GB2295396A - Thermal insulant materials - Google Patents

Thermal insulant materials Download PDF

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Publication number
GB2295396A
GB2295396A GB9116012A GB9116012A GB2295396A GB 2295396 A GB2295396 A GB 2295396A GB 9116012 A GB9116012 A GB 9116012A GB 9116012 A GB9116012 A GB 9116012A GB 2295396 A GB2295396 A GB 2295396A
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GB
United Kingdom
Prior art keywords
plastics
thermally
insulant
plastics composition
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9116012A
Other versions
GB2295396B (en
GB9116012D0 (en
Inventor
Mark James Parry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nortel Networks Ltd
Original Assignee
Northern Telecom Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Northern Telecom Ltd filed Critical Northern Telecom Ltd
Priority to GB9116012A priority Critical patent/GB2295396B/en
Publication of GB9116012D0 publication Critical patent/GB9116012D0/en
Publication of GB2295396A publication Critical patent/GB2295396A/en
Application granted granted Critical
Publication of GB2295396B publication Critical patent/GB2295396B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
    • F02K9/08—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using solid propellants
    • F02K9/32—Constructional parts; Details not otherwise provided for
    • F02K9/34—Casings; Combustion chambers; Liners thereof
    • F02K9/346—Liners, e.g. inhibitors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/04—Reinforcing macromolecular compounds with loose or coherent fibrous material
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/16—Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/26—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment
    • C08L23/32—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment by reaction with compounds containing phosphorus or sulfur
    • C08L23/34—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers modified by chemical after-treatment by reaction with compounds containing phosphorus or sulfur by chlorosulfonation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
    • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C08L27/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L9/00—Compositions of homopolymers or copolymers of conjugated diene hydrocarbons
    • C08L9/02—Copolymers with acrylonitrile

Abstract

A thermally insulating plastics material, e.g. for lining the casing of a solid fuelled rocket motor, comprises an elastomer filled with a fibrous material which, on heating, degrades endothermically to carbon. Typically the filler comprises partially oxidised polyacrylonitrile, and the elastomer is EPDM, chlorosulphonate polyethylene, or a nitrile rubber/polyvinyl chloride mixture.

