WO2020008191A1 - Composition d'écran thermique ablatif - Google Patents

Composition d'écran thermique ablatif Download PDF

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Publication number
WO2020008191A1
WO2020008191A1 PCT/GB2019/051883 GB2019051883W WO2020008191A1 WO 2020008191 A1 WO2020008191 A1 WO 2020008191A1 GB 2019051883 W GB2019051883 W GB 2019051883W WO 2020008191 A1 WO2020008191 A1 WO 2020008191A1
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WO
WIPO (PCT)
Prior art keywords
composition
sporopollenin
resin
weight
heat shield
Prior art date
Application number
PCT/GB2019/051883
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English (en)
Inventor
Mark Sephton
Christian POTISZIL
Original Assignee
Imperial College Of Science, Technology And Medicine
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Application filed by Imperial College Of Science, Technology And Medicine filed Critical Imperial College Of Science, Technology And Medicine
Publication of WO2020008191A1 publication Critical patent/WO2020008191A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/52—Protection, safety or emergency devices; Survival aids
    • B64G1/58—Thermal protection, e.g. heat shields
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
    • C08L61/04—Condensation polymers of aldehydes or ketones with phenols only
    • C08L61/06—Condensation polymers of aldehydes or ketones with phenols only of aldehydes with phenols
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/65—Additives macromolecular

