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A comparison has been made of four prosthetic ligament replacements, in clinical use at the time of this study. The anterior cruciate ligament of 24 rabbits was replaced using either a xenograft, carbon fibre, carbon fibre/polyester composite or polyester composite. At three, six and 12 months the synovium, intraarticular and intraosseous sections of the ligaments were examined. Macroscopic, histological and scanning electron microscope studies revealed little ingrowth, and a significant incidence of rupture intraarticularly. Any ingrowth in the bony tunnels was predominantly fibrous in nature and governed by the design rather than the material from which the replacement was manufactured.

Optimum processing parameters were searched for pilot scale production of woodpolyester composite materials by studying the effect of initiation rate on the curing process. The radiation initiation of the following systems were examined: methyl methacrylate, mixture of styrene and acrylonitrile, and their combinations with unsaturated polyester. In the most cases, the over-all rate of the whole process of polymerization in wood matrix is proportional to the square root of the initiation rate. The most favourable composite was made from a ternary resin based on styrene, acrylonitrile, and unsaturated polyester, which can be cured in the wood with a very low dose. Fur die Bestimmung der optimalen technologischen Parameter der Herstellung von Holz-Polyester-Kompositmaterialien in halbtechnischem Masstab wurde der Effekt der Initiierungsgeschwindigkeit auf den Aushartungsvorgang untersucht. Die strahlenchemische Initiierung der Polymerisation von folgenden Systemen in Holz wurde untersucht: Methylmethacrylat, Gemisch von Styrol und Acrylnitril und ihre Kombinationen mit ungesattigtem Polyesterharz. In den meisten Fallen ist die Bruttogeschwindigkeit der Gesamtpolymerisation im Holz der Quadratwurzel der Initiierungsgeschwindigkeit proportional. Das beste Komposit-System wurde auf der Basis eines Dreikomponentenharzes, bestehend aus Styrol, Acrylnitril und ungesattigtem Polyester, hergestelt. Dieses Dreikomponentenharz kann in Holz mit einer sehr niedrigen Dosis ausgehartet werden.

The measuring of the exothermic effect of a polymerization gives a simple method for monitoring the curing process of unsaturated polyester-monomer mixtures in a wood matrix, or generally in composites. A new approach different from the known methods, is proposed for the evaluation of temperature vs. time records. An exact mathematical interpretation is developed to follow the polymerization process separately from the physical phenomenon of cooling. A practically applicable simple approximation of this treatment is also proposed using the first or even the second derivative of the temperature vs. time curves where the last inflexion point will define the practical end-point of the polymerization. Durch das Messen des exothermen Effektes bei Polymerisationen ergibt sich eine einfache Methode zur Verfolgung des Aushartungsvorganges von ungesattigten Polyester-Monomer-Mischungen in Holz, oder ganz allgemein in Kompositsystemen. Ein neues, von bekannten Methoden abweichendes Verfahren der Auswertung von Temperatur-Zeit-Kurven wird vorgeschlagen. Eine mathematische Auswertung, die es ermoglicht, die Verfolgung des Polymerisationsprozesses von dem physikalischen Phanomen der Kuhlung getrennt durchzufuhren, wurde erarbeitet. Es wurde auch eine andere, einfachere Annaherungsmethode fur die Praxis vorgeschlagen. Bei der Errechnung der ersten und der zweiten Ableitung der Temperatur-Zeit-Kurven wird der praktische Endpunkt der Polymerisation durch den letzten Inflexionspunkt angezeigt.

For the purpose of clarifying the fracture toughness and microfracture mechanism of fiber reinforced plastics composites at cryogenic temperature 4K, fracture toughness tests were performed for a short glass fiber reinforced polyester composite. Acoustic emission signals were also detected during the fracture toughness tests to obtain a reasonable explanation of the microfracture mechanism. The results are summarized, as follows:(1) The maximum load on the load-displacement curve at 4K increases by about three times that at room temperature 297K.(2) The AE activity for the specimen at 4K is extremely higher than that at 297K.(3) The fracture toughness KAE, which is defined as the critical stress intensity factor corresponding to the abrupt increase of AE energy, becomes larger with decreasing temperature below room temperature.(4) The fracture toughness obtained by the 5% offset procedure of ASTM standard does not agree with the fracture toughness KAE.(5) The AE signals were discriminated into two types by the spectrum analysis and the microfracture mechanism was discussed.

The water absorption characteristics of unidirectional glass reinforced vinylester and polyester laminates in distilled water and in 95% relative humidity at 25°C, 50°C, 60°C and 70°C were investigated. The results show that the calculated values and the experimental data agree reasonably well, but deviation occurred at higher temperatures.

