Page 266 - Mechanical Engineer's Data Handbook

254 MECHANICAL ENGINEER'S DATA HANDBOOK
Polyesters (unsaturated) Redux adhesive

These have limited use and are unsuitable for glass- This is a mixture of polyvinyl formal powder and
reinforced plastic. They bond copper, copper alloys, phenol formaldehyde liquid resin which gives a strong
most fabrics, PVC, polyester films and polystyrene (in metal-to-metal joint that is better than riveting and
certain cases). spot-welding. It is normally useful up to 80"C, but can
be formulated to 250 "C.
Polyimides
6.16.5 Other adhesives
These cure at 260-370 "C and require post-curing for
maximum strength which is retained up to 400°C. Sodium silicate
These structural adhesives will bond metals, but the
cost is high.
Known as 'water glass', this is a cheap, colourless
adhesive used for bonding aluminium foil to paper,
Epoxy resins
insulating materials to walls and for dry-mould bond-
ing.
These adhesives are available as a two-part mixture
(resin and hardener) for self-curing at room tempera-
ture or as one part for heat curing. Curing can take Ceramic adhesive
from 5 min (two part) to 24 h (one-part). They bond
metal, glass, ceramics, wood, many rubbers and some This is typically borosilicate glass compounded with
plastics. They have excellent resistance to oils and alkaline earths and oxides of alkaline metals set by
good resistance to water and most solvents. The shear firing at 7W12OO"C. It is used for metal-to-metal
strength is up to 35MNm-'. joints.
Epoxy phenolics Bitumen

These have an increased service temperature with 50% This is a substance derived from coal and lignite. It is
strength at 200 "C and are useful up to 565 "C, with low used in solution or as a hot melt in the car industry and
creep. They are useful in the car industry. for roofing and tiles.
Epoxy polyamides 6.16.6 Maximum and minimum service
temperatures for adhesives
These have improved flexibility and peel strength, but
relatively low shear strength.
Temperature ("C)
Epoxy polysulphides
Adhesive Minimum Maximum
These have improved peel strength and flexibility, with
a shear strength of 28 MNm-'. Cyanoacrylate - 80
90
EPOXY
Epoxy silicones Epoxy phenolic - 200
-
Epoxy polyamide - 100
These have the best heat resistance (up to 300 "C) and a Epoxy polysulphide - 90
shear strength of 14MNm-'. They are used for Epoxy silicone - 300
bonding metals and laminates. Natural rubber - 40 65
Natural rubber - 30 90
Phenolic polyvinylacetates
(vulcanized)
Neoprene -50 90
These set under pressure and at elevated temperatures. Nitrile - 50 150
They have good strength and good resistance to water, Polyurethane - 200 150
oils and solvents.