Definitions

  • the present disclosure relates to an ablative heat shield composition.
  • the present disclosure also relates to a composite comprising such a composition, as well as to a vehicle part comprising such a composite.
  • the present disclosure also relates to the use of sporopollenin as an ablative material.
  • Objects require thermal shielding to protect themselves from atmospheric heating on passage through the Earth’s atmosphere. Heat is transferred to the thermal shields of such objects by aerodynamic heating, which occurs when friction is generated from the displacement of atmospheric gases (Reculusa et al., 2006). Ablative materials can be used to dissipate the flux of heat to the surface of the re-entering object.
  • an ablative material In order for an ablative material to dissipate heat effectively, gas production must be fast, abundant and occur over a wide temperature range (Clark and Me Lain, 1965).
  • An example of an ablative material is a composite comprising cork and a phenolic resin, commercially available under the trademark Norcoat ® (Reculusa et al., 2006).
  • Figures 1 to 4 are pyrolysis/gasification FTIR spectra recorded for cork ( Figure 1 ), sporopollenin (Figure 2), cutan ( Figure 3) and chitin ( Figure 4);
  • Figures 5 to 8 are pyrolysis/gasification FTIR spectra recorded for the phenolic resins employed in the Example;
  • Figures 9 to 10 are pyrolysis/gasification FTIR spectra recorded for the
  • Figures 1 1 and 12 show the mass lost for the biopolymers and resins subjected to pyrolysis/gasification at 200 to 1000 degrees C;
  • Figures 13 and 14 show the residual mass of the biopolymers and resins subjected to pyrolysis/gasification at 200 to 1000 degrees C; and [0007] Figures 15 to 18 show SEM images of biopolymers before and after
  • the present disclosure provides an ablative heat shield composition comprising sporopollenin and resin.
  • the present disclosure also provides a composite comprising a substrate and an ablative heat shield composition as described herein.
  • the present disclosure provides a vehicle part comprising a composite described herein.
  • the present disclosure also provides the use of sporopollenin as an ablative material in the manufacture of an ablative heat shield composition.
  • an object travelling through a planet’s may experience aerodynamic heating, which occurs when friction is generated from the displacement of atmospheric gasses. Aerodynamic heating can be severe and space vehicles and other aircraft (e.g. missiles, planes) that travel through the planetary atmosphere are usually provided with ablative heat shields to reduce the risk of damage to the aircraft.
  • sporopollenin may be used as an ablative material in the manufacture of an ablative heat shield composition.
  • Sporopollenin is a biological polymer. It is a major component of the exterior (exine) walls of plant spores and pollen grains.
  • resin for example, a phenolic resin
  • the resulting composition may be used as an ablative heat shield composition.
  • a char layer is formed, which can act as a thermal insulator.
  • the char layer can maintain its structural integrity, while material underneath it continues to decompose and outgas (e.g. by pyrolysis and/or gasification). These gaseous products can percolate through the char layer and cool surfaces underlying the char layer. Accordingly, when the ablative heat shield composition is applied to the surface of an object that is subjected to aerodynamic heating, the percolation of gaseous product through the char layer formed on the surface of the object can cool the object’s surface by transpiration.
  • Sporopollenin has been found to be stable at elevated temperatures. For example, when sporopollenin is subjected to elevated temperatures of, for example, above 600 degrees C, it exhibits desirable resistance to mass loss. This temperature stability allows sporopollenin to maintain its structural integrity in the char layer formed during pyrolysis and/or gasification. Thus, sporopollenin can provide an effective 3-dimensional framework through which gas produced can escape.
  • sporopollenin may provide an improved resistance to mass loss under high-temperature conditions. Accordingly, sporopollenin may provide improved structural integrity to the char layer formed by e.g. pyrolysis and/or gasification, allowing ablative cooling to performed more effectively.
  • the ablative heat shield composition may comprise any suitable amount of sporopollenin.
  • the composition may comprise at least 5 weight % sporopollenin, preferably at least 10 weight % sporopollenin, most preferably at least 20 weight % sporopollenin.
  • Sporopollenin may be present in the composition in an amount of at most 95 weight %, preferably at most 90 weight %, more preferably at most 85 weight %.
  • the composition may comprise 10 to 90 wt % sporopollenin, preferably 20 to 85 weight % sporopollenin, more preferably 40 to 80 weight % sporopollenin, for example, 60 to 75 weight % sporopollenin.
  • the sporopollenin is present in an amount of about 70 weight %.
  • the sporopollenin may have an average particle size of 15 to 80 micrometres, preferably 20 to 50 micrometres, for example, 30 micrometres, e.g. measured using a microscope and graticule.
  • the weight ratio of sporopollenin to resin may be 1 : 1 to 8: 1 , preferably 3:2 to 5: 1 , more preferably 2: 1 to 4: 1 , for example, 5:2 to 3:1 .
