literature survey I resutvev Prepared by M.E. Adams, R.P. Harrison, M. Mulheron and J.W. Rock

CARBON FIBRES

Analysis of magnetic susceptibility of carbon fibres McClure, J W. and Htckman, B.B. Carbon Vol 20 No 5 (1982) pp 373-378 The trace of the magnetic suseeptibdity of carbon fibres has been calculated assuming the structural model of a very long, longttu- dmally folded, monolayer rtbbons of graphite The results depend strongly on the width of the ribbon, the tightness of the fold and the &stance between the folds

Electron spin resonance and the structure of carbon fibres Breedon Jones, J and Smger, L S Carbon Vol 20 No 5 (1982) pp 379-385 The ESR properties of 3000°C heat-treated fibres derived from mesophase pttch and PAN are measured and compared wtth computer-simulated spectra These spectra were in agreement with the experiment and are said to be useful m the determma- tton of 'single crystalhte' ESR parameters The relattonshlp between ESR and fibre structure is discussed

Inhibition of carbon fibre growth from naph- thalene with halogens Egashtra, M, Katsukl, H., Uchlkawa and Kawasumt S Carbon Vo120 No 4 (1982) pp 283-286 The mfluence of HCI, CI2, Br2 and I2 on the vapour phase growth of carbon fibres from naphthalene was examined at 1100*C with the expectation of a promotwe effect similar to H2S However, the halogen addi- tives were found not to catalyse but to inhibit the growth The mhibttion ts attri- buted to the accelerated decompositton of napthalene into soot-like carbon

The microstructure of intercalated graphite fibres Kwizera, P., Dresselhaus, M S., Uhlmann, D R , Perkins, J S. and Desper, C R Car- bon Vol 20 No 5 (1982) pp 387-399 A study of the mlcrostructure of two types of graphite fibres; GY70, a VAN-based fibre and UC4104B, a pitch-based fibre, is reported. Techniques such as scanning and transmtsston electron microscopy, and small and wt~le angle X-ray diffracuon are used. A higher degree of crystalline order- mg was found for the pitch-based fibres.

Structure and reactivity of carbons: from ear- bon black to carbon composites Donnet, J B Carbon Vol 20 No 4 (1982) pp 267-282 Dealing with various types of carbonaceous materials, carbon blacks, graphites and car- bon fibres, tt Is shown that the chemtcal reactivity of carbon toward oxtdatmn reag-

ents depends primarily on their degree of crystalline orgamzatton The surface energy of carbon materials of dtfferent structures or surface treatment are discussed (George Skakel Memorial Award Lecture, 25th June 1981)

CEMENT MA TRICES

Factors influencing the workability of steel- fibre reinforced concrete - Part I Narayanan, R and Kareem-Palanpan, A,S Concrete (October 1982) pp 45-48 • It is shown that to achteve a workable mix mcorporatmg a large volume fractton of fibres, the sand content of the concrete mix should be as large as possible.

The relationship between tensile and bending properties of non-linear composite materials Laws, V Journal o f Materials Science Vol 17 (1982) pp 2919-2924 The effect of a Wetbull distribution of flaws on the strength of non-hnear composite materials, eg glass-remforced cement, ts outhned It ts then shown that, by comparing the tensile strength measured in dtrect ten- sion wtth that applymg bendmg, it ts posstble to esttmate the ratto modulus of rupture to ultimate tensile strength of such compo- sites

CERAMIC MA TRICES

Discussion of the indentation hardness of a glass-ceramic with particulate microstruc- tare Mlyata, N. and Jmno, H Journal o f Matert- als Science Vol 17 (1982) pp 2693-2699 Pubhshed hardness data for a Zn0-Al203- St02 glass/ceramic, consisting of dispersed gahnite (ZnAl204) crystal particles m a glass mamx, have been interpreted on the basis of a theory for the mdentation hardness of glass matrix partsculate composites. Using th is t h e o r y , the h a r d n e s s of the glass/ceramic, and Its variatton with heat treatment, was m good agreement with that expected from the measured properties and amount of the constituent phases.

