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Effects of prepreg ageing and post-cure hygrothermal conditioning on the mechanical behaviour of carbon-fibre epoxy laminates
Literaturesurvey The literature survey is prepared b> M. R. Alexander, J. Collins, J.D. Hague and A.J. Hosty, of the liniversity of Shqffield. UK
Matrix,‘reinforcement wave consolidated with SIC
Characterisation membranes
of polyurethaneurea
composite
Dimov. A.. Stoyanova. M.. Petrov, S. and Tsevi, R. Polwrer Contrtrrrrricclfions Vol 31 No 8 (1990J PJI 317-319 A thin-film composite membrane was constructed by dip-coating polyurethane onto a fnely porous ultrafiltration membrane. The resultant composite exhibited a high water permeability. The influence of preparation conditions on the water permeability and rejection was investigated. Heat treatments and their eflect on the membrane properties were also investigated. Self lubricating polymer transfer film lubrication
Fusard.
composites for space
R. L. Trihology
NO 2 (1990)
and polymer applications
Inrerrulrional
Vol 23
pp IOj-122
This paper reviewed the mechanisms of composite lubrication and wear, transfer film lubrication and wear. The advantages and disadvantages of polymers in space were discussed along with the relevant variables. Current space tribology applications were outlined.
METAL
MA TRICES
The e&t of matrix fracture in Ti-6Al-4V
Loretto.
M.H.
TrunsucGons 1579- I589
reinforcement reaction base composites
and Konitzer,
D.G.
A
No
Vol
21A
on
iZleral/ttrgica/ 6
( 1990)
pp
The yield stress, tensile strength and ductility have been ascertained in tension for composites of 10% TIC or Sic fibres and the matrix alloy Ti-6AI-4V at room and elevated temperatures. This behaviour was interpreted in terms of analysis of the reaction zones and failure mechanisms by SEM and TEM. The failure at room temperature for the TiC composite was by failure of the reinforcement, while for Sic failure occurred by embrittlement and fracture of the matrix leading to fracture at the Fibreireaction zone interface. At 760°C fracture was controlled by failure in the fibres for both cases. Voids are found in the TiC and at the interface in Sic.
Composites
Manufacturing
December
1990
interactions aluminide
Rhodes, C.G., Vassilou, M.S., and Spurling. R.A. Metullurgicul A Vol JIA
GENERAL
titanium
No 6 ( 19901
in shockreinforced
Mitchell,
M.R.
Trunsucrions pp 1589-1593
Explosive shock wave consolidation was utilized to form a composite from gammaphase titanium aluminide and particulate Sic. During the consolidation the surface of the titanium aluminide powder melts and reacts with the SIC. Titanium silicide and titanium carbide are formed in the reaction zone. depleting it of titanium. Reaction Nb,SiC
Baumann.
zone microstructure composite
S. F., Brindley,
in a Ti,AI
P.K. and Smith,
Metcdlurgicul Trutwctiotls (1990) pp 1559-1570 -
A
Vol
2IA
+
S. D. No
6
The interracial reaction zone was studied in a Ti-ZSAI-l3Nb matrix/Sicfibre composite fabricated by vacuum hot pressing alternate layers of alloy powder cloths and mats of unidirectional Sic fibres. Analysis was carried out using SEM and analytical TEM. The matrix had reacted only with the carbon-rich outer surface of the libres and formed two concentric zones of differing carbon concentration. Some microporosity and beta-phase depletion were also found. A study of fibre-reinforced
the reaction zone in a titanium alloy composite
Das. G. Merullurgical Tramactions No 6 (1990) pp 1571-1578
SIC
A Vol2IA
The reaction zone in an alpha-phase titanium alloy reinforced with coated Sic libres fabricated by hot isostatically pressing a mild steel can of alloy powder and Fibres was studied using SEM. TEM, K-rays and scanning Auger microscopy (SAM). SAM revealed a high oxygen concentration and a non-stoichiometric amount of carbon in the SIC fibres. The reaction zone consisted of fine recrystallized grains containing both TiC and TiSi, and was thought to involve simultaneous consumption of fibres and matrix. Voids were found in the reaction zone. Dislocation pile-up and matrix hardening were found adjacent to the reaction zone.
