“Thermoplastic” (as opposed to “thermoset”) has to do with the way the material responds to heat. Thermoplastics become liquid (i.e. have a “glass transition”) at a certain temperature. They can be heated to their melting point, cooled, and re-heated again without significant degradation. Instead of burning, thermoplastics (like ABS ) liquefy which allows them to be easily injection molded and then subsequently recycled.
By contrast, thermoset plastics are fixed, and can only be heated once (typically during the injection molding process). Only upon contact with a special chemical (catalyst) or heat will it polymerize (set), resulting in a chemical change that cannot be reversed (attempting to reheat a thermoset plastic to a high temperature a second time would burn the plastic). This characteristic makes thermoset materials poor candidates for recycling. Examples of thermoset plastics include epoxy resins and silicones.
Poly(methyl methacrylate) (PMMA), also commonly known as acrylic (Plexiglass and Acylite are all brand name acrylics) is a transparent thermoplastic often used in sheet form as a lightweight or shatter-resistant alternative to glass. The Idea Shop stocks acrylic in following thickness and respective colors:
- 0.0625" (1.5mm) Acrylic
- white, black
- 0.125" (3mm) Acrylic:
- opaque red, clear, glass tint , orange, white, black, opaque grey
- 0.25" (6mm) Acrylic
- clear, white, black
Acrylic can be used in many different ways and can be formed into different shapes and sizes. Here in the Idea Shop, the panel saw, table saw, band saw, as well as the laser cutter, can all be used to cut acrylic. We also have a line bender for folding and curving sheets of acrylic.
Lasers + Acrylic = A match made in heaven
The best option for cutting acrylic is the laser cutter. As a side effect of laser cutting is immense heat, the heat leaves acrylic with a polished edge, highly suitable for adhering. Using the laser to cut acrylic offers the best surface finish possible for the edges.
Acrylonitrile Butadiene Styrene (ABS) is an opaque thermoplastic and amorphous polymer. The glass transition temperature of ABS is approximately 105 °C (221 °F).
ABS has a strong resistance to corrosive chemicals and/or physical impacts. It is very easy to machine and has a low melting temperature making it particularly simple to use in injection molding manufacturing processes or 3D printing on an FDM machine (note: none of the 3D printers in the Idea Shop use ABS filament).
- ABS is well suited for use on the vacuum former.
- ABS is prohibited on the laser cutter. Consider using the CNC instead
PETG is a clear amorphous thermoplastic that can be injection molded, sheet extruded or extruded as filament for 3D printing. Clear PETG sheets are a good alternative to acrylic, as PETG it is more flexible and less brittle than acrylic and less prone to shattering.
- PETG is well suited for use on the vacuum former.
- PETG is prohibited on the laser cutter.
High Impact Polystyrene (HIPS) is a thermoplastic polymer and can be solid or foamed. The glass transition temperature of PS is approximately 100 °C (212 °F). HIPS is available in FDA approved grades and is compatible with food packaging applications.
- HIPS is well suited for use on the vacuum former.
- HIPS is prohibited on the laser cutter. Consider using the CNC instead
"Welding" with Acrylic Cement
Note: always wear surgical gloves before working with acrylic solvent. It is also highly flammable. Acrylic solvent is low viscosity transparent fluid that will bond and dissolve two sections of acrylic permanently. Acrylic solvent is not an adhesive; rather, the solvent softens the acrylic, and allows the molecules from each piece to intertwine and fuse together into one piece.
The video below offers a great introduction to using acrylic solvent.
- The two bonding pieces must be held securely together. Consider using clamps or a jig.
- In a situation where there is excess solvent on the bonding surface, do not attempt to wipe up the solvent, as it will leave a cloudy smudge. Instead, allow the solvent to evaporate.
- Allow a minimum of 24 hours for the solvent to cure before exerting load on it. Use of excess acrylic solvent may leave a frosty texture around the bonding surfaces.