A series of polymeric composites were prepared with sand/polyester ratio 92:8%. The sand used was local one. The polymeric composites were tested for their compressive strength, exterior volume, porosity, water uptake, specific gravity, volume of open pores and bulk density. The mechanical properties of these polymeric composites were within the range required for building bricks. No significant differences were observed between the polymeric composites made of glass sand and those from untreated sand except in exterior volume and compressive strength. Medium untreated sand was found to give better results in the mechanical properties.

The major progress in fiberglass-reinforced polyester composites since the 1940s has been attributed to the development of silane coupling agents that improve the bond across the interface [1]. Among the best coupling agents for polyesters is 3-methacryloxypropyltrimethoxysilane (γ-MPS), first described in 1962 (Fig. 1). Other methacrylate-functional silane coupling agents show comparable coupling activity in fiberglass reinforced general purpose polyester composites [2] (Table 1). The bond between glass and polyester with these coupling agents was “perfect,” i.e., fracture surfaces after 2-h water boil showed essentially no interfacial bond failure.

Of a number of methods for testing materials under biaxial stress conditions, the cruciform specimen with tension/compression loading of the arms allows exploration of the whole in-plane failure envelope. This paper highlights the problems arising in the measuring, monitoring and control of strains in cruciform specimens subject to static and cyclic biaxial loading. Three extensometers are described which have been used respectively for testing high strain fatigue in steels, fatigue crack propagation in steels and fatigue and fracture of a glass reinforced polyester composite. Each extensometer uses a full bridge resistance strain gauge circuit; two are based on bending of a beam and the third on deformation of a thin ring. Examples are shown of stress/strain loops for equibiaxial and shear conditions from fatigue tests on a steel and g.r.p.

Work on the axial compression of axisymmetric tubes, to be used in energy absorbing applications, has been extended to cones. This paper describes the results of compression tests on a range of truncated conical shells made from a chopped strand mat glass/polyester material. For cones with a wall thickness greater than 2 mm, failure occurs by progressive crushing which starts at the small end: unlike tubular specimens, no trigger is necessary. The specific energy absorption varies with cone angle, wall thickness and diameter in a complex way, and in some cases exceeds the values recorded for axisymmetric tubes. The crush zone morphology and failure micromechanisms also vary with specimen geometry. An initial assessment has been made of the relationship between energy absorption and failure mode.

The fracture mechanism and fracture toughness of glass-cloth/polyester composite laminate (GPCL) at low temperature (77 °K) were studied by experimental technique. The results show that the fracture toughness of GPCL at 77 °K is much greater than at ambient temperature (300 °K). In addition, the fracture phenomenon of net matrix material and matrix with a few bunches of glass fibers is also researched.

The paper commences with a discussion of the assumptions embodied in the normal method of presenting results of environmental stress-rupture tests. Results are presented from two test programmes on glass fibre-reinforced polyesters: a chopped strand mat laminate in air; and a mixed woven rovings/chopped strand mat laminate in aqueous environments, revealing very large experimental scatter. The author then describes methods which have been employed in an attempt to extract from the data predictions of the long term behaviour of the composites and indications of the environment upon them.

The concept of sandwich constructions offers many advantages for structures where low weight, high strength and high stiffness are required. The complex build-up of sandwich structures makes, however, quality control difficult. Hence, the development of novel, efficient non-destructive testing methods for such structures is vital. In this paper such a method based on thermography is presented. Thermography with an infrared (IR) scanner has been used to detect prefabricated defects within sandwich panels. The sandwich panels had faces of glass/polyester composite laminates (GRP) and a core of rigid cellular PVC foam. Different types of disbonds were simulated, perpendicular and parallel to the faces. All disbonds were successfully detected and it is particularly interesting that a simulated disbond centred in the core, parallel to the faces, was found. Cavities within the core were also simulated and detected.

An attempt has been made to find new uses for natural fibres — one renewable resource which is otherwise under-utilized. The structure and properties of the fibres, and the fabrication and physical and mechanical properties of their polyester-based composites are described. The performance of these composites is evaluated after exposure to indoor and outdoor weathering by both destructive and non-destructive testing methods. The preparation of various consumer articles such as a voltage stabilizer cover, mirror casing, a projector cover and roofing are also reported. This study demonstrates the potential of natural fibres for non-conventional applications and points out some of their limitations.