Fabrication and properties of model compo- site (fireclay) refractories Chaklader, A.C.D. and Albon, D American Ceramtc Society Bulletin (September 1982) pp 977-981 Commercial size composite refractories were fabricated usmg a superduty fireclay composmon and coal. The brick possessed a porostty gradtent m the transverse direc- tion, hawng a dense hot f a c e - to resist abras ion- and a back-up insulating layer. The measured thermal properties of the bucks agreed well with the values predicted by heat flow analysis

Highly reinforced precast monolithic refrac- tories Lankard, D. R. and Lease, D H. American Ceramtc Soctety Bulletin (July 1982) pp 728-732 Steel fibre addittons to refractory concretes and other monolithtc refractories can pro- vtde stgntficant tmprovements m thetr per- formance A new procedure which mcreases the steel fibre content from 2% to 16%, by volume, is descrtbed. The procedure mvol- yes the mfiltratton of a packed bed of steel fibres wtth a fire-grained refractory slurry Engmeermg properttes are dtscussed

GENERAL

Analysis of cylindrical joints of composite materials for torsional Ioadings Coyle, E J , Crochet, M and Ptpes, R B Journal o f Reinforced Plasucs and Compo- sttes Vol 1 No 3 (July 1982) pp 195-205 A fmlte element model for analysts of axisymmetric and mhomogeneous orthot- roptc shafts of variable cross sectton ts developed and verified A generic torque shaft joint is defined, and then character- ized with a stattsttcal analysts used m con- junction with the fimte element model

Analysis of tubular lap joint in torsion Chon, C.T Journal o f Composite Materials Vol 16 No 4 (1982) p 268 A mathemattcal investtgatton of the stress distribution tn a tubular lap jomt whose adherends are composite materials, was carried out. Variations in parameters such as wrap angles, overlap length and thick- ness of the adhesive layer on the stress concentrattons at or near to the end of the jomt were investigated

Damping characteristics of fibre composites with imperfect bonding Part I - low volume fraction composites Nanda Kishore, N., Ghosh, A., and Agar- wal, B O. Journal o f reinforced Plastics and Composites Vol 1 (1982) pp 40-63 A theoretical investtgatton is presented of the improvement of the damping capacity of low fibre volume fractton composttes by the deliberate mtroduction of slip at the fil- ler/matrix interface. The study first estab- lishes mterface zones at which slip, no,-shp and separation can occur at various loads and precompresstons. Therorettcal loss factors are then calculated for various coefficients of friction at the interface, based on a model of a single mclusion in an infimte matrix

Damping characteristics of fibre composites with imperfect bonding Part H - high volume fraction composites Nanda Kishore, N., Ghosh, A. and Agar-

COMPOSITES . APRI L 1983 163

wal, B O. Journal o f Reinforced Plastics and Composites Vol 1 (1982) pp 64-81 A theoretical method is presented to find the improvement of the damping capacity of high fibre volume fraction composites by the mtroductlon of shp at the fibre/matrix interface The analysts is a modified version of one derived for low volume fraction composites presented by the same authors Under certain conditions the analysts pre- dicts loss factors as high as 0 12

Effects of diffusion and heat transfer in eutectoid solidification Basu, R Journal o f Reinforced Plastics and Composites Vol 1 No 3 (July 1982) pp 270-2 75 A theoretical model is formulated which considers radial as well as umdlrecttonal solute diffusion. It is found that a boundary layer exists where the concentration vanes rapidly from the interface to the steady state value m the fibre The concentration variation takes place wlthm a very small dis- tance, about 10tzm

Effect of transverse shear deformation on anisotropic plate buckling Cohen, G A Journal o f Composite Materi- als Vol 16 No 4 (1982) p 301 The m-plane normal and shear loads of rectangular amsotropic lammmated plates were calculated using the shell code FASOR program Normal buckling loads were ver- ified for simply supported orthotroplc lami- nates with mtdplane symmetry, by a closed- form solution derived from transverse deformation plate theory The results are compared to those previously reported for three dimensional elasticity theory and clas- sical plate theory It is demonstrated that classical plate theory is m error by more than 40cA in shear buckhng, compared to the FASOR program

