SOYBEAN OIL PLASTICIZERS AS REPLACEMENT OF PETROLEUM OIL IN RUBBER

Vulcanization kinetics and reinforcement behaviour of natural rubber-carbon black composites: Addition of Shea-butter versus aromatic oil as plasticizers

This work is a comparative study between Shea butter (SB) and treated distillate aromatic extract oil (TDAE) as plasticizers in the vulcanization of natural rubber (NR)- carbon black (CB) vulcanizates (-CB-S-NR-). The plasticized -CB-S-NR- composites extended scorch (Ts2) and optimum (T90) curing times. The delays in crosslinking reaction were suspected to be due to the increased viscosity (ML) and insulation of the reacting species (NR, CB, Sulfur and other curing aids) by the films of plasticizers. This effect increased the activation energy (Ea (KJ/mol)) for vulcanization. The -CB-S-NR- without plasticizer SB (SBO), showed higher ML, crosslinking density index (ΔM), rheological strength (MH) and low cure reversion properties than others. In comparison, the SB loaded -CB-S-NR- composites showed improvement in ML, ΔM, T90, with lowers Ea (KJ/mol) than TDAE samples. Also, the SB compounds exhibited higher Young's modulus Eo(MPa) than SBO and TDAE compounds. For instance, the Eo(MPa) of SB5 was over 7 and 1200 % higher than SBO and STD5 respectively. However, -CB-S-NR- filled with TDAE generally showed higher strength(MPa), attributed to stronger CB-NR interactions. Therefore, environmentally friendly SB could replace petroleum based oils for compounding rubbers.

Rubber Compounds from Devulcanized Ground Tire Rubber: Recipe Formulation and Characterization

In this study, our focus was on developing and investigating rubber recipes that are suitable for devulcanized ground tire rubber (dGTR). Devulcanized rubber has a powdery or sticky uncured rubber-like appearance depending on the extent of main-chain degradation that occurs with selective crosslinking scission. Still, it has a significantly shorter scorch time than a new rubber compound. Therefore, our primary goal was to slow down the vulcanization process of dGTR and improve its mechanical properties via recipe development. We formulated several recipes (sulfur-, peroxide-, and phenolic resin-based) and studied the vulcanization process and the main properties of the revulcanized rubber sheets. We observed that the vulcanization process could be altered with different vulcanization methods: using peroxide and vulcanizing resin extended the process significantly. Peroxide vulcanization also provided enhanced elongation compared to sulfuric systems. With a balance of properties in mind, we selected a semi-efficient sulfur-based recipe and studied the characteristics of natural rubber/dGTR mixtures with the help of plasticizer oils. We successfully replaced a notable portion of natural rubber with dGTR, maintaining its properties without much compromise.

Polyurethane Glycerolysate as a Modifier of the Properties of Natural Rubber Mixtures and Vulcanizates

Chemical recycling of polyurethanes can be realized in several different ways, but the most important methods are glycolysis and glycerolysis. Both methods permit recovery of polyols (when the process is realized with the mass excess of depolymerizing agent) or substitutes of polyols, which contain urethane moieties in the main chains and terminate mainly in hydroxyl groups (when the process is realized with the mass excess of depolymerized polyurethane). Oligomeric products with urethane groups in the chemical structure can also be used as modifiers of rubber mixtures and vulcanizates. The main aim of the presented work is to study the effect of polyurethane glycerolysate on the performance of natural rubber mixtures and vulcanizates. The influence of the modifier on the vulcanization kinetics and swelling of rubber mixtures, and the thermo-mechanical and mechanical properties of rubber vulcanizates, was studied. The prepared materials were also subjected to accelerated thermal aging in air. It was found that polyurethane glycerolysate affects the vulcanization process of rubber mixtures (for example, promotes the activation of vulcanization) and acts as an antidegradant under thermoxidative conditions (higher stability of mechanical properties was observed in comparison to a reference sample without modifier). The obtained results show that chemical recycling products can be valuable modifiers of natural rubber mixtures and vulcanizates, which extends the possible applications of polyurethane chemical recycling products.

