Prevulcanised Latex

Introduction

Natural Rubber Latex (NRL) obtained from the rubber tree Hevea brasiliensis is a colloidal suspension of rubber particles in an aqueous serum. The aqueous medium contains a number of dissolved non rubber substances like amino acids, proteins, carbohydrates, organic acids, inorganic salts etc.

Field latex coagulates 6 to 10 hours after tapping. Anti coagulants are normally added to latex depending on the final product to which field latex is processed into.

For processing into 60% centrifuged latex, ammonia, ZnO, TMTD etc are used as preservatives. The field latex is then centrifuged into 60% concentrate (CL 60). This CL 60 forms the raw material for making prevulcanised latex.

CL 60 has the following basic spec
                        drc      60%
                        NH3    0.07%        (High Ammonia)
                        0.03%        (Low Ammonia)
There are a number of other properties which will be elaborated in the course of the paper.

Check out Moulded rubber product manufacturers in Kerala

Prevulcanised Latex

Prevulcanised Latex is defined as one in which the rubber particles are chemically cross linked and remains in fluid state so that on drying the latex a vulcanized film is obtained. The possibility of vulcanizing the disperse phase of NRL without any prior coalesce of particles was first investigated by Schidrowitz in 1914 – 1918 period.

His method of prevulcanisation was to heat NRL with sodium poly sulphide, sulphur and zinc oxide in steam at 145oC for 30 to 45 minutes. At the conclusion of the process the latex was cooled, sedimented, sieved and packed. Later, when high speed water soluble accelerators where available the curing condition was altered to 1 hour at 70-80oC preceded by a 1 hour rise to that temperature.
Methods of Prevulcanisation
The three common methods of prevulcanisation are

1. Sulphur vulcanization
2. Peroxide vulcanization
3. High energy radiation vulcanization

Since the economical and most common method of prevulcanisation is the sulphur vulcanization, the discussio9n will be confined to this method.

Read the full article here

Sulphur!!- the VULCANIZING AGENT

 

VULCANIZING AGENTS

Sulphur is a multivalent non-metal, abundant, tasteless and odourless. In its native form sulphur is a yellow crystalline solid. In nature it occurs as the pure element or as sulfide and sulfate minerals.

Elemental sulphur is used in black gunpowder, matches, and fireworks; in the vulcanization of rubber; as a fungicide, insecticide, and fumigant; in the manufacture of phosphate fertilizers; and in the treatment of certain skin diseases.

Sulphur vulcanization is a chemical process for converting natural rubber or related polymers into materials of a variety of hardness, elasticity, and mechanical durability by heating them with sulphur or other equivalent curatives or accelerators.

Read the full article here

Dispersing Agent

    Dispersants, also called dispersing agents, are chemical agents used to break up oil into smaller droplets in the        water column. Dispersants can be applied on surface oil or below the surface, closer to an uncontrolled release of     crude oil from a well blowout source.

Dispersing agents are specialized wetting agents that wet out surfaces of particles during the dispersion process, and subsequently stabilize the dispersion such that the particles do not re-agglomerate. Dispersing agents prevent re-agglomeration by either electrostatic repulsion or by steric hindrance. Dispersing agents consist of a polar head that "attaches" to the particle to be dispersed, and a polymer chain that is compatible in the media in which the particle is being dispersed. Check out Rubber chemical dispersion manufacturer in Kerala

What is the purpose of dispersant?

Dispersants are chemicals that are sprayed on a surface oil slick to break down the oil into smaller droplets that more readily mix with the water. Dispersants do not reduce the amount of oil entering the environment, but push the effects of the spill underwater.

Our product ‘Damol’ is an anionic dispersing additive, tailor-made according to the need of making Chemical dispersions especially for the Rubber and Textile sector. The compound is designed with basic knowledge about the raw materials and corresponding production process of dispersions. The product characteristics are as follows:-

A-Specifications

(1) Physical form Brown coloured Spray dried powder
(2) Chemical nature Anionic in nature
(3) Solubility Soluble in water
(4) PH (1%Solution) 7±1
(5) Active nature About 82%
(6) Moisture content 5% max

Read the full article here