| Abstract: | Isora fibre-reinforced natural rubber (NR) composites were cured at 80, 100, 120 and 150°C using a low temperature curing accelerator system. Composites were also prepared using a conventional accelerator system and cured at 150°C. The swelling behavior of these composites at varying fibre loadings was studied in toluene and hexane. Results show that the uptake of solvent and volume fraction of rubber due to swelling was lower for the low temperature cured vulcanizates which is an indication of the better fibre/rubber adhesion. The uptake of aromatic solvent was higher than that of aliphatic solvent, for all the composites. As the fibre content increased, the solvent uptake decreased, due to the superior solvent resistance of the fibre and good fibre-rubber interactions. The bonding agent improved the swelling resistance of the composites due to the strong interfacial adhesion. Due to the improved adhesion between the fibre and rubber, the ratio of the change in volume fraction of rubber due to swelling to the volume fraction of rubber in the dry sample (V,) was found to decrease in the presence of bonding agent. At a fixed fibre loading, the alkali treated fibre composite showed a lower percentage swelling than untreated one for both systems showing superior rubber-fibre interactions. |
| URI: | http://dyuthi.cusat.ac.in/purl/806 |
| Files | Size |
|---|---|
| Lovely Mathew a ... of curing...,July2005.PDF | (6.828Mb) |
| Abstract: | In this paper we report the preparation and dielectric properties of poly o-toluidine:poly vinyl chloride composites in pellet and film forms. The composites were prepared using ammonium persulfate initiator and HCl dopant. The characterization is done by TGA and DSC. The dielectric properties including dielectric loss, conductivity, dielectric constant, dielectric heating coefficient, absorption coefficient, and penetration depth were studied in the microwave field. An HP8510 vector network analyzer with rectangular cavity resonator was used for the study. Sbands (2-4 GHz), C band (5-8 GHz), and X band (8-12 GHz) frequencies were used in the microwave field. Comparisons between the pellet and film forms of composites were also included. The result shows that the dielectric properties in the microwave field are dependent on the frequency and on the method of preparation. |
| URI: | http://dyuthi.cusat.ac.in/purl/800 |
| Files | Size |
|---|---|
| Honey John and ... ferent forms...Feb2006.PDF | (6.158Mb) |
| Abstract: | 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. |
| URI: | http://dyuthi.cusat.ac.in/purl/822 |
| Files | Size |
|---|---|
| V V Rajan,Effec ... isulfides....Sept.2006.PDF | (12.78Mb) |
| Abstract: | ABSTRACT: Polyaniline was synthesized by using ammonium persulfate initiator in the presence of 1M HC1. It was dried under different drying conditions like room temperature drying (for 48 h), oven drying (at 50-60°C for 8 h under a vacuum), and vacuum drying (at room temperature for 16 h). The conductivities of these samples were measured at microwave frequencies. These samples were also pelletized and the measurements were repeated. The cavity perturbation technique was used for the study. |
| URI: | http://dyuthi.cusat.ac.in/purl/852 |
| Files | Size |
|---|---|
| Dyuthi-P00420.pdf | (241.2Kb) |
| Abstract: | Selected grades of low density polyethylene (LDPE) polystyrene (PS) were extruded in a laboratory extruder by varying the feeding rate at different revolutions per minute and temperatures. The mechanical properties of the extruded plastic sheets were determined. LDPE shows a marked variation in mechanical properties with feeding rate while PS shows a marginal change in mechanical properties with feeding rate. However, for both plastics there is a particular feeding rate in the starved region which results in maximum mechanical properties. |
| URI: | http://dyuthi.cusat.ac.in/purl/863 |
| Files | Size |
|---|---|
| P J Joseph Fran ... of feeding..,July1997.PDF | (8.184Mb) |
| Abstract: | 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. |
| URI: | http://dyuthi.cusat.ac.in/purl/803 |
| Files | Size |
|---|---|
| K K Sasidharan ... fect of the...,Dec2004.PDF | (5.168Mb) |
| Abstract: | Blends of chlorobutyl rubber (CIIR) with two grades of ethylene-propylene diene monomer rubber (EPDM) were prepared and the effect of blend ratio on the cure characteristics, hot air ageing resistance, steam ageing resistance, and mechanical properties were evaluated. The blend of CIIR with EPDM grade 301 T showed additive behavior and the blend with the other grade of EPDM (NDR 4640) showed synergistic behavior. |
| URI: | http://dyuthi.cusat.ac.in/purl/815 |
| Files | Size |
|---|---|
| Sunil Jose and Rani Joseph,2008.PDF | (8.594Mb) |
