A shrinkable tubular article comprises a tubular inner elastomeric member held in a radially expanded configuration by a tubular outer restraining means. The restraining means is prepared from a blend of a relatively rigid thermoplastic material and a segmented copolymer having at least one segment compatible with the thermoplastic and at least one segment compatible with the elastomer of the inner member. Optionally, the restraining means contains a tackifier. The inner surface of the outer member and the outer surface of the inner member are directly bonded together (i.e. without an interfacial adhesive). The bond between the members is sufficiently strong to restrain the inner elastomer member from shrinking to, or toward, its unexpanded configuration. In addition, the bond weakens sufficiently on application of solvent to permit the elastomeric member to peel away from the restraining outer member. Use of a blend of a thermoplastic and a segmented copolymer and optional tackifier, described above, for the restraining member permits the article to be produced in a continuous manner, e.g. by coextrusion.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a dimensionally recoverable elastomeric tubular 
article, a method for producing the article and a method of covering a 
substrate using the article. In particular, it relates to a dimensionally 
recoverable elastomeric tubular article comprising a radially expanded 
elastomeric inner member held in the expanded configuration by a 
relatively rigid outer restraining means. 
2. Background Information 
U.S. Pat. Nos. 4,070,746 and 4,135,553 to Evans and Wolfe, 4,179,320 and 
4,287,012 to Midgley and Nyberg, and 4,338,970 to Krackeler and Wier, each 
disclose recoverable articles of the same general type as the articles of 
this invention. The recoverable article comprises an elastomer member held 
in an expanded condition by an outer restraining means. The elastomeric 
member is bonded to the outer restraint. In use, the article is positioned 
around a substrate to be covered and the elastomer member is released from 
the restraint. Due to the elastic properties of the expanded elastomeric 
member, it will then recover (or shrink) toward its unexpanded 
configuration and into contact with the substrate. 
In U.S. Pat. No. 4,135,553, the elastomeric member is released from the 
restraint by applying a solvent which weakens the adhesive bond between 
the members. In U.S. Pat. No. 4,179,320, the elastomeric member is 
released from the restraint by peeling strips of the restraining means 
from the elastomer member. In U.S. Pat. No. 4,338,970, the elastomeric 
layer is released by breaking or segmenting the restraint and removing the 
pieces or segments from the elastomer member thereby allowing it to 
recover to its unexpanded configuration. 
In U.S. Pat. No. 4,135,553 ('553), it is asserted that the bond between the 
elastomeric member and the restraint may be formed simply by adhesion of 
the elastomeric member to the restraint. In the practice of the '553 
invention, it has been found that such a bond is inadequate to prevent 
premature recovery of the elastomeric member. The use of an adhesive to 
provide an adequate bond has been found to be necessary. It has also been 
found necessary to employ the fabrication procedures disclosed in U.S. 
Pat. No. 4,135,553. Such procedures involve forming the restraint, coating 
its inner surface with adhesive, forming the elastomeric member, coating 
its outer surface with adhesive, cross-linking the elastomer and expanding 
the elastomeric member into contact with the restraint. An alternate 
method is to form the elastomeric member and then injection mold the outer 
restraint around the member. Both these methods are non-continuous 
procedures in which each article must be manufactured individually. 
This invention provides a method for the continuous manufacture of 
recoverable elastomer articles of this type. Prior attempts to coextrude 
the elastomeric member and the restraint were unsuccessful. The bond 
formed either had inadequate strength to restrain the elastomeric member 
from premature recovery, particularly if stored at temperatures of about 
60.degree. C., or would not release the elastomeric member when solvent 
was applied. It has now been unexpectedly discovered that the 
incorporation of a segmented copolymer, as defined hereinafter, and 
optionally a tackifier into a thermoplastic material to be used for the 
restraint overcomes these problems and enables the continuous manufacture 
of dimensionally recoverable article of this type. 
SUMMARY OF THE INVENTION 
One aspect of the present invention, provides a shrinkable tubular article 
comprising: 
(1) a tubular inner member comprising an elastomeric material which is held 
under tension in a radially expanded configuration; and 
(2) a tubular outer restraining means comprising a blend of a relatively 
rigid thermoplastic polymeric material and a segmented copolymer having at 
least one segment compatible with the thermoplastic material and at least 
one segment compatible with the elastomeric material; 
the inner surface of the restraining means being directly secured to the 
outer surface of said inner member by a bond whose peel strength is at 
least about 2 pounds per linear inch at 21.degree. C., said bond being 
sufficiently weakened by the application of a solvent to allow the inner 
member to pull away from the restraining means and to return to or toward 
its unexpanded configuration. 
