Composites news

COMPOSITES

news

Applications Composite ce~tainers

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Food containers for use in the Swedish Army are being manufactured from a laminate material. The design of the containers provides for an inner and outer unit made of polyethylene and for an insulating layer in between of 25mm polyurethane foam (Fig 1). The material is marketed by Bayer Leverkusen under the trade name Hartmoltopren. The containers made by Grubernes Spraengstoffabriker a/s of Oslo, have a capacity of 13L and are suitable for use as thermos drums.

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Farbenfabriken Bayer ag, LeverkusenBayerwerk, West Germany

Computer room flooring A lanfinate for cladding panels of elevated flooring used in computer rooms and calibration or pharmaceutical laboratories has been introduced by Formica Ltd. Produced in 1.6mm thicknesses the laminate is claimed to double the strength of plywood panels as regards stiffness and wear resistance, whilst providing 8 0 - 100 times the resistance to indentation shown by materials such as linoleum or vinyl tiles. A high

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electrical resistance and therefore a minimal tendency to build up a static field attracting dust and interfering with instrumentation, meets the requirements laid down by computer manufacturers. The laminate has a suede finish giving high reflectance which is diffused to prevent glare (Fig 2). Formica Ltd, De La Rue House, P O Box No 2, 84•86 Regent Street, London WI, England

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GRP bolts A half-inch bolt, manufactured from polyester resin and glass fibre reinforcement is claimed to be corrosion proof and to have good tensile and t~rque strength. The thermosetting moulding compound was specially developed for the purpose. The glass fibre bolts resemble metal ones except that the head is extended to spread the wrenching stresses over a greater area. Glastic Corporation, 4321 Glenridg¢ Road, Cleveland, Ohio, USA

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G RP dome lights A new range of light weight plastic dome lights made from a combination of GRP and wire supported P v c has been introduced by BXL. The lights are made of integral GRP skirts and glazed in Armourbax wire supported clear transparent p v c . The units are delivered ready for installation. The manufacturers claim they are light and easy to handle but strong enough to offer a good degree of security. They should provide years of service with little maintenance. BXL Building Materials, Manningtree, Essex, England

68

COMPOSITESDecember1969

G RP f i l t e r disc An interesting application of glass reinforced pre-impregnated material is the filter disc used in the paper industry for separating water from the pulp shown in Fig 3. The disc is moulded in Flomat, manufactured by Fothergill and Harvey Ltd. In use it is

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Pipe insulation A thermal insulating tape, consisting of an asbestos glove sheath filled with a glass slither insulating medium has been designed by the Bath Iron Works Corporation for use in insulation of small diameter pipe and tubing in ship construction. The manufacturers claim that pipes can be covered faster and more effectively by using this material. The tape is folded over the pipe in a lateral instead of a spiral wrap (Fig 4). It is held temporarily in position by masking tape or tack stitch until it is securely hand sewn by needle and ashestos thread. It is then ready for a finishing coat of paint. The tape is currently being applied ahoard three destroyers of the US Navy. l'he tape is manufactured in

A G R P Celmar tank has been specially designed to store a 14% solution of sulphuric acid at the Earley power station near Reading (Fig 5). This particular material - a polypropylene glass fabric laminate reinforced with polyester glass fibre lay-up

Fothergill and Harvey. Ltd, Littleborough, Lancashire, England

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Sulphuric acid storage tank

fully covered with a special shrunk-on gauze. This is seen in the left hand portion of the photograph. The gauze allows the water to flow down through the channels seen in the right hand portion.

twenty-five foot lengths and according to Bath Iron Works, is more adaptable than conventional sectional-moulded covering particularly around curves where the moulded covering must be cut to fit and mitred as well as cemented" at joints. The sheath is woven of ASTM Grade AA asbestos yarn (90% asbestos). The outer side of the sheath is close textured to make it a better recipient of paint while the inner side has an open sheath to facilitate overlapping of the pipe. The manufacturers claim that this style is more durable and resistant aboard ship especially in areas along passage ways and bulkheads where pipe covering is subjected to hand holding.

