Shiny Palaty

Xanthate Accelerators for Low Temperature Curing of Natural Rubber

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 tempera- tures 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.

Studies on xanthate–zinc diethyl dithiocarbamate accelerator combination in natural rubber

Abstract Zinc salts of ethyl, isopropyl, and butyl xanthates have been prepared in the laboratory. The synergistic effect of these xanthates with zinc diethyl dithiocarbamate (ZDEC) on the vulcanisation of natural rubber was studied at different temperatures. The amount of the three xanthates and ZDEC in the compounds was optimised by varying the amount of ZDEC from 0 to 1·25 pphr and the xanthates from 0 to 1·5 pphr. The cure characteristics were also studied. The rubber gum compounds with the three xanthate accelerators and ZDEC were cured at various temperatures from 60 to 150°C. The sheets were moulded and properties such as tensile strength, tear strength, crosslink density, elongation at break, compression set, heat buildup, abrasion resistance, and flex resistance were evaluated. The properties showed that the zinc xanthate–ZDEC accelerator system has a positive synergistic effect on the curing and mechanical properties of natural rubber compounds.

Low Temperature Curing of NBR for Property Improvement

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.

Characterisation and Thermal Decomposition Behaviour of Xanthate Compounds

Zinc methyl xanthate [Zn(mext)2], zinc ethyl xanthate [Zn(ext)2], zinc isopropyl xanthate [Zn(ipxt)2], zinc butyl xanthate [Zn(bxt)2], and zinc ethylene glycol xanthate [Zn(egxt)2] were prepared in the laboratory. The reaction temperature, reaction time, and yield were optimised. The thermal decomposition behaviour of these xanthates was studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques.

Effect of Dopants and Preparation Conditions on the Conductivity of Polyaniline

Aniline has been polymerised in the presence of inorganic acid dopants (HCl, H2SO4, HNO3, and HClO4) via chemical oxidative polymerisation at room temperature. The d.c. and a.c. conductivities were measured, and HClO4-doped polyaniline (PANI) was selected as the most conductive. The effect of morphology and particle size on conductivity was confirmed from SEM studies. To study the effect of preparation temperature on conductivity, PANI was prepared at different temperatures using HClO4 as dopant. The a.c. and d.c. conductivities were measured. SEM studies and X-ray analysis were carried out. PANI prepared at low temperature was found to be more conductive. The low-temperature-prepared PANI was dried at different temperatures, and conductivities were measured. Results reveal that PANI dried at high temperature shows higher conductivity. This is further confirmed by IR spectroscopy.

Studies on the Optimisation of the Preparation Method and the Characterisation of Zinc Butyl Xanthate

Zinc butyl xanthate (Zn(bxt)2) was prepared using both AR-grade and commercial-grade n-butyl alcohol (n-BuOH), potassium hydroxide (KOH), carbon disulphide (CS2), and zinc chloride (ZnCl2). The effect of the order of mixing of the reactants on the reaction time and the yield of Zn(bxt)2 was studied. The effect of the amount of ZnCl2 used for precipitation on the yield of Zn(bxt)2 was also investigated. The irritating smell of Zn(bxt)2 could be reduced considerably by using commercial-grade reagents. The yield of Zn(bxt)2 could be increased and the reaction time reduced. The maximum yield was obtained when 1 mol% ZnCl2 was used. The Zn(bxt)2 obtained was characterised by means of Fourier transform IR spectroscopy (FTIR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and proton magnetic resonance (1H NMR) spectroscopy.

Effect of Storage on the Colloidal Properties of Room-temperature Prevulcanised Natural Rubber Latex

This paper reports on the study of the prevulcanisation of natural rubber latex (NRL) at room temperature. NRL was prevulcanised at room temperature using a zinc butyl xanthate [Zn(bxt)2]–zinc diethyl dithiocarbamate [ZDC] accelerator system. High-temperature (55–60°C) prevulcanisation of NRL was also done using the conventional accelerator system. Effect of storage on the colloidal properties of room-temperature prevulcanised latex was studied up to 30 days, and these properties were compared with those of conventional high-temperature prevulcanised latex. The colloidal properties were found to be superior for the room-temperature prevulcanised latex. The mechanical stability time (MST) of room-temperature prevulcanised latex increases on storage. The room temperature prevulcanised latex is found to be stable for 30 days of storage.

Studies on synthesis and characterisation of zinc butyl xanthate and its room temperature curing property in natural rubber

Zinc butyl xanthate [Zn(bxt)2] was prepared in the laboratory. It was purified by reprecipitation and was characterised by infrared spectroscopy (IR), Proton Magnetic Resonance spectroscopy (H-NMR) and thermogravimetric analysis (TGA) techniques. Gum and black filled natural rubber (NR) compounds were prepared using zinc butyl xanthate alone and zinc butyl xanthate in combination with zinc diethyl dithiocarbamate (ZDC) as accelerators and were cured at room temperature. The sheets were moulded and properties such as tensile strength, tear strength, crosslink density, elongation at break, compression set, abrasion resistance etc. were evaluated. NR latex was compounded using Zn(bxt)2/ZDC accelerator combination. It was prevulcanised at room temperature and properties like mechanical stability time (MST), pH, potassium hydroxide (KOH) number and Volatile fatty acid (VFA) number of the prevulcanised latex were measured. Sheets were prepared by casting and tensile properties were measured. The results showed that Zn(bxt)2 and Zn(bxt)2/ZDC combination were effective for the vulcanisation of NR and NR latex at room temperature.