  • the ablative heat shield composition may comprise a
  • biopolymer in addition to sporopollenin.
  • suitable biopolymers include suberin (which dominates the material cork), cutan and chitin.
  • cork and sporopollenin are employed.
  • the additional biopolymer may be present in an amount of 0.5 to 10 weight %, preferably 1 to 5 weight %.
  • Any suitable resin may be used in the ablative heat shield composition.
  • a flame-resistant resin or an ablative resin may be employed.
  • suitable resins include epoxy resins, silicone resins and phenolic resins. Phenolic resins are preferred.
  • Suitable phenolics resins may include phenolic-formaldehyde resins selected from the group of novolac resins, resole resins, etherified resins, and combinations thereof.
  • one such phenolic resin is a novolak resin.
  • the novolak resins sometimes referred to in the art as two-stage resins, useful with the application can be prepared by the polycondensation reaction of at least one aromatic hydrocarbon selected from, but not limited to, -creso!, o-creso!, p-cresoi s 2,5-xylenol, 3,5-xyieno!, resorcinol, pyrogailol, phenol, trisphenol, o-ethyi phenol, m-eihyl phenol, p- ethyl phenol, propyl phenol, n-butyl phenol, t-butyl phenol, 1 -iiaphthol, and 2-naphthol, with at least one aldehyde or ketone selected from, but not limited to, formaldehyde, acetaldehyde, propion aldehy
  • a resole resin When used with the method of the application, it may be an organic hydrocarbon and an aldehyde polycondensation product where the two components are present in nearly equal molar ratio to an excess of the aldehyde.
  • the components useful for making the resole are the same as those designated as useful for preparing a novoiac resin.
  • Resoles are generally prepared with an excess of aldehyde in the presence of a basic catalyst.
  • Suitable phenolic resins may be available from Hexion under the trademark DuriteTM Resin SC1008, and Ce!!obondTM J2027X01. Other examples include resins include phenol-aralkyl resins. Examples include resins available from Bitrez under the trademarks Cura!okTM (e.g. 55-200 AT70) and BDP 4002.
  • the resin may be present in the ablative heat shield composition in an amount of at least 5 weight %, preferably at least 10 weight % and more preferably at least 20 weight %.
  • the resin may be present in the ablative heat shield composition in an amount of at most 80 weight %, preferably at most 50 weight % and more preferably at most 30 weight %.
  • the composition may comprise 5 to 80 weight % resin, preferably 20 to 50 weight % resin, and more preferably 25 to 30 weight % resin.
  • a combination of two or more resins may be employed.
  • the ablative heat shield composition may additionally comprise a refractory material.
  • a refractory material may be employed. Examples include alumina, silica, magnesia, lime and carbon.
  • the refractory material comprises alumina and/or carbon.
  • the refractory material may take the form of fibres. Suitable fibres include fibres that are from 0.1 to 2 mm in length, for example, 0.3 to 1.5 mm in length. Suitable fibres include alumina fibre and/or carbon fibre.
  • the refractory material may be present in the ablative heat shield composition in an amount of at least 0.1 weight %, preferably at least 0 5 weight %.
  • the refractory material may be present in the ablative heat shield composition in an amount of at most 20 weight %, preferably at most 10 weight %.
  • the composition may comprise 0.1 to 20 weight % refractory material, preferably 0.5 to 10 weight % resin, and more preferably 1 to 3 weight % refractory material.
  • the ablative heat shield composition may additionally comprise a fungicide.
  • the composition may comprise 0.1 to 20 weight % fungicide, preferably 0.5 to 10 weight %, more preferably 1 to 3 weight % fungicide.
  • the ablative heat shield composition comprises sporopollenin and a phenolic resin.
  • the composition may comprise 40 to 90 weight % sporopollenin and 10 to 60 weight % of a phenolic resin.
  • the composition may comprise 60 to 75 weight % sporopollenin and 25 to 40 weight % of a phenolic resin.
  • Refractory material and/or fungicide may also be present.
  • the composition may comprise:
  • any suitable method may be used to prepare the ablative heat shield composition.
  • the components of the composition may be mixed together to form a homogeneous mixture.
  • the resins may be heated according to industry guidelines. For example, the resins may be heated to temperatures of at least 100 degrees C, for instance, at least 130 degrees C.
  • Sporopollenin may be mixed in liquid resin to form a homogeneous mixture.
  • the resulting mixture may then be cured, for example, by heating.
  • the ablative heat shield composition may be applied onto a substrate.
  • the present disclosure also relates to a composite comprising a substrate and an ablative heat shield composition as described herein.
  • suitable substrates include substrates comprising metal.
  • the composite may be used as or to form a vehicle or a building part (e.g. flame-resistant cladding).
  • the composite may be used to protect the vehicle or building from exposure to elevated temperatures.
  • the composite may form an outer surface of the vehicle or building and help to dissipate heat from the surface of the vehicle or building in the event of e.g. a fire or exposure to aerodynamic heating.