was selected because the excluded polypropylene lining is highly resistent to corrosive chemicals and its h o m o genous character prevents the formation of pin holes which would allow the liquids to seep out. The tank has the capacity of 455L and contains a mixture of water with 14% sulphuric acid. Two GRP ribs are supported on the fixed section and they carry the electric motor for the agitator inside the tank. A water gauge is fitted outside the tank for its full height. Concentrated sulphuric acid is fed in from a small reservoir tank. A n o t h e r tank of 682L (150 pal) capacity is awaiting installation. This is heated by two thermostatically controlled emersion heaters and will maintain a solution of caustic soda at a temperature of 65°C. All pipe connections have flanged joints. The plant of which these tanks form a vital part, handles some 100,000L (22,000 Pal) o f Thames river water per day to feed the massive boilers. A 1.5 to 2.5 make-up of distilled water is made to replace losses in the system. The incoming water is given lime soda treatment, filtered through sand and followed by a simple mixed bed demineralisation process involving the use of the sulphuric acid solution from the tank already installed. 5

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Bath Iron Works Corporation, Bath, Maine, USA

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COMPOSITES December 1969

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The caustic soda used in this process is at present contained in an iron tank. Organic molecules in the river water tend to foul the filter systems and it is necessary to d e a n the media with a hot brine wash. Although caustic soda does not attack iron, the brine washing does and the resins can become contaminated with iron. It is for this reason that the new tank will be installed.

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British Celanese Ltd, Chemicals a n d Plastics Group, 345 Foleshill Road, Coventry, Warwickshire, England

ESRO- l b satellite launched

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The European Space Research Organisation announced the successful launch of ESRO-Ib on October 1st in California• The satellite is designed to study ionospheric and auroral phenomena (Fig 6). The construction is based on a right circular axial thrust cone o f magnesium alloy to which are attached four vertical, aluminium-cladded, honeycomb instalment panels mounted at right angles to carry experiments and subsystems. Four upright Iongerons are attached to the outer edge of the instrument panels and to a magnesium alloy equatorial ring. These carry the eight cylindrical honeycomb skin panels and the end caps. The $44 detectors are mounted on glass fibre telescopic booms and reach out 1.25m on each side of the Z axis.

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Design Testing honeycombs A technique which can be used to produce images of defects in materials • such as aluminium honeycomb, carbon/carbon composites, stainless steel which is bonded to glass and other materials has been developed by Battelle-Northwest scientists for the United States A t o m i c Energy Commission. The new technique can be used to test large areas more rapidly than is possible with any present nondestructive testing methods. Approximately three seconds is required to test aluminium honeycomb panels regardless of their size.

70

COMPOSITESDecember1969

The technique uses a type of thermal transducer which is capable of produci'ng images of bond defects and thermal property differences within test specimens. Applications of this technique have been demonstrated in testing the bond and glue-line thickness of aluminium h o n e y c o m b panels, testing of bonds in nuclear fuel elements, location of voids in graphite, testing of bonds between thin coatings and substrates and measurement o f their thermal properties. The transducer is constructed by coating a thin conductive layer with a dielectric material. This layer is placed in contact with the test specimen and light pressure is applied uniformly over its entire area. Heat is generated by passing an electrical current througll

the conductive layer and the temperature distribution within the layer• is scanned. This temperature distribution is used to form an image of defects within the test specimen. Two methods for eliminating the effects o f variations in the coupling between the transducer and test specimen have been developed. Battelle Memorial Institute, Pacific Northwest Laboratory, PO Box 999, Richland, Washington 99352, USA

Filament winding machine A filament winding machine designed to strengthen plastic piping has been designed by Stanford Plastics. The process winds glass fibre reinforcement impregnated with polyester resin around plastic pipes.