Another aspect of the present invention, provides a shrinkable tubular 
article comprising: 
(1) a tubular inner member comprising an elastomeric material which is held 
under tension in a radially expanded configuration; and 
(2) a tubular outer restraining means comprising a blend of a relatively 
rigid thermoplastic polymeric material, a tackifier and a segmented 
copolymer having at least one segment compatible with the thermoplastic 
material and at least one segment compatible with the elastomeric 
material; 
the inner surface of the restraining means being directly secured to the 
outer surface of said inner member by a bond whose peel strength at about 
60.degree. C. is at least about 2 pounds per linear inch, said bond being 
sufficiently weakened by the application of a solvent to allow the inner 
member to pull away from the restraining means and to return to or toward 
its unexpanded configuration. 
Another aspect of this invention comprises a method of preparing a 
shrinkable tubular article comprising a tubular inner member comprising an 
elastomeric material which is held under tension in a radially expanded 
configuration and a tubular outer restraining means, which method 
comprises: 
(i) preparing a blend of a thermoplastic polymeric material and a segmented 
copolymer having at least one segment compatible with the thermoplastic 
material and at least one segment compatible with the elastomeric 
material; 
(ii) coextruding the blend and the elastomeric material to form a tube 
having the blend as the outer member and the elastomer as the inner 
member; 
(iii) radially expanding the tube to form the shrinkable tubular article. 
Optionally (i) can contain a tackifier. 
Yet another aspect of this invention comprises a method of covering a 
substrate which comprises: 
(a) positioning over the substrate a shrinkable tubular article comprising 
(1) a tubular inner member comprising an elastomeric material which is held 
under tension in a radially expanded configuration; and 
(2) a tubular outer restraining means comprising a blend of a relatively 
rigid thermoplastic polymeric material and segmented copolymer having at 
least one segment compatible with the thermoplastic material and at least 
one segment compatible with the elastomeric material; the inner surface of 
the restraining means being directly secured to the outer surface of said 
inner member by a bond whose peel strength is at least about 2 pounds per 
linear inch at 21.degree. C., said bond being sufficiently weakened by the 
application of a solvent to allow the inner member to pull away from the 
restraining means and to return to or toward its unexpanded configuration; 
and 
(b) applying a solvent to the bond between the inner and outer members 
thereby weakening the bond sufficiently to permit the elastomeric member 
to pull away from the restraint and shrink into contact with said 
substrate. 
Optionally the tubular outer restraining means further comprises a 
tackifier.

DETAILED DESCRIPTION OF THE INVENTION 
The tubular inner member of the article of this invention comprises an 
elastomeric material. The elastomeric material must be capable of being 
stretched or expanded to an extended condition in the radial direction 
from which the elastomeric material can recover, i.e. shrink, upon removal 
of the restraint holding it in the stretched or expanded condition. 
Virtually any desired material possessing elastomeric recovery properties 
may be used. The elastomeric material should be one which does not exhibit 
a substantial permanent set or decrease in recovery on storage. Suitable 
elastomers include materials such as natural and synthetic polyisoprenes, 
polybutadiene, styrenebutadiene rubber (SBR), butadiene rubber, 
polychloroprene (Neoprene), butyl rubber, polysulfide, silicone rubber, 
urethane rubber, polyacrylate, epichlorohydrin homo and copolymers, 
propylene oxide rubber, fluorosilicone rubber, fluorocarbon rubber, 
chlorosulfonated polyethylene, chlorinated polyethylene, ethylene 
propylene rubber, nitroso rubber and phosphonitrilic rubber. Preferred 
elastomers are ethylene-propylene-diene monomer rubber (EPDM), 
polychloroprene (Neoprene) and silicone rubber. 
The properties of the elastomeric member or sleeve are to a large extent, 
dependent upon the intended use of the sleeve. Thus, if the sleeve is to 
be used primarily as an electrical insulation, its electrical properties 
will be of primary importance. On the other hand, if the sleeve will be 
subjected to much physical abuse, it may be necessary to provide a sleeve 
which has toughness, good flame resistance, good solvent resistance, etc. 
