TWI Frequently asked questions
As a general rule, dissimilar plastics cannot be welded successfully, but there are a few exceptions to this rule. A typical example is a car rear light cluster. The PMMA (polymethylmethacrylate) lens can be hot plate welded to theABS (acrylonitrile butadiene styrene) housing. It is possible to weld PMMA to ABS because they are both amorphous and possess similar T g (glass transition temperature) values; T g for PMMA is 85-105°C, T g for ABS is 110-125°C.
Other combinations of dissimilar plastics that can be welded are PS (polystyrene) to ABS, and PMMA to PC (polycarbonate). The table below provides a summary of other potential dissimilar combinations
Further information on plastic welding processes can be found in the Plastics Welding Toolkit.
Specialist advice can be obtained from plastics@twi.co.uk
| | Not weldable |
| x | Weldable |
| - | Some grades weldable |
| ? | Some reports of successful welding |
Other polymers do not form dissimilar welds.
| | | ABS | ABS/PC | Acrylic | Modified PPO | PA 12 | PBT | PC | PE | PEI | PET | Polysulphone | PP | PPO | PS | PVC | SAN | SBC | SBS |
|---|
| Acrylonitrile butadiene styrene | ABS | x | x | x | ? | | ? | x | | ? | | | | | - | - | - | | - |
| Acrylonitrile butadiene styrene/polycarbonate blend | ABS/PC | x | x | - | | | | x | | | | | | | | | - | | |
| Polymethylmethacrylate | Acrylic | x | - | x | | | | - | | | | | | | - | ? | - | | x |
| Noryl | Modified PPO | ? | | | x | | | ? | | | | | | x | x | | - | | |
| Nylon 12 | PA 12 | | | | | x | | ? | | | | | | | | | | | |
| Polybutylene terephthalate | PBT | ? | | | | | x | ? | | ? | | | | | | ? | | | |
| Polycarbonate | PC | x | x | - | ? | ? | ? | x | | - | ? | - | | | - | | | | |
| Polyethylene | PE | | | | | | | | x | | | | ? | | | | | ? | |
| Polyetherimide | PEI | ? | | | | | ? | - | | x | | | | | | | | | |
| Polyethylene terephthalate | PET | | | | | | | ? | | | x | | | | | | | | |
| Polysulphone | Polysulphone | | | | | | | - | | | | x | | | | | | | |
| Polypropylene | PP | | | | | | | | ? | | | | x | | | | | | |
| Polyphenylene oxide | PPO | | | | x | | | | | | | | | x | | | | | |
| Polystyrene | PS | - | | - | x | | | - | | | | | | | x | | - | | - |
| Polyvinylchloride | PVC | - | | ? | | | ? | | | | | | | | | x | | | |
| Styrene acrylonitrile | SAN | - | - | - | - | | | | | | | | | | - | | x | | - |
| Styrene block copolymer | SBC | | | | | | | | ? | | | | | | | | | x | |
| Styrene-butadiene-styrene | SBS | - | | x | | | | | | | | | | | - | | - | | x |
Sources
1 Reinhold Martin, 'The Use of Lasers with Technical Polymers', AILU Conference, 'Laser Processing of Polymer-Based Materials', February 2004
2 Grewell, Benatar & Park, 'Ultrasonic Welding' in Plastics & Composites Welding Handbook, Hanser 2003, ISBN 3-466-19534-3
3 Benatar, 'Implant Induction (Electromagnetic) Welding' in Plastics & Composites Welding Handbook, Hanser 2003, ISBN 3-466-19534-3
4 Froment, 'Linear & Orbital Vibration Welding' in Plastics & Composites Welding Handbook, Hanser 2003, ISBN 3-466-19534-3
5 Watson, Rivett & Johnson 'Plastics - an Industrial & Literature Survey of Joining Techniques', The Welding Institute Research Report 301/1986