  • the ablative heat shield composition may be applied to a vehicle or vehicle part.
  • the vehicle may be any suitable vehicle.
  • the vehicle may be any vehicle that may be exposed to aerodynamic heating, for example, on re-entry into the Earth’s planetary atmosphere.
  • aerodynamic heating for example, on re-entry into the Earth’s planetary atmosphere.
  • Examples of such vehicles include space craft, for instance, space shuttles.
  • Other examples include missiles and planes.
  • the ablative heat shield composition may be applied onto a substrate at variable thicknesses.
  • the ablative heat shield composition may be suitable for withstanding heat flows of 0.5 to 10 MW/m 2 .
  • the ablative heat shield composition may be resistant to elevated temperatures of greater than 300°C, preferably greater than 600°C. In some embodiments, the ablative heat shield composition may be resistant to elevated temperatures of greater than 800°C, preferably greater than 900°C.
  • Cork (dominated by the biopolymer suberin), chitin and sporopollenin were obtained already processed, whilst cutan required isolation from Agave americana leaf cuticles, which was carried out with reference to the method of Boom et al. (2005).
  • the leaf cuticles were cut from the leaves using a scalpel, after heating in an aqueous solution of 1 .6% oxalic acid and 0.4% ammonium oxalate for 6 h. A series of acid hydrolysis steps were then carried out in order to remove hydrolysable material.
  • the cuticles were added to a 2 M solution of trifluoroacetic acid, then a 12 M solution of sulphuric acid and finally a 5 M solution of sulphuric acid, the cuticles were rinsed with water, methanol and dichloromethane between each step. Finally, in order to remove the cutin bio-polyester, treatment of the cuticles with a 2 M solution of KOH in methanol was undertaken. The residue left behind was an off white powder, which is in agreement with the description of cutan in Boom et al. (2005).
  • the resins were prepared according to industry guidelines.
  • the Hexion Durite® SC1008P and Cellobond® J2027X01 resins were heated for 24 h at 170 °C and 140 °C, respectively.
  • the Bitrez BDP resin was heated at 170 °C for 4.5 h, whilst the Bitrez Curalok resin required a more complex heating profile.
  • the Curalok resin was heated up to 100 °C over the course of ⁇ 1 h and then held at that temperature for a further hour, before being heated to 170 °C over the course an additional hour and held at this temperature for a further 16 hours.
  • the composite materials were prepared from -40 vol.% biopolymer and 60 vol.% resin, which equated to 4:96 wt% for cork/Hexion SC1008P and 14:86 wt% for sporopollenin/Hexion SC1008P.
  • the setting of the composites was undertaken using the same heating procedure as the Hexion SC1008P resin.
  • the FTIR spectra confirm that low molecular weight organic units are being produced by all the biopolymers, resins and composites studied. Flowever, the nature, timing and abundance of the organic units released differ between these organic materials.
  • the mass loss profile ( Figure 1 1 ) of the biopolymers is different for each biopolymer.
  • a small loss of mass at 200 °C for sporopollenin and cork may represent the desorbing of gasses adsorbed to the surfaces of the biopolymers.
  • Cutan and chitin displayed a much greater mass loss and cutan looked melted and darkened in appearance at 200 °C ( Figure 13), which likely represents the loss of low molecular weight organic units.
  • Cork loses the largest quantity of mass at 600 °C, whilst the other biopolymers are characterised by smaller individual losses at 400 °C and 600 °C. Cutan also records a large loss of mass at 1000 °C.
  • the mass loss profiles alone do not highlight which biopolymer is more stable over the whole temperature range, but instead at individual temperatures.
  • Residual mass ( Figure 13) is another way of recording the stability of a biopolymer over the entire temperature range studied. Cork is the most stable at temperatures up to 600°C, demonstrated by the least cumulative loss of mass over this temperature range. However, between 600 °C and 1000 °C sporopollenin records less overall mass loss and is therefore the most stable over the entire temperature range of the biopolymers studied. [0043] The residual mass profiles of the resins ( Figure 14) agree with the mass loss profiles, confirming that the Bitrez Curalok resin loses a greater mass than the Flexion SC1008P. The survival of any object re-entering the atmosphere depends the ability of these resins to undergo a phase change and thus transfer heat away to the atmosphere.
  • the Bitrez Curalok resin demonstrates the best potential as a resin for use in future ablation shields, out of the resins studied.
  • Chitin does have some apparent layers observable within the flakes and these do seem unaffected after pyrolysis/gasification.
  • the cutan sample is composed of many tiny plates stuck together in a random arrangement. After pyrolysis/gasification the cutan plates lose definition and appear to have significantly loss structural integrity, which makes them an unsuitable candidate for use in ablation shields.
  • HINENO M. 1977. Infrared spectra and normal vibration of b-d-glucopyranose. Carbohydrate Research, 56, 219-227.