For high voltage uses, it may be desirable to have a sleeve which has been 
made semiconductive by dispersing large amounts of suitable fillers or 
conductive particles in the sleeve or possesses resistance to tracking 
and/or erosion. 
The tubular outer restraining means comprises a blend of a relatively rigid 
thermoplastic material, a segmented copolymer and optionally a tackifier. 
Preferably the copolymer is present in an amount of about 2.5 to about 
60%, most preferably from about 10 to about 30%, by weight based on the 
weight of the blend. 
The blend of thermoplastic material, segmented copolymer and optional 
tackifier should have a 2% secant modulus at 21.degree. C. of at least 
about 4,000 psi, preferably at least about 13,000 psi and preferably does 
not exceed about 500,000, particularly 200,000. (The 2% secant modulus is 
measured, at the indicated temperature, by the method of ASTM D638-72 
using a 0.5 inch wide straight specimen, a cross-head speed of 0.5 inch 
per minute, a jaw separation of 5 inch and a chart speed of 20 inch per 
minute.) This provides a sufficient rigidity that the restraining means 
formed of the blend will not undergo buckling which will interfere with 
the use of the article. Further, the blend should have an ultimate 
elongation at 21.degree. C. and at a separation speed of 200% per minute, 
which is preferably at least 10%, most preferably at least 35% and 
preferably does not exceed 120%, particularly 100%. In some embodiments, 
the elongation may be as high as 300% or even higher. (The ultimate 
elongation is measured, at the indicated temperature, by the method of 
ASTM D412-75 using dumb bell specimens (Die D) and 1 inch bench marks, the 
separation speed being 2 inch per minute for measurement at a separation 
speed of 200% per minute and 20 inch per minute for measurement at a 
separation speed of 2,000% per minute.) The blend also should be notch 
sensitive. Notch sensitivity of the material means that when the material 
is scored, or notched, for example axially along the length of the 
restraining means, and then flexed, the restraining means breaks along the 
score line exposing the underlying elastomeric member. Solvent can then be 
applied along this line to facilitate release of the elastomeric member. 
The relatively rigid thermoplastic material can be, for example, 
polystyrene, polymethylmethacrylate, poly-methyl styrene, nylon and the 
like. The thermoplastic material is selected on the basis of its 
mechanical properties. The thermoplastic material selected should have a 
2% secant modulus, elongation and notch sensitivity such that when blended 
with the segmented copolymer the resulting blend will have the desired 
properties. Further, the relatively rigid thermoplastic material should 
have a solubility parameter and a critical surface tension higher than 
that of the elastomeric material selected for the inner member. 
Tackifiers which can be used include, for example, rosin, modified rosin, 
rosin derivatives such as rosin sales or rosin esters, hydrocarbon resins, 
modified hydrocarbon resins, polymerized petroleum hydrocarbons, 
polyterpenes, phenolic resins, terpene/phenolic resins, coumarone-indene 
resins and the like. 
To achieve the desired bonding between the restraining means and the 
elastomeric member, the segmented copolymer used should have at least one 
segment compatible with the elastomeric material. The copolymer is 
preferably present in an amount of about 2.5 to about 60%, most preferably 
from about 10 to about 30%, by weight based on the weight of the blend. In 
order to obtain a blend of the segmented copolymer and the thermoplastic, 
the copolymer should have at least one segment compatible with the 
thermoplastic. Further, the segment compatible with the elastomer should 
be incompatible with the thermoplastic and the segment compatible with the 
thermoplastic should be incompatible with the elastomer. The degree of 
compatibility of polymers can generally be determined by the solubility 
parameter (Hildebrand) of the polymers. Polymers of similar solubility 
parameters are generally compatible and those with diverse solubility 
parameters are generally incompatible. It has been determined that, for 
the blend used for the restraining means of this invention, the 
thermoplastic material and the segment of the copolymer compatible with 
the thermoplastic material should have higher solubilty parameters and 
critical surface tensions than the elastomeric material and the segment of 
the copolymer compatible therewith, respectively. 