An explanation for the rate-of-loading and the duration-of-loading effects in wood in terms of fracture mechanics Nadeau, J S , Bennett, R and Fuller J r , E R Journal o f Materials Science Vol 17 (1982) pp 2831-2840 This paper describes a set of experiments m which the kinetics of wood fracture was examined by measuring the rate-of-loading effect m notched and unnotched speci- mens It is shown that the results can be explained by a relatively simple model and mathematical analysts, based on fracture mechanics. According to this model, the delayed failure of wood is caused by sub- critical crack growth

Material characterization by the finite ele- ment method Delcourt-Bon, C R , and Stenne, E Journal o f Reinforced Plastics and Composites Vol 1 (1982) pp 82-91 A Newton-Raphson method, combined with a weighted least mean squares techni- que, is presented to determine the stiffness coefficients of elastic composite materials The exact coefficients are determined using a finite element static analysis of the struc- ture and comparing sucesstve computed displacements to measured displacements Results show that the procedure converges rapidly even for poor starting approxima- tions of stiffness but the technique is sensi- tive to measurement errors.

A micromechanical prediction of elastic properties of composites with spherical par- ticles Lmdeman, Z R , Witemberg-Perzyk, D and Perzyk, M A Journal o f Reinforced Plastics and Composttes Vol 1 (January 1982) pp 3-15 From an analysis of a single spherical elastic inclusion m an elastic body, the stress and strain distribution in a composite material, consist ing of a matrix and regularly arranged spherical particles, is approxi- mated. Calculated values of Young's mod- ulus and Polsson's ratio of such a composite are presented graphically as a function of the elastic properties and concentrations of both composi tes . Good ag reemen t is observed between theoretical calculations and published experimental results

Moving cracks in layered composites Slh, G C , and Chen, E.P. International Journal o f Engineering Scwnce Vol 20 No 11 (1982) pp 1181-1192 The stabll,ty of a crack in the centre layer of a three-layered composite model is anal- ysed using Galilean transformation, Fourier transforms and Fredholm integral equa- tions Dynamic local stress intensities are found to either increase or decrease with crack length, depending on the material properties of the outer layers Results are discussed in terms of the dynamic stress fac- tor and displayed graphically

Optimal study of interface axial shear stres- ses in two-layer axisymmetric shell induced during curing treatment Poe, Y.C and Peterson, K Journal o f Composite Materials Vol 16 (1982) p 204 The axial stresses that arise at the interface of a two-layer shell were studied as a func- tion of ply thickness ratio and fibre orienta- tion, by means of a mechanics of materials approach It was found that the fibre orien- tation substantially affected the interracial shear stress

Orthogonal fibre composites as micro- morphic materials Malcolm, D J International Journal o f Engmeermg Science Vol 20 No 10 (1982) pp 1111-1124 This paper establishes an analogy between a first order mlcromorphlc material and a model of an orthogonally reinforced matrix A simple deformation pattern is assumed and a physical ,nterpretation of all terms in the relative stress and couple stress tensors is g i v e n . A n 8 - n o d e d , 4 - s i d e d lsoparametnc, displacement finite element is developed for plane stress and plane strain and results for a circular hole in a uniform tension field are shown to agree well with exact results for a mlcropolar medium

The room-temperature shapes of four-layer unsymmetric cross-ply laminates Hyer, M W. Journal o f Composite Materials Vol 16 No 4 (1982) p 318 Studies of the four possible stacking sequ- ences, obtained using cross-ply laminates (4 plies) showed that at room temperature there are three possible shapes that a lami- nate may take-up These are a stable cyhn- dncal, a stable saddle and an unstable cyhndncal which snaps through to another unstable cylindrical shape The actual shape

is dependent upon stacking sequence and the ratio of the two major dimensions of the plate A theory for predicting the room temperature shape is developed, and com- parison with a previous theory based upon laminate theory indicates that there is very little difference between the two sets of predicted results

Stiffness and strength behaviour of woven fabric composites Ishlkawa, T and Chou, T - W Journal o f Materials Science Vol 17 (1982) pp 3211- 3220 Three analytical models for the investiga- tion of the stiffness and strength of woven fabric composi tes are presented The 'mosaic model' is used to predict the elastic properties, while the "fibre undulation model' represents the 'knee behavlour' exhibited by plan weave fabric composites The "bndgmg model' simulates the load transfer among the interlaced regions m action composites and explains why the elastic stiffness and knee stress m satin composites are higher than those m plain weave composites

