PMMA polymer exhibits glass-like qualities – clarity, brilliance, transparency, translucence – at half the weight with up to 10 times the impact resistance. It is more robust and have less risk of damage. Let’s discuss PMMA properties & benefits in detail:
Transmittance – PMMA (Acrylic) polymer has a Refractive Index of 1.49 and hence offers high light transmittance. PMMA grades allow 92% of light to pass through it, which is more than glass or other plastics. These plastic materials can easily be thermoformed without any loss in optical clarity. As compared to polystyrene and polyethylene, PMMA is recommended for most outdoor application thanks to its environmental stability.
PMMA is suitable for processing by injection molding, extrusion, extrusion blow molding (impact modified acrylics only), thermoforming and casting.
Pre-drying is not necessary if a vented cylinder is used but if a normal cylinder is used then PMMA must be processed dry and it is advisable to pre-dry the granules for up to 8 hours at 70-100°C. Surface defects and blisters will form if damp granules are processed.
· Melt temperature : 200-250°C
· Mold temperature : 40-80°C
· High injection pressures are needed because of poor flow properties and it may be necessary to inject slowly to get the correct flow
· Internal stresses can be eliminated by heating at 80°C
· Extrusion temperature : 180-250°C
· A degassing screw with an L/D ratio of 20-30 is recommended