While not wishing to be bound by any theory, it is believed that the 
segments of the copolymer compatible with the elastomeric material and 
incompatible with the thermoplastic material, that is segments with the 
lower solubility parameter and lower critical surface tension, tend to 
migrate to the surface of the blend, that is to the surface of the 
restraining means. Since these segments are compatible with the 
elastomeric material they are generally capable of forming a bond with the 
elastomeric material. This bond is sufficiently strong to hold the 
elastomeric material in an expanded condition yet weakens on application 
of solvent to release the elastomer. 
The bond formed between the elastomeric member and the restraining means 
should have a peel strength of at least about 2 pounds per linear inch 
(pli), preferably at least about 4 pli, most preferably at least about 8 
pli. The bond generally will have a peel strength not greater than about 
30 pli but this is not critical. Preferably the peel strength is not more 
than about 20 pli to permit manual removal of a segment of the restraining 
means to facilitate application of the solvent to the interface between 
the elastomeric member and the restraining means during use of the 
article. The peel strength is measured, at the indicated temperature, by 
the following procedure. A rectangular specimen free from score lines is 
cut from the article. With the aid of solvent applied to one end of the 
specimen, the inner member is separated from the restraining means over a 
limited distance. After evaporation of the solvent, the separated end of 
the inner member is placed in one jaw of an Instron Tester and the 
separated end of the restraining means is placed in the other jaw. The 
peel strength is determined at a jaw separation speed of 2 inches per 
minute, taking the average of the highest and lowest values. 
The segmented copolymer is a copolymer containing different repeat units 
grouped together in segments. Such copolymers can be, for example, block 
or graft copolymers. 
A block polymer is a polymer whose molecule is made up of comparatively 
long segments that are of one monomer, these segments being separated by 
comparatively long segments of a different monomer. A graft copolymer is 
obtained by grafting a monomer segment onto a straight chain polymer 
segment to produce a branched chain copolymer. 
As is evident from the above discussion the segmented copolymer used 
depends on both the thermoplastic material with which it is to be blended 
and the elastomer to be used. Generally, the elastomer is selected 
depending on its desired use, for example, what substrate to be covered. 
After selection of the elastomer the restraining means can be determined. 
For example, if ethylene-propylene-diene monomer rubber (EPDM) is selected 
as the elastomer, the relatively rigid thermoplastic should have a 
solubility parameter higher than the EPDM rubber. In the case of EPDM 
rubber, which has a solubility parameter of 7.7, polystyrene (homopolymer 
or high impact grades) having a solubility parameter of about 9.2, 
provides a suitable choice for the thermoplastic of the restraining means. 
A segmented copolymer which has a segment compatible with EPDM rubber and 
a segment compatible with polystyrene is a block copolymer of styrene and 
butadiene. The styrene-based block (or blocks) is compatible with the 
polystyrene and incompatible with the EPDM while the butadiene-based block 
(or blocks) is compatible with the EPDM rubber and incompatible with the 
polystyrene. 
Other examples of typical elastomer/thermoplastic/segmented copolymer which 
can be used include: polybutadiene 
rubber/polystyrene/styrene-butadiene-styrene block copolymer; EPDM 
rubber/polymethyl methacrylate/graft copolymer of methyl methacrylate 
grafted on to natural rubber; polybutadiene rubber/polymethyl 
methacrylate/graft copolymer of methyl methacrylate grafted onto natural 
rubber; neoprene rubber/ethylene-vinyl acetate copolymer/segmented block 
copolyester containing segments of polytetramethylene ether and 
polytetramethylene terephthalate; and silicone rubber/poly 
.alpha.-methylstyrene/dimethylsiloxane/poly .alpha.-methylstyrene 
segmented block copolymer. 
Other segmented block and graft copolymers can be used in appropriate 
systems. One skilled in the art with the teaching of this specification 
before him, can, without undue experimentation, determine appropriate 
blends for use in preparing a restraining means for a selected elastomer. 
Optionally, the blend can contain a tackifier. It has been found that the 
presence of a tackifier improves the bond between the restraining means 
and the inner elastomeric member at elevated temperatures such as 
60.degree. C. for a period of time. Temperatures up to about 60.degree. C. 
are encountered during typical storage conditions for products of this 
type. If a tackifier is not included in the blend, the inner elastomeric 
member tends to delaminate from the restraining means comprised of the 
blend if the article is maintained at 60.degree. C. for a period of time. 