Stress concentration factors for cylindrically orthotropic plates Hoff. N J. and Muser, C. Journal o f Corn- postte Materials Vol 16 No 4 (1982) p 313 A rigorous solution for the stress concentra- tion factors for circular plates of cylindrical orthotropy, with circular holes, when the outer edge is under uniform umaxial trac- tion is presented The formulae may be used to obtain approximate values if the plate is not circular

METAL/VIA TRICES

Analysis of creep for metal matrix compo- sites Mm, B K and Crossman, F.W Journal o f Composue Materials Vol 16 (1982) p 188 The development of a continuum model for the pre&ctlon of the creep behavlour of unidirectional metal-matrix composites is given This is then tested against experi- m e n t a l r e s u l t s o b t a i n e d f r o m a graphlte/alumlnium composite A greater creep rate than predicted was observed, and was thought to be due to the high value of the strain hardening parameter, which had been me asu r ed on unre tn fo rced alumlmum Microscopical examination of the virgin composite revealed microcrack- ing, which was predicted to close at increased temperatures due to the decrease of the damage parameter with temperature

Microstructure of Si3N4-TiNcomposites pre- pared by chemical-vapour deposition Hayashl, S , Hiral, T., Hlraga, K. and Htrabayashl, M Journal o f Materials Sczence Vol 17 (1982) pp 3336-3340 The shape and distribution ot TIN within SI3N4-TIN composites prepared by the chemtcal-vapour deposmon of a S1C14-T1C1 ,- NI-I3-H 2 system was mvestsgated using electron microscopy The TIN dispersion m the amorphous 513N4 matrix was granular with a maximum size of 3 nm; whereas m the u-SI3N4 an average size of 10 nm was observed. TIN dispersions in B-SI3N4 were columnar with a diameter of several nm

164 COMPOSITES. APRI L 1983

having its axis ex tended m the c-ax~s of the B-SI~N4 crystal

On the presence of voids in bronze-route multi-filamentary Nb3Sn superconducting wires Nourbakhsh, S , Haslcek, Y S , Gonnge , M J and Martin, J W Journal o f Materials Scwnce Vol 17 (1982)pp 3204-3210 The effect of the presence of Kirkendall voids on the ductility of commercial super- conducting Nb/Cu-Sn compos, te wires was examined The shape, density and nuclea- tion sites of such vmds in composite wires, and wires of similar goemet ry but different scale, were investigated both exper imen- tally and theoretically. The results indicate that voids have no apparent effect on crack ruination or distribution and do not reduce the ductility of the wire.

Tensile properties of SiC/aluminium filamen- tary composites: Thermal degradation effects Skinner, A , Koczak, M J and Lawley, A Power Metallurgy Internauonal Vol 14 No 3 (1982) p 144 An examination on the thermal degradat ,on of the tensile propert ies of a um&rec tmnal S iC-re inforced a lumin ium meta l -ma t r ix composi te is descnbed . The SiC fibre s trength was found to be unaffected by isothermal exposure at 500 ° for 75 hours Similarly. the room tempera tu re tensile s t rength of the composi tes was also unaf- fected after 150 hours at 500"C However , the loss modulus increased above 201YC indicating matrix softening A study of the fracture morphology revealed that the fibre/matrix bond controlled the failure mode

A unifying strain criterion for fracture of fibrous composite laminates Poe Jr , C C Engtneemng Fracture Mechamcs Vol 17 No 2 (1983) pp 153-171 It has been previously shown that a general fracture toughness pa ramete r Qc was a material constant for centrally cracked b o r o n / a l u m m m m specimens Values of Qc/etuf (where etuf IS the ult imate tensile strain of the fibres) are calculated, and shown to be reasonably constant for a van - ety of composi te materials which did not de laminate or split extensively m the 0* layer at the crack up

RESIN/VIA TRICES

Analysis of bonded repairs to damaged fibre composite structures Jones, R , Callinan, R.J. and Aggarwal, K C Engineering Fracture Mechamcs Vol 17 No 1 (1983) pp 37-46 A finite e l ement method for analysing the behaviour of flaws in thin fibre composi te sheets which are repaired with a bonded overlay is described An example of the repair of a hole of crack in var ious graphi te /epoxy laminates is discussed and it is shown that m each case a bonded overlay of ei ther boron/epoxy or t i tanium provides an effective repair.