RESIN MATRICES
A basic theory of reinforcement fibrous composites
Wilczynski, Technology
A. P. Vol38
Composites No 4 (1990)
for unidirectional
composites. The author states that comparison of this theory with experimental data shows that the proposed theory predicts rigidity constants of the material with sufficient accuracy for both practical and theoretical applications. This leads the author to the supposition that stressconcentration predictions may be of the same value, giving together a useful tool for dimensioning structures or for optimizing the material itself.
The effect of cooling fracture in IM6,‘PEEK
Cantwell, Composite 151-171
W.J.,
Davies,
Srructures
rate on deformation composites
P. and Kausch,
and
K.K.
Vol 14 .Yo 2 ( 1990)
pp
This work examines the influence of cooling rate on the shortand long-term creep properties of IM6;PEEK. Extensive use of differential scanning calorimetry, optical and scanning electron microscopy was made in order to study the influence of this processing parameter in detail. Tests have shown that below the glass transition temperature of the PEEK matrix, the tensile mechanical properties of the composite are not influenced by the microstructure of the matrix. but, above the T,. varying the degree of crystallinity results in a change in the shortand long-term properties of the composite. Slower cooled laminae had a superior ultimate stress and an improved creep resistance. Optical micrographs indicate that fast-cooled laminae incurred considerably more internal cracking and delamination during the course of testing. It is believed that such volume damage results from thermal strains induced by rapid cooling. Therefore, it is suggested that fast cooling. a procedure that is used to control the level of crystallinity, may be more detrimental to the mechanical properties than slow cooling.
Effect of recycling on the mechanical properties of wood fibre-polystyrene composites. Part I: Chemithermomechanical pulp as a reinforcing filler
Maldas. Vol II
D. and Kokta. No 2 ( 1990)
B.V. Polwer pp 77-83
Composites
Composites were constructed from high impact polystyrene and hardwood aspen fibre (chemithermomechanical pulp. CTMP). Mechanical properties and dimensional stability under extreme conditions were investigated for the original polymer, composite. rmycled composite and treated composites lcouphng agents and polvmer-coated tibres). Recycled composites exhibited little or no deteriation in performance compared with original composites and treated composites showed improved properties under all environmental conditions.
Science and pp 327-337
This paper proposes algorithms to obtain analytical results for a simple theory of reinforcement suitable for polymeric fibrous
Effects of prepreg ageing and post-cure hygrothermal conditioning on the mechanical behaviour of carbon-fibre eposy laminates
263
Akay. M. Composites vat
38 NO 4 (1990J
Science and Technolog?, pp 359-370
This paper describes the results obtained from unidirectional carbon-fibre ‘epoxy prepregs with known out-of-fridge times, as cured. and after hygrothermal conditioning. It was found that ageing times of almost twice handling life caused slight variation in relaxation-transition behaviour but had no significant effect on flexural, ILSS, compressive and impact properties tested at room temperature. Hot/wet conditioning affected failure modes and caused a constant level of deterioration in mechanical properties over the prepreg out-time range. Moisture plasticization also reduced the glass transition temperature by 50°C. A model for the thermal and chemorheological behaviour of thermoset processing: (II) unsaturated polyester based composites
Kenny, J.M., Matfezzoli, A. and Nicolais, L. Composites Science and Technology 4 (1990) pp 339-35s
Vol38
No
The authors develop a computer program which usesthe heat transfer and heat generation characteristics of polymerizable systems to analyse rheological and thermokinetic aspects of the cure of unsaturated polyester-based composites. The temperature and extent of reaction profiles, calculated according to an appropriate kinetic and heat transfer model, have been used to predict the corresponding viscosities by an empirical model. A commercial polyester system commonly used in resin transfer moulding has been characterized by differential scanning calorimetry and dynamic viscosity measurements and the results processed
to produce corresponding sub-models. Experimental temperature p’ofiles measured during the processing of the systems studied are compared with theoretical values obtained from the master model. Press-forming thermoplastic
of continuous-fibre-reinforced composites
Manson, J.-A. E., Schneider, T.L. and Seferis, J.C. Polymer Composites Vol I I No 2 ( 1990)
Fracture mechanics and electron microscopy showed that crack initiation was the major energy absorption mechanism during brittle fracture, whilst crack propagation was dominant in ductile fracture. The extruded composites exhibited anisotropy. Self-vulcanizable and miscible blend system based on epoxized and polychloroprene
ternary natural
rub&r rubber
pp 114-120
Alex, R., De, P.P. and De, K.D. Polymer
Continuous fibre-reinforced polyetheretherketone (PEEK) laminates were processed by press forming at high production rates. Degree ofconsolidation, compaction and tibre/matrix uniformity were assessed by calorimetry, density measurements, microscopy and fracture toughness measurements for the variables cooling rate(0.3- 120°C min-‘)andannealing temperature ( 177 and 300°C). The importance of a uniform pressure distribution over the laminate for void-free and homogeneous laminates was demonstrated.