| Abstract: | Ethylene-propylene-diene rubber (EPDM) and isobutylene-isoprene rubber (IIR) were compounded, precured to a low degree, and then were blended with natural rubber (NR). The compounding ingredients for NR were then added and the final curing was done. NR/ EPDM and NR/IIR blends, prepared using this method, were found to possess much improved mechanical properties as compared to their conventional counterparts. The optimum precuring crosslink density that has to be given to the EPDM and IIR phases has been determined. |
| URI: | http://dyuthi.cusat.ac.in/purl/829 |
| Files | Size |
|---|---|
| N Suma and others,Improved mechanical...,1993.PDF | (5.868Mb) |
| Abstract: | An investigation on the panchromaticity of a silver-doped poly(vinyl alcohol)/acrylamide photopolymer system is presented in this paper. Frequency-doubled Nd:YAG (532 nm) and Arþ (488 nm) lasers were used for the characterization of the films. Previous studies using an He–Ne laser (632:8 nm) showed that plane-wave transmission grating with a high diffraction efficiency of 75% could be stored in the optimized film. From the present study, it was noted that transmission gratings with 70% diffraction efficiency could be recorded using Arþ and Nd:YAG lasers, thereby elucidating the possibility of using the developed photopolymer system as a competent panchromatic recording medium |
| Description: | APPLIED OPTICS / Vol. 50, No. 18 / 20 June 2011 |
| URI: | http://dyuthi.cusat.ac.in/purl/4709 |
| Files | Size |
|---|---|
| Investigation o ... crylamide photopolymer.pdf | (782.6Kb) |
| Abstract: | 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. |
| URI: | http://dyuthi.cusat.ac.in/purl/805 |
| Files | Size |
|---|---|
| Laliamma Jose a ... eph,Latex stage...2001.PDF | (4.891Mb) |
| Abstract: | ABSTRACT: Linseed oil is used in the dual roles of the plasticizer and the fatty acid component of the activator in nitrile rubber vulcanizates. The study shows that the substitution can substantially improve the mechanical properties in addition to other advantages such as increased cure rate, reduced leachability and reduced compound cost. |
| URI: | http://dyuthi.cusat.ac.in/purl/850 |
| Files | Size |
|---|---|
| V Nandanan and others,Linseed oil..,1996.PDF | (4.764Mb) |
| Abstract: | Zinc salts of ethyl, isopropyl, and butyl xanthates are prepared in the laboratory, and the effect of these xanthates with zinc diethyl dithiocarbamate (ZDC) on the vulcanization of HAF-filled nitrile butadiene rubber (NBR) compounds has been studied at different temperatures. The cure times of these compounds have been compared with that of NBR compounds containing TMTD/MBTS. The rubber compounds with the three xanthate accelerators and ZDC are cured at various temperatures from 60 to 150°C. The sheets are molded and properties such as tensile strength, tear strength, cross-link density, elongation at break, compression set, abrasion resistance, flex resistance, etc. have been evaluated. The properties show that zinc salt of the xanthate/ZDC accelerator system has a positive synergistic effect on the cure rate and mechanical properties of NBR compounds. |
| URI: | http://dyuthi.cusat.ac.in/purl/812 |
| Files | Size |
|---|---|
| Shiny Palaty an ... ow temperature...,2006.PDF | (6.047Mb) |
| Abstract: | A series of short-isora-fiber-reinforced natural rubber composites were prepared by the incorporation of fibers of different lengths (6, 10, and 14 mm) at 15 phr loading and at different concentrations (10, 20, 30, and 40 phr) with a 10 mm fiber length. Mixes were also prepared with 10 mm long fibers treated with a 5% NaOH solution. The vulcanization parameters, processability, and stress-strain properties of these composites were analyzed. Properties such as tensile strength, tear strength, and tensile modulus were found to be at maximum for composites containing longitudinally oriented fibers 10 mm in length. Mixes containing fiber loadings of 30 phr with bonding agent (resorcinol-formaldehyde [RF] resin) showed mechanical properties superior to all other composites. Scanning electron microscopy (SEM) studies were carried out to investigate the fiber surface morphology, fiber pullout, and fiber-rubber interface. SEM studies showed that the bonding between the fiber and rubber was improved with treated fibers and with the use of bonding agent. |
| URI: | http://dyuthi.cusat.ac.in/purl/808 |
| Files | Size |
|---|---|
| Lovely Mathew a ... roperties...,April2006.PDF | (8.573Mb) |