Valorization of camelina oil to biobased materials and biofuels for new industrial uses: a review

Global environmental pollution is a growing concern, especially the release of carbon dioxide from the use of petroleum derived materials which negatively impacts our environment's natural greenhouse gas level. Extensive efforts have been made to explore the conversion of renewable raw materials (vegetable oils) into bio-based products with similar or enhanced properties to those derived from petroleum. However, these edible plant oils, commonly used for human food consumption, are often not suitable raw materials for industrial applications. Hence, there is an increasing interest in exploring the use of non-edible plant oils for industrial applications. One such emerging oil seed crop is Camelina sativa, generally known as camelina, which has limited use as a food oil and so is currently being explored as a feedstock for various industrial applications in both Europe and North America. Camelina oil is highly unsaturated, making it an ideal potential AGH feedstock for the manufacture of lower carbon footprint, biobased products that reduce our dependency on petroleum resources and thus help to combat climate change. This review presents a brief description of camelina highlighting its composition and its production in comparison with traditional plant oils. The main focus is to summarize recent data on valorization of camelina oil by various chemical means, with specific emphasis on their industrial applications in biofuels, adhesives and coatings, biopolymers and bio-composites, alkyd resins, cosmetics, and agriculture. The review concludes with a discussion on current challenges and future opportunities of camelina oil valorization into various industrial products.

Liquid Guayule Natural Rubber, a Sustainable Processing Aid, Enhances the Processability, Durability and Dynamic Mechanical Properties of Rubber Composites

Petroleum-based oils are widely used as processing aids in rubber composites to improve processability but can adversely affect rubber composite performance and increase carbon footprint. In this research, liquid guayule natural rubber (LGNR), produced from guayule natural rubber, was used as a renewable processing aid to replace naphthenic oil (NO) in Hevea natural rubber, styrene-butadiene rubber (SBR) and guayule natural rubber (GNR) composites. The rheological properties, thermal stability, glass transition temperature, dynamic mechanical properties, aging, and ozone resistance of rubber composites with and without NO or LGNR were compared. Natural and synthetic rubber composites made with LGNR had similar processability to those made with NO, but had improved thermal stability, mechanical properties after aging, and ozone resistance. This was due to the strong LGNR–filler interaction and additional crosslinks formed between LGNR and the rubber matrices. The glass transition temperature of SBR composites was reduced by LGNR because of its increased molecular mobility. Thus, unlike NO, LGNR processing aid can simultaneously improve rubber composite durability, dynamic performance and renewability. The commercialization of LGNR has the potential to open a new sustainable processing-aid market.

Application of Different Vegetable Oils as Processing Aids in Industrial Rubber Composites: A Sustainable Approach

Rubber composites based on renewable vegetable oils are being increasingly developed, as these materials significantly reduce the use of petroleum-based carcinogenic oils as plasticizers in rubber products. Apart from renewability, vegetable oils have some major advantages, such as easy availability, biodegradability, and environmentally friendly nature. Until now, vegetable oils, such as palm oil, soybean oil, and linseed oil, have been successfully used as processing oils to replace petroleum-based oils in engineered rubber composites. So far, the concept of a vegetable-oil-based plasticizer has been applied to rubber composites containing different industrially important fillers, like carbon black, silica, calcium carbonate, and expandable graphite. In the near future, the trend of utilizing vegetable-oil-based plasticizers may bring considerable advancements in the performance of filled rubber composites in an environmentally acceptable and sustainable manner.

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.

Effect of a Natural Processing Aid on the Properties of Acrylonitrile-Butadiene Rubber: Study on Soybean Oil Fatty Acid from Seed Crop

For the industrial production of rubber, one of the key ingredients is a processing aid. It not only facilitates the processability but also tunes the final properties of the resultant rubber. In general, for a polar rubber like acrylonitrile-butadiene rubber (NBR), the processing aids earning the most attention are synthesized from petroleum, such as dioctyl phthalate (DOP). However, due to their toxicity, many rubber chemists have tried to find alternative chemicals that are environmentally friendly and derived from a renewable resource. In this research, we investigated the effects of the soybean oil fatty acid (SBOFA), synthesized in house via hydrolysis of SBO, on the properties of NBR in comparison with DOP. Initially, it was found that the addition of SBOFA improved the flowability of the NBR compound, as indicated by the progressive decrease in the Mooney viscosity with increasing levels of SBOFA. The results from various techniques indicated that the crosslink density of the NBR vulcanizates passed through the maximum at the SBOFA loading of 4 phr. Upon loading SBOFA up to 4 phr, there was no significant deterioration in the mechanical strength of the SBOFA-plasticized NBR vulcanizates. Typically, the presence of SBOFA at 4 phr enhanced the thermal resistance of the NBR vulcanizate by shifting the thermal decomposition to a higher temperature. At a given loading, it was found that the SBOFA-plasticized NBR vulcanizate showed a comparable plasticizing efficiency and mechanical strength with the DOP-plasticized one. The result from this study shows that SBOFA is a good alternative sustainable eco-friendly processing aid to use for NBR.