Communicalions 366-368
Epoxidized natural rubber was incorporated into the immiscible blend of carboxylated nitrile rubber and polychloroprene rubber. This resulted in a miscible ternary blend which was self-vulcanizable without the need for a vulcanizing agent. The properties of the moulded blend reported were similar to those of conventional rubber vulcanizates.
Processing, microstructure in short-fibre-reinforced composites
Pukanszky, B., Tudos, F., Kolarik, J. and Lednicky, F. Polymer Composites Vol I1 No 2
Wu,G.M.
and failure hehaviour poly(ether ether ketone)
(1990)
and Schultz, J.M. Polymer
Vol II No 2 (19901
Ternary composites and filler: analysis
Camposires
pp 126-132
Compression and extrusion moulded plaques ofshort fibre-reinforced PEEK composites were produced under the same thermal history. For compression mouldings, the tibre exhibited in-plane random orientation, whilst for extrusions a characteristic injection-mouldingstyle three-layer orientation was achieved.
Vol
31
No
9 (1990)
of polypropylene, of phase structure
pp
elastomer formation
pp 98-104
Morphology and properties of polypropylene, ethylene-propylene-diene terpolymer and filler composites were investigated. Two possible structures were formed, either a separate dispersion of the components or encapsulation of the filler by the elastomer. The latter was shown to be thermodynamically favourable and its formation depended upon the relative magnitude of adhesion and shear forces.
BONDING AND REPAIR OF COMPOSITES II 12th and 13th March 1991 Hotel International
Zurich, Switzerland
An International Conference organized jointly by Rapra Technology Limited and Butterworth-Heinemann Limited - e For further details contact: Kay Royle, Rapra Technology Limited, Shawbury, Shrewsbury, Shropshire SY4 4NR, UK. Tel: (0939) 250383.Telex: 35134. Fax: (0939) 251118.
264
Composites
Manufacturing
December
1990
Matrix,‘reinforcement wave consolidated with SIC
Characterisation membranes
of polyurethaneurea
composite
Dimov. A.. Stoyanova. M.. Petrov, S. and Tsevi, R. Polwrer Contrtrrrrricclfions Vol 31 No 8 (1990J PJI 317-319 A thin-film composite membrane was constructed by dip-coating polyurethane onto a fnely porous ultrafiltration membrane. The resultant composite exhibited a high water permeability. The influence of preparation conditions on the water permeability and rejection was investigated. Heat treatments and their eflect on the membrane properties were also investigated. Self lubricating polymer transfer film lubrication
Fusard.
composites for space
R. L. Trihology
NO 2 (1990)
and polymer applications
Inrerrulrional
Vol 23
pp IOj-122
This paper reviewed the mechanisms of composite lubrication and wear, transfer film lubrication and wear. The advantages and disadvantages of polymers in space were discussed along with the relevant variables. Current space tribology applications were outlined.
METAL
MA TRICES
The e&t of matrix fracture in Ti-6Al-4V
Loretto.
M.H.
TrunsucGons 1579- I589
reinforcement reaction base composites
and Konitzer,
D.G.
A
No
Vol
21A
on
iZleral/ttrgica/ 6
( 1990)
pp
The yield stress, tensile strength and ductility have been ascertained in tension for composites of 10% TIC or Sic fibres and the matrix alloy Ti-6AI-4V at room and elevated temperatures. This behaviour was interpreted in terms of analysis of the reaction zones and failure mechanisms by SEM and TEM. The failure at room temperature for the TiC composite was by failure of the reinforcement, while for Sic failure occurred by embrittlement and fracture of the matrix leading to fracture at the Fibreireaction zone interface. At 760°C fracture was controlled by failure in the fibres for both cases. Voids are found in the TiC and at the interface in Sic.
Composites
Manufacturing
December
1990
interactions aluminide
Rhodes, C.G., Vassilou, M.S., and Spurling. R.A. Metullurgicul A Vol JIA
GENERAL
titanium
No 6 ( 19901
in shockreinforced
Mitchell,
M.R.