Work has been done to develop and optimize a procedure for the preparation of electrically conductive exfoliated-graphite filled unsaturated polyester composites. The exfoliated graphite flakes impart excellent electrical properties to the polyester composite. EMI (electromagnetic interference) shielding effectiveness, comparable to that of exfoliated graphite alone, has been observed over a frequency range of 0 to 1000 MHz with composite samples containing as little as 4 weight percent of exfoliated graphite. The resistivities approached the value for exfoliated graphite in the c-direction (0.03 μ-cm) at a graphite loading of 11 weight percent. It has been observed that the mechanical integrity of the composite remained good up to graphite loadings of some 17 weight percent. The polyester readily wets the graphite and penetrates most of the graphite open pore volume during processing. Flow visualization measurements have been made in a transparent compression molding apparatus. No effect of the flow conditions on the apparent electrical properties has been found.

The water absorption of cellulose fibers has been reduced after the cellulose surface was treated by mono- ordi-methylomelamine(DMM) resin. The wet strength of cellulose-polyester composites was also enhanced considerably. Scanning electron microscopy, transmission electron microscopy, and electron spectroscopy for chemical analysis were used as the tools for surface analysis in this study. The surface composition and micro morphology have been characterized. Qualitative and semiquantitative results have been obtained for the cellulose fiber surfaces treated with DMM.

The uniaxial compressive strength and fatigue behaviour of a glass fibre-reinforced polyester composite was studied at 77 K and 300 K. The scattering of the compressive strength data was analysed using a Weibull distribution function. The fatigue life of the composite was investigated as a function of fatigue wave shape, temperature and the ratio of peak to ultimate stresses. The material exhibited a longer fatigue life under sinusoidal loading than under half triangular ramped loading. Fatigue life was also found to increase at 77 K, whilst the fatigue life dependence on the ratio of peak to ultimate stresses was the same at both temperatures studied. Failure in this composite was initiated by delamination along the long glass fibre bundles, and was followed by catastrophic shear failure across the short glass fibre mat.

An exact strain-optic law for othotropic materials has been derived using Pockels' theory of crystalline photoelasticity. The law requires three experimentally determined photoelastic constants. Photoelastic response of materials such as glass-fiber-reinforced epoxy or polyester composites subjected to any state of strain can be predicted through this law. However, due to practical difficulties, this law is not sufficient to solve for principal strain differences or the direction of principal strain from conventional measurements in a polariscope. An approximate strain-optic law, which has been derived by minimizing square of the error between predictions of exact and approximate laws, can be employed to estimate the difference between principal strains and their directions. The error in using the approximate law appears to be small. The approximate strain-optic law has been found to be preferable over an approximate stress-optic law.

In this study, the tensile behavior of clay-filled unsaturated orthophthalic polyester composites was evaluated. Specifically, ultimate strength, yield strength, fracture strain, and Young's modulus of two composites with small but varying fractions of clay particulates were determined. Several predictive approaches were considered for correlation with experimental values. Only the Young's modulus of the composites could be predicted satisfactorily. The irregular shape and size distribution of clay particulates seriously complicate attempts to analytically model the mechanical behavior of filled composites. Microcracking response of the composites was evaluated using an acoustic emission (AE) technique. The addition of clay is shown to embrittle the composites and is confirmed by the AE count rate and amplitude distribution data. Scanning electron microscopy of the fracture surface shows evidence of flaw initiated fracture. This study provides an insight into the influence of clay particulates in altering the properties of a polyester matrix.

Impact tests were carried out, using the falling weight method, to determine the factors which affect the impact strength of glass-fibre-reinforced polyester resin rods. Tests were also carried out to determine the effect of environmental attack on impact strength. Notched samples were subjected to chemical attack for periods of up to fifty days in a variety of media.

This paper presents a theoretical treatment of the tensile strength of a unidirectional fibrous composite, subjected to a tensile load in the fibre direction. The fibres are treated as having a statistical strength distribution which results in fibre failure prior to composite failure. The failure geometry of the model is similar to the observed geometry of fractured glass/epoxy and glass/polyester composites. Failure criterion is established and the strength is shown to decrease as the length of the specimen is increased. This size effect is very small.

This paper presents an experimental investigation on the specific wear rate between Kenaf Polyester Composite (KPEC) and Kenaf Epoxy Composite (KEC). The raw material used in the present work was long kenaf fiber. The epoxy resin and unsaturated polyester were mixed with hardener at weight ratios of 3:1 and 10:1, respectively. The wear test was carried out using an Abrasion Resistance Tester (TR-600) in dry sliding conditions at a constant velocity of 1.4 m/s. The test was conducted at room temperature with different applied loads ranging from 5 and 30N. It was observed that the wear characteristic of KPEC is comparative to KEC composite material. Both sample materials tested exhibited the same amount of specific wear rate at the certain distance.

