ASBESTOS PLASTICS - CONTENTS: history, manufacturing process, products, asbestos content, uses in asbestos plastics and molded plastic products
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This article series about asbestos plastics & molded materials describes the history, manufacturing process & uses of asbestos plastics and molded materials such as asbestos reinforced handles, the Vanguard rocked nose cone, automobile parts & housings, electronic equipment (radar scanner), asbestos-filled Teflon, rocket motor parts, plastic drop tanks for the Hawker Sea Hawk, and hundreds of other products.
Page top photo: the asbestos-plastic drop tank for the Hawker Sea Hawk - Adapted from Rosato (1959) .
This articles series about the manufacture & use of asbestos-containing products includes detailed information on the production methods, asbestos content, and the identity and use of asbestos-containing materials.
Asbestos reinforced and filled plastics have played an
important role in the progress of the growth of industry
since the turn of the century.
[Click to enlarge any image]
Since the development of
phenol-formaldehyde resins in 1909, asbestos has been used
in large quantities as a reinforcement, additive, and filler.
There have been large quantities of short asbestos used in
plastics such as those shown in Figure 9.1. Figure 9.2 shows
the use of long fiber asbestos in asbestos-reinforced plastic
rocket nose cones.
Figure 9.1. Typical difficult molding of long handle which has a
hollow center to accommodate the electrical thermostat and wiring
for Dominion skillet. - Courtesy Durez Plastics Div., Hooker Electro-Chemical Co.
Plastic materials are available which can be reinforced
with such different fibers as asbestos, glass fiber, glass flakes,
cotton, and Fiberfrax. These varied fibers provide for either
different characteristics or in some cases, they can produce
equivalent properties for specific applications. The review
in this chapter concerns only asbestos reinforced plastics.
Generally, when reviewing the subject of asbestos filled
or reinforced plastics, phenolic resins or condensation type
resins are discussed. However, asbestos is used with such
other resins as those listed in Table 9.1. Asbestos fibers, and
in particular short fibers, are used in combinations with such
other fibers (including long asbestos fibers) as polyester
Figure 9.3 below shows an automobile air
conditioning housing which is made up of 55 per cent by
weight of asbestos shorts or floats, 10 per cent chopped
glass fiber, and 35 per cent polyester resin (with styrene).
An extremely large quantity of asbestos fibers is used with
these types of compounds but in most cases they are not
identified as containing asbestos.
Plastics is one of the few billion dollar industries in the
United States. It is one of the fastest growing industries with
approximately a 300 per cent increase in production in the
last ten years. The term "plastics" pertains to many different
products. Asbestos is used in many of them. In most applications
it provides for meeting property requirements at low
cost. As the plastic industry grows, more use of asbestos also
develops both in thermoplastic and thermosetting resins.
Typical uses of asbestos in plasatic components - Rosato ca 1952
SOME USES OF ASBESTOS IN PLASTIC COMPOSITIONS *
Type of Asbestos-Containing Resin
Products & Applications Using This Asbestos Plastic Resin
Method of Fabrication of the Asbestos-Plastic Resin Product
Rosin, with or without waxes,
gilsonite, creosote, shellac,
mineral oils, phenolic resins,
Hot molding, chilling
Shellac, with rosin, creosote,
Electrical insulations and miscellaneous
Hot molding, with or without
Asphalts, tars and pitches, with
chlorinated rubber, oils, solvents,
Heat insulator coatings for metal pipes
Parts for electrical and heat appliances
Drying, cold molding, using
Waxes (Montan, carnauba, etc.)
with shellac, natural resins,
gilsonite, modified rosins, mineral
Casting, coating, molding
Box toe compositions
Hot molding, chilling
Hot molding, chilling
Hot pressing, chilling
Joints, coating compositions, etc.
Brushing, trowelling, etc.,
Rubber or chlorinated rubber,
with or without alkyd resins,
etc. with or without organic
filler and asbestos
Brake linings, clutch facings, valve discs,
gaskets, packings, etc.
Hot molding, curing
Phenolics, alone or with natural
resins, rubber, inorganic filler
(silica or mica) and asbestos,
floats, long fiber, paper, yarn
Friction materials, automotive applications,
"Haveg" type compositions
Coating compositions, books, papers, etc.
Molded heat resistant compositions
Impregnated sheets, panels, or boards,
gaskets, valve discs, etc.
Asbestos fabric pressed as blocks
Asbestos sheet as spacers for heat insulators
Asbestos yarns, etc. for clutch facings,
Laminated under heat and
Heat and pressure
Asbestos and cellulose esters used to in-
crease strength and toughness of
glycerol phtholate molding compounds
Door stripes, electrical spools, etc.
Wood veneer panels
Acid proof coatings
Hot molding, chilling, curing
Hot molding, chilling
Cold molding, curing
To increase adherence to coated surface,
to increase flexibility of undercoatings,
on metal surfaces, also used in
packings, putties and boards
Varies depending on application
Sheet protection for metal surfaces
Asbestos paper or sheet is connected to metal surface by phenolic resin and
then coated with the same material
Curing by heat and pressure
* A. B. Cummins, "Asbestos in Plastic Compositions" Modern Plastics.