Trunsucrions pp 1589-1593
Explosive shock wave consolidation was utilized to form a composite from gammaphase titanium aluminide and particulate Sic. During the consolidation the surface of the titanium aluminide powder melts and reacts with the SIC. Titanium silicide and titanium carbide are formed in the reaction zone. depleting it of titanium. Reaction Nb,SiC
Baumann.
zone microstructure composite
S. F., Brindley,
in a Ti,AI
P.K. and Smith,
Metcdlurgicul Trutwctiotls (1990) pp 1559-1570 -
A
Vol
2IA
+
S. D. No
6
The interracial reaction zone was studied in a Ti-ZSAI-l3Nb matrix/Sicfibre composite fabricated by vacuum hot pressing alternate layers of alloy powder cloths and mats of unidirectional Sic fibres. Analysis was carried out using SEM and analytical TEM. The matrix had reacted only with the carbon-rich outer surface of the libres and formed two concentric zones of differing carbon concentration. Some microporosity and beta-phase depletion were also found. A study of fibre-reinforced
the reaction zone in a titanium alloy composite
Das. G. Merullurgical Tramactions No 6 (1990) pp 1571-1578
SIC
A Vol2IA
The reaction zone in an alpha-phase titanium alloy reinforced with coated Sic libres fabricated by hot isostatically pressing a mild steel can of alloy powder and Fibres was studied using SEM. TEM, K-rays and scanning Auger microscopy (SAM). SAM revealed a high oxygen concentration and a non-stoichiometric amount of carbon in the SIC fibres. The reaction zone consisted of fine recrystallized grains containing both TiC and TiSi, and was thought to involve simultaneous consumption of fibres and matrix. Voids were found in the reaction zone. Dislocation pile-up and matrix hardening were found adjacent to the reaction zone.
RESIN MATRICES
A basic theory of reinforcement fibrous composites
Wilczynski, Technology
A. P. Vol38
Composites No 4 (1990)
for unidirectional
composites. The author states that comparison of this theory with experimental data shows that the proposed theory predicts rigidity constants of the material with sufficient accuracy for both practical and theoretical applications. This leads the author to the supposition that stressconcentration predictions may be of the same value, giving together a useful tool for dimensioning structures or for optimizing the material itself.
The effect of cooling fracture in IM6,‘PEEK
Cantwell, Composite 151-171
W.J.,
Davies,
Srructures
rate on deformation composites
P. and Kausch,
and
K.K.
Vol 14 .Yo 2 ( 1990)
pp
This work examines the influence of cooling rate on the shortand long-term creep properties of IM6;PEEK. Extensive use of differential scanning calorimetry, optical and scanning electron microscopy was made in order to study the influence of this processing parameter in detail. Tests have shown that below the glass transition temperature of the PEEK matrix, the tensile mechanical properties of the composite are not influenced by the microstructure of the matrix. but, above the T,. varying the degree of crystallinity results in a change in the shortand long-term properties of the composite. Slower cooled laminae had a superior ultimate stress and an improved creep resistance. Optical micrographs indicate that fast-cooled laminae incurred considerably more internal cracking and delamination during the course of testing. It is believed that such volume damage results from thermal strains induced by rapid cooling. Therefore, it is suggested that fast cooling. a procedure that is used to control the level of crystallinity, may be more detrimental to the mechanical properties than slow cooling.
Effect of recycling on the mechanical properties of wood fibre-polystyrene composites. Part I: Chemithermomechanical pulp as a reinforcing filler
Maldas. Vol II
D. and Kokta. No 2 ( 1990)
B.V. Polwer pp 77-83
Composites
Composites were constructed from high impact polystyrene and hardwood aspen fibre (chemithermomechanical pulp. CTMP). Mechanical properties and dimensional stability under extreme conditions were investigated for the original polymer, composite. rmycled composite and treated composites lcouphng agents and polvmer-coated tibres). Recycled composites exhibited little or no deteriation in performance compared with original composites and treated composites showed improved properties under all environmental conditions.
