GB1582260A - Energy absorbing compositions - Google Patents

Energy absorbing compositions Download PDF

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Publication number
GB1582260A
GB1582260A GB40063/76A GB4006376A GB1582260A GB 1582260 A GB1582260 A GB 1582260A GB 40063/76 A GB40063/76 A GB 40063/76A GB 4006376 A GB4006376 A GB 4006376A GB 1582260 A GB1582260 A GB 1582260A
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GB
United Kingdom
Prior art keywords
composition
energy
bitumen
layers
bituminous 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.)
Expired
Application number
GB40063/76A
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.)
BP PLC
Original Assignee
BP PLC
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 BP PLC filed Critical BP PLC
Priority to GB40063/76A priority Critical patent/GB1582260A/en
Priority to DE19772741262 priority patent/DE2741262A1/en
Priority to FR7728924A priority patent/FR2365435A1/en
Publication of GB1582260A publication Critical patent/GB1582260A/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B11/00—Layered products comprising a layer of bituminous or tarry substances
    • B32B11/10—Layered products comprising a layer of bituminous or tarry substances next to a fibrous or filamentary layer
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/022—Non-woven fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/024—Woven fabric
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
    • B32B5/026—Knitted fabric
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N5/00—Roofing materials comprising a fibrous web coated with bitumen or another polymer, e.g. pitch
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/546—Flexural strength; Flexion stiffness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/56—Damping, energy absorption

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Laminated Bodies (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Road Paving Structures (AREA)
  • Vibration Dampers (AREA)