Description

THERMAL INSULANT MATERIALS This invention relates to thermal insulant materials, and in particular to materials suitable for providing a thermally insulating barrier between the propellant charge and the casing of a solid fuel rocket motor.
A typical solid fuel rocket motor comprises a body or charge of propellant material disposed in a steel casing having an opening through which gas generated by the burning propellant is ejected. It is desirable to place a thermally insulating barrier between the propellant and the casing for two reasons. Firstly, the very high temperature and the gas ablative effects generated by the burning charge can burn through the casing and thus severely impair the operation of the motor. Secondly, the propellant gas is subjected to cooling via the thermally conductive casing this reducing the gas pressure available to operate the motor.
The provision of an insulant barrier effectively reduces the above problems. However, the selection of suitable materials has introduced further difficulties.
For example, ceramic materials are very effective but are very difficult to manufacture. Plastics materials have therefore been proposed, but the thickness of conventional plastics for effective insulation severely reduces the volume available for the propellant charge.
The object of the invention is to minimise or to overcome the above disadvantages.
According to the invention there is provided a thermally insulant plastics material including an elastomeric matrix incorporating a fibrous filler material the filler material being in the form of short fibres and comprising a partially degraded polymer adapted to carbonise by an endothermic reaction or the application of heat to the plastics material.
Typically the fibrous filler comprises polyacrylonitrile. We have found that exposure of this material to intense heat causes transformation of the partially oxidised polyacrylonitrile (PAN) fibres to carbon fibres so as to provide a carbonaceous support for the thermally degraded plastics material. This maintains the thermal insulating properties of the material for a significant period of time following exposure to a heat source. We have also found that the transformation of the partially oxidised PAN fibres to carbon fibres is an endothermic process. The heat absorbed by this process provides a local cooling effect and further enhances the thermal insulating properties of the material.
Advantageously the composition further includes finely divided silica which provides a bulky refractory ash content and further improves the heat insulation effect.
A number of elastomer materials may be employed to form the thermoplastics matrix. For example, we have successfully employed ethylene propylene diene monomer, chlorosulphonate polyethylene and nitrile rubber/polyvinyl chloride. The cost of these materials is of particular advantage as, under high temperature conditions it undergoes an endothermic degradation process, similar to that of the partially oxidised PAN fibre, thus further contributing to the effectiveness of the material as a thermal barrier.
The materials may be formed by compounding the polymeric material with the partially oxidised PAN fibres and a curing agent. Preferably the mix also incorporates finely divided silica. The compounded material is formed into a sheet and is then heated to effect curing.
Typically the sheet is between 1 and 2 mm in thickness.
Advantageously the PAN fibres are about 2 mm in length and about 10 microns in diameter.
The materials are of particular application as thermal insulants for solid fuelled rocket motors. For this purpose the material may be worked on a two-roll mill before being calendered to form a sheet approximately 2um thick. The calendered sheet may be used to line a tubular motor casing, a number of layers being used to build up the required thickness. A plastics bladder is inserted and inflated to apply pressure to the liner which is then cured, e.g. by heating in an autoclave for about 1 hour at a temperature of 140 to 1600C.
To simulate exposure to a burning rocket propellant, we have tested these materials by exposure to an oxygen/acetylene flame by the method described in ASTM E285. As a result of these tests we have found that the thermal insulant materials described herein retain their heat insulating properties for periods of time significantly longer than those exhibited by conventional materials.
To demonstrate the invention a number of plastics compositions have been prepared and tested by the method of ASTM IE 285. The results of these tests are summarised in the following example.
EXAMPLE A number of polymeric compounds were prepared using EPDM, a chlorosulphonate polyethylene and a PVC based nitrile rubber, the batch compositions being summarised below. The compounds were mixed in an Internal mixer using a fill factor of 0.9 - 0.93. A conventional mix cycle was used with the polymer and process aids being added first. The silica and fibres were then incorporated into the polymer matrix, finally the cure system was added. The temperature of the mixing commenced at between 75 and 800C and the batch was dumped before the temperature had reached 1200C. The dumped material was then consolidated on a two-roll mill to form a homogeneous hide.
For t st ç roses each hide was cut into small pieces and co ression moulded for 60 minutes at 1500C using a simple plate mould to form sheets nominally 1.5 and 6mm thick.
Samples of the sheets were subjected to flame testing by the method described in ASTM E285, the result being summarised below. For comparative purposes similar testing was carried out on two conventional ceramic filler materials.
Batch No. ML043 EPDM based (Ethylene Propylene Diene Monomer) Parts by weight Nordes N2760 (EDPM) 97 Hypalon 40 3 Zinc Oxide 5 Polyethylene Oxide 3 Tetrone A 2.5 ( Cure System Stearic acid 1 Vulcanford ZDEC 0.5 Coumarone Resin 5 Process Aid Microsil ED (silica) 40 Oxidised PAN fibres (2mm) 12 Batch No.ML062 Hypalon Based (Chlorosulphonate Polyethylene) Parts by weight Hypalon 40 100 Nordel N2760 3 Maglite D (MgO) 4 Pentaerythritol 3 ( Cure System Tetrone A 2 Coumarone Resin 2.5 Microsil ED (Silica) 35 Oxidised PAN fibres 2mm 12 Ucarsil DSC RC1/50 10 Batch No. 057 Nitrile Rubber.PVC based Parts by weight Perbunan NVC/70 100 Renocure 2.5 Vulcacit C2/EG 1.5 ( Cure System Vulcacit Thiuram C 0.2 Microsil ED 35 Ucarsil DSC RC1/50 10 Oxidised PAN fibres 2mm 12 COMPARATIVE ABLATION RESULTS OF THERMAL INSULANT MATERIALS FORMULATIONS CL2759 CL7225 ML043 ML057 ML062 UNITS EPOM NBR/PVC Hypalon (currently used materials) (BNRE developed materials) Density kg/m3 1760 1094 1098 1243 1317 Insulation to density performance/80 S.m2/kg 0.99 0.07 6.45 6.48 6.60 " /180 S.m2/kg 1.00 0.27 7.67 7.49 7.26 " /380 S.m2/kg 1.03 2.56 7.87 7.88 7.62 Average time to burn-throught S 13.8 20.5 60.7 69.6 72.3 Average erosion rate m/s x 10-4 5.04 3.316 1.140 1.004 0.966 Average insulation index /80 S/m 1734 75 7080 8056 8699 " /180 S/m 1763 292 8418 9308 9556 " /380 S/m 1806 2796 8639 9790 10036 Average time to 80 S 12.0 0.5 48.9 56.0 60.7 " 180 S 12.2 2.0 58.1 64.7 66.7 " 380 S 12.5 18.7 59.6 68.0 70.0 These results illustrate the effectiveness of the materials described herein as thermal insulants.

Claims (8)

