Use of Amine Terminated Liquid Natural Rubber as a Plasticiser in Filled NR andNBR Compounds

Amine Terminated Liquid Natural Rubber (ATNR) was used as a plasticiser in filled NR and NBR compounds replacing oil/DOP. The scorch time and cure time were found to be lowered when ATNR was used as the plasticiser. ATNR was found to improve the mechanical properties like tensile strength, tear strength and modulus of the vulcanizates . The ageing resistance of the vulcanizates containing ATNR was superior compared to the vulcanizates containing oil/DOP.

Studies on 50/50 Natural Rubber/Styrene Butadiene Copolymer Blend

A carbon black filled 50/50 natural rubber (NR)/styrene-butadiene rubber (SBR) blend is vulcanized using several conventional curing systems designed by varying the amounts of sulphur and accelerator. The cure characteristics and the properties of the vulcanizates are compared. The quantity and quality of crosslinks in each case are evaluated by chemical probes to correlate them with the properties.

The utilisation of latex reclaim rubber in natural rubber

Scrap latex products contain rubber hydrocarbon of very high quality, that is only slightly crosslinked. A novel economic technique for converting such latex waste into a processible material is developed. This paper reports the effect of adding this latex reclaim to natural rubber. It is shown that latex reclaim can replace raw natural rubber up to about 50 wt.% without affecting mechanical properties.

Studies on natural rubber-bound diphenylamine antioxidants

Diphenylamine was chemically attached to depolymerised natural rubber by photochemical reaction. The rubber-bound diphenylamine was characterised by TLC, HNMR, IR and TGA. The efficiency and permanence of the bound diphenylamine was compared with conventional amine type antioxidant in natural rubber vulcanizates. The rubber-bound diphenylamine was found to be less volatile and less extractable compared to the conventional antioxidant. The vulcanizates showed improved ageing resistance in comparison to vulcanizates containing conventional antioxidant . Also, the presence of liquid rubber-bound diphenylamine reduces the amount of plasticiser required for compounding.

Studies on Natural Rubber Bound Para -Phenylenediamine Antioxidants in NBR

Para-phenylenediamine (PD) was chemically attached to depolymerized natural rubber by a photochemical reaction . The rubber bound PD was characterized by TLC, 1H-NMR, IR, and TGA. The efficiency and permanence of the bound PD were compared with conventional antioxidants in NBR vulcanizates . The rubber bound PD was found to be less volatile and more resistant to water and oil extraction . The vulcanizates showed improved aging resistance in comparison to vulcanizates containing conventional antioxidants. The liquid rubber bound antioxidant reduces the amount of plasticizer required for compounding

The Use of Carboxy Terminated Liquid Natural Rubber (CTNR) as an Adhesive in Bonding Rubber to Rigid and Non-rigid Substrates

Carboxy Terminated Liquid Natural Rubber (CTNR) was prepared by photochemical reaction using maleic anhydride and masticated natural rubber (NR). The use of CTNR as an adhesive in bonding rubber to rubber and rubber to metal was studied. The peel strengths and lap shear strengths of the adherends which were bonded using CTNR were determined. The effect of using a tri isocyanate with CTNR in rubber to metal bonding was also studied. It is found that CTNR can effectively be used in bonding rubber to rubber and rubber to mild steel.

Synthesis and Characterization of Chlorinated Paraffin Wax-Bound Paraphenylenediamine Antioxidant and ItsApplication in Natural Rubber

ABSTRACT: p-Phenylenediamine was chemically attached to low molecular weight chlorinated paraffin wax. The polymer-bound p-phenylenediamine was characterized by vapor-phase osmometry (VPO), proton magnetic resonance spectroscopy ('H-NMR), infrared spectroscopy (IR), and thermogravimetric analysis (TGA). The efficiency and permanence of the polymer-bound p-phenylenediamine as an antioxidant was compared with a conventional amine-type antioxidant in natural rubber vulcanizates. The vulcanizates showed improved aging resistance in comparison to vulcanizates containing a conventional antioxidant. The presence of liquid polymer-bound p-phenylenediamine also reduces the amount of the plasticizer required for compounding.

Preparation and Characterisation of Novel Polymer Bound Phenolic Antioxidants and Its Use in Natural Rubber

ABSTRACT: Phenol was chemically attached to low molecular weight chlorinated polyisobutylene and stearic acid respectively. These phenolic antioxidants were characterised by IR, 1H NMR and TGA. The efficiency and permanence of these bound antioxidants were compared with conventional antioxidants in natural rubber vulcanisates. The vulcanisates showed comparable ageing resistance in comparison to vulcanisates containing conventional antioxidants. The presence of liquid polymer bound phenol reduce the amount of plasticiser required for compounding.