The tackifier is preferably present in an amount of about 5 to about 60%, 
and in particular about 10 to about 25%. 
As stated above, the thermoplastic material, tackifier segmented copolymer 
and optional tackifier should have a 2% secant modulus at 21.degree. C. of 
at least about 4,000 psi, preferably at least about 13,000 psi. The 
tackifier, if present, may reduce the modulus of the blend to an 
undesireably low level. In this event, a second relatively rigid 
thermoplastic material can be added to the blend to provide the desired 
modulus. For example, where the thermoplastic material is a polystyrene, 
the second thermoplastic material can be, for example, polyphenylene 
oxide, preferably added as a blend of polyphenylene oxide and polystyrene. 
Other rigid thermoplastics which can be added as the second thermoplastic 
material included, for example, poly .alpha.-methyl styrene and a blend of 
polycarbonate and a styrene copolymer. 
The relatively rigid thermoplastic material, optional tackifier and the 
segmented copolymer can be admixed by any convenient technique. They can 
be blended, for example, on a two roll mill, in a Banbury or Brabender 
internal mixer, in an extruder or the like. 
It is an important feature of this invention that the article can be 
produced in a continuous process. Preferably the article is produced by 
coextruding the elastomeric material and the thermoplastic blend. The 
materials are coextruded using a conventional extruder. The resulting tube 
is then expanded preferably continuously or as discrete articles, if 
desired. 
Following extrusion, the elastomeric material of the article preferably is 
cross-linked. This can be achieved chemically or by irradiation. Chemical 
cross-linking is achieved by incorporating a cross-linking agent into the 
elastomeric material prior to the coextrusion step. Following coextrusion 
cross-linking is accomplished by heating the coextruded article. Suitable 
cross-linking agents depend on the particular elastomer selected and are 
well known to one skilled in the art. Preferably, the elastomeric material 
is cross-linked by subjecting the article to irradiation, for example, 
from an electron beam. In this event the blend of the restraining means 
should be selected so that it is not detrimentally affected by the 
irradiation. The thermoplastic material of the restraint may also be 
cross-linked. 
Expansion can be accomplished by internal air pressure within the 
coextruded tube or by passing it over a mandrel of the desired diameter. 
Since expansion is of both the inner and outer members, the blend forming 
the restraining means must be capable of expanding to the desired degree. 
Generally, the coextruded tube is expanded to about twice its original 
diameter. 
The articles of this invention can be used to apply a covering or enclosure 
of elastomeric material over a substrate. The article is positioned around 
the substrate and solvent is applied to the interface between the 
elastomeric material and the restraining means. This typically takes place 
at ambient temperatures (about 21.degree. C.). The solvent weakens the 
bond between the elastomer and restraining means permitting the expanded 
elastomeric member to recover toward its unexpanded state and into contact 
with the substrate. Preferred substrates are pipes, conduits, cables, 
particularly cable splices, and the like. 
The term solvent is used herein to denote any fluid which will 
substantially weaken the forces securing the inner member to the 
restraining means. Solvents which can be used are chlorinated solvents 
such as chlorinated aliphatic hydrocarbons, for example, chloroform, 
methylene dichloride, trichloroethylene, or 1,1,1-trichloroethane, 
aromatic hydrocarbons, for example toluene, ketones, for example, methyl 
ethyl ketone or acetone and esters. 
The elastomeric and thermoplastic materials can contain various additives 
for example, stabilizers, flame retardants, notch-sensitive improvers, 
pigments, plasticizers, tackifiers and the like can be present. 
The tubular articles of the present invention are generally utilized in the 
tubular configuration. It is to be understood, however, that after 
coextrusion, the tubular article may be formed into other configurations, 
for example into a cap by providing one end of the tube with a seal or by 
pinching the walls at the end of the tube together. This invention also 
contemplates articles which are formed into a tubular configuration during 
use. For example, a coextruded sheet of an elastomer and restraining 
means, as described herein, may be positioned around a substrate, such as 
a cable, thereby forming a tubular article. The longitudinal edges can be 
held together by suitable fastening means and solvent applied to release 
the elastomer. 