Semiquantitative Solid-State NMR Study of the Adsorption of Soybean Oils on Silica and Its Significance for Rubber Processing

Soybean oil (SBO) is a renewable material used as an alternative to conventional petroleum-derived oils in the processing of rubber composites. Upon chemical modifications, such as epoxidation, its performance in the processing of rubber can be significantly improved, as indicated by a considerable reduction of the mixing energy. Although it has been hypothesized that hydrogen bonding between functional groups (e.g., epoxy) of SBOs and silanols present on the silica surface plays a key role, there is still a lack of direct evidence supporting this hypothesis. In this work, it is demonstrated that there is an overall correlation between the epoxy concentration of SBOs and the mixing energy, consistent with the long-held hypothesis. In particular, a correlation between the SBO-silica adsorption affinity and the degree of epoxidation is revealed by a set of surface-selective solid-state nuclear magnetic resonance (ssNMR) experiments. In addition, the surface-selective ssNMR technique demonstrated in this work could also be used to evaluate the adsorption affinity of other oils and/or additives more broadly.

WASTE MORINGA OLEIFERA GUM AS A MULTIFUNCTIONAL ADDITIVE FOR UNFILLED SBR COMPOUND

A natural waste (gum) of the drumstick tree, Moringa oleifera, was used for the first time as a sustainable multifunctional additive in an SBR compound. Improved cure rate with lower optimum cure time was obtained by using the gum as an accelerator activator. Tack strength of the M. oleifera gum–SBR compound was superior to both the control and the compound containing commercial phenol–formaldehyde resin at 5 parts per hundred of rubber loading. At different loadings, the gum acted as a plasticizer for the rubber and augmented processing by reducing the viscosity of the compound. The glass transition temperature of the compounds decreased by 2 °C compared with the pristine SBR. Moringa oleifera gum at any loading reduced the die swell of SBR. This study has relevance because the rubber industry is looking for feasible sustainable additives as alternatives to existing petroleum-based compounding ingredients.

DERIVATIZATION OF SOYBEAN OIL TO ENHANCE PERFORMANCE AS A PROCESSING OIL IN SBR-BASED RUBBER COMPOUNDS

Although soybean oil (SBO) has been used as a bio-based processing oil (PO) for rubber compounds, direct replacement of a conventional petroleum-based PO with SBO often results in a reduction of some important properties. As a result, it was of interest to investigate two higher molecular weight SBO-derived materials as POs, namely, sucrose octasoyate (SS) and poly(2-vinyloxyethyl)soyate (P2VOES). When these compounds were used in carbon black (CB)-filled SBR, mechanical properties were significantly improved. This result was mainly attributed to higher crosslink densities resulting from their higher degree of unsaturation per molecule as compared with SBO. Higher unsaturation per molecule increases the probability that the PO will be incorporated into the crosslinked network as elastically effective crosslinks as opposed to dangling chain ends. With regard to tire tread performance, both SS and P2VOES-based vulcanizates showed a lower predicted rolling resistance than the SBO-based control, and the P2VOES vulcanizate showed a better balance between rolling resistance and wet traction. Vulcanizates derived from SS and P2VOES showed a small tangent delta peak between −13 and 35 °C that might be associated with relatively highly crosslinked domains rich in SS or P2VOES.

Study on the Synthesis of Castor Oil-Based Plasticizer and the Properties of Plasticized Nitrile Rubber

A series of new environment-friendly plasticizers was synthesized from castor oil and used to plasticize nitrile rubber (NBR). The test results showed that tensile strength, elongation at break, and tear strength of NBR vulcanizates plasticized by castor oil-based plasticizers were found to be better than that of dioctyl phthalate (DOP). The aging test taken demonstrated that the castor oil-based plasticizers could improve the hot air and oil aging resistance of NBR vulcanizates. The thermal stability test illustrated that castor oil-based plasticizers enhanced the thermal stability of NBR vulcanizates, and the initial decomposition temperatures (T10%) were about 100 °C higher than that of DOP. In general, the studies manifested that EACO and EBCO can replace DOP to plasticize NBR and are used in fields that require high mechanical properties, aging resistance, and thermal stability. This study emphasizes the effects of sustainable, cost-effective, and high-efficiency plasticizers on NBR.

Influence of Bio-Based Plasticizers on the Properties of NBR Materials

A high number of technical elastomer products contain plasticizers for tailoring material properties. Some additives used as plasticizers pose a health risk or have inadequate material properties. Therefore, research is going on in this field to find sustainable alternatives for conventional plasticizers. In this paper, two modified bio-based plasticizers (epoxidized esters of glycerol formal from soybean and canola oil) are of main interest. The study aimed to determine the influence of these sustainable plasticizers on the properties of acrylonitrile–butadiene rubber (NBR). For comparison, the influence of conventional plasticizers, e.g., treated distillate aromatic extract (TDAE) and Mesamoll^® were additionally investigated. Two types of NBR with different ratios of monomers formed the polymeric basis of the prepared elastomers. The variation of the monomer ratio results in different polarities, and therefore, compatibility between the NBR and plasticizers should be influenced. The mechanical characteristics were investigated. In parallel, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) were performed and filler macro-dispersion was determined. Bio-based plasticizers were shown to have better mechanical and thermal properties compared to conventional plasticizers. Further, thermo-oxidative aging was realized for 500 h, and afterwards, mechanical characterizations were done. It was observed that bio-based plasticizers have almost the same aging properties compared to conventional plasticizers.