| Abstract: | The mechanism of devulcanization of sulfur-vulcanized natural rubber with aromatic disulfides and aliphatic amines has been studied using 23-dimethyl-2-butene (C5H1,) as a low-molecular weight model compound. First C6H12 was vulcanized with a mixture of sulfur, zinc stearate and N-cyclohexyl-2-benzothiazylsulfenamide (CBS) as accelerator at 140 °C, resulting in a mixture of addition products (C(,H 1 i-S,-C5H 1 i ). The compounds were isolated and identified by High Performance Liquid Chromatography (HPLC) with respect to their various sulfur ranks. In it second stage, the vulcanized products were devulcanized using the agents mentioned above at 200 °C. The kinetics and chemistry of the breakdown of the sulfur-hridges were monitored. Both devulcanization agents decompose sulfidic vulcanization products with sulfur ranks equal or higher than 3 quite effectively and with comparable speed. Di phenyldisulfide as devulcanization agent gives rise to a high amount of mono- and disulfidic compounds formed during the devulcanization, hexadecylamine, as devulcanization agent, prevents these lower sulfur ranks from being formed. |
| URI: | http://dyuthi.cusat.ac.in/purl/819 |
| Files | Size |
|---|---|
| V V Rajan and others,Mdel compound studies....PDF | (9.175Mb) |
| Abstract: | Natural rubber, styrene-butadiene rubber, and polybutadiene rubber were used to replace part of the butadieneacrylonitrile rubber in a 70/30 butadiene-acrylonitrile rubber/ poly(vinyl chloride) blend. Such replacement up to 15% of the total weight of the blend improved the mechanical properties, while decreasing the cost of the blend. Styrenebutadiene rubber could replace butadiene-acrylonitrile rubber up to 30% of the total weight of the blend without deterioration in the mechanical properties. |
| URI: | http://dyuthi.cusat.ac.in/purl/827 |
| Files | Size |
|---|---|
| K E George and ... ification of..,aug1987.PDF | (3.477Mb) |
| Abstract: | Polychloroprene (neoprene) has been blended with polyvinylchloride (PVC) in different proportions using a new stabiliser system (magnesium oxide and zinc oxide with stearic acid) for PVC. The physical properties of the blends show that they can advantageously replace neoprene in many applications. |
| URI: | http://dyuthi.cusat.ac.in/purl/833 |
| Files | Size |
|---|---|
| Rani Joseph an ... ification of..,1985PDF.PDF | (2.779Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/825 |
| Files | Size |
|---|---|
| K E George and others, modification of...1986.PDF | (2.058Mb) |
| Abstract: | New oligomer-bound antioxidants have been prepared by condensation reaction. The efficiency and permanence of these oligomer- bound paraphenylene diamines as antioxidants has been compared with conventional amine type antioxidants in NR, SBR, IIR and NBR and in elastomer blends like NR/BR and NR/SBR. The oligomer-bound antioxidants are found to impart improved ozone, flex resistance and mechanical properties to the vulcanizates of NR, SBR, IIR and NBR and to blends of NR/BR and NR/ SBR in comparison with those containing conventional antioxidants. |
| URI: | http://dyuthi.cusat.ac.in/purl/860 |
| Files | Size |
|---|---|
| P B Sulekha and ... mer-bound...,march2002.PDF | (11.09Mb) |
| Abstract: | Zinc salts of ethyl, isopropyl, and butyl xanthates were prepared in the laboratory. The effect of these xanthates in combination with zinc diethyldithiocarbamate (ZDC) on the vulcanization of silica-filled NBR compounds has been studied at different temperatures. The cure times of these compounds were compared with that of NBR compounds containing tetramethylthiuram disulphide/dibenzthiazyl disulphide. The rubber compounds with the xanthates and ZDC were cured at various temperatures from 60 to 150°C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density, elongation at break, compression set, abrasion resistance, flex resistance, heat buildup, etc. were evaluated. The properties showed that zinc salt of xanthate/ZDC combination has a positive synergistic effect on the cure rate and mechanical properties of NBR compounds. |
| URI: | http://dyuthi.cusat.ac.in/purl/811 |
| Files | Size |
|---|---|
| Shiny Palaty an ... accelerator...,Mar2006.PDF | (3.435Mb) |
| Abstract: | Significant results of our experimental investigations on the dependence of pH on real time transmission characteristics on recording media fabricated by doping PVC with complexed methylene blue are presented. The optimum pH value for faster bleaching was found to be 4 . 5. In typical applications, the illumination from one side, normal to the surface of this material, initiates a chemical sequence that records the incident light pattern in the polymer. Thus direct imaging can be successfully done on this sample. The recorded letters were very legible with good contrast and no scattering centres. Diffraction efficiency measurements were also carried out on this material. |
| URI: | http://dyuthi.cusat.ac.in/purl/858 |
| Files | Size |
|---|---|
| M Ushamani,Optimization of...,Feb2003.PDF | (4.204Mb) |
Dyuthi Digital Repository Copyright © 2007-2011 Cochin University of Science and Technology. Items in Dyuthi are protected by copyright, with all rights reserved, unless otherwise indicated.