The drawing illustrates a typical article in accordance with this invention 
and its use in covering a substrate. In FIG. 1 an article, 1, in 
accordance with this invention comprises elastomeric member, 2, which is 
held in a radially expanded configuration by restraining means, 3. In the 
illustrated embodiment the elastomeric member, 2, comprises EPDM rubber 
and the restraining means, 3, is made from a blend of high impact 
polystyrene and a styrene-butadiene block copolymer. There is no adhesive 
at the interface between the restraining means, 3, and the elastomeric 
member, 2. 
FIG. 2 illustrates the use of the article of FIG. 1 to cover a substrate. 
The article, 1, is positioned around the substrate, 4, to be covered by 
elastomeric member, 2. The elastomeric member, 2, is in a radially 
expanded configuration, held there by restraining means, 3. A solvent, 5, 
is being spraying from a container (not shown) through a nozzle, 6, onto 
the interface between elastomeric member, 2, and the restraining means, 3. 
As the solvent is applied to the interface, the elastomeric member, 2, 
will pull away from the restraining means, 3, and shrink into contact with 
substrate, 4. Restraining means, 3, can then be removed from the substrate 
and discarded. 
The following examples illustrate preparation of typical elastomeric 
materials and blends suitable for use for the restraining means. 
EXAMPLE 1 
This example illustrates the preparation of compositions useful for 
preparing an article of this invention. In this, EPDM is the elastomer and 
a blend of high impact polystyrene and a styrene-butadiene block copolymer 
is shown to be useful for the restraining means. 
Preparation of the Elastomeric Materials 
The following ingredients, in the amounts indicated, were mixed together in 
a Banbury mixer. 
______________________________________ 
Ingredient Amount (parts by weight) 
______________________________________ 
Ethylene-propylene- 100 
5-ethylidene-2-norbornene terpolymer 
(Vistalon 2504 from Exxon) 
Diphenylamine-acetone 
2 
reaction product 
Zinc 2-mercaptobenzotriazole 
3 
Red Iron Oxide (Fe.sub.2 O.sub.3) 
2 
Clay 40 
Silane coupling agent 
1.2 
(Silane A-172 from Dow Corning) 
Polyisobutylene 15 
Mineral Oil 5 
Red lead (Pb.sub.3 O.sub.4) 
3 
Trimethanol propane 4 
trimethacrylate 
______________________________________ 
Preparation of a thermoplastic blend for use in a restraining means 
The following ingredients, in the amounts indicated, were blended on an 
Banbury mixer. 
______________________________________ 
Ingredient Amount 
______________________________________ 
High impact polystyrene 
75 
(Styron 492U from Dow) 
Styrene-butadiene block 
25 
copolymer (Krayton 1102 
from Shell) 
Tetrakis [methylene-3-(3',5'- 
0.1 
di-tert-butyl-4'- 
hydroxyphenyl propionate)] methane 
Mixed ester of thiodipropionate 
0.05 
Calcium Carbonate 50 
Red pigment 2 
______________________________________ 
The resulting blend had an ultimate elongation at 21.degree. C. of 40% and 
a 2% secant modulus of 53,000 psi. 
For evaluation for use in preparing an article of this invention, 
6".times.6" slabs of the materials (75 mils thick) were prepared. A slab 
of the elastomeric material and a slab of the thermoplastic blend were 
superimposed and placed between two steel plates, each coated with 
polytetrafluoroethylene (PTFE). The samples were pressed at 300.degree. 
F., at 1000 psi for 3 minutes and 5000 psi for 30 seconds. The samples 
were cooled in a cold press for 2 minutes at 10,000 psi. The samples were 
irradiated using an electron beam with a dosage of 20 megarads on each 
side. 
The peel strength of the bond between the slabs was 8 pli (measured by 
ASTMD-3167). On application of solvent to the interface between the slabs, 
the bond was sufficiently weakened to permit ready separation of the 
slabs. These results indicate that the materials are suitable for 
preparing a tubular article of this invention using the above elastomeric 
material as the inner member and the thermoplastic blend as the outer 
restraining means. 
EXAMPLE 2 
The procedures of Example 1 were repeated using a slightly different 
elastomeric material with the same thermoplastic blend. 
