Polyurethane
is a thermoplastic, that is, it
is one of a variety of materials that have the
property of becoming hard and rigid when cured and are moldable
when heated. Polyurethane softens or fuses when heated and
hardens and become rigid again when cooled without undergoing
any appreciable chemical change. A polyurethane
is any polymer consisting of a chain of organic units joined
by urethane links. Polyurethane is
available generally in two forms, Thermoplastic Urethane
(TPU) or Thermoplastic (TP). The TPU is a product of BF Goodrich,
now Novion, the TP is a Dow Plastics product. PU is widely
used in flexible and rigid foams, durable elastomers and
high performance adhesives and sealants, fibers, seals, gaskets,
condoms, carpet underlayment, and hard plastic parts. Polyurethane
products are often called "urethanes". They should
not be confused with the specific substance urethane, also
known as ethyl carbamate. Polyurethanes are not produced
from ethyl carbamate, nor do they contain that substance.
Polyurethane products may be altered by chemicals added to
them in the manufacturing process, producing differing properties
-- they also come in varying thicknesses
-- both of which may affect their coefficient of expansion ("COE").
Successful long term bonding of polyurethane to itself and to other substrates,
requires careful preparation and matching of the adhesive being used with the
differing COEs of the substrates involved. BONDiTTM products
are among the few available that can be used to bond polyurethane successfully
over long periods of time to substrates with other COE's for harsh environments
and long deployment without debonding.
Our first recommended product for polyurethane is either our BONDiTTM B-45
or B-482, depending on the grade of TP or TPU and whether it is polyether or
polyester.
Our other recommended product for polyurethane is simply using any
of
the
BONDiTTM B-4X line products, unless high chemical or
moisture resistance is required -- in which case we recommend using an adhesive
promoter
BONDiTTM A-3
first.
Among the other substrates which polyurethanes can be bonded to using BONDiTTM products
are: UHMW, Delrin, fluoropolymers, rubber, polyethylene, polyolefin,
polypropylene, other polyurethanes, silicone, thermoplastics, thermosets, urethane,
ceramics, glass, fiberglass, wood, metals, stone, aggregate and concrete.
To see our chart showing rankings by property, including elongation, for the
various BONDiTTM products click here.
Call or email us for advice on for COE ratings and matching BONDiTTM products
for your application at (707) 284-8808 or reltek@reltekllc.com