NBR – Nitrile Butadiene Rubber
HNBR – Hydrogenated Nitrile Butadiene Rubber
CR – Neoprene
FKM – Fluoro elastomer ( VITON )
MVQ – Methyl Vinyl Silicone
EPDM – Ethylene Propylene Diene Monomer
PU – Polyurethane
PTFE – Poly Tetra Fluoro Ethylene ( TEFLON )
PE – Polyethylene
PP – Polypropylene
PVC – Poly Vinyl Chloride
Nylon ( Polyamide )
NITRILE-BUTADIENE RUBBER (NBR)
It is been recommended for the most part of the sealing elements applications and it has a very common use. Nitrile (NBR) is a Butadiene-Acrylo Nitrile (ACN) polymer. At Kastaş the percentage of Acrylo nitrile in the nitrile compound varies between 30% and 50%. The variation in the percentage of ACN changes the volume, gas permeability, elasticity and compression set of the compound used in mineral oils, grease and fuel. Nitrile is very durable against aliphatic hydrocarbons (i.e. propane, butane, petroleum, etc), mineral oils (lubricants, H, HL, HLP type of hydraulic oils), greases, HFA, HFB, HFC, vegetal-animal oils, light heating oil and diesel oil. For fuels and industrial fluids, different mixtures are prepared. Our standard nitrile compound is recommended to be used between 30°C, +105°C. For short period of time, it can be increased to +120 °C. With special additives to increase the lowest temperature resistance the nitrile compound can be used up to -40°C. The compression set of nitrile rubber is very good so it is been widely used as sealing elements.
HYDROGENATED NITRILE-BUTADIENE RUBBER (HNBR)
It is a kind of elastomer which is made in a way that a part or the complete part of NBR polymer is hydrogenised with double linked Butadiene. Vulcanized with peroxide, HNBR has durability against high temperature and oxidation. Having higher temperature resistance and mechanical properties than standard NBR compound, HNBR is recommended to be used between -30°C and 150°C. It has wide range of use especially in automotive sector and special applications in mobile hydraulics.
This material under the trademark Neoprene has good resistance to rupture, tear and wearing out between the temperatures -45°C and 100°C. It has durability to flame. Its resistance against mineral oils with high aniline point, silicone oil, greases and alcohol is good. It is also being used in applications where durability for lubricants and atmospheric conditions are required.
This material under the trademark Viton or Florel has less durability against all types of greases, lubricants and solvents. It has very good resistance against many chemicals. It gives good results in vacuum systems due to the low gas permeability. Mechanical properties and the temperature range can be improved with special additives. It has very low resistance to steam, hot water, methanol and other polar solvents. FKM can be used between -30°C and 225°C.
Silicone keeps its elasticity between -60°C and 200°C. It is not recommended to be used in dynamic applications. It has good resistance to ozone, air and grease. With special additives to increase the lowest temperature resistance MVQ compound can be used up to -90°C. It has less durability against oxidizing lubricants, some hipoits and lubricants of E.P. type.
ETHYLENE-PROPYLENE DIENE RUBBER (EPDM)
It can be used between the temperatures -40°C and 145°C. It has very good resistance to brake fluids, esther based lubricants, hot water and steam.
It is widely used in the sealing elements due to the improvements on the compression set property over the last 15 years. It has perfect durability against rupture, tear and wearing out between the temperatures -30°C and 100°C. Its resistance to mineral oils, grease and aliphatic hydrocarbon is good. Its resistance to polar solvents, aromatics, brake fluids, acid and alkaline is not very good. Especially, it is used as a shaft stripper and high pressurized sealing element. polyurethanes are used in the manufacture of nonflexible, high-resilience foam seating; rigid foam insulation panels; microcellular foam seals and gaskets; durable elastomeric wheels and tires (such as roller coaster, escalator and skateboard wheels); automotive suspension bushings; electrical potting compounds; high performance adhesives; surface coatings and surface sealants; synthetic fibers (e.g., Spandex);carpet underlay; hard-plastic parts (e.g., for electronic instruments and hoses.)