The elastomeric material used was: 
______________________________________ 
Ingredient Amount 
______________________________________ 
Polybutadiene 100 
Ethylene-propylene- 100 
5-ethylidene-2-norbornene 
terpolymer (Vistalon 2504 from Exxon) 
Diphenylamine acetone 2 
Zinc 2-mercaptobenzotriazole 
3 
Red Iron Oxide (Fe.sub.2 O.sub.3) 
2 
Clay 40 
Silane coupling agent 1.2 
(Silane A-172 from Dow Corning) 
Polyisobutylene 15 
Mineral Oil 5 
Red lead (Pb.sub.3 O.sub.4) 
3 
Trimethanol propane 4 
trimethacrylate 
______________________________________ 
EXAMPLE 3 
The procedures of Example 1 were repeated using the following materials. 
Elastomeric material--the elastomeric material of Example 1 (EPDM rubber). 
Thermoplastic blend: 
______________________________________ 
Ingredient Amount (Parts by weight) 
______________________________________ 
Polymethyl methacrylate 
50 
(VM-100 from Rohm and Haas) 
Graft copolymer of 50 
polymethyl methacrylate 
on natural rubber (Haveaplus 
MG-30 from Natural Rubber 
Producers Research Association) 
Tetrakis [methylene-3-(3',5'- 
0.1 
di-tert-butyl-4'- 
hydroxyphenyl propionate)] methane 
Mixed ester of thiodipropionate 
0.05 
______________________________________ 
The bond between the slabs was releasable on application of either 
1,1,1-trichloroethane or toluene. The bond had a peel strength of 2.11 
pli. 
EXAMPLE 4 
Example 3 was repeated using the elastomeric material of Example 2 
(polybutadiene) and the polymethylmethacrylate/graft copolymer blend of 
Example 3. 
The bond between the slabs was releasable on application of 
1,1,1-trichloroethane and toluene. The peel strength of the bond was 3.55 
pli. 
EXAMPLE 5 
The procedures of Example 1 were repeated using silicone rubber (Silastic 
GP-45 available from Dow Corning) as the elastomeric material. 
The thermoplastic blend used contained a mixture of the following 
ingredients, in the amounts specified. 
______________________________________ 
Ingredients Amount (Parts by weight) 
______________________________________ 
Polydimethyl siloxane/ 
75 
poly .alpha.-methylstyrene segmented 
block copolymer (X9-6318 from 
Dow Corning) 
Poly .alpha.-methylstyrene 
25 
(18-290 from Amoco) 
______________________________________ 
The peel strength of the bond between the slabs is 14. The bond was 
releasable on application of acetone, methyl ethyl ketone, toluene and 
1,1,1-trichloroethane. 
EXAMPLE 6 
This example illustrates the preparation of compositions useful for 
preparing an article of this invention. In this, EPDM is the elastomer and 
a blend of high impact polystyrene, a hydrocarbon resin tackifier, a 
styrene/ethylene/butylene segmented block copolymer and a second 
thermoplastic material comprising a blend of polyphenylene oxide and 
polystyrene is shown to be useful for the restraining means. 
Preparation of the Elastomeric Materials 
The following ingredients, in the amounts indicated, were mixed together in 
a Banbury mixer. 
______________________________________ 
Ingredient Amount (parts by weight) 
______________________________________ 
Ethylene-propyleneo 100 
5-ethylidene-2-norbornene terpolymer 
(Vistalon 6505 from Exxon) 
Diphenylamine acetone 
2 
Zinc 2-mercaptobenzotriazole 
3 
Red Iron Oxide (Fe.sub.2 O.sub.3) 
2 
Clay 40 
Silane coupling agent 
1.2 
(Silane A-172 from Dow Corning) 
Polyisobutylene 15 
Mineral Oil 5 
Red lead (Pb.sub.3 O.sub.4) 
3 
Trimethanol propane 4 
trimethacrylate 
______________________________________ 
Preparation of a thermoplastic blend for use in a restraining means 
______________________________________ 
Composition A 
Composition B 
Ingredient Amount Amount 
______________________________________ 
High impact polystyrene 
75 62.5 
(Styron 492U from Dow) 
Styrene-ethylene-butylene 
33.3 45 
block copolymer (Krayton 
1650 from Shell) 
Hydrocarbon Resin Tackifier 
33.3 45 
(Escorez 5320 from Exxon) 
Blend of Polyphenylene Oxide 
25 37.5 
and Polystyrene (Noryl 
EN625 from General Electric) 
Tetrakis [methylene-3-(3',5'- 
0.66 0.66 
di-tert-butyl-4'0 
hydroxyphenyl propionate)] 
methane 
Lauryl thiodipropionate 
0.33 0.33 
Calcium Carbonate 
66.5 66.5 
Red pigment 2.66 2.66 
2% Secant Modulus in psi 
at 21.degree. C. 7.5 .times. 10.sup.4 
1.8 .times. 10.sup.4 
at 60.degree. C. 4.0 .times. 10.sup.4 
1.2 .times. 10.sup.4 
______________________________________ 
For evaluation for use in preparing an article of this invention, 
6".times.6" slabs of the materials (25 mils thick) were prepared. A slab 
of the elastomeric material and a slab of the thermoplastic blend were 
superimposed and placed between two steel plates, each coated with 
polytetrafluoroethylene (PTFE). The samples were pressed at 300.degree. 
