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The Characteristic,application,processing Of PVDF (2)
- Jul 02, 2018 -

Physical information of PVDF


PVDF White powder crystalline polymer. The density 1.75-1.78g/cm3. glass transition temperature -39 C, embrittlement temperature -62 C, melting point 170 degrees C, thermal decomposition temperature of about 350 degrees C, long-term use temperature - 40~150 C. Can be formed by the general thermoplastic processing method. Its outstanding characteristics are high mechanical strength, good radiation resistance. Good chemical stability. It is qualitatively not corroded by acid, alkali, strong oxidizing agent and halogen at room temperature, smoke sulphuric acid, strong alkali, ketone, and ether a few chemicals can dissolve or partially dissolve, and two methyl acetamide and two methyl sulfoxide can dissolve them into colloidal solutions. The most common process is emulsion polymerization and suspension polymerization.PVDF Granule  film production FR904.jpg


Tensile strength of PVDF Resin

 

PVDF resin mainly refers to vinylidene fluoride homopolymer or vinylidene fluoride with a small amount of fluorovinyl monomer copolymers PVDF resin has the characteristics of fluorine resin and common resin, except good chemical corrosion resistance, high temperature resistance and oxidation resistance. Besides weathering and radiation resistance, it also has special properties, such as piezoelectric, dielectric and thermoelectric properties. It is the second largest production of fluorinated plastics at present, with a global annual production capacity of more than 43000 tons.


Processing Methods of PVDF Resin

 

PVDF plastic raw materials can be processed by general thermoplastic processing methods, such as Extrusion, Injection Molding, Pouring, Molding and Transfer moulding. 


(1) PVDF with extruded polymer order has better melt strength and can be formed into thin films by extrusion. According to the shape of the equipment used and the products processed, the temperature is controlled between 210 degrees Celsius and 270 degrees Celsius, and the molding temperature is controlled at 180 degrees Celsius, 240 degrees Celsius, etc. The temperature must be strictly controlled so that it does not exceed its melting temperature for a long time. General screw extruder can be used for extrusion forming equipment. 


(2) The injection molding PVDF resin with low molecular weight has a high melt flow rate, which can be processed by injection molding. Generally speaking, a general injection molding machine is used, but corrosion resistant Ni-based alloys are best used for cylinder plunger, nozzle and so on.

 

(3) Dimethylacetamide / N-methylpyrrolidone was used as solvent, and the solid content was 20% solution. 


(4) In molding, PVDF pellets are usually preheated in the oven or in a preheating furnace at a preheating temperature of 215 ~ 235 degrees Celsius, and then the preheated materials are added to a pre-heated mould of 180 ~ 195 degrees Celsius, and pressure is exerted at 14 MPA to keep the pressure. The holding time depends on the time required for melting and flow. Thick wall products must be kept under 90 degrees Celsius to be demoulded to avoid vacuum bubbles or deformation.

 

(5) Transfer molding is usually made by extruder, then the material is transported to the storage tank, and the material in the cylinder is injected into the mould by piston pump, and the material is cooled by keeping pressure. Whether molded or transmissible, it is mainly used to produce products with larger volume and thicker wall. 


Other processing methods can also be used in PVDF processing, such as impregnation, co-extrusion and compounding.


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PVDF Resin  Lithium Battery.jpg