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Abstract

La présente invention concerne une composition d'écran thermique ablatif comprenant de la sporopollénine et de la résine. La présente invention concerne également un composite comprenant une telle composition, ainsi qu'une partie de véhicule comprenant un tel composite, la présente invention concerne en outre l'utilisation de sporopollénine en tant que matériau ablatif.
PCT/GB2019/051883 2018-07-04 2019-07-03 Composition d'écran thermique ablatif WO2020008191A1 (fr)

Applications Claiming Priority (2)

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GB1810970.2 2018-07-04
GBGB1810970.2A GB201810970D0 (en) 2018-07-04 2018-07-04 Ablative heat shield composition

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WO2020008191A1 true WO2020008191A1 (fr) 2020-01-09

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3126645A1 (fr) * 2021-09-06 2023-03-10 Speedinnov Panneau avec fonction coupe-feu

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US20130207028A1 (en) * 2010-04-22 2013-08-15 Astrium Sas Heat-protection material
DE102012216190A1 (de) * 2012-09-12 2014-04-10 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Komposite und Beschichtungsstoffe mit in biologischem Hüllmaterial inkludierten Wirkstoffen

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Publication number Priority date Publication date Assignee Title
US20130207028A1 (en) * 2010-04-22 2013-08-15 Astrium Sas Heat-protection material
DE102012216190A1 (de) * 2012-09-12 2014-04-10 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Komposite und Beschichtungsstoffe mit in biologischem Hüllmaterial inkludierten Wirkstoffen

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CLARK, L. E.MC LAIN, A. G.: "Performance of five ablation materials as coating for structures in a region of separated flow", NASA TECHNICAL NOTE, vol. D - 3 0 9, 1965
CORDEIRO, N.BELGACEM, M. N.SILVESTRE, A. J. D.NETO, C. P.GANDINI, A.: "Cork suberin as a new source of chemicals.: 1. Isolation and chemical characterization of its composition", INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, vol. 22, 1998, pages 71 - 80
COURT, R. W.SEPHTON, M. A.: "Meteorite ablation products and their contribution to the atmospheres of terrestrial planets: An experimental study using pyrolysis-FTIR", GEOCHIMICA ET COSMOCHIMICA ACTA, vol. 73, 2009, pages 3512 - 3521, XP026302071, DOI: doi:10.1016/j.gca.2009.03.006
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HINENO, M.: "Infrared spectra and normal vibration of β-d iucopyranose", CARBOHYDRATE RESEARCH, vol. 56, 1977, pages 219 - 227
JUNG-HYUN LEE ET AL: "Pollen: A novel, biorenewable filler for polymer composites", MACROMOLECULAR MATERIALS AND ENGINEERING, WILEY VCH VERLAG, WEINHEIM, DE, vol. 296, 12 November 2011 (2011-11-12), pages 1055 - 1062, XP002692948, ISSN: 1438-7492, [retrieved on 20110606], DOI: 10.1002/MAME.201000459 *
MONTGOMERY, W.POTISZIL, C.WATSON, J. S.SEPHTON, M. A.: "Sporopollenin, a natural copolymer, is robust under high hydrostatic pressure", MACROMOLECULAR CHEMISTRY AND PHYSICS, vol. 217, 2016, pages 2494 - 2500
POLJANSEK, I.KRAJNC, M.: "Characterization of phenol-formaldehyde prepolymer resins by in line FT-IR spectroscopy", ACTA CHIMICA SLOVENICA, vol. 52, 2005, pages 238, XP055126029
PRABU, K.NATARAJAN, E.: "Isolation and FTIR spectroscopy characterization of chitin from local sources", ADVANCES IN APPLIED SCIENCE RESEARCH, vol. 3, 2012, pages 1870 - 1875
RECULUSA, S.TRINQUECOSTE, M.DARIOL, L.DELHAES, P.: "Formation of low-density carbon materials through thermal degradation of a cork-based composite", CARBON, vol. 44, 2006, pages 1316 - 1352

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3126645A1 (fr) * 2021-09-06 2023-03-10 Speedinnov Panneau avec fonction coupe-feu

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