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> Polymer Nomenclature
The classification system used in the rubber industry for naming
elastomers is based on that described in ISO 1629-1976. The last
letter of the identification code defines the basic group to which
the polymer belongs whilst the earlier ones provide more specific
information and in many cases define the polymer absolutely. The
list below is not exhaustive but covers many of the more common
elastomers or rubbers and some “rubber-like” materials.
'M' Group: Rubbers with a Saturated
-C-C- Main Chain:
Polyisobutylene (e.g. VISTANEX),
a soft inert polymer.
Copolymer of ethylene and propylene,
A terpolymer of ethylene, propylene
and a di- or polyene giving pendent olefin groups
as crosslinking sites (e.g. NORDEL).
(e.g. HYPALON), containing both C-Cl and C-SO2CI groups.
Cl content 20-45%; S content 0.5-2.5%. Optimum properties
30% Cl, 1.5% S; ozone-resistant rubber also used in
Fluoro/fluoroalkyl groups on
C-C backbone (e.g. VITON, FLUOREL - copolymers of
hexafluoropropylene and vinylidene fluoride).
(e.g. TECHNOFLON copolymer of vinylidene fluoride
As FPM, but containing Cl as
well as F; vinylidene fluoride (VF): chlorotrifluoroethylene
(CTFE) copolymer (e.g. VOLTALEF, KEL F).
‘O’ Group: Rubbers
with Carbon and Oxygen in the Main Chain:
These materials have good heat resistance and
good low temperature properties.
H) - the parent material from which comes:
Copolymer of epichlorohydrin
and ethylene oxide (HERCLOR C).
Copolymer of propylene oxide
and allyl glycidyl ether (PAREL).
‘Q’ Group: Silicone Rubbers:
These are all relatively stable thermally and because of their
cold cure characteristics may be used as electrical insulants,
seals, moulds, etc.
on the molar mass this can be an oil, wax or rubber.
as MQ with the addition of
as above but with vinyl
as MQ but fluorinated.
'R' Group: Rubbers with an Unsaturated Carbon
Refers to copolymers of butadiene
and methyl methacrylate (e.g. BUTAKON ML) used to
impregnate paper but also includes the terpolymer
with acrylonitrile (primer, before adhesive layer
applied) and tetrapolymer with styrene (used as
a synthetic rubber).
Poly(butadiene) - available
as high cis (98%+), high trans (98% +) and anywhere
in between. Can also have vinyl groups present at
any level. General-purpose rubbers usually 90%+
cis or about 45% cis 45% trans 10% vinyl. High vinyls
have some specialist uses.
(e.g. CHLOROPRENE, NEOPRENE). Two main types, 'G',
amber in colour with large molar mass range centred
at about 100 000; 'W’, white, molar mass of
narrower range and centred about 200 000. Used as
an adhesive or where oil or ozone resistance required;
gaskets, subaqua suits, etc.
Copolymer of isobutylene and
diene such as butadiene or isoprene (BUTYL). Only
a small amount of diene added (ca 2% - 5%) to give
crosslinkable sites. Has low gas permeability, hence
uses in inflatable products, and as general-purpose
Chlorinated IIR} with 2-3%
w/w halogen to decrease gas.
Brominated IIR} permeability
and improve self-adhesion on building.
(e.g. CARIFLEX, NATSYN, SKI3) cis level
90-99%, remainder trans and vinyl.
Copolymer; acrylonitrile and
butadiene (e.g. KRYNAC, NITRILE) available with
a wide range of ACN loadings to alter hardness;
oil-resistant applications. Also available is terpolymer
(see ABR) and tetrapolymer with styrene.
natural rubber, essentially 100% cis, trans/vinyl
<0.1%. Contains about 95% polyisoprene. Various
grades available RSS, SMR, SIR, SLR, NIG with number
identifying grade - 5, 10, 20. Also modified NR
- PA, SP, OENR, ENR, DPNR. NR was the original general
purpose (GP) rubber.
Random copolymer of styrene
and butadiene. Styrene level varies from 10% to
80% but the general purpose level is 23.5%. Many
types available and the exact type identified by
a numeric code. General purpose rubber. Vast amounts
used in tyres. Also available as ter/tetra polymer
systems (see ABR & NBR).
‘T’ Group: Rubbers with Carbon,
Oxygen and Sulphur in the Main Chain
Polymer of bischloroalkylether
(or formal), with sulphur. Most common one uses
bis-2-chloroethylformal; CH2(OCH2CH2Cl)2 (with a
little 1,2,3-trichloropropane for crosslinking)
As above, but copolymerized
with ethylene dichloride. All of these smell strongly
of sulphur and are used for oil and solvent seals.
The liquid polymers cold cure and are used as sealants
in the building trade. Popular ones include Poly(ethylene
disulphide) and Poly(butyl ether disulphide).
'U' Group: Polymer Chain Contains Carbon, Oxygen
A wide range of materials used as oil-resistant materials, in
oxidation-resisting applications and as lightweight shoe soling.
Although not elastomers, certain other polymeric
materials can exhibit “rubber-like” behaviour:
Poly(vinylchloride); hard brittle
material (d = 1.4) often copolymerised with vinylidine
chloride, vinyl acetate, styrene, ABR, ethylene
vinyl acetate etc. for a wide range of applications.
When plasticized, usually with esters such as phthalates,
it becomes quite ‘rubbery’, used in
conveyer belts, paints, varnishes, floor coverings,
erasers (rubbers), flexible tubing, wellington boots
and many cheap “rubber” goods. Thermoplastic.
Polyethylene; a wide range
of types available - HDPE (high density PE) and
LDPE (low density PE). Numerous applications - medical
implants to polythene bags, blended with elastomers
such as EPDM to produce thermoplastic elastomers.
Type distinguished by their melting points. - LDPE
<110°C, HDPE up to 136°C. A reclaimed
mixture shows a spread of melting points.
Polypropylene; similar applications
to PE but higher melting (165°C). Also used
to make thermoplastic elastomers.
Polystyrene; occasionally met
as a reinforcing plastic within a continuous elastomeric
phase (e.g.shoe soling) but can be considered to
be present in some thermoplastic elastomers such
as the block copolymers:
Chlorinated rubber; refers specifically
to chlorinated natural rubber. Used for paints and adhesives.
The theoretical level for (C5H8Cl2)n is 51% but commercial chlorinated
rubber contains 65% Cl.
Rubber hydrochloride; again refers
specifically to hydrochlorinated natural rubber - usually with
about 90% of the double bonds hydrochlorinated (30% Cl). Plasticized
material produced as film (e.g. PLIOFILM) was used for packaging.
M. G. Rubber; natural rubber to which
methyl methacrylate has been grafted, commercial materials generally
contain 30% or 49% w/w methacrylate.
GuttaPercha and Balata; Polyisoprene,
with 100% of the units trans; pure material not unlike PVC in
feel and, when plasticized, can have similar uses.
Chicle; a naturally occurring mixture
of cis and trans polyisoprene (25:75), with resins, used in chewing-gum.
Guayule; natural cis-polyisoprene
isolated from the shrub Parthenium argentatum by solvent extraction.
Uses and properties as for NR, but smell reminiscent of gin. Efforts
to develop commercial exploitation have not been particularly