PPS is a very common engineering plastic with excellent chemical and thermal stability and high mechanical strength. However, to obtain strong adhesive bonding for PPS is not an easy task.
Due to its chemical and thermal stability, bonding to PPS is an inherently difficult challenge for all types of materials. Adhesive bonding to PPS parts normally requires extensive mechanical, thermal or chemical surface treatments, such as abrasion, flame, corona, plasma or acids before applying the adhesive. Typical lap-shear adhesive strength still ranges in the low single-digit MPa’s even for high-performance adhesives.
With RadiBond for PPS, you can bond PPS directly onto almost any substrate, using insert-molding or welding techniques.
Bonding PPS and metal using RadiBond
RadiBondTM PPS is a surface treatment for the metal part that you need to adhere to the PPS material. The treatment creates a coating of ~50 nanometers on the surface of the metal that is capable of bonding the PPS. The coating cosists of thin polymer chains that are able to integrate into the PPS as the interface is heated. The metal parts could be almost any stabel metals, such as stainless steel, aluminium, titanium, magnesium, chromium etc.
There are several ways, where this heating can be applied to activate the bonding process between the materials. It could either be over-molding processes using injection molding for insert molding of parts or it could be utilizing various welding techniques.
Adhesion of PPS in insert molding
Coated parts of metal, glass, ceramics or carbon could be used directly in insert molding processes, where the coated part is inserted into a mold and over-molded with the PPS. The bonding is obtained directly in the overmolding processes without any subsequent gluing or hardening.
Adhesion of PPS in welding processes
Ever welded plastic directly onto metal? Usually that requires a mechanical structuring of the metal surface, as the plastic will not bond to the metal only integrate into any mechanical strutures.
With RadiBond treatment of the metal, welding of PPS directly to metal surfaces obtaining a strong and tight interface becomes possible. PPS will react with the RadiBond coating and form a strong chemical bonding directly between then materials.
Welding a PPS Thermoplastic Composite
PPS Composite materials are extremely interesting for lightweight applications. Composite plates of thermoplastic PPS can be thermoformed and shaped into any form you need. However, bonding the PPS composites to any other material is inherently difficult, if not impossible. With RadiBond Welding Primer, you can weld thermoplastics to otherwise incompatible materials.
With RadiBond treatment of the adherent part, you can weld PPS Thermoplastic Composites directly to metal, glass, ceramic or carbon parts getting a bonding strength up to 25 MPa.
Any welding techniques – ultrasonic welding, laser welding, induction welding, etc. – as long as you are able to achieve the needed ~280oC in the interface between the material which is neeeded to melt the PPS material.
Welding of PPS to Stainless Steel
Our coatings of are applicable for almost all stainless steel types, where the most widely used are ASTM 316 or ASTM 304. But also higher grade alloys like inconel could be bonded to PPS using RadiBond.
Welding of PPS to Aluminium
Most high grade aluminium materials can be coated with RadiBond PPS and hence used to achieve strong adhesive bonding between aluminium and PPS in welding or over-molding processes. Our strongest experience are with the 6-thousand aluminium series, but most other alloys will be useful.
How is RadiBond PPS applied?
RadiBond is a surface treatment in two steps. The first step is an activation of the adherent part – usually a metal, glass or ceramic part. This step is adapted to the material, product and processing needs as dip-coating, spray-coating, electrochemical or vapor process. We have all the capabilities to test and veriy what procedure will be the most efficient for your specific needs.
The second step is a dip-coating process, where the polymer brush coating (RadiBond) is growing from the surface.
The entire process is achievable in 5-60 minutes depending on your specific material and product needs.
Bonding Fiberglass Reinforced PPS/FGL
Very often PPS is used as a metal replacement material for lightweighting. Hence, to increase strength PPS is filled with 20-40% glass to increase properties such as tougness.
Watertight bonding between PPS and metals
Another effect of adding glass to PPS, is that it decreases the water permeability of PPS significantly. Hence, glass-filled PPS is very often used for water tight enclosures etc. due to its thermal and chemical stability. However, a tight enclosure is worth nothing, if the interface to other materials is not tight. With RadiBond as the bonding solution you achieve a perfectly watertight bonding between PPS and metals like stainless steel.
Bonding PPS to Glass
RadiBond coatings are also applicable on glass substrates. Hence, achieving strong bonding between glass and PPS is also possible using the same techniques. It will require a glass, that withstands the welding or over-molding temperature and pressure. For glass, laser welding may be a very strong solution.