The pipe is strengthened by increasing its longitudinal stiffness, hoop strength and bursting pressure. It does not significantly affect the weight of the pipe. The machine is about 21m long and is entirely automatic. 32m lengths of piping are fed into the equipment at one end and proceed through it without rotating. Longitudinal and helical glass roving reinforcement give a combination of strength and weathering properties to the laminate. The resin- is a Crystic material supplied by Seot{-Bader. Immediately the strengthening has been applied to the outside surface of the tube it is wrapped in tape so it can be handled immediately by hand. 1 4 5 - 730m per hour can be fed through the machine. A four speed gear box permits the amount of glass reinforcement applied by rotating heads to be varied to suit individual customer requirements. The weight per metre run compared with steel shows a dramatic reduction. A 114mm bore plastic pipe reinforced for a working pressure of 3447 x 103N/m ~ would weigh 0.7kg against 5kg for the equivalent steel pipe. The manufacturers intend to reinforce Im bore piping with corresponding increase in the working pressure from 5170 x 10 ~ N/m ~ as soon as possible. Stanford Plastics, Billingshurst, Sussex, England

Structural exhibition building the span was l$m (SOft). Each basic module is 7.6m (2$ft) long x l.Sm (5ft) wide and weighs approximately 82kg (1801b). The entire building was emoted by three men in two days (Fig 7).

A glass fibre reinforced plastics building was erected for the Institute of Baths Management Exhibition at Torquay. The exhibition was held from September 30th to 3rd October of this year. The blue and white building of folded plate design was moulded by Anmac Ltd using Crystic polyester resin reinforced with glass fibre. The overall length was 24.38m (8Oft), and

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Materials GRP b o o k l e t

A well illustrated booklet covering the use of polyester resin for glass fibre reinforced plastics has been issued by Scott Bader Limited. The booklet covers a wide area of G R P application. They include vehicles, buildings, chemical plant structures, ships, hovercrafts and aerials. Scott-Bader also show that these materials can be used by the artist. Fig 8 shows a statue depicting fibre reinforced plastics. The statue was sculptured by Peter. Perry and is .qtuated above the entrance to the Scott-Bader polyester technical service laboratories at Wollaston. Scott-Bader and Company Ltd, Wollaston, 'Wellingborough, Northamptonshire NN9 7RL ' England

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Dry-bearing material A unique PTFE lubricated laminate has been developed by the Tribology Research Unit o f the Tufnol Laboratories. They claim this is a technical achievement in the development of low cost, high performance, dry-bearing materials. The new laminate is claimed to combine the mechanical strength, rigidity, wear resistance, easy machining and dimensional stability o f Tufnol laminates with the inherent self lubricating properties and low coefficient of friction associated with PTFE. It iS available in sheet form only but tubes and rods will be a d d e d to the range shortly. The material, Fluon - ICI's PTFE is dispersed throughout and not as a coating or in layers. When components are machined the lubricity is always present at the bearing surface. The manufacturers claim that the material achieves low wear rate, elimination o f running-in period and a long bearing life at low cost compared with other

types of dry bearing materials. The new bearing material has many potential applications. The manufacturers suggest household appliances, m o t o r vehicles, aircraft, fans and meters. Wherever there are rotating or oscilating parts there are possible applications for this long life, noncontaminating, silent running, drybearing material. Tufnol Ltd, Perry Barr, Birmingham 22B, England

Metal matrix process A process incorporating the simultaneous electro-deposition of aluminium and refractory fibres can produce complicated metal matrix composites claim the developers, General Electric C o m p a n y . . T h e reinforcing fibres can be graphite, silicon carbide or alumina whiskers. Graphite is preferred because it is electrically conductive. The electroplating bath is aluminium chloride in pure ether, and the

anode is alumumitlm. The cathode is in a form of the desired finislied product. A current dissolves the anode and with the aluminium ions in the bath, and the fibres, they move to the cathode and coat it. Fibres are kept dispersed in the electrolyte by ultrasonic vibration. As they have no electric charge they move to the cathode with the aluminium ions. The finished electroforms take the shape of the cathode which is removed when the plated coating is thick enough. The process is carried out at room temperature and atmospheric pressure.