Compression-fatigue behaviour of notched composite laminates Walsh J r .R .M. and Pipes, R.B. Journal o f Matermls Science Vol 17 (1982) pp 2567- 2576

The effects of compress ion-compress ion fatigue on graphi te /epoxy laminates con- taming a 6 35 mm diameter circular hole have been investigated Tests on four &f- ferent laminate configurations revealed two modes of compressive failure: diagonal shear (DS) and net compression (Nc) DS was predominant in the f ibre-dominated lami- nates and NC was predominant In the quasHsot rop tc laminates The laminate s tackmg sequence was found to influence both the failure mode and the intraply crack development . The fadure mechan- isms were essentmlly the same for the two materials systems studied (Normco 5208 and 5209)

Detection of moisture in graphite/epoxy laminates by X-ray diffraction Predeckl, P and Barrett , C S Journal o f Compostte Matermls Vol 16 No 4 (1982) p 260 The determinat ion of the moisture content and residual s t resses m graphi te /epoxy laminates by means of X-ray &ffractton is described By placing a layer of a lumlmum powder be tween the first and second plies, the residual stress m the laminate may be moni tored by measur ing the diffraction peak positions of the a luminium A change of 0.624 °+ 0.015°20 was found be tween dry laminates and those that were com- pletely wet at 50°C; this change was revers- able. The authors used the technique to study m m s t u r e content , and anneal ing effects.

Edge effects in uniaxial compression testing of cross-ply carbon-fibre laminates Ditcher, A K and Webber , J P H Journal o f Composue Matertals Vol 16 (1982) p 228 E x p e r i m e n t a l r e su l t s , o b t a i n e d us ing cross-ply carbon fibre laminates (Clba- Gelgy F ibredux 914C-HTS-S p rep reg ) tested in umaxlal compression, are com- pared with theoretical values predicted using a non-hnear laminated plate analysis The existence of edge effects, as pre&cted by the theory, was confirmed exper imen- tally from microscopical examination of par- trolly loaded spec imens No sign of trans- verse cracking or resin crazing was found in ei ther 0 ° or 90 ° plies

The effect of filler-volume fraction and strain rate on the tensile properties of iron-epoxy particulate composites Theocans , P .S , Papanicolaou, G C. and Kontou, E .A Journal o f Reinforced Plastws and Composues Vol 1 No 3 (July 1982) pp 206-224 The stress/strata behaviour of metal-filled polymeric composi tes was s tu&ed at various deformat ion rates. The dependency of the mechamcal propert ies of iron/epoxy com- posites, such as elastic modulus, maximum load, breaking-strain and breaking energy, on the rate of deformation, as well as on the filler volume fraction was studied and found to agree satisfactorily with theoretical results.

Effects of ultra-rme particles on the elastic properties of oriented polypropylene compo- sites Sumita, M., Ookuma, T., Mlyasaka, K. and Ishtkawa,~K.tJournal o f Matertals Science Vol 17 (1982) Isotactlc polypropylene (pv) was filled with varying levels of one of two spherical fillers

(soda-lime glass and SiO2) with d iameters ranging from 40 nm to 125/am. These com- posites were then cold-drawn and the elas- tic propert ies were de te rmined and com- pared with unfilled cold-drawn PV It was concluded that the modulus of the compo- sites was de te rmined by (1) the molecular orientation of the matrix polymer; (2) filler size and volume fraction; and (3) the frac- tion of voids ,ntroduced by drawing The moduh of such composi tes were m good ag reement with values calculated from an equation based on the assumption of the mdependance of the three effects

Electrical permittivity and conductivity of carbon black-polyvinyl chloride composites Chung, K T , Sabo, A and Pica, A P. Jour- nal o f Applied Physics Vol 53 No 10 (October 1982)pp 6867-6879 Electrical conductivity and permltt ivlty were s tud ied over a wide f r equency spect rum (PC - 1.3 GHz). Conductivity increased with higher volume fraction of carbon black, but the rate is different above and below the percolation threshold due to different mechanisms being involved. Bulk electrical permlttwlty was found to increase unti l t he c o m p o s i t e p e r co l a t i o n was reached, after which it decreased to zero after fully connected paths had been estab- hshed The percolation behavlour of spher- Ical carbon blacks was found to show good a g r e e m e n t with B r u g g e m a n ' s effect ive medium theory, m te rms of both the perco- lation threshold and frequency dependence of conductivity at percolation

