composite: a comparative study

In this article the method of fabrication of green nano cellulose/rubber composite (CNC-NR) and a comparative study of chemically treated sisal fibre/rubber (SF-NR) composite and (CNC-NR). Effects of process parameters such as surface modification of fibres and weight percentage of sisal fibre or cellulose on tensile strength of composite are discussed briefly. Extraction of Nano cellulose from sisal plant was done by acid hydrolysis and preparation of (CNC-NR) and (SF-NR) composite was done using hand lay-up method. The effects of NaOH, NAClO2, were found very effective as bleaching agents, which are used for removing lignin, pectin, wax and other impurities adhered to the surface of the fibre. Morphological and mechanical properties were studied briefly to see how chemical treatment (treat.) and weights % (wt%) is affecting composites properties. A mathematical model has been developed from the obtained tensile test results that are optimized using RSM modelling in MINITAB Release 14.1 software. Tensile strength was increased from 0.4 to 0.55 MPa. Diameter of fibre was reduced after chemical treatment. The strength of bleached fibre composite was found to be more than nano cellulose rubber composite.

Systemic perspectives on scaling agricultural innovations. A review

Agricultural production involves the scaling of agricultural innovations such as disease-resistant and drought-tolerant maize varieties, zero-tillage techniques, permaculture cultivation practices based on perennial crops and automated milking systems. Scaling agricultural innovations should take into account complex interactions between biophysical, social, economic and institutional factors. Actual methods of scaling are rather empirical and based on the premise of ‘find out what works in one place and do more of the same, in another place’. These methods thus do not sufficiently take into account complex realities beyond the concepts of innovation transfer, dissemination, diffusion and adoption. As a consequence, scaling initiatives often do not produce the desired effect. They may produce undesirable effects in the form of negative spill-overs or unanticipated side effects such as environmental degradation, bad labour conditions of farm workers and loss of control of farming communities over access to genetic resources. Therefore, here, we conceptualise scaling processes as an integral part of a systemic approach to innovation, to anticipate on the possible consequences of scaling efforts. We propose a method that connects the heuristic framework of the multi-level perspective on socio-technical transitions (MLP) to a philosophical ‘modal aspects’ framework, with the objective of elucidating the connectedness between technologies, processes and practices. The resultant framework, the PRactice-Oriented Multi-level perspective on Innovation and Scaling (PROMIS), can inform research and policymakers on the complex dynamics involved in scaling. This is illustrated in relation to three cases in which the framework was applied: scaling agro-ecological practices in Nicaragua, farmer field schools on cocoa cultivation in Cameroon and ‘green rubber’ cultivation in Southwest China.

Enhancement of carbon-steel peel adhesion to rubber blend using atmospheric pressure plasma

The surface of carbon-steel plates was modified by non-equilibrium plasma of diffuse coplanar surface barrier discharge (DCSBD) in order to improve the adhesive properties to the NR (natural rubber) green rubber compound. The effect of different treatment times as well as different input power and frequency of supplied high voltage was investigated. The samples were characterized using contact angle and surface free energy measurement, measurement of adhesive properties, scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface chemical composition was studied by energy-dispersive X-ray spectroscopy (EDX). Significant increase in wettability was observed even after 2 s of plasma exposure. The surface modification was confirmed also by peel test, where the best results were obtained for 6 s of plasma treatment. In addition the ageing effect was studied to investigate the durability of modification, which is crucial for the industrial applications.