Description

(54) ENERGY ABSORBING COMPOSITIONS (71) We, THE BRITISH PETROLEUM COMPANY LIMITED, of Britannic House, Moor Lane, London, EC2Y 9BU, a British Company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to energy absorbing compositions particularly compositions for absorbing kinetic energy.
Compositions capable of absorbing energy, particularly kinetic energy, are of potential interest for e.g. vehicle bumpers, crash barriers, ships fenders, marine breakwaters and wave height reduction rafts. Many existing compositions based on rubber or other elastic polymers are known but these act more to reflect and deflect energy than to absorb it. Other compositions e.g. of metal which are relatively rigid can absorb energy effectively but have little resilience.
The present invention is concerned with particular compositions which can absorb energy by heat dissipation through flexing and deformation (i.e. a composition with a relatively high energy absorption) but which has sufficient rigidity to withstand shock (i.e. a composition with, also, a relatively high flexural modulus). In contrast to rubbers, the compositions are relatively stiff with a slow elastic recovery, and in constrast to metals, they have the ability to deform and recover slowly without breaking.
According to the present invention a bituminous composition suitable for absorbing energy comprises a plurality of layers of bitumen intercalated with a plurality of layers of mineral or organic fibres, the thickness of each layer and the number of layers being such that the composition has a total thickness of at least 1 centimetre and such that the composition has an energy absorption of at least 50% and a flexural modulus of at least 15 MN/m2.
The energy absorption may be determined on a rectangular beam of material by the application of viscoelastic theory.
Measurements of load against deflection when the centre of a beam supported on double knife edges is displaced above and below its equilibrium positions may be measured on, for example, as Instron Universal Testing Machine and, with a material showing high energy loss, load against deflection hysteresis loops are obtained.
The energy absorbing qualities of a composition using the Instron Universal Testing machine can be obtained quite simply by measuring the energy absorbed and the energy applied and dividing the one by the other to get the efficiency of energy absorption.
However, energy absorption capability is inter-related both in theory and in practice with the stiffness of the composition as measured by the flexural modulus (Youngs modulus in flexure). Flexural modulus may conventiently be measured as described in ASTM D 797.
Preferably the composition has an energy absorption of at least 70%. The flexural modulus may be at least 30 MN/m2 and it may be as high as 1000 MN/m2.
A relatively high flexural modulus is desirable both to increase the energy loss and to give the composition structural strength.
The bitumen may be natural bitumen or the material commonly known as mineral pitch or bitumen obtained as a product from the coal and oil industries. Preferably it is petroleum bitumen obtained as residue from the vacuum distillation of crude oil or a portion of such a residue, e.g. precipitated asphalt obtained by extracting the residue with a low boiling normal paraffin e.g. propane.
The bitumen may be a straight-run or blown bitumen and may suitably have a penetration of from 10 to 200 as measured by IP 49/72 and a Ring and Ball softening point of from 30"C to 1500C as measured by IP 198/66. It may be convenient to use different grades of bitumen in different parts of the composition.
If desired the bitumen may be blended with a polymer, preferably a thermoplastic polymer, and/or a filler.
Suitable proportions may be Bitumen 100 parts by weight Polymer 0-50 parts by weight Filler 0-500 parts by weight.
Examples of suitable polymers include polychloroprene, chlorosulphonated polyethylene, ethylene-propylene-diene terpolymer, and styrene-butadiene copolymer. The filler should, as is normal practice, be a fine powder having a particle size passing 200 mesh BSS (less than 75 microns) and may be any of the known fillers e.g. calcium carbonate, carbon black, pulverised fuel ash, silica, kieselguhr or sepiolite.
In the fibre layers the mineral or organic fibres are desirably in some ordered form and may be in the form of woven, knitted, or non-woven fabrics. Examples of mineral fibres are glass, rock wool and asbestos fibres and examples of organic fibres are polyethylene terephthalate, nylon, cotton, rayon and polyolefin fibres. As will be described hereafter the compositions may be produced by impregnating fibre layers with molten bitumen, and with this method of production the fibres should have melting points sufficiently high to withstand the temperatures involved.
As previously indicated, to give the required energy absorbing qualities and adequate stiffness, the composition should have a thickness of at least 1 cm. The thickness will normally be up to 100 cm, but for special applications (e.g. wave reduction rafts) large thicknesses of up to 10 metres may be necessary. Preferably there are at least 3 layers of bitumen and of fibres and the outer layers may be either of bitumen or fibres. if fibres are used as the outer layers they are, however, preferably in woven or knitted fabric form.
Desirably each layer is relatively thin in relation to the total thickness to give a multiplicity of layers. Thus each fibre layer is preferably not more than 2 mm thick and each bitumen layer not more than 5 mm thick and there may be 6 or more layers of each.
The relative thicknesses of the layers will influence the ratio of bitumen to fibres in the composition and preferably the compositions have a weight ratio of bitumen (including any polymer or filler present) to fibres of from 5:1 to 1:5.
The number of layers and the thickness of each layer may vary depending on the balance of properties required and the use for which the composition is designed. However, the energy absorption and flexural modulus for any given composition can readily be determined by experiment. In practice, therefore, no difficulties should be experienced in the selection of suitable combinations.
A simple and convenient method of preparing compositions according to the present invention is to bond a plurality of layers of bituminous felt used e.g. for roofing. As is well known roofing felt is formed by impregnating a fabric, usually a non-woven fabric, with bitumen. Sometimes all the bitumen required is applied in a single stage and sometimes the bitumen is applied in two stages viz: an impregnation stage and a coating stage. Felt formed by either method may be used and the required number of layers may be obtained by bonding under heat and pressure or, preferably, by bonding with additional molten bitumen.
When the composition is formed in this manner different grades of bitumen can be used for the impregnation, coating and bonding stages.
The bitumen used for the impregnation and bonding stages may suitably have a penetration of from 25-200 as measured by IP 49/72 and a Ring and Ball softening point of from 30"-60"C as measured by IP 198/66. For the coating stage, corresponding figures are 10-40 and 80-150"C.
It will be apparent from general principles as well as from the above method of preparation that the layers of fibres used in the compositions of the present invention are likely to be permeable and hence liable to contain some bitumen within them and the term layers of fibres is to be understood in this sense.
The invention is illustrated by the following example.
A composition according to the present invention was prepared by heating bitumen of 40"C softening point and 50 penetration to 1 800C and bonding layers of roofing felt with the bitumen. 7 layers of glass fibre reinforced roofing felt (Berry Wiggins Type 3B) were used.
In the final composition the layers of fabric were 1 mm thick, the layers of bitumen 0.5 mm thick and the weight ratio of bitumen to fibres was 2.1:1.
Strips 2.5 cm wide and 1 cm thick were tested for energy absorption using an Instron Universal Testing machine. The double knife edges supporting the strip were 8 cm apart and the deflection of the strip at its mid-point was + I cm at 10 cm/minute giving a cycle time of 12 seconds. The temperature was 23"C.
the energy applied and the energy absorbed per cycle were measured in Joules by estimating the area under the stress/strain curve and the area swept by the hysteresis loop and converting these areas to energy.
The efficiency of energy absorption was defined as energy absorbed x 100% energy applied The flexural modulus was also determined by measuring the average slope of the hysteresis loop between its two extremities.
The results are shown in Table 1 below.
Table 1 Efficiency Thickness Energy Energy of of applied absorbed energy Flexural Composition beam per cycle per cycle absorption modulus cm j j % MN/m2 7 layers of 1.09 0.98 0.84 85 53 glass fibre reinforced roofing felt (Berry Wiggins Type 3B) The results of Table 1 show that the composition had a high efficiency of energy absorption and reasonably high flexural modulus.
WHAT WE CLAIM IS: 1. A bituminous composition suitable for absorbing energy comprising a plurality of layers of bitumen intercalated with a plurality of layers of mineral or organic fibres, the thickness of each layer and the number of layers being such that the composition has a total thickness of at least 1 centimetre and such that the composition has an energy absorption of at least 50% and a flexural modulus of at least 15 MN/m2.
2. A bituminous composition as claimed in claim 1 wherein the energy absorption is at least 70% and the flexural modulus is at least 30 MN/m2.
3. A bituminous composition as claimed in claim 1 or 2 wherein the bitumen has a penetration of from 10 to 200 and a Ring and Ball softening point of from 30 to 1500.
4. A bituminous composition as claimed in claim 1, 2 or 3 wherein the bitumen layers have the composition Bitumen 100 parts by weight Polymer 0- 50 parts by weight Filler 0-500 parts by weight 5. A bituminous composition as claimed in any of claims 1 to 4 wherein the fibres are in the form of a woven, knitted, or non-woven fabric.
6. A bituminous composition as claimed in any of claims 1 to 5 wherein the composition has a thickness of up to 100 cm.
7. A bituminous composition as claimed in any of claims 1 to 6 having at least 3 layers of bitumen and of fibres, preferably at least 6 layers of each.
8. A bituminous composition as claimed in any of claims 1 to 7 wherein each fibre layer is not more than 2 mm thick and each bitumen layer not mdre than 5 mm thick.
9. A bituminous composition as claimed in any of claims 1 to 8 wherein the weight ratio of bitumen to fibres is from 5:1 to 1:5.
10. A method of preparing a bituminous composition as claimed in any of claims 1 to 9 comprising bonding together a plurality of sheets of bituminous felt.
11. A bituminous composition as claimed in claim 1 substantially as described in the Examples.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