Graphite/epoxy (+45)s tubes. Their static axial and shear properties and their fatigue behaviour under completely reversed load controlled loading Krempl, E and Nlu, T M Journal o f Com- posite Materials Vol 16 (1982) p 172 The fabrication of ( _+45)s graphite/epoxy tubes with tapered ends, and the special grips developed to hold these tubes are described Measu remen t of the following paramete rs were made , elastic moduli (both tension and compresston), ult imate tensile and compresswe strengths, torsional s t rength, shear proper t ies and fat igue behavlour T ime dependen t behaviour was observed once out of the relatwely small elastic region

The influence of environmental conditions on the vibration characteristics of chopped- fibre-reinforced composite materials Gibson, R F . , Yau, A , Mende , E.W and Oshorn, W E. Journal o f Reinforced Plastws and Composues Vol 1 No 3 (July 1982) pp 225-241 The effects of exposure to elevated t emp- eratures and common au tomotwe fluids on the dynamic stiffness and internal damping of several E-glass /polyester automat ive composite materials was measured . Stiff- ness and damping were measured over the t empera tu re range 200-120°C and during 1000 hour soaking tests m dtstdled water, salt water, motor otl, gasoline and anti- f reeze solutions Wate r was found to have t he greatest effect on dynamic properUes.

Influence of fiber orientation and ply thick- ness on hygroscopic boundary-layer stresses in angle-ply composite laminates Wang, S.S. and Choi, I. Journal o f Compo-

COMPOSITES. APRI L 1983 165

sue Materials Vol 16 (1982) p 244 The determinat ion of complete elastic solu- tions for angle ply composi tes subjected to uniform moisture sorptlon are presented Detai led numerical results of boundary- layer stress singularities and hydroscopic stress dlstrtbutmn are given for ( O, - O, - O, 0 ) graphite/epoxy laminates, with various ply orientations and thicknesses Both vari- ables are shown to have significant effects upon the deve lopment of m-plane and Interlamlnar hydroscopic s tresses

Influence of layer thickness on the strength of angle-ply laminates Herakovlch, C T Journal o f Composue Materials Vol 16 (1982) p 216 A study of the effect of stacking sequence upon the s t r e n g t h and t o u g h n e s s of g raph i t e / epoxy angle ply l amina tes is described An Increase m strength and toughness was found in laminates with alternating layer stacking compared with those with a clustered configuration From an examination of the specimens before and after failure, two of failure mode were found which depended upon the stacking sequence and fibre orientation These fail- ure modes were explained as being due to the magni tude of the lnterlamlnar shear stresses, which are lower in the case of alternating stacking

M o i s t u r e gradient considerations in environmental fatigue of CFRP Edge, E C Journal of Composite Materials Vol 16 No 4 (1982) p 285 A mathemat ica l Investigation into the e f f e c t s of e n v i r o n m e n t a l f a t i g u e is described If the frequency of change of an environmental condition is much greater than expected under service conditions, then it is shown that the amount of damage by moisture will be greater This was found due to different moisture gradients existing in the composite under service conditions, and when environmental ly fatigued

Prediction of the stress-strain curve of a short-fibre reinforced thermoplastic Taya, M and Chou, T W Journal of Mater- lals Science Vol 17 (1982) pp 2801-2808

The prediction of the stress/strain curve of a carbon fibre-reinforced nylon matrix is discussed in the light of three-s tage model The first l inear stage is model led by the elastic deformat ion of the composite Next the initiation of f ibre-end cracks and their subsequent arrest by adjacent short fibres is postulated The third stage deformat ion is model led by the extension of arrested cracks Into the matrix. Close ag reemen t be tween the theoretical predictions and exper imental data are reported regarding the overall non-hnear l ty of the stress/strain curve, the transition s tresses be tween con- secutlve stages, and the failure strain of the composite.