Proprietes mecaniques et dynamomecaniques de polyesters renfermant du sable ou du caoutchouc broye cryogeniquement

Acoustic emission studies, using amplitude distribution analysis, have been carried out on glass fibre-polyester laminates, loaded in simple tension. The composite was tested in the unmodified state, and with a modifying rubber (a toughening agent) incorporated as a fine particulate dispersion in the resin matrix. Modification had little effect upon the orthodox mechanical properties of the laminate, but A. E. response was significantly altered. A detailed study was made of the evolution of AE event count in specified ranges of amplitude. This is interpreted as showing that modification with rubber particles causes resin matrix cracking to be deferred to higher strains. Preliminary micrographic evidence is presented in support of this contention.

Publisher Summary This chapter discusses the progress made in the studies of fracture mechanics in Turkey. Concerning the applications in industry, the only appreciable work that deserves mentioning is the one on the fracture of filament wound composites that are ultimately to be used as casings. This application is heavily worked on both by the Rocket Research Center of the Industry of Machine and Chemistry and GATOM which is an establishment in the body of the Scientific and Technical Research Council of Turkey (TBTAK). The scientific studies on fracture are in progress in various universities throughout the country. Studies concerning the kinetics of slow crack growth in polymer matrix composites are aimed at finding an explanation to the slow crack-growth phenomena in particle-filled polyester composites. Another study concerning the effects of curing process on the properties of highly cross-linked resin composites is being carried out.

• We evaluated the safety of insulating the heads of premature infants in servocontrolled thermal environments. We measured the body temperatures of premature infants (seven in incubators, seven under radiant warmers) before, during, and after application of a headwrap made with an olefin and polyester composite (Thinsulate, 3M Co, St Paul). All infants were tested while abdominal skin temperature was maintained at a constant level by servocontrol. Temperatures of the tympanic membrane, rectum, abdomen, and heel remained constant. The insulated headwrap increased the scalp temperature of incubator infants but not radiant warmer infants. Head insulation reduced variability in scalp temperature for radiant warmer infants. We found no evidence of overheating in these infants. (AJDC1986;140:940-942)

A superconductive energy storage magnet requires a large quantity of low-thermal-conductive, high-load-carrying supporting structures to carry the radial and axial compressive loads from the 1.8 K magnet coils to room temperature bedrock.1–3 Engineering data is needed on low cost commercial composites for struts to be used in the superconductive energy storage magnet designs at the University of Wisconsin-Madison. The main properties are compressive strengths, delamination strengths, shear properties and compressive fatigue properties at cryogenic temperatures and room temperatures.4–7

The Wisconsin superconductive energy storage magnet requires a large, low-thermal-conductive, high-load-carrying, supporting structure to carry the radial and axial compressive loads from 1.8-K magnet coils to room temperature bedrock. For economic reasons, fiberglass-polyester composite (Extren, with glass content of 44%, manufactured by Morrison Molded Fiberglass) was chosen over fiberglassepoxy composite.

This work has described the production of single-polymer composites by the film-stacking method. Two types of single-polymer composites with different mass fractions of the polyester reinforcement phase (10% and 20%) and the PETG matrix were investigated. The produced composites were subsequently recycled by injection moulding, pressing, and extrusion. Selected properties of the processed composites were determined: density, viscosity-average molecular weight, impact resistance, and tensile strength. The work done in this paper has demonstrated the benefits and drawbacks of each recycling method for these materials. The selected properties of single-polymer polyester composites and single-polymer polyester composites that were recycled by extrusion have also been compared.

To achieve a particular property, it is possible to mix two or more materials to form composites. In this study, to obtain superior characteristics, new composites are made with multi-components reinforcement. In order to improve the interface properties and brittleness of Glass/Polyester composites, glass woven fabrics are modified by using more elastic yarns of polyester. Polyester yams are located either parallel to glass yams or perpendicular to them. In this way, a new fabric made of Glass and Polyester fibers is manufactured. Fabrics are manufactured in the form of cross-plies or unidirectional plies in order to make superior hybrid laminated composites. A Comparison between the buckling behaviour of hybrid composites with glass woven composites shows that under similar conditions, the use of hybrid fabrics increases the buckling strength. Also, high resilience of polyester yams in hybrid fabric composites returns the sample, after failure, nearly to its original shape.

The aim of this work was to assess the level of damage on hybrid jute/glass-polyester composites resulting from different impact energies through post-impact mechanical tests monitored by Acoustic Emission (AE). The specimens were impacted and then subjected to post-impact four-point bending. Four different impact energies were considered: 5 J, 10 J, 12.5 J and 15 J. To allow for a comparison, E-glass/polyester laminates were tested following the same procedures described above. The degree of impact damage, established in terms of the decrease of mechanical properties (namely flexural strength and modulus) as a function of increasing impact energy, has been correlated with the AE activity.

