The potential of naturally available oils as additives instead of processing aids and activators in carbon black filled natural rubber was investigated in this study. Physical properties and cure characteristics of the vulcanizates containing the natural oils were compared with those of the standard vulcanizate which was prepared using an aromatic oil. Soybean oil, palm oil and sunflower oil were selected as the natural oils and used at a fixed dose (5phr) in the compounding process as processing aids. The natural oils were incorporated in the compounding process, to examine their potential as activators and processing aids simultaneously. The results indicate that soybean oil, palm oil and sunflower oil are better alternative processing aids than petroleum based aromatic oils which have been reported to be carcinogenic. In addition, palm oil has the best heat resistance ability. Further, the cure characteristics and mechanical properties of the vulcanizate based on soybean oil suggest that it could be used as a co-activator for rubber compounding .

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Study on natural oils as alternative processing aids and activators in carbon black filled natural rubber

With environmental and toxicity concerns becoming more critical, there are increasing efforts to remove phthalates from polymer compounds around the globe more rapidly. Phthalates can be replaced by natural products; in particular, those obtained from vegetable oils and fats. In the present study, a natural-based plasticizer, synthesized by epoxidation of non-toxic rice bran oil (RBO) with peroxy acid generated in situ has been added to poly(vinyl chloride). The influence of various reaction parameters on epoxidation was studied by investigating the reaction ratio, temperature, reaction time and stirring speed. Epoxidized rice bran oil (ERBO) obtained from an optimized reaction condition was analyzed by iodine number and oxirane content. FTIR was used to analyze epoxy group formation. Product ERBO was obtained with 82 % oxirane conversion within 3 h of reaction period. PVC sheets were formulated using a conventional plasticizer di-(octyl) phthalate and was partially replaced by synthesized ERBO. The effect of ERBO addition was tested by mechanical properties (tensile strength, modulus, elongation-at-break, shore D hardness) and compared with commercially available ESBO (epoxidized soybean oil). ERBO presented fairly good incorporation and plasticizing performance, as demonstrated by the results of mechanical properties, exudation, migration tests, thermal stability by thermogravimetric analysis, T
 g values as shown by differential scanning calorimetry, replacing about 60 % of the total plasticizer.

Epoxidized rice bran oil (ERBO) as a plasticizer for poly(vinyl chloride) (PVC)

A new bio-based oil, tea oil (TO), was studied as possible alternative processing oil to the commonly used but potentially carcinogenic petroleum-based oils, viz. heavy naphthenic oil (HNO) and light naphthenic oil (LNO). Comparison was also made with two other bio-based oils, palm oil (PO) and coconut oil (CO). The results revealed that all bio-based oils studied exhibit higher thermal stability than LNO and, in the case of silica-filled natural rubber (NR), provide superior processing properties over the petroleum-based oils. These include higher thermal stability, greater mixing efficiency of NR with silica, improved silica dispersion in NR compound and greater plasticising effect for silica-filled NR compounds when compared under similar mixing condition. For cure characteristics of the rubber compounds, they are not significantly affected by the processing oil type and content. The results show the potential of the bio-based oils studied, TO, PO and CO, as possible alternative processing oils to replace petroleum-based oils.

Effects of Bio-based Oils on Processing Properties and Cure Characteristics of Silica-filled Natural Rubber Compounds

It is known that rubber mixes containing vegetable oils and vulcanized vegetable oils give better flow properties, plasticizing action, low temperature flexibility and ozone resistance. Now, in this investigation, the aim was to provide additional information about the effect of two vegetable oils (linseed oil and peanut oil) upon accelerated sulfur vulcanization system using thermal analysis—differential scanning calorimetry (DSC) and thermogravimetry. Several combinations of curatives (ZnO, sulfur and 2-t-butylbenzothiazole sulfenamide or TBBS) with stearic acid or vegetable oils were investigated, and DSC curves showed that vulcanization systems where linseed oil or peanut oil replaced stearic acid as activator proceeded an outline of basic steps similar to conventional mixture. However, the formation of the complex between Zn2+, sulfur and products of TBBS decomposition, main step in the vulcanization reaction, required much more energy. Exothermic ΔH values of 45.4 and 20.3 J g−1 were found for ZnO/S/TBBS/linseed oil and ZnO/S/TBBS/peanut oil, respectively, against only 5.8 J g−1 in the case of ZnO/S/TBBS/stearic acid mixture.

Thermal analysis of the sulfur vulcanization

The random copolymer of chloroprene and acrylonitrile is a newly developed rubber whose features and value propositions are not scientifically explored yet. This article focuses on the basic characterizations and properties of acrylonitrile-chloroprene rubber. Qualitative analyses through infrared (FTIR) and nuclear magnetic resonance (1H-NMR) spectra confirm the presence of both the -Cl and -CN groups in the new rubber. As evidenced through differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA), the single glass transition temperature of acrylonitrile-chloroprene rubber reflects its monophasic random microstructure. While compared against commercial grades of chloroprene rubber (CR) and nitrile rubber (NBR), the new rubber provides a distinctive combination of properties that are not available with either of the elastomer alone. Acrylonitrile-chloroprene rubber demonstrates slightly lower specific gravity, an improved low-temperature compression set, higher flex-fatigue resistance, and lower volume swelling in IRM 903 and Fuel C to chloroprene rubber. As compared to nitrile rubber, the new copolymer shows appreciably better heat aging and ozone resistance. Good abrasion resistance, low heat buildup, and remarkably high flex-fatigue resistance indicate excellent durability of the acrylonitrile-chloroprene rubber under dynamic loading. Based on the preliminary results, it is apparent that the new copolymer can be a candidate elastomer for various industrial applications which demand good fluid resistance, high heat and low-temperature tolerances, good weatherability, and durability under static and dynamic conditions.

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Introduction to the New Copolymer of Chloroprene and Acrylonitrile with Differentiated Properties

The use of rioe bran oil as a processing aid in styrene butadiene rubber has already been Investigated in this laboratory . Based on the encouraging results obtained from this study, we thought also of trying this oil inrubbers like nitrilebutadiene(NBR) and polychloroprene (CR) . In this study an attemptis madeto see whether rice bran oil which is a natural product, devoid of any toxic effects, can function as co-activator, antioxidant and as a processing aid in nitrile and as processing aid andantioxidant in polychloroprene rubber . The plasticizer, co-activator and antioxidant properties are compared with DOP, stearic acid and styrenated phenol, respectively, in the NBR vulcanization system and antioxidant, stearic acid and aromatic oil are replaced by the oil in the potychloroprene system . The mixes were evaluated for cure character- istics . Scorch time, cure time and the cure rate index values have shown that thisoil can effectively replace plasticizer, co-activator and antioxidant form NBR mixes and processing aid and antioxidant form CR systems. The evaluationof mechanicalproperties and ageing studies of the valcanizates also indicate that rice bran oil can be used as a multi-purpose additive in these rubbers.

A Pylee Kuriakose

Papers

The Compounding of Nitrile and Polychloroprene Rubbers with Rice Bran Oil