Asbestos sheet jointing A soft asbestos sheeting for low to moderate pressu{es has been introduced by Richard Klinger Ltd. The material, Klingerpac is available in three grades and is claimed to be easy to handle and to display remarkably tough properties. It consists ofashestos fibre bonded with synthetic rubber

BRADLEY 8 TURTON LIMITED - - t h e press manufacturer with the proven range of presses for

CARBON FIBRE COMPOSITES 10 to 4 0 0 Ton machines now regularly producing a variety of Composite Components

Caldwall Works, Kidderminster, England. Tel. 2217/8

the people who know about presses 72

COMPOSITESDecember1969

binder. The process ensures that the asbestos fibre throughout the sheet is coated with the binder, thus minimising the possibility o f fibre becoming detached and contaminating the contained media. High compressibility together with relatively high recovery enables the gasket to form readily and compensate for imperfections in flange faces. The manufacturers claim that Klingerpac will often cure leakage problems in gaskets with widely spaced bolts. It is also claimed to be soft enough to replace rubt~er or cork composition gaskets yet has the toughness and durability of an asbestos material. The material produced is continuous rolls. The standard thicknesses available are 1.59mm (1/16in), 0.79m (1/32in) and 0.4 (1/64in). Richard Klinger Ltd, Klingerit Works, Sidcup, Kent

Table 1

NEMA grade

The report L15-1969 entitled NEMA temperature indices of industrial thermoset laminates, has just been issued. It concerns a 4-year thermal ageing programme for industrial thermoset laminates based on a test programme carried out at the NEMA industrial laminate R and D facility located at the University of Delaware in co-operation with Underwriters Laboratory Incorporated on thermal classifications or indices (general ternperature ratings) of industrial sheets, rods, and tubes (rolled and moulded) (Table I). A basic objective of the programme was to develop engineering information which would assist the user in the selection of the proper NEMA grade of thermoset laminate best suited for use in electrical insulation systems and products which may operate at higher than room temperatures. Hitherto, the design engineer has not had such industry information available based on actual tests. All characteristic measurements were ' m a d e at room temperature. The time at which 50% degradation occured was considered the end-point for the temperature. The report is available from the National Electrical Manufacturers Association, 155 East 44th Street, New York, New York 10017, USA

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COMPOSITESDecember 1969

thickness (in)

Base material Paper

Resin

X XP ,XPC XX

Paper Paper Paper

Phenolic Phenolic Phenolic ;Phenolic

XXP

Paper

Phenolic

XXX

Paper

Phenolic

XXXP XXXPC C

Paper Paper Cotton fabric

Phenolic Phenolic Phenolic

CE L LE

Temperature indices o f laminates

Mechanical test index (flexural (electric strength) • * strength)** Electrical

Nominal

Cotton fabric Cotton fabric Cotton fabric

Phenolic Phenolic Phenolic

A

Asbestos paper Phenolic

AA

Asbestos fabric Phenolic

G-3

FR-2

Continuous filament glass cloth Continuous filament glass cloth Continuous filament glass cloth Continuous filament glass cloth Continuous filament glass cloth Continuous filament glass cloth Paper

