Question

68. Describe the processing to produce micro-foaming?

Answer 1

Solution Processing to produce Micro-foaming Micro-foaming Technalogy has evolved around thin-walled applications: The foaming step can be carried out in matched heated mould to attain a contoured shape. saturated sheet Hot Platen 1 Force مه t CO2 Hot Platen 1 9 Force Unsaturated Sheet Micro-foaming sheet >00 poocoooeeoa е оооооо Gradient micro structure panel of a micro cellular

Processes of Micro-foaming production 0 The Solid State Batch Process The basic solid-state micro cellular process is a three stage batch process, In the first stage, the polymer is placed in pressure vessel with a high-pressure and a non-reacting gas · The second stage occurs when the specimen uis removed from the pressure vessel and brought to atmospheric pressure. In the third stage, the super saturated specimen is heated to a temperature above the glass transition temperature of the polymer gas mixture, stormed the foaming temperature. This step is typically carried out in a heated bath with temperature control unsaturated sample Supersaturated Sample Foamed sample Co₂ gas cylinder Pressure vessel

The semi- Continuous Process А process to scale up the batch process in order to produce rall of microcellular sheet use a roll of polymer film of 10 cm thickness and put in the pressure vessel far Saturation with gas. The concept in the semi-continuous process is that the polymer soll is first interleaved with a gas channeling device such as a roll of paper towel. When this roll is put in the the entwie rall gets satwiated in the same amount of time that it takes for one polymer gas a hat bath to quench the microstu cture. The gas channeling device can be collected and re-used. press wre vessel layer. The saturated roll is passed through Paper Towel (Recycle) Gas Saturated Roll Foam Roll Hot bath Cold bath

3. The the poly mer and make it easier to Gas- Impregnated nated Thermofoaming Process gas dissolved in the polymer plasticizes deform and shape the polymer. Thus if the foam sheet in the semi-continuous process is thermo formed while it still has a significant amount of gas in it, formed articles can be produced in an energy efficient process. This is known as the Gas- Impregnated Thermoforming process used in micro-foaming process. and has been successfully Pressure Box Foaming Area מס mold