WHAT IS FEP AND HOW ABOUT ITS PROPERTIES?
First of all we need to know that FEP is the third most used fluoroplastic
The most used fluoroplastic is PTFE, the second most used is PVDF and the third most used is FEP.
Today we will introduce you to the characteristics and properties of FEP.
FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene
1.FEP stands for Fluorinated Ethylene Propylene and is also known as F46.
FEP is a copolymer of tetrafluoroethylene and hexafluoropropylene, the content of hexafluoropropylene is about 15%, which is a modified material of polytetrafluoroethylene.
2. FEP has a lower crystallinity than PTFE, a lower melting point and better processing properties
In chemistry, structure determines performance and structure influences crystallinity. The simpler the chemical structure of the polymer chain, the higher the symmetry of the links and the smaller the substituents, the more supple the chain and the easier it is to crystallise. PTFE is a linear polymer with a symmetrical structure, while FEP is a branched polymer, so the crystallinity of FEP is not as high as PTFE, the processing performance is better than PTFE and the melting point is lower.
Properties of FEP:
FEP resin is a crystalline polymer with a lower crystallinity than PTFE. with a crystalline melting point of 580F and a density of 2.15g/cm3 (g/cm3), FEP is a soft plastic with lower tensile strength, wear resistance and creep resistance than many engineering plastics.
When the molten FEP resin is slowly cooled to a temperature below the crystal melting point, the degree of crystallinity is greater, between 50% and 60%; when the melt is rapidly cooled by quenching, the degree of crystallinity is smaller, between 40% and 50%. the FEP resin is a spherical crystal structure, and its structure can vary somewhat depending on the processing temperature of the resin and the heat treatment method.
2. Chemical stability
The chemical stability of FEP resin is similar to that of PTFE, with excellent chemical stability. Except for the reaction with fluorine, molten alkali metals and chlorine trifluoride at high temperatures, it does not corrode when in contact with other chemicals.
3. Insulating properties
The electrical insulation properties of FEP resin are very similar to those of PTFE. The dielectric coefficient remains constant over a wide range of temperatures and frequencies (-80~200°C, 50~1010Hz); the dielectric loss angle tangent changes with frequency, but is not greatly affected by temperature.The volume resistivity of FEP resin is very high, generally greater than 1015Ω.m, and changes very little with temperature, and is not affected by water. The arc resistance is greater than 165s.The breakdown field strength of FEP resin increases as the thickness decreases, and when the thickness is greater than 1mm, the breakdown field strength is above 30KV/mm, but does not vary with temperature.
4. Heat stability
FEP resin is less heat resistant than PTFE and can be used continuously in a temperature range of -80 to 200°C. It can also be used for short periods at the limits of -200°C and 260°C.The thermal decomposition temperature of FEP resins is higher than the melting point temperature and significant thermal decomposition does not occur until 400°C or more. However, due to the presence of trace amounts of unstable end groups in FEP resins, which also decompose at temperatures above the melting point, proper ventilation must be observed when processing above 300°C.
5. Physical properties
FEP resin has a slightly higher hardness and tensile strength than PTFE, and a slightly higher coefficient of friction than PTFE. At room temperature, FEP has good creep resistance; however, when the temperature is higher than 100°C, the creep resistance is not as good as that of PTFE.
APPLICATIONS IN THE HOSE INDUSTRY：
Product category: chemical hose
Type code: DSC FEP
Inner tube: fluorinated ethylene propylene
Reinforcement: synthetic textile with embedded steel helix
Outer cover: EPDM rubber
Electrical properties: built-in conductive wire
Constant operation:-40˚C to + 150˚C
Advantage: chemical resistant, weather resistance