Recent studies have shown that focusing on industrial waste materials will enable us to recover the economical. values. In line with the objective of present study, walnut shell is a waste material was selected to ensure economic recovery. Furthermore, biaxial fiber glass based fabrics were used in order to improve the mechanical properties of the composite materials to be produced. Thermosetting polyester resin was used as matrix material in producing composite materials. Nine different composite materials were produced as a result of addition of walnut shells at different sizes and ratios. Mechanical tests and thermal conductivity tests of these composite materials were carried out and the results were assessed.

The aging of sewer infrastructure is an ongoing problem. As a result, different materials and methods are being used in alternative sewer rehabilitation approaches. This work was conducted to study ...

In present study the authors determine the impact of active environment on destruction processes developing in single polymer polyester composites. The processes impact on the structure and selected (e.g. viscosity) mechanical features of these composites were examined. The work included the following stages: manufacturing of ordered and disordered linear fiber single polyester composites, preparation of samples in accordance with applicable testing standards, performing composites� degradation tests in different media (distilled water and sea water at 30oC,). Literature review has shown that this kind of material has not been examined in reference to active media impact on degradation processes. This work is part of the research on discussed composites� properties and recycling.

The study compares flexural strength of single polymer polyester composites. Composites under examination had the form of laminates differing in the content of the reinforcement phase and the type of material subject to simulated absorption of distilled water and sea water. Simulation tests of distilled water and sea water absorption for single polymer polyester composites with 5% to 20% reinforcing phase were made in accordance with the PN-EN ISO 62:2008 standard. The determination of the measure of degradation of the composites, the magnitude of the bending stress, was conducted in accordance with the PN-EN ISO:178 standard. This work is part of a research relating to the quality and recycling of single polymer composite materials. The testing part of the research is aimed to define the properties of examined materials before they are used commercially in specific products.

This report summarizes an investigation into the mechanical fracture of a pipeline sleeve to be utilized as a crack arrestor. The sleeve, intended for commercial use, is a filament- wound unidirectional E-glass/polyester composite as determined by our spectroscopic and microscopic analysis. The tensile stress-strain and fracture behavior of the crack arrestor are evaluated both in-situ and also by using the ASTM standards E:399-81 and E:23-82.

This study aims to evaluate the result of experimental investigation carried out on free vibration characteristics and damping factors of short sisal & glass fiber polyester composite. Composites specimen is fabricated in random fiber orientation using to hand lay-up method by Influence of fiber length (10mm) and weight percentage (5, 10, 15, 20 wt. %) . Studies revealed that increase in the fiber content will in-crease the natural frequency (Hz) and decrease the damping factor is given by the composites having a fiber loading of 20 wt. percentage ranges. The properties were compared with neat polyester. In this work, increasing fiber content increases the natural frequency (Hz) and decrease the damping factors of the composite.

Composites of chopped sunhemp fibres with polyester resin have been examined; ultimate tensile strength (UTS) and impact strength have been determined. UTS of sunhemp-polyester composites increases with increase in volume fraction of sunhemp fibre. This increase in UTS has been explained on the basis of adhesion between fibre and matrix. Impact strength of the composites increases with increase in volume fraction of fibre because the fibres help in arresting and diverting cracks.

Multiaxial deformation and failure behavior of a random short-fiber sheet molding compound (SMC) composite are studied. Experiments are conducted on an SMC-R50 glass-fiber reinforced polyester composite system under various combinations of multiaxial stresses. A sandwich specimen, consisting of SMC-R50 composite face plates adhesively bonded with aluminum honeycomb core, is specially designed for the multiaxial test. Analytical and numerical studies are performed to insure proper specimen design and to determine multiaxial stress in the SMC composite during deformation and fracture. The analytical study is formulated on the basis of elastic theory of bending and torsion of a multiphase composite system with the aid of a finite-element technique. The general nature and unique characteristics of the SMC-R50 composite deformation and fracture under multiaxial loading are determined. A multiaxial stress failure criterion for the composite material is also obtained from the test and analysis of the sandwich specimen.

Lightweight and toughness are key considerations for protective armor. Composite armor of Kevlar 29 aramid fabric and polyester resin was prepared using techniques developed for fiberglass/polyester armor. Commercial preimpregnated fabric was press-molded to prepare the target samples. The samples of the preimpregnated fabric were cured in a Pasadena press for 1 h at 165°C and 690 kPa.

This study investigated ageing-resistant properties of carboxyl-terminated polyester (polyethylene glycol terephