Studies on the use of Nanokaolin, MWCNT and Graphene in NBR and SBR

The current research investigates the possibility of using unmodified and modified nanokaolin, multiwalled carbon nanotube (MWCNT) and graphene as fillers to impart enhancement in mechanical, thermal, and electrical properties to the elastomers. Taking advantage of latex blending method, nanoclay, MWCNT and graphene dispersions, prepared by ultra sound sonication are dispersed in polymer latices. The improvement in material properties indicated better interaction between filler and the polymer.MWCNT and graphene imparted electrical conductivity with simultaneous improvement in mechanical properties. Layered silicates prepared by microwave method also significantly improve the mechanical properties of the nanocomposites. The thesis entitled ‘Studies on the use of Nanokaolin, MWCNT and Graphene in NBR and SBR’ consists of ten chapters. The first chapter is a concise introduction of nanocomposites, nanofillers, elastomeric matrices and applications of polymer nanocomposites. The state-of-art research in elastomer based nanocomposites is also presented. At the end of this chapter the main objectives of the work are mentioned. Chapter 2 outlines the specifications of various materials used, details of experimental techniques employed for preparing and characterizing nanocomposites. Chapter3 includes characterization of the nanofillers, optimsation of cure time of latex based composites and the methods used for the preparation of latex based and dry rubber based nanocomposites. Chapter4 presents the reinforcing effect of the nanofillers in XNBR latex and the characterization of the nanocomposites. Chapter5 comprises the effect of nanofillers on the properties of SBR latex and their characterization Chapter 6 deals with the study of cure characteristics, mechanical and thermal properties and the characterization of NBR based nanocomposites. Chapter7 is the microwave studies of MWCNT and graphene filled elastomeric nanocomposites. Chapter 8 gives details of the preparation of layered silicates, their characterization and use in different elastomeric matrices. Chapter 9 is the study of mechanical properties of nanoclay incorporated nitrile gloves .Chapter 10 presents the summary and conclusions of the investigation.

Studies on Latex Stage Carbon Black Masterbatching of NR and its Blend with SBR

Carbon Black is incorporated In natural rubber latex in , the presence of polyethylene glycol. The dispersion of carbon blade in the vulcanizatea is analyzed using polaroid M.4 land camera The mechanical properties of the carbon black meeterbatched NR/SBR blend Is compared with that of conventional NR/SBR blend before and after ageing , The resilience, flex resistance and hardness are found to be superior for N-LCMISBR compounds. The compression set and abrasion resistance are comparable for both types of blends . The processebiity and die swell of these blends at different shear rates are also compared.

Studies on in situ precipitated silica filled rubber composites with special reference to NR, NBR and SBR

Precipitated silica is the most promising alternative for carbon black in tyre tread compounds due to its improved performance in terms of rolling resistance and wet grip.But its poor processability is a serious limitation to its commercial application.This thesis suggests a novel route for the incorporation of silica in rubbers,i.e.,precipitation of silica in rubber latex followed by coagulation of the latex to get rubber-silica maseterbatch.Composites with in situ precipitated silica showed improved processability and mechanical properties,when compared to conventional silica composites.

Production of latex reclaim and its utilisation in polymer blends

The overall objective of the present study was to develop a novel and economic reclaiming process that does not adversely affect the quality of rubber and to investigate methods of utilising the reclaim. Since waste latex products represent a potential source of high quality rubber hydrocarbon, it was decided to develop a process based on such latex wastes. The study revealed that latex reclaim could replace raw natural rubber upto about 50 per cent of its weight without any serious deterioration in mechanical properties.

Effect of the Vulcanization Time and Storage on the Stability and Physical Properties of Sulfur-Prevulcanized Natural Rubber Latex

Prevulcanized natural rubber latex was prepared by the heating of the latex compound at 55°C for different periods of time (2, 4, 6, 8, and 10 h). The changes in the colloidal stability and physical properties were evaluated during the course of prevulcanization. The prevulcanized latex compounds were stored for 300 days, and the properties were monitored at different storage intervals (0, 20, 40, 60, 120, 180, 240, and 300 days). During prevulcanization, the mechanical stability time increased, and the viscosity remained almost constant. The tensile strength increased during storage for a period of 20 days. The degree of crosslinking, modulus, elongation at break, and chloroform number were varied with the time of storage.

Latex Stage Blending of Natural Rubber and Poly(Vinyl Chloride ) for Improved Mechanical Properties

A novel method of blending natural rubber with polyvinylchloride in the latex stage was developed, Dioctyl phthalate (DOP) and Amine terminated natural rubber (ATNR) were used as plasticisers, for improving the mechanical properties of these blends. Properties of the latex stage blends were compared with those of dry blends. Latex stage blends showed superior mechanical properties compared to the blends prepared in the dry state. The ageing resistance, oil resistance and processability were found to be improved by latex stage blending.