1. A thermally insulant plastics material including an elastomeric matrix incorporating a fibrous filler material the filler material being in the form of short fibres and comprising a partially degraded polymer adapted to carbonise by an endothermic reaction or the application of heat to the plastics material.
2. A thermally insulant plastics material as claimed in claim 1, wherein the fibrous filler comprises partially oxidised polyacrylonitrile.
3. A thermally insulant material as claimed in claim 1 or 2, wherein the elastomer comprises ethylene propylene diene monomer, chlorosulphonate polyethylene or a nitrile rubber/polyvinyl chloride mixture.
4. A thermally insulant material as claimed in claim 1, 2 or 3, and incorporating finely divided silica.
5. A thermally insulant material as claimed in claim 2, 3 or 4, wherein the fibrous filler comprises about 12 wt % of the material.
6. A thermally insulant material as claimed in claim 1 and substantially as described herein.
7. A solid fuel rocket motor lined with an insulant material as claimed in any one of claims 1 to 6.
Amendments to the claims have been filed as follows 1. A plastics composition adapted to provide thermal insulation at elevated temperatures, the composition comprising an elastomeric matrix incorporating a fibrous filler material in the form of short fibres and consisting of a partially degraded polymeric material, wherein the filler is such that, when the plastics composition is in use exposed to a heat source causing thermal degradation of the elastomeric matrix, the filler material carbonises via an endothermic process whereby to absorb heat and to provide a carbonaceous support for the thermally degraded elastomeric matrix.
2. A plastics composition as claimed in claim 1, wherein the fibrous filler comprises partially oxidised polyacrylonitrile.
3. A plastics composition as claimed in claim 2 wherein said films are about 2mm in length and about 10 microns in diameter.
4. A plastics composition as claimed in claim 1, 2, or 3, wherein the elastomer comprises ethylene propylene diene monomer, chlorosulphonate polyethylene or a nitrile rubber/polyvinyl chloride mixture.
5. A plastics composition as claimed in claim 1, 2, 3 or 4, and incorporating finely divided silica.
6. A plastics composition as claimed in claim 2, 3 4 or 5, wherein the fibrous filler comprises about 12 wt % of the material.
7. A plastics composition as claimed in claim 1 and substantially as described herein.
8. A solid fuel rocket motor lined with plastics composition as claimed in any one of claims 1 to 7.
GB9116012A 1991-07-25 1991-07-25 Thermal insulant materials Expired - Fee Related GB2295396B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9116012A GB2295396B (en) 1991-07-25 1991-07-25 Thermal insulant materials

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9116012A GB2295396B (en) 1991-07-25 1991-07-25 Thermal insulant materials

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GB9116012D0 GB9116012D0 (en) 1995-11-29
GB2295396A true GB2295396A (en) 1996-05-29
GB2295396B GB2295396B (en) 1996-10-09

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011338A1 (en) * 1998-08-19 2000-03-02 Cordant Technologies, Inc. Rocket assembly ablative materials formed from, as a precursor, staple cellulosic fibers, and method of insulating or thermally protecting a rocket assembly with the same
WO2000014397A2 (en) * 1998-08-19 2000-03-16 Cordant Technologies, Inc. Rocket assembly ablative materials formed from solvent-spun cellulosic precursors, and method of insulating or thermally protecting a rocket assembly with the same
RU2525820C2 (en) * 2012-11-30 2014-08-20 Открытое акционерное общество Научно-производственное объединение "Искра" Method of protecting bodies of composite materials from moisture

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112391002B (en) * 2019-08-16 2022-05-27 南京理工大学 Heat-shrinkable coating layer for solid propellant and preparation method thereof

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714111A (en) * 1970-08-31 1973-01-30 Carborundum Co Ablative composites containing novolac fibers
EP0315244A2 (en) * 1987-10-23 1989-05-10 The Dow Chemical Company Use of a multiplicity of non-linear,non-flammable carbonaceous reinforcing fibers for improving the adhesion to a polymeric matrix

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3714111A (en) * 1970-08-31 1973-01-30 Carborundum Co Ablative composites containing novolac fibers
EP0315244A2 (en) * 1987-10-23 1989-05-10 The Dow Chemical Company Use of a multiplicity of non-linear,non-flammable carbonaceous reinforcing fibers for improving the adhesion to a polymeric matrix

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000011338A1 (en) * 1998-08-19 2000-03-02 Cordant Technologies, Inc. Rocket assembly ablative materials formed from, as a precursor, staple cellulosic fibers, and method of insulating or thermally protecting a rocket assembly with the same
WO2000014397A2 (en) * 1998-08-19 2000-03-16 Cordant Technologies, Inc. Rocket assembly ablative materials formed from solvent-spun cellulosic precursors, and method of insulating or thermally protecting a rocket assembly with the same
US6235359B1 (en) 1998-08-19 2001-05-22 Cordant Technologies Inc. Rocket assembly ablative materials formed from, as a precursor, staple cellulosic fibers, and method of insulating or thermally protecting a rocket assembly with the same
WO2000014397A3 (en) * 1998-08-19 2002-10-17 Cordant Tech Inc Rocket assembly ablative materials formed from solvent-spun cellulosic precursors, and method of insulating or thermally protecting a rocket assembly with the same
CN1119522C (en) * 1998-08-19 2003-08-27 阿利安特技术系统公司 Rocket assembly ablative materials formed from, as precursor, staple cellulose fibers, and method of insulating or thermall protecting rocket assembly with same
USRE43867E1 (en) 1998-08-19 2012-12-18 Alliant Techsystems Inc. Rocket assembly ablative materials formed from, as a precursor, staple cellulosic fibers, and method of insulating or thermally protecting a rocket assembly with the same
RU2525820C2 (en) * 2012-11-30 2014-08-20 Открытое акционерное общество Научно-производственное объединение "Искра" Method of protecting bodies of composite materials from moisture

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Publication number Publication date
GB2295396B (en) 1996-10-09
GB9116012D0 (en) 1995-11-29

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20070725