  1. **WARNING** start of CLMS field may overlap end of DESC **.
    the energy applied and the energy absorbed per cycle were measured in Joules by estimating the area under the stress/strain curve and the area swept by the hysteresis loop and converting these areas to energy.
    The efficiency of energy absorption was defined as energy absorbed x 100% energy applied The flexural modulus was also determined by measuring the average slope of the hysteresis loop between its two extremities.
    The results are shown in Table 1 below.
    Table 1 Efficiency Thickness Energy Energy of of applied absorbed energy Flexural Composition beam per cycle per cycle absorption modulus cm j j % MN/m2
    7 layers of 1.09 0.98 0.84 85 53 glass fibre reinforced roofing felt (Berry Wiggins Type 3B) The results of Table 1 show that the composition had a high efficiency of energy absorption and reasonably high flexural modulus.
    WHAT WE CLAIM IS: 1. A bituminous composition suitable for absorbing energy comprising a plurality of layers of bitumen intercalated with a plurality of layers of mineral or organic fibres, the thickness of each layer and the number of layers being such that the composition has a total thickness of at least 1 centimetre and such that the composition has an energy absorption of at least 50% and a flexural modulus of at least 15 MN/m2.
  2. 2. A bituminous composition as claimed in claim 1 wherein the energy absorption is at least 70% and the flexural modulus is at least 30 MN/m2.
  3. 3. A bituminous composition as claimed in claim 1 or 2 wherein the bitumen has a penetration of from 10 to 200 and a Ring and Ball softening point of from 30 to 1500.
  4. 4. A bituminous composition as claimed in claim 1, 2 or 3 wherein the bitumen layers have the composition Bitumen 100 parts by weight Polymer 0- 50 parts by weight Filler 0-500 parts by weight
  5. 5. A bituminous composition as claimed in any of claims 1 to 4 wherein the fibres are in the form of a woven, knitted, or non-woven fabric.
  6. 6. A bituminous composition as claimed in any of claims 1 to 5 wherein the composition has a thickness of up to 100 cm.
  7. 7. A bituminous composition as claimed in any of claims 1 to 6 having at least 3 layers of bitumen and of fibres, preferably at least 6 layers of each.
  8. 8. A bituminous composition as claimed in any of claims 1 to 7 wherein each fibre layer is not more than 2 mm thick and each bitumen layer not mdre than 5 mm thick.
  9. 9. A bituminous composition as claimed in any of claims 1 to 8 wherein the weight ratio of bitumen to fibres is from 5:1 to 1:5.
  10. 10. A method of preparing a bituminous composition as claimed in any of claims 1 to 9 comprising bonding together a plurality of sheets of bituminous felt.
  11. 11. A bituminous composition as claimed in claim 1 substantially as described in the Examples.
GB40063/76A 1976-09-27 1976-09-27 Energy absorbing compositions Expired GB1582260A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB40063/76A GB1582260A (en) 1976-09-27 1976-09-27 Energy absorbing compositions
DE19772741262 DE2741262A1 (en) 1976-09-27 1977-09-14 BITUMINOESE MASS SUITABLE FOR ENERGY ABSORPTION
FR7728924A FR2365435A1 (en) 1976-09-27 1977-09-26 BITUMINOUS COMPOSITION ALLOWING TO ABSORB ENERGY, ESPECIALLY KINETIC ENERGY