F., at 1000 psi for 3 minutes and 5000 psi for 30 seconds. The samples 
were cooled in a cold press for 2 minutes at 10,000 psi. The samples were 
irradiated using an electron beam with a dosage of 20 megarads on each 
side. 
The peel strength of the bond between the slabs was measured by ASTM 
D-3167. The results are as follows: 
______________________________________ 
Peel Strength in pli 
(ASTM-3167) A B 
______________________________________ 
at 21.degree. C. 6.8 8.5 
at 60.degree. C. 4.5 5.6 
______________________________________ 
On application of solvent to the interface between the slabs, the bond was 
sufficiently weakened to permit ready separation of the slabs. These 
results indicate that the materials are suitable for preparing a tubular 
article of this invention using the above elastomeric material as the 
inner member and the thermoplastic blend as the outer restraining means. 
EXAMPLE 7 
(Comparative Example) 
The procedures of Example 6 were repeated using the same elastomeric 
material with a blend of a thermoplastic and a segmented copolymer which 
does not contain a tackifier. 
The thermoplastic blend was prepared by mixing the following ingredients, 
in the amounts (parts by weight) indicated, on a Banbury mixer. 
______________________________________ 
Composition A 
Ingredient Amount 
______________________________________ 
High impact polystyrene 
100 
(Styron 492U from Dow) 
Styrene-ethylene-butylene block 
33.3 
copolymer (Krayton 1650 
from Shell) 
Tetrakis [methylene-3-(3',5'- 
0.66 
di-tert-butyl-4'- 
hydroxyphenyl propionate)] methane 
Lauryl thiodipropionate 
0.33 
Calcium Carbonate 66.5 
Red pigment 2.66 
2% Secant Modulus in psi 
at 21.degree. C. 8.3 .times. 10.sup.4 
at 60.degree. C. 5.8 .times. 10.sup.4 
______________________________________ 
For evaluation for use in preparing an article of this invention, 
6".times.6" slabs of the materials (25 mils thick) were prepared. A slab 
of the elastomeric material and a slab of the thermoplastic blend were 
superimposed and placed between two steel plates, each coated with 
polytetrafluoroethylene (PTFE). The samples were pressed at 300.degree. 
C., at 1000 psi for 3 minutes and 5000 psi for 30 seconds. The samples 
were cooled in a cold press for 2 minutes at 10,000 psi. The samples were 
irradiated using an electron beam with a dosage of 20 megarads on each 
side. 
The peel strength of the bond between the slabs was measured by ASTM 
D-3167. The results are as follows: 
______________________________________ 
Peel Strength in pli 
(ASTM-3167) A 
______________________________________ 
at 21.degree. C. 3.75 
at 60.degree. C. 1.0 
______________________________________ 
The low peel strength at 60.degree. C. indicates this blend would not be 
suitable for use where storage at 60.degree. C. was required. 
On application of solvent to the interface between the slabs, the bond was 
sufficiently weakened to permit ready separation of the slabs. These 
results indicate that the materials are suitable for preparing a tubular 
article of this invention using the above elastomeric material as the 
inner member and the thermoplastic blend as the outer restraining means, 
providing storage at 60.degree. C. was not required. 
While the invention has been described herein in accordance with certain 
preferred embodiments thereof, many modifications and changes will be 
apparent to those skilled in the art. Accordingly, it is intended by the 
appended claims to cover all such modifications and changes as fall within 
the true spirit and scope of the invention.