How to Choose Aramid vs Polyester Yarn in Silicone Heater/Coolant/ Braided Hoses considering the technical parameters?

 

Aramid yarns known by the brand name Kevlar yarn from Dupont is a high-performance yarn which can sustain temperatures in the range of 250 degree Celsius, as it was initially developed by Dupont their brand name became pretty popular in the name Kevlar although its chemical name is Poly-para-phenylene terephthalamide. Para-Aramid fibres are produced by a two-step process - polymer production followed by spinning. The first step is the low-temperature-solution polymerization of diacid chlorides (e.g. terephthaloyl chloride) and diamines (e.g. para-phenylenediamine) in amide solvents. Polar solvents such as N-methyl pyrrolidone and dimethylacetamide are used as polymerization solvents; formerly, hexamethyl phosphoramide was used. The para-aramid polymer is neutralized and then isolated from the polymerization solution.

Next, a 'spinning solution' is created by redissolving the polymer in concentrated sulfuric acid. This liquid crystalline solution is extruded through a spinneret, and the acid is extracted and neutralized; the result is a highly oriented fibre.

Polyester yarns are formed by a three step process of polymerization, Spinning and Drawing

Condensation polymerization occurs when acid and alcohol are reacted in vacuum at high temperatures, polymerized material is extruded and cut into chips like, these chips are melted at 260 C to form syrup like solution, the melted solution then extruded through spinneret and filaments are subsequently drawn for polyester Fibers.

After extrusion from spinneret the Fibers are drawn or elongated with help of godet wheels, the yarn can be drawn at different deniers based on the wheels and kept in a bobbin for further use.

Polyester Vs Aramid yarn when in use inside silicone hose

·      Temperature

Polyester usually sustains temperature of 175 degree C working temperature

Aramid usually sustains temperatures of 250 degree C

·      Colour

Yarn usually white in Colour as standard

Yarn usually yellow in Colour as standard

·      Processing

Low filamentation issues and can be drawn through different surfaces

High Filamentation issues, should be processed carefully with special custom made equipment and tools

·      Price

Cost is very low in the range of 200-300 per kg

Yarn is costly with range of 2000-3000 per kg

·      Availability

Good availability if the quantity is small too

Limited availability and limited manufacturers

·      Strength at Break

A 1500 denier polyester yarn has around 11-12 kgf strength

A 1500 denier aramid yarn has around 20-25 kgf strength

·      Deniers

Available in all Deniers

Available in standard deniers like 1500 to 3000

The regular hoses available in the market are made of polyester yarns and will not sustain working temperatures over 175 degree Celsius, also if the denier, yarn not properly selected it may not sustain the pressure also. Our Aramid heater hoses are specially designed to withstand working temperature of around 220 C and can go up to 240 C for the short time. It can withstand a pressure of minimum 10 bar and have an adhesion of minimum 1.5 kg/cm between the layers making it SAE J 20 compatible.

For more details Click or contact : www.centroidpolymer.com