FR-3

Paper

FR-4

Continuous filament glass cloth Continuous filament

G-5

G-7

G-9

G-10

G-11

FR-5

Phenolic

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1/32 and over 1/32 and over 1/32 and over 1/32 - 1/16 1/16 and over 1132- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32 and over 1/32 and over 1/32- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32- 1/16 1/16 and over 1/32 and over

test index

130 130 130 130 140 130 140 130 140 125 125

130 130 130 130 140 130 140 130 140 125 125

85

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115

125

85

85

115

125

85

85

115

125

85

85

115 140 155 140 155 140

125 140 155 140 155 170

Melamine 1/32 and over

140

Silicone

220

1/32 and over 170

Melamine 1/32 and over

140

Epoxy

1/32 and over 130

140

Epoxy

140 1/32- 1/16 1/16 and over 170

160 180

75 Phenolic 1/32- 1/16 1/16 and over 105 90 1/32- 1/16 Epoxy 1/16 and over i 110 Epoxy 1/32 and over i130

75 105 90 110 140

Epoxy

160 180

1/32 - 1/16 140 1/16 and over 170

• Not recommended for electrical application at elevated temperatures "" Based on a reference standard for XXXPC " ' ' 1 / 3 2 in = 0.794 ram. 1/16 in = 1.588 mm.

ASTM task group

fumes from the Kjeldahl digestion process used to determine the organic nitrogen content in samples of river water at the Trent River Authority's analytical laboratories in Nottinglaam The manufacturers claim that theae fans were chosen for the laboratory because the materials used have a high resistance to severely corrosive inorganic gases and organic solvents. The fan impeller is a homogenous casting of epoxy resins, and the fan housing is moulded from polyester resins reinforced with glass fibre. Both materials are thermosetting and remain unaffected by temperatures up to 120°C. A resistance to high temperature is important in this particular

application because the fan extracting from the Kjeldahl unit has also to extract the heat applied to the flask containing the samples• The manufacturers claim that once the fans are installed they require little maintenance because captive inserts are used and no metal parts are in contact with the fumes. The motor shaft is protected by seals. Bri-glass fans are made with impeller diameters of 229, 304, 381 and 457mm (9, 12, 15 and 18in).

GRP Antarctic laboratory building

fabricated glass fibre laminated panels supported by a steel frame on concrete piers. To prevent fine snow particles from being blown into the building and causing damage to equipment and discomfort to the base personnel all the joints between the panels a r e sealed with vinyl tape. The tape is a self-adhesive tape manufactured by Rotunda Ltd. The base team report that the building has remained wind and weather-proof throughout the long winter blizzards (Fig 9).

The first meeting of the American Society for Testing and Materials new Task Group on laminated composite materials was held on October 27th at the Sheraton-Cadillac Hotel in Detroit, Michigan. The task group is under the jurisdiction of the sub-committee on inorganic matrix composites of committee D-30 on high modulus fibres and their composites and will be meeting in conjunction with them. The purpose of the group is to develop research and testing techniques for laminated composite materials such as roll-bonded, diffusionbonded, and flake-reinforced metallic laminates.

British Fan and Electric Co Ltd, 728 London Road, High Wycombe, Buckinghamshire, England

American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103, USA

Glass reinforced gypsum A one-day seminar on the new system of glass reinforced gypsum partitions was held at the Building Research Station on the 12th November. Of particular interest to materials producers and systems users, the seminar offered lectures on the properties of glass reinforced gypsum as a material, on designing to a performance specification and on the fabrication techniques used to produce the components of the system. A film was shown of the method of erection of the partitioning system and a practical demonstration was given of the measurement of the sound transmission of a wall built with the system. Delegates were able to see a section of a typical school decorated and furnished, built using the GRG system.

Signey Island is one of the six bases maintained in the Antarctic by the British Antarctic Survey. The survey is responsible for all the UK activities in the British sector of the south polar continent. All living and laboratory accommodation at these bases is specially designed and insulated to withstand the severe climatic conditions in an area where temperatures well below freezing point and 100mph winds are common. The specially designed two storey laboratory and living hut on Signey Island is entirely constructed of pre-

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Three British river authorities are now using resin based centrifugal fans especially developed to extract corrosive fumes given off during laboratory tests. The Bri-glass fans were nLide by British Fan and Electric Co I.td. A 381ram (15in) fan has been installed to extract sulphuric acid

COMPOSITES December 1969

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