Science and pp 327-337
This paper proposes algorithms to obtain analytical results for a simple theory of reinforcement suitable for polymeric fibrous
Effects of prepreg ageing and post-cure hygrothermal conditioning on the mechanical behaviour of carbon-fibre eposy laminates
263
Akay. M. Composites vat
38 NO 4 (1990J
Science and Technolog?, pp 359-370
This paper describes the results obtained from unidirectional carbon-fibre ‘epoxy prepregs with known out-of-fridge times, as cured. and after hygrothermal conditioning. It was found that ageing times of almost twice handling life caused slight variation in relaxation-transition behaviour but had no significant effect on flexural, ILSS, compressive and impact properties tested at room temperature. Hot/wet conditioning affected failure modes and caused a constant level of deterioration in mechanical properties over the prepreg out-time range. Moisture plasticization also reduced the glass transition temperature by 50°C. A model for the thermal and chemorheological behaviour of thermoset processing: (II) unsaturated polyester based composites
Kenny, J.M., Matfezzoli, A. and Nicolais, L. Composites Science and Technology 4 (1990) pp 339-35s
Vol38
No
The authors develop a computer program which usesthe heat transfer and heat generation characteristics of polymerizable systems to analyse rheological and thermokinetic aspects of the cure of unsaturated polyester-based composites. The temperature and extent of reaction profiles, calculated according to an appropriate kinetic and heat transfer model, have been used to predict the corresponding viscosities by an empirical model. A commercial polyester system commonly used in resin transfer moulding has been characterized by differential scanning calorimetry and dynamic viscosity measurements and the results processed
to produce corresponding sub-models. Experimental temperature p’ofiles measured during the processing of the systems studied are compared with theoretical values obtained from the master model. Press-forming thermoplastic
of continuous-fibre-reinforced composites
Manson, J.-A. E., Schneider, T.L. and Seferis, J.C. Polymer Composites Vol I I No 2 ( 1990)
Fracture mechanics and electron microscopy showed that crack initiation was the major energy absorption mechanism during brittle fracture, whilst crack propagation was dominant in ductile fracture. The extruded composites exhibited anisotropy. Self-vulcanizable and miscible blend system based on epoxized and polychloroprene
ternary natural
rub&r rubber
pp 114-120
Alex, R., De, P.P. and De, K.D. Polymer
Continuous fibre-reinforced polyetheretherketone (PEEK) laminates were processed by press forming at high production rates. Degree ofconsolidation, compaction and tibre/matrix uniformity were assessed by calorimetry, density measurements, microscopy and fracture toughness measurements for the variables cooling rate(0.3- 120°C min-‘)andannealing temperature ( 177 and 300°C). The importance of a uniform pressure distribution over the laminate for void-free and homogeneous laminates was demonstrated.
Communicalions 366-368
Epoxidized natural rubber was incorporated into the immiscible blend of carboxylated nitrile rubber and polychloroprene rubber. This resulted in a miscible ternary blend which was self-vulcanizable without the need for a vulcanizing agent. The properties of the moulded blend reported were similar to those of conventional rubber vulcanizates.
Processing, microstructure in short-fibre-reinforced composites
Pukanszky, B., Tudos, F., Kolarik, J. and Lednicky, F. Polymer Composites Vol I1 No 2
Wu,G.M.
and failure hehaviour poly(ether ether ketone)
(1990)
and Schultz, J.M. Polymer
Vol II No 2 (19901
Ternary composites and filler: analysis
Camposires
pp 126-132
Compression and extrusion moulded plaques ofshort fibre-reinforced PEEK composites were produced under the same thermal history. For compression mouldings, the tibre exhibited in-plane random orientation, whilst for extrusions a characteristic injection-mouldingstyle three-layer orientation was achieved.
Vol
31
No
9 (1990)
of polypropylene, of phase structure
pp
elastomer formation
pp 98-104
Morphology and properties of polypropylene, ethylene-propylene-diene terpolymer and filler composites were investigated. Two possible structures were formed, either a separate dispersion of the components or encapsulation of the filler by the elastomer. The latter was shown to be thermodynamically favourable and its formation depended upon the relative magnitude of adhesion and shear forces.
BONDING AND REPAIR OF COMPOSITES II 12th and 13th March 1991 Hotel International
Zurich, Switzerland
An International Conference organized jointly by Rapra Technology Limited and Butterworth-Heinemann Limited - e For further details contact: Kay Royle, Rapra Technology Limited, Shawbury, Shrewsbury, Shropshire SY4 4NR, UK. Tel: (0939) 250383.Telex: 35134. Fax: (0939) 251118.
264
Composites
Manufacturing
December
1990