How does an engineer plastic extruder extrude to form engineering plastics?
Publish Time: 2022-04-17 Origin: Site
The advantage of engineering plastics is that they can act as a structural member under stress, and can maintain dimensional stability for a long time with unchanged performance. The tensile strength of engineering plastics is more than 40MPa, with excellent comprehensive mechanical properties, corrosion resistance, good electrical insulation, and high and low-temperature resistance. They are widely used in automobiles, aerospace, household appliances, mechanical construction, and the chemical industry for various structural parts, transmission parts, insulating parts, corrosion-resistant parts, seals, etc. Engineering plastics are processed and molded by various synthetic resins, and many of their properties are determined by the properties of the synthetic resin. No matter what kind of engineering plastic, it can be molded and processed into certain shapes of products, mainly because the polymer in the synthetic resin as its matrix has excellent molding processability, including extrudability, moldability, ductility, and viscoelasticity. It is due to these properties that engineer plastic extruders offer the possibility of engineering plastics being suitable for various molding and processing processes. The main molding and processing properties of engineering plastics are listed below.
The following is a list of the contents
Moldable properties
Ductility properties
Extrudable properties
Viscosity and elasticity
Moldable Properties
The shape of a polymer under temperature and pressure can be called moldability. With moldability, polymers can be molded into various parts by filling the mold cavity under temperature and pressure.
Ductility properties
When a polymer deforms when stretched or calendered in one or both directions, it is called ductility.
Extrudable properties
The ability of a polymer to gain shape and hold on to its shape when extruded and deformed is called extrudability. Engineering plastics are often extruded during the molding process, such as in the barrels and molds of extruders and injection molding machines. Engineering plastics can usually only be extruded in a viscous flow state to obtain useful deformation. The extrudability of engineering plastics depends primarily on the melt viscosity. The melt viscosity of most engineering plastics decreases with increasing shear or shear rate. If the melt viscosity of engineering plastics is low during extrusion, it is less capable of adhering to shape despite outstanding flow; conversely, if the melt viscosity is high, it creates flow difficulties and makes molding difficult. The extrudability of engineering plastics is also related to the structure of processing equipment. Engineering plastics in the extrusion process of the melt flow plastic with the increase in pressure and add. The flow rate can be measured to determine the pressure required for the molding process and the few scales of the equipment.
Viscosity and elasticity
Engineering plastics in the molding process usually from solid to melt, and then from melt to solid, become products, in the molding process reflects the solid elasticity and melt viscosity, but because the movement of the long-chain structure of polymer macromolecules is gradual, so what is reflected is not simply elasticity and viscosity, but two generalized functions, namely viscoelasticity.
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