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Properties of asbestos based or asbestos filled formed or plastic products: this article describes all major properties of asbestos-based plastic & formed or molded products except for electrical behaviours which are discussed separately at ASBESTOS PLASTIC ELECTRICAL PROPERTIES.
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.
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 and hundreds of other products.. Page top photo: Rocket motor body asbestos-plastic exhaust cone and
ring - Adapted from Rosato (1959) .
Properties of Asbestos Reinforced or Filled Plastics: thickness vs strength
Properties of asbestos reinforced or filled plastics will
vary depending upon the various conditions of the asbestos
and also of the resin or binders. Length of fiber is related to
strength properties. In the commercial type of asbestosphenolic
molding compound such as those listed in Military
Specification MIL-M-14, the asbestos shorts and floats are
The strength properties are lower than
those reported in Table 9.3 below, where longer fibers are given.
In addition to length of fiber, it is important that contaminants
or foreign matter generally associated with short
fibers be considered as well as fiberization of longer fibers.
Chrysotile asbestos is principally used. Its pertinent properties are
Modulus of elasticity, 25 x ioe psi
Tensile strength, 80 to 200 x 101psi
Specific gravity, 2.5
Fusion point, 2,770°F
The percentage of asbestos used in plastic compounds is
an important requirement. In all resin systems, there is a
certain percentage required to give maximum mechanical
strength. A different percentage may be used to produce
such desirable properties as chemical resistance, thermal
insulation, impact, erosion, and resistance.
will generally differ from one resin system to another.
For example, with phenolic resin maximum strength is obtained
with 25 per cent long fiber, but with silicone resin
the percentage is approximately 45 per cent long fiber. With
short fibers, there is a relatively small range in difference
of properties; the percentage of fibers can range from 30 to
60 per cent.
THICKNESS vs. STRENGTH,-ASBESTOS SHEET STYLE A
PHENOLIC RESIN LAMINATES
Laminate Thickness, Inch
Press Time, Minutes
Not Post Cured
E x 10 -6
E x 10 -6
Note: Parallel layup: longitudinal data; press cure 400 psi and 300
post cure 24 hr/300
F, 24/350 and 24/400.
High-Temperature Structural Properties of Asbestos-Based Plastics
Data and requirements
for a basically structural type of asbestos
plastics are given in Military Specification MIL-P-25770,
entitled "Plastic Materials, Asbestos Base-Phenolic Resin,
Low Pressure Laminates."
Table 9.4 lists requirements after
room temperature testing. Table 9.5 lists requirements at
high temperatures. Commercially available asbestos-phenolic
plastics data are shown in Table 9.6. These data are
for parallel layup with tests conducted in a longitudinal or
high strength direction.
LONGITUDINAL MECHANICAL PROPERTIES OF Low PRESSURE
LAMINATED ASBESTOS BASE PHENOLIC RESIN PLASTIC (0.125 ± 0.010
INCH THICK) AT STANDARD CONDITIONS * - [Click to enlarge]
LONGITUDINAL MECHANICAL PROPERTIES OF LOW-PRESSURE
LAMINATED ASBESTOS BASE PHENOLIC RESIN PLASTIC (0.125 ± 0.010
INCH THICK) AT ELEVATED TEMPERATURES * [Click to Enlarge]
TABLE 9.6. PROPERTIES OF ASBESTOS-PHENOLIC RESIN LAMINATES* [Click to Enlarge]
The principal reason for developing asbestos-silicone products has been to produce high temperature strength, heat insulation, and good electrical properties which will operate for long periods of time. Table 9.7 shows the prop-
erties obtained with using principally asbestos sheet with
such resins as Dow Corning's DC-2106 and DC-R-7141.
TABLE 9.7. PROPERTIES OF ASBESTOS-SILICONE REINFORCED PLASTICS [Click to enlarge]
Chemical Properties of Asbestos Reinforced Plastics
With regard to the chemical or acid
resistant properties of asbestos plastics, contributions have
been made in solving chemical problems as well as operating
problems in the textile fibers manufacturing plants by the
use of asbestos-phenolic parts. Early spinning buckets for
rayon spinning machines were made of molded hard rubber,
aluminum and plastic lined
However, they were
unsatisfactory and asbestos-phenolic parts were substituted.
Polyester resin systems are used in order to provide room
temperature cure systems without pressure. However, phenolic
resin systems have also been developed to meet similar
curing conditions. Improved chemical resistant properties
have been obtained with the relatively newly developed
epoxy laminating resins.
Asbestos products are of particular interest where strong
alkaline conditions are encountered or for exposure to chemical
salts in high concentration.
The type of chemical parts or applications include tubes
or pipes (with fittings), valves, tanks and liquid containers
(tank liners), fume ducting and systems, pumps, towers,
agitators and such miscellaneous parts as packing, trays,
flooring, buhings, spinning buckets and chemical splash
guards. In addition to asbestos plastics being used, asbestos
millboard is used as aprons or as guard plates on which fluids
in glass containers can be heated.
Thermal Properties of Asbestos-Reinfoced Plastics, Laminates & Molding Compounds
The following thermal properties are
based on laminates or molding compounds. The density of
these materials ranges from 1.6 to 1.8.
Phenolic Asbestos Properties
Specific heat, room temperature to 500°F:
C, = 0.308 Btu/lb/OF
Specific heat determinations were made by means of a
dry-type adiabatic colorimeter. Specific heat for laminates
exhibit straight-line temperature enthalpy curves.
Thermal conductivity, room temperature to 500°F:
Mean Temp. for Asbestos Plastics
Mean Temperature °F
Btu hr/sq ft/°F/in.
Thermal conductivity determinations were made in a
guarded hot-plate apparatus (ASTM Specification Cl 77-45).
Thermal coefficient, room temperature to 600°F:
2to4 X 10 6 / 11 °F
Silicone Asbestos Properties
Specific heat, 100 to 200°C:
Ct = 0.292 to 0.355 Cal/gm/°C
Thermal conductivity (100°C):
6.5 x 10-4 Cal/cm/cm°/sec/°C.
Thermal coefficient (room temperature to 310°C:
2 x 10 -5 /°C
Table 9.2 - general information
concerning asbestos felts.
TABLE 9.2. Properties of Standard Asbestos Felts
Thickness (based on height of 10
plies), in. ± 10 %
Weight per 100 sq ft, lb, ± 5%
ASTM Grade ( D375-52)
Asbestos fiber contained in the felt,
Note: significant data for modern readers is that the asbestos content in these felt product ranges from 80% t0 99%! - Ed.
In molding compounds, short asbestos fibers such as
"shorts and floats" can produce attractive surface finishes
and satisfactory molding properties. Long asbestos fibers
tend not to produce highly attractive surface finishes and
have inferior flowing characteristics. To remedy these problems,
shorter asbestos fibers are generally mixed with the
Increasing filler content increases the viscosity of the
resin systems. For example an unfilled polyester resin system
with a viscosity of 2,500 centipoises at 75°F would increase
to 60,000 centipoises with 20 per cent asbestos filler. Actually
thick and stiff putties or pastes can be made with a
high percentage of asbestos fillers in the various resin
In many of the past applications, asbestos reinforced or
filled plastics were not evaluated as basically structural
materials. However, in the past decade there have been
tremendous strides with regard to reporting and developing
high strength and high modulus asbestos base plastics by
industry. These types of plastics are gradually entering into
such diversified fields as automotive parts, electronic parts,
chemical equipment, aircraft, and missiles.
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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
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
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