This material is known as Teflon, the trademark of DUPONT Company. PTFE material does have the lowest coefficient of friction. Due to the low friction coefficient and high wear resistance, it performs well on poorly lubricating conditions as well as high sliding speeds. PTFE can be used in temperatures between -200˚C to +260˚C. It has very good resistance to all chemicals except alkaline metals, high pressure-temperature chlorotriflour and basic flourines. Hardness and elasticity make the material to be used widely in hydraulic applications. Depending onto the application; glass, graphite, carbon, MoS2 and bronze filled PTFE can be used to increase mechanical and physical properties. The influence of the hydraulic media, the behavior in contact with the counter surface and the form stability depending on the operating temperature are the important properties when selecting the PTFE compound among the others.
Polyethylene is a thermoplastic polymer consisting of long hydrocarbon chains. Depending on the crystallinity and molecular weight, a melting point and glass transition may or may not be observable. The temperature at which these occur varies strongly with the type of polyethylene. For common commercial grades of medium- and high-density polyethylene the melting point is typically in the range 120 to 180 °C (248 to 356 °F). The melting point for average, commercial, low-density polyethylene is typically 105 to 115 °C (221 to 239 °F).
Polypropylene (PP), a polymer prepared catalytically from propylene which differs from HDPE by having an isostatic replacement of a hydrogen atom by a methyl group on alternate carbon atoms in the main chain. Although largely unreactive chemically the presence of the methyl groups makes Polypropylene slightly more susceptible to attack by strong oxidizing agents than HDPE. A major advantage is Polypropylene's higher temperature resistance, this makes PP particularly suitable for items such as trays, funnels, pails, bottles, carboys and instrument jars that have to be sterilized frequently for use in a clinical environment. Polypropylene is a translucent material with excellent mechanical properties and it has gradually replaced the polyethylenes for many purposes. Dynalab Corp's plastic fabrication shop fabricates thousands of catalog and custom PP products.
POLY VINYL CHLORIDE
Polyvinyl Chloride (PVC) is a major plastics material which finds widespread use in building, transport, packaging, electrical/electronic and healthcare applications. PVC is a very durable and long lasting construction material which can be used in a variety of applications, either rigid or flexible, white or black and a wide range of colours in between. Due to its very nature, PVC is used widely in many industries and provides very many popular and necessary products.PVC's major benefit is its compatibility with many different kinds of additives, making it a highly versatile polymer. PVC can be plasticised to make it flexible for use in flooring and medical products. Rigid PVC, also known as PVC-U (the U stands for "unplasticised") is used extensively in building applications such as window frames and cladding. Its compatibility with additives also allows for the possible addition of flame retardants although PVC is intrinsically fire retardant because of the presence of chlorine in the polymer matrix.
A polyamide is a macromolecule or polymer in which the monomers are linked together by amide bonds. Polyamide occurs both naturally and artificially and is used in the making of a variety of materials. Naturally occurring polyamides are wool and silk which are nothing but proteins, while artificially manufactured polyamides are nylon, sodium poly(asparate) and aramids. As far as Polyamide Fabric is concerned, it is generally sold as nylon in all parts of the world. In fact, nylon is defined as a group of synthetic polyamide polymer. Nylon was discovered as a substitute for imported and expensive silk and the first thing that was manufactured commercially with nylon was the stockings worn by women. Nylon has fibers that are stretchy and are used to make carpets, fishing line, ropes and tents as well.
Nylon is light-weight, but at the same time, a strong fabric. The fibers that are used to make nylon are smooth and non-absorbent, meaning anything that is made up of nylon dries up easily and quickly. Nylon is also dirt resistant and is not affected by any chemicals or sweat. But nylon melts at high temperatures and therefore strict rules should be followed while ironing clothes made up of nylon.
Nylon is chemically chains of amide molecules and the chains are arranged parallel to each other and are attached by hydrogen bonds. A polymerization process takes place that makes nylon fibers strong and since, this is a condensation reaction, no water is retained.