Permabond 240

For high-speed production lines assembling plastics, rubber, or metals, Permabond 240 is a high-viscosity cyanoacrylate that fills gaps up to 0.4 mm and prevents rapid absorption on porous substrates. It polymerises quickly when pressed into a thin film between parts, utilising surface moisture to develop handling strength in 15 to 20 seconds without mixing or heat curing.

What it does

Permabond 240 is a 100% reactive, solvent-free ethyl cyanoacrylate. Its high viscosity (1,200 to 2,500 mPa.s) prevents the adhesive from running off components or soaking immediately into porous materials, ensuring enough adhesive remains in the joint to bridge gaps. The single-part formula polymerises when compressed, achieving high shear strength on metals like steel, aluminium, and zinc, as well as plastics including ABS and PVC. For existing military designs, the formulation is approved to MIL-A-46050C Type II Class 3.

Numbers that matter

• 0.4 mm maximum gap fill: High-viscosity formula allows reliable bonding across larger tolerances in metal and plastic assemblies.
• 15 to 20 seconds fixture time: Rapid initial strength development on steel, Buna N rubber, and phenolic substrates to maintain high-speed production flow.
• 21 to 25 N/mm² shear strength (Steel): High ultimate joint strength on steel surfaces, with substrate failure occurring on ABS (>8 N/mm²) and PVC (>11 N/mm²).
• -55°C to 85°C temperature limits: Maintains standard performance across this thermal range, and can withstand brief exposure to higher temperatures for paint baking and wave soldering if the joint is not under stress.
• 24-hour full cure: Complete polymerisation time required to reach final physical properties and chemical resistance.

Where to use it

This adhesive is formulated for bonding porous substrates, rubber, plastics, and metals. Compatible substrates include:

• Metals: Steel, Aluminium, and Zinc.
• Plastics and Synthetics: ABS, PVC, Polycarbonate (PC), Phenolic, and Buna N Rubber.
• With primer: Polypropylene, polyethylene, PTFE, and silicone can be bonded if primed first with Permabond Polyolefin Primer (POP).

Installation

To prevent premature failure and ensure rapid polymerisation, follow these application steps:

• Surface preparation: Surfaces must be clean, dry, and free of grease. Degrease surfaces using acetone or isopropanol. For aluminium, copper, and copper alloys, lightly abrade the surface with emery cloth to remove the oxide layer before bonding.
• Application: Apply the adhesive sparingly to one surface. Bring the components together quickly, ensuring correct alignment. Apply sufficient pressure to spread the adhesive into a thin film.
• Cure assistance: Larger gaps or acidic surfaces will reduce cure speed. This can be overcome by applying Permabond C Surface Activator (CSA) or Permabond QFS 16. For difficult or porous surfaces, using a Permabond activator is recommended.
• Clean-up: Uncured surplus adhesive can be removed using Permabond CA solvent, nitromethane, or acetone.

Limitations

• Not recommended for use in contact with strong oxidising materials or polar solvents, though it will withstand a brief solvent wash without bond degradation.
• Cure speeds will slow down in larger gaps, at lower humidity, or on acidic surfaces unless an activator is used.
• Must be stored between 2°C and 7°C. Always allow the bottle to reach room temperature before opening to prevent condensation from forming inside the container, which reduces shelf life.