Key Difference – POM-H vs POM-C
POM stands for polyoxymethylene, a high molecular weightthermoplastic polymer这是一个广泛用于许多工业应用tions. It is also known as polyacetal, acetal, polyformaldehyde. The POMcopolymerof formaldehyde is composed of –CH2O- repeating units. POM polymers, in general, provides excellent mechanical properties like high tensile strength, low friction, high fatigue resistance and, better stiffness and toughness. Furthermore, POM shows high scratch resistance properties and low moisture absorption. Moreover, it is resistant to many strong bases, many organic solvents, and weak acids, However, due to the chemical structure of the POM, it is not stable in acidic conditions (pH <4) and elevated temperatures as the polymer is degraded under these conditions. Hence, the POM is often copolymerized with cyclic ethers such as ethylene oxide or dioxilane to disturb the chemical structure, thus enhancing the stability of the polymer. POM is available in two variants; copolymers (POM-Cs) and homopolymers (POM-Hs). These two types of POM differ in many ways, but thekey difference between POM-H and POM-C is their melting point. The melting point of POM-C is between 160-175 °C whereas, that of POM-H is between 172-184 °C.Their applications are determined based on the properties of POM-H and POM-C. This article elaborates the difference between POM-H and POM-C.
What is POM-H?
What is POM-C?
POM-Cstands for polyoxymethylene copolymer. This is produced by cationic polymerization of trioxane. During this process, a small amount of comonomers is added in order to increase the tightness, while lowering the crystallinity. The POM-C however, has low stiffness and strength than POM-H. But its processability is high when compared to POM-H. Because of this reason, POM-C has become the most widely used POM (75% of total POM sales). POM-C is well suited for applications where the property like low coefficient of friction is needed.
What is the difference between POM-H and POM-C?
POM-H：Its full name is POM homopolymer.
POM-C:Its full name is POM copolymer.
Properties of POM-H and POM-C
POM-H：POM-His hard and stiff
POM-C:POM-Cis not as hard and stiff as POM-H.
POM-H：Processability is low.
POM-C:Processability is high.
POM-C:Melting point is 160-175 °C.
POM-H：Processing temperature of POM-H is 194-244°C.
Elastic modulus (MPa) (tensile with 0.2% water content)
POM-C:Elastic modulus is 3105.
Glass transition temperature (tg)
POM-H：Glass transition temperature is -85°C.
POM-C:Glass transition temperature is -60°C.
POM-H：Tensile strength is 70 MPa.
POM-C:Tensile strength is 61 MPa.
POM-H：POM-Hrepresents around 25% of total POM sales.
POM-C:POM-Crepresents around 75% of total POM sales.
POM-H：Bearings, gears, conveyor belt links, seat belts and grinding accessory of hand mixtures are some examples of POM-H.
POM-C:Electric kettles, water jugs, component with snap fits, chemical pumps, bathroom scales, telephone keypads, housings for domestic applications, etc. are some applications of POM-C.
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“Polyoxymethylene” By Yikrazuul – Own work (Public Domain) viaCommons Wikimedia