Role of fibre sufrace-matrix combination in carbon fibre reinforced epoxy composites Manocha, L M Journal o f Matermls Scemce Vol 17 (1982) pp 3039-3044 The tensile strength of carbon fibres t reated with nitric acid at different concentrat ions for various t imes are reported and com- pared with values for the unt rea ted fibre Composi tes made with both t reated and unt rea ted carbon fibres In an epoxy matrix, Araldlte LY556, were also tested The ten- slle and flexural s t rengths as well as the fracture behavlour of such composites, indi- cate that physical interlocking be tween the fibres and the matrix yields bet ter proper- ties than purely chemical bonding

Spectroscopic characterization of the matrix-silane coupling agent interface in fibre-reinforced composites Chlang, C -H and Koenig, J L Journal o f Polymer Sczence Vol 20 No 11 (November 1982) pp 2135-2143 The copolymerlzatlon of anhydr ide-cured epoxy resin to glass fibre surfaces t reated with a coupling agent is investigated using Fourier- t ransform infra-red spectroscopy The number of mterfacml bonds formed depends on the amount of sllane coupling agent deposi ted on the glass and the reac- tion conditions. The sllane/resln Interphase is formed by the epoxy resin copolymerlza- tlon with the coupling agent, the in terphase chemically bonds the epoxy matrix to the

coupling agen t - ex t enswe copolymerlzatlon being required for a strong bond.

Strain analysis of dual laminate cylindrical fibre-glass reinforced plastic vessel Hoa, S V Journal of Reinforced Plasncs and Composites Vol 1 No 3 (July 1982) pp 242-253 Stains on a dual laminate glass fibre- reinforced cylindrical vessel were measured at internal pressure up to 0 96 MPa Lami- nate theory was used to calculate the strains which were in reasonable ag r eem en t with exper imenta l values

The strength of the fibre-polymer interface in short glass fibre-reinforced polypropylene Mlttal, R K and Gupta, V B Journal of Materials Science Vol 17 (1982) pp 3719- 3188 In this paper, a method of measur ing the mterfaclal bond strength in well-aligned short glass f ibre-reinforced polypropylene is ou thned The variation of the interfaclal shear stress during the deformat ion process is accounted for and this enables consistent results to be obtained at all values of com- posite strain The influence of fibre orienta- tion is considered using macro-mechanical analyses for stiffness and strength The method and results are compared with those of o ther workers already reported in the l i terature

Structural integrity studies in particulate composites by thermal capacity measure- ments Theocarls , P S , Papanlcolaou. G C and Siderldls, E P Journal o f Reinforced Plastics and Composites Vol 1 (1982)pp 92-105 This paper presents values of the glass transition tempera tures , Tg, for various iron powder/epoxy composi tes as de t e rmined from heat capacity m e a s u r e m e n t s The effect of heating rate. filler volume fraction, and particle d iameter on the measured value of Tg were included In the study Tg va lues were also ob ta ined from TMA measu remen t s and those values are com- pared with those obtained by DSC meas- u remen t s

al flracts oF Abstracts of British Patents are prepared by Dr F.R. Jones, Department of Metallurgy, University of Surrey, UK

UK PATENTS

COMPONENTS

Fibre-resin springs (Celanese Corporation, USA) GB 2 041 152 A (3 September 1980) A coil spring of high strength and low weight comprises a braid of carbon fibres at an angle of *- 45* (with some 0* fibres) The impregnated braid Is wound helically into the groove of a mandrel

Glass-polycarbonate laminate (General Electric Company, USA) GB 2 041 826 A (17 September 1980) Sllane adhesive promotors for the above material are described

Reinforced glass (Cornmg Limited, UK) GB 2 045 161 A (29 October 1980) Glass chemical plant can be protected from Impact damage by a glass fibre-reinforced covering and silicone rubber coating The vessel remains translucent with correct choice of resins

A reinforced, laminated wood panel and a method for producing such a panel (Scla Socleta Compensat l Implallacclature Ed Affml SpA, Italy) GB 2 050 941 A (14 January 1981) A glass f ibre-reinforced UV/Mv/beech- wood laminated burglar and bullet proof door is described

Carbon fibre controls (Chloride Silent Power Limited, UK) GB 2 052 460 A (28 January 1981) A ne ed le -punched-mesophase-p i t ch-based carbon fibre mat is used as the cathode of a sodium/sulphur battery

166 COMPOSITES. APRIL 1983