Development, influencing parameters and interactions of bioplasticizers: An environmentally friendlier alternative to petro industry-based sources

The current industrial revolution emphasized the necessity to use environmentally friendlier sources and strategies to meet the bio-based economy challenges of the modern world. Owing to the finiteness, human health and environmental impacts of fossil resources, current research efforts are switched to search and develop renewable, sustainable and eco-friendly alternatives of commercial plasticizers to meet the green agenda to establish a green society. The substitution of petroleum-based plasticizers with bioplasticizers offers noteworthy advantages, such as recyclability, biodegradability, high lubricant power, low diffusion coefficients in the polymeric matrix and very low volatility. Moreover, bioplasticizers provide the most suitable platform due to their global availability and industrially-relevant applications. Numerous parameters such as solubility, polarity, and structural compatibility are considered important and can influence the designing of efficient plasticizers. In this context, a plethora of research has given their structural attributes along with their compatibility with different elastomers and plastics. Herein, the valorization of bioplasticizers in several industrial and biotechnological processes is presented with suitable examples. Additionally, it highlights the insight of selection criteria and generalities concerning plasticization theories. A brief discussion is also given on the mechanism of plasticization and modifications, which are being made in the current industrial practices. The description extends towards the design of effective plasticizers with their dependence on structure and how we can improve their performance to the polymer industry.

Fatty Acid-Based Radically Polymerizable Monomers: From Novel Poly(meth)acrylates to Cutting-Edge Properties

The increasing price of barrels of oil, global warming, and other environmental problems favor the use of renewable resources to replace the petroleum-based polymers used in various applications. Recently, fatty acids (FAs) and their derivatives have appeared among the most promising candidates to afford novel and innovative bio-based (co)polymers because of their ready availability, their low toxicity, and their high versatility. However, the current literature mostly focused on FA-based polymers prepared by condensation polymerization or oxypolymerization, while only a few works have been devoted to radical polymerization due to the low reactivity of FAs through radical process. Thus, the aim of this Review is to give an overview of (i) the most common synthetic pathways reported in the literature to provide suitable monomers from FAs and their derivatives for radical polymerization, (ii) the available radical processes to afford FA-based (co)polymers, and (iii) the different applications in which FA-based (co)polymers have been used since the past few years.

The Effect of Palm Oil-Based Hybrid Oils as Green Multifunctional Oils on the Properties of Elastomer Composites

Hybrid oils in an elastomer matrix provide superior physical and chemical properties over conventional elastomer composites. In this study, we investigated the possibility of utilizing palm-based hybrid oil as a processing oil, with various other added oils such as methylester, palm monoglyceride and dammar, and their effects on the curing characteristics, mechanical, abrasion resistance and heat build-up properties of elastomer composites. The elastomer composites with the hybrid oils exhibit remarkable improvements in mechanical properties such as modulus, tensile strength, elongation and toughness, which were ascribed to the enhanced dispersion of the fillers in the elastomer matrix. Also, the hybrid oils in the elastomer matrix showed outstanding heat build-up, abrasion and rebound resilience properties at low loadings. The synergistic effects in the elastomer matrix achieved by the hybridization of palm oil and other oils represent a significant contribution to advanced, stronger elastomer composites in various applications.

Vegetable derived-oil facilitating carbon black migration from waste tire rubbers and its reinforcement effect

Three dimensional chemically cross-linked polymer networks present a great challenge for recycling and reutilization of waste tire rubber. In this work, the covalently cross-linked networks of ground tire rubber (GTR) were degraded heterogeneously under 150 °C due to the synergistic effects of the soybean oil and controlled oxidation. The degradation mechanism was discussed using Horikx theory and Fourier transformation infrared spectroscopy (FTIR). The results showed that the structural evolution of sol and gel parts, which indicated that the sols consisted of degraded GTR chains with low molecular weight, while the gels were mainly composed of bound rubber coated carbon black, which are separated from the cross-linked network of GTR in a high degradation degree. The degraded GTR compound demonstrated an excellent reinforcing effect on solution styrene-butadiene rubber (SSBR), due to the presence of core-shell structured carbon black. This work provide an efficient and economic approach to degrade GTR and transform it into useful products.