Xanthate Accelerators for Low Temperature Curing of Natural Rubber

ABSTRACT: Zinc salts of ethyl, isopropyl, and butyl xanthates were prepared in the laboratory. They were purified by reprecipitation and were characterized by IR, NMR, and thermogravimetric analysis techniques. The melting points were also determined. The rubber compounds with different xanthate accelerators were cured at temperatures from 30 to 150°C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density, elongation at break, and modulus at 300% elongation were evaluated. The properties showed that all three xanthate accelerators are effective for room temperature curing.

A Study on the Use of Castor Oil as Plasticizer in Natural Rubber Compounds

Mechanical properties and thermal degradation of natural rubber compounds containing castor oil were studied to evaluate its suitability as plasticizer. Naphthenic oil was used as a reference plasticizer. The cure time was marginally lower in the case of castor oil mixes, probably due to the presence offree fatty acids in it. The tear strength and modulus were better in the case of mixes containing castor oil, while most of the other mechanical properties were comparable to the mixes containing naphthenic oil. The heat build up and compression set were higher than that of the naphthenic oil mixes. Thermal studies showed an increase of 8 °C in the temperature of initiation of degradation and an increase of 6 °C in the temperature at which the peak rate of degradation occurred. The peak rate of degradation was comparable to that of the reference compound

A Study on the Use of Coconut Oil as Plasticiser in Natural Rubber Compounds

Mechanical properties and thermal degradation characteristics of natural rubber compounds captaining coconut oil were compared with that of a control compound containing naphthenic oil. Cure time was marginally lower in the case of coconut oil mixes, probably due to the presence of free fatty acids. Tensile strength , tear strength, resilience and abrasion resistance were better than the naphthenic oil-based compounds . Compression set and hardness were marginally inferior The coconut oil mixes had a crosslink density comparable to that of the reference compound. Thermal studies showed that the temperature of initiation of degradation was increased by 10°C and the temperature at which the peak rate of degradation occured was increased by 7°C. The peak rate of degradation was compa rable to the control compound.

Short Isora Fibre Reinforced Natural Rubber Composites

The present study deals with the short isora fibre reinforced natural rubber composites. In recent years there has been a tremendous advancement in the field of science and technology of short fibre reinforced polymer composites. The low density, high strength, high stiffness to weight ratio, excellent durability and design flexibility are the primary reasons for their use in many diversified fields such as air crafts, automobiles, marine industry etc. Compared to the various natural and synthetic fibres used as reinforcement for elastomer composites isora fibre is superior in many aspects. `Isora' is a natural lignocellulosic fibre which is easily available in South India especially in Kerala. The fibre is separated from the bark of the Helicteres isora plant by retting process. This fibre has excellent mechanical properties and is easily amenable to physical and chemical modifications. The study shows that composites with poor interfacial bonding tend to dissipate more energy than that with to interfacial bonding. The mechanical loss also can be related to interfacial bonding. The effect of chemical treatment of isora fibre on damping was also studied. Both in the low and high temperature region which indicates that this composite posseses low damping and hence good interfacial bonding characteristics. Hence these composites are better candidates for high damping applications. Composites with longitudinally oriented fibres showed high storage modulus than transversely oriented ones due to the effective stress transfer between fibre and matrix.

Supply response and Cost of production of natural rubber- an econometric study

The study deals with the short and long term supply response of the natural rubber in India and to analyse the macro economic environment of NR industry and causative factors of the rubber price crash. It determines the minimum cost of production of natural rubber and to forecast the potential production of NR in India. There is positive response of short run and long run supply to prices. Since correlation analysis show close association between international and domestic price level, international price changes will have its domestic echo. Production and consumption will sustain its rising trend. This makes plans for increasing production estimates show that a mid way level i.e. the range between Rs.32-Rs.38 will give a fair enough profit to the grower in the present situation and provide for the viable sustenance of rubber cultivation. Identification of the SWOT of rubber cultivation would help in supporting rubber cultivation if remedial measures are undertaken with the true spirit. This would help Indian rubber to attain global competitiveness. Then the inflow of valuable foreign exchange will overcome the other economic drawbacks of rubber cultivation

Preparation of Low-Protein Natural Rubber Latex: Effect of Polyethylene Glycol

Low-protein content natural rubber latex was produced by using a nonionic surfactant-polyethylene glycol (PEG). Extractable protein content of natural rubber latex was found to decrease with PEG treatment and reduction increased with increase in the molecular weight of PEG. The low-protein latex samples were characterized by tensile testing, Fourier transform infrared and thermogravimetric analysis. The results have shown 35% reduction in the extractable protein content, without any compromise on the mechanical properties of the latex; however, thermal stability of low-protein latex was found to be reduced marginally with PEG treatment.