Studies on Thermoplastic Elastomer Based on Linear Low-Density Polyethylene and Latex Product Waste Modified with Thiocarbanilide

Latex waste like glove waste was effectively modified using a new reclaiming agent, thiocarbanilide. This modified waste was blended with linear low-density polyethylene (LLDPE) to develop a novel thermoplastic elastomer. Both uncrosslinked and dynamically crosslinked blends were prepared and their properties were studied. The results were found to be comparable to those of conventional thermoplastic elastomers.

Recycling of NR Based Cured Latex Material Reclaimed with 2,2'-Dibenzamidodiphenyldisulphide in a TruckTire Tread Compound

It is observed that reclamation of natural rubber latex based rubber using 2,2'-dibenzamidodiphenvldisulphide as reclaiming agent is an optional methodology for recycling of waste latex rubber (WLR). For progressive replacement of virgin natural rubber by the reclaim, two alternatives curing system were investigated: adjustment or reduction of the curing system with increasing reclaim content, to compensate for the extra amount of curatives brought along by the reclaim. For fixed curing system, as if the reclaim were equivalent to virgin NR. The cure behavior, final crosslink density and distribution, mechanical properties, and dynamic viscoelastic properties of the blends with reclaimed WLR are measured and compared with the virgin compound. The morphology of the blends, sulfur migration, and final distribution are analyzed.The mechanical and dynamic viscoelastic properties deteriorate for both curing systems, but to a lesser extent for fixed curing system compared to adjusted curing system. With the fixed cure system, many properties like tensile strength and compression set do still deteriorate, but tan 6 and Mrrr„/Murxr, representative for the rolling resistance of tires are improved. On the other hand, with the adjusted cure system both mechanical and dynamic properties still deteriorate.

Science and technology of rubber reclamation with special attention to NR-based waste latex products

A comprehensive overview of reclamation of cured rubber with special emphasis on latex reclamation is depicted in this paper. The latex industry has expanded over the years to meet the world demands for gloves, condoms, latex thread, etc. Due to the strict specifications for the products and the unstable nature of the latex as high as 15% of the final latex products are rejected. As waste latex rubber (WLR) represents a source of high-quality rubber hydrocarbon, it is a potential candidate for generating reclaimed rubber of superior quality. The role of the different components in the reclamation recipe is explained and the reaction mechanism and chemistry during reclamation are discussed in detail. Different types of reclaiming processes are described with special reference to processes, which selectively cleave the cross links in the vulcanized rubber. The state-of-the-art techniques of reclamation with special attention on latex treatment are reviewed. An overview of the latest development concerning the fundamental studies in the field of rubber recycling by means of low-molecular weight compounds is described. A mathematical model description of main-chain and crosslink scission during devulcanization of a rubber vulcanizate is also given.

Effect of Diphenyldisulfides with Different Substituents on the Reclamation of NR Based Latex Products

The latex industry has expanded over the years to meet the world demands for gloves, condoms, latex thread etc. Because of the strict specifications for the products and the unstable nature of the latex, as high as 15%, of the final latex products are rejected. Since waste latex rubber (WLR) represents a source of high quality rubber hydrocarbon, it is a potential candidate for generating reclaimed rubber of superior quality. Two types of WLR with different amounts of polysulfidic bridges are used in these experiments, which are reclaimed with variation of the concentration of the reclaiming agents, the reclamation temperature and time, Di phenyldisultide, 2-aminophenyldisulfide and 2,2'-dibenzamidodiphenyldisulfide (DBADPDS) are used as reclaiming agents, and the effect of diphenyldisulfides (DPDS) with different substituents, on the reclamation efficiency of WLR is investigated. A kinetic study of the reclamation reaction with the three reclaiming agents is done. The reaction rates and activation energies are calculated and compared with literature values. The comparative study of the three different reclaiming agents shows that (DBADPDS) is able to break the crosslinks at temperature levels 20'C below the temperature levels normally used with DPDS. Another advantage of this reclaiming agent is the reduced smell during the reclamation process and of the final reclaims, one of the most important shortcomings of other disulfides used for this purpose.

Polymer-Solvent Interaction Parameter for NR/SBR and NR/BR Blends

Polymer-solvent interaction parameters for the blends of natural rubber (NR) with styrene-butadiene rubber (SBR) and polybutadiene rubber ( BR) are calculated using the Flory-Rehner equation by equating the network density of the vulcanizates in two solvents.

Studies on the Cure Characteristics and Vulcanizate Properties of 50 / 50 NR /SBR Blend

Blends of 50/50 natural rubber (NR) and styrene-butadiene rubber (SBR) are vulcanized using several conventional and semi-EV systems. The cure characteristics and vulcanizate properties are compared. The quantity and quality of crosslinks in each case are deciphered by chemical probes to correlate them with the vulcanizate 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 THE CELL STRUCTURE AND MECHANICAL PROPERTIES OF NR/LATEX RECLAIM/HSR BASED MICROCELLULAR SHEETS

In natural rubber/high styrene resin microcellular sheets, part of natural rubber was replaced by latex reclaim prepared from waste latex products. The mechanical properties and cell structure of the products were evaluated. It was found that latex reclaim can replace about 30% of natural rubber without affecting the technical properties of the microcellular sheets.