Figure 9.2. Vanguard rocket nose cone is made of asbestos-phenolic
material. It is subjected to aerodynamic heating, shock heat, and
structural loads. The two-piece cone splits apart and drops off after
the rocket leaves the atmosp
Applications of Asbestos-Reinforced Plastic Materials
Typical commercial applications of asbestos-plastic materials
include pulleys, casters, electrical circuit breakers,
pipes, roller and sleeve bearings, metal bearing retainers,
bushings, containers, ducts, and washing machine agitators.
Architects and engineers are developing more uses for asbestos
based plastics too, inasmuch as they provide for
increased resistance to fire and increase structural strength.
Information concerning the impact-porosity resistance of -
plastics is applicable to doors or paneling, containers, boats
(hull and floor), radomes, pressure bottles or tubes, plywood
surface, rocket tubes, decorative panels, and ducts. Asbestos
sheet products can be used on the surface, in the center or
interleaved with other reinforcements to provide for high
The impact-porosity resistance of glass fabric or glass
woven roving-polyester resin laminates is increased threefold
when glass fabric is interleaved and/or surfaced with
asbestos felts or
One of the more important and spectacular applications
of asbestos reinforced plastics involves its use in missiles.
Its insulation, ablation, and fine structural characteristics
are all required in order that parts may function properly.
Special asbestos-base plastics have been developed for use
in direct rocket blasts which in turn have helped solve some
of the high temperature problems.
Parts which are involved
in the use of this type of product include nose cones, thermal
- insulation barriers between propellant and steel motor
bodies, rocket exhaust tubes, electrical conduits, aft insulators,
deflector plates, rocket motor pressure plugs, turbine
wheels, ducts, bulk head, fins, shrouds, and sliver traps. See
Figures 9.8 through 9.10 inclusive.
* U.S. Navy, Bureau of Ships, Final Report, "The Use of Asbestos
Fiber Materials in Glass Reinforced Plastic Laminates," Project
4860-Q-27 NS034-045 (Aug., 1957).
Figure 9.8. The Nike-Hercules sustainer motor contains asbestosphenolic
insulation from the forward end to the exhaust end. - Courtesy The Thiokol Corporation. Click this or any image at InspectApedia to see a detailed, enlarged version.
Figure 9.9. A rocket motor tube tailpipe fabricated from asbestosphenolic
plastic. -Courtesy The Bristol Aeroplane, Ltd.
Figure 9.10. Rocket motor body asbestos-plastic exhaust cone and
Experimental tests using temperatures as high as 20,000°F
have been conducted on various asbestos products. The materials
are very poor conductors of heat and therefore help
to solve some of the thermal problems. During their exposure
to extremely high temperatures for short periods of
time their surfaces will oxidize or carbonize and produce a
protective outer surface. Ablation or errosion occurs at a
relatively slow rate.
Various parts have been made by such different techniques
as compression molding, vacuum bag, autoclave, and transfer
molding. These plastic parts can be easily mass produced.
They have been used in modern development and
Figure 9.11. Asbestos base plastic 75-gal drop tank for the Hawker
Sea Hawk. This tank is the first plastic drop tank in the world to
have received full design approval.
The Bristol Aeroplane Company, Ltd., Filton, Bristol,
England, has now received world wide acceptance of its
asbestos-phenolic external auxiliary fuel tanks for aircraft.
This is the first world wide acceptance of any reinforced
plastic part. These drop-tanks are shown in Figure 9.11.
They are required in large numbers and they form an important
and costly item in modern air force inventory. The
Bristol tank capacities are varied—SO, 100, 150, 200, 300,
and 500 gal.
The Bristol tanks have been developed as a logical sequence
to the company's work on plastics for primary structures.
The production techniques used, i.e., the molding of
cylindrical fuselage sections by the autoclave process and
the hydraulic press methods used for central sections and
frames, have both been found to be readily adaptable to the
manufacture of drop-tanks; the former process is used for
the shell and the latter for the internal structure.
Newly developed [1950's - Ed.] high strength asbestos reinforced honeycomb
is now in pilot-plant production. This new type of core
material is the first of its kind where good physical properties
at room and elevated temperatures are developed with asbestos.
The presently available type utilizes a heat resistant
Summary of preliminary properties of this
type material identified as Hexcel Type XHRP % 6 —Asb.-
9.0 are shown in Table 9.11. A structural honeycomb utilizing
silicone resin with asbestos reinforcement is in an early
stage of development.
TABLE 9.11. ASBESTOS-PHENOLIC HONEYCOMB DATA * [click to enlarge]
Shear Specimens for asbestos phenolic honeycomb material 3 in. by 8 in., simple support over 6 in. span, core
% in. thick with Al. facings .091 in. thick.
Compression Specimens for asbestos phenolic honeycomb material 2 in. by 2 in., % in. thick core, Al facings
.091 in. thick.