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB40063/76A GB1582260A (en) 1976-09-27 1976-09-27 Energy absorbing compositions

Publications (1)

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GB1582260A true GB1582260A (en) 1981-01-07

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Application Number Title Priority Date Filing Date
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DE (1) DE2741262A1 (en)
FR (1) FR2365435A1 (en)
GB (1) GB1582260A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8705654U1 (en) * 1987-04-16 1988-08-11 Dr. Kohl GmbH & Cie, Dachbelag- und Bautenschutzmittel-Fabrik, 4270 Dorsten Polymer bitumen membrane

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE505405A (en) *
US2610928A (en) * 1943-08-07 1952-09-16 Carey Philip Mfg Co Mineralized bituminous roofing
US2455923A (en) * 1944-02-04 1948-12-14 Koppers Co Inc Bituminous laminated material
US3536557A (en) * 1967-07-14 1970-10-27 Allen Ind Method of making a composite contoured sound insulating panel
FR2316407A1 (en) * 1975-06-30 1977-01-28 Soprema Usines Alsac Emulsion PROCESS FOR MANUFACTURING A HIGH-STRENGTH ELASTIC SEALING SCREED, AND THUS OBTAINED SCREED

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Publication number Publication date
FR2365435A1 (en) 1978-04-21
DE2741262A1 (en) 1978-03-30

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CSNS Application of which complete specification have been accepted and published, but patent is not sealed