* Hexel Co.
Use of Asbestos Plastic in the 1951 Delta Aircraft Wing
In 1951, a Delta Aircraft wing made of asbestos-phenolic
laminate was displayed at the Exhibition of the Society of
British Aircraft Constructors at Farnsborough, England.
The Royal Aircraft Establishment, Ministry of Supply
provided the exhibit in order to show progress on reinforced
plastic aircraft parts. The wing was approximately 8 ft
from the fuselage with approximately an lift chord at the
root. The shell of the wing continued around a leading edge
and over the whole area back to the ailerons. There were
no outer skin joints.
Fabrication of the wing was accomplished by two techniques;
i.e., zexo pressure and vacuum technique. In the zero
pressure process, asbestos-phenolic sheet material (Durestos)
was saturated with warm water producing a very soft
sheet which could be hand rolled into simple curvatures.
applying heat, these sheets would tend to delaminate and to
produce low physical properties. To eliminate this problem,
the softened sheets were treated with a water-soluble, coldsetting
resorcinol resin. This resin penetrates the material
and produces a solid compressed sheet. During the cure, the
resorcinol resin shrinks. Inasmuch as one side of the molded
material will be exposed to the air, water is free to evaporate.
This method of fabrication is a specialized art; it is
not a standard procedure.
The vacuum process is a more desirable method of.fabrieating
parts at low pressure, inasmuch as it provides for the
elimination of condensation formed during the curing of the
phenolic resin. The phenolic preimpregnated asbestos sheet
material is manufactured so that suitable flow and resin
conditions exist for this type of fabrication. A male or
female mold is used in conjunction with a vacuum bag which
is generally made of rubber.
Two different basic internal structures were manufactured
for the Delta wing construction. One was designed to provide compartments for various equipment. The other design
involved internal fuel tanks.
Asbestos-phenolic plastics were used in the manufacture
of a high performance experimental wing for a glider by the
Plastics Division of F. G. Miles, Ltd., Shoreham Airport,
Sussex, England (1953).
The wing was of the high-performance
type, being designed for laminar flow and having an
aspect ratio of 18. The wing had a 60 ft span, a 5 ft chord
at the root, and weighed 155 lb. This plastic type of wing
had been manufactured inasmuch as a high degree of accuracy
was required in the contour of the wing. This accuracy
permitted the production of a low cost item as compared
with the conventional methods of manufacture.
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 Asbestos, its Industrial Applications, D.V. Roasato, engineering consultant, Newton MA, Reinhold Publishing Co., NY, 1959, Library of Congress Catalog No. 59-12535. We are in process of re-publishing this interesting text. Excerpts & adaptations are found in InspectApedia.com articles on asbestos history, production & visual identification in and on buildings.
 "Asbestos in Plastic Compositions", A.B. Cummins, Modern Plastics [un-dated, pre 1952]
 "Asbestos in Your Home," Spokane County Air Pollution Control Authority, Spokane WA 509-477-4727 www.scapa.org provides a one-page image, a .pdf file drawing of a house warning of some possible sources of asbestos in the home. The sources are not ranked according to actual risk of releasing hazardous levels of airborne asbestos fibers and the list is useful but incomplete.
 The US EPA provides a sample list of asbestos containing products epa.gov/earth1r6/6pd/asbestos/asbmatl.htm
 "Characterization of asbestos exposure among
automotive mechanics servicing and handling
asbestos-containing materials", Gary Scott Dotson, University of South Florida, 1 June 2006, web search 3/9/2012 original source: scholarcommons.usf.edu/cgi/viewcontent.cgi?article=3505&context=etd [copy on file as /hazmat/Automotive_Asbestos_Exposuret.pdf ].
 Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
 Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
 Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
 "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
 EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460 Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Basic Information about Asbestos, US EPA, web search 08/17/2010, original source: http://www.epa.gov/asbestos/pubs/help.html
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Copy on file as - /hazmat/Asbestos_in_Your_Home_US_EPA.pdf - Asbestos in Your Home - U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
[copy on file as /hazmat/Vermiculite_US_EPA.pdf/ Current Best Practices for Vermiculite Attic Insulation - May 2003, U.S. EPA
[copy on file as] /hazmat/Vermiculite_Health_Canada.pdf] Vermiculite Insulation Containing Amphibole Asbestos - September 2009, Health Canada
Managing Asbestos in Place, How to Develop and Maintain a Building Asbestos Operations and Maintenance (O&M) Program, U.S. EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/management_in_place.html
Asbestos Strategies, Lessons Learned about Management and Use of Asbestos: Report of Findings and Recommendations on the Use and Management of Asbestos, 16 May 2003, US EPA, web search 01/20/2011, original source: http://www.epa.gov/asbestos/pubs/asbstrategiesrptgetf.pdf
prepared by the: Global Environment & Technology Foundation, 7010 Little River Turnpike, Suite. 460, Annandale VA 20003
Other US EPA Publications on asbestos: web search 01/20/2011, see http://www.epa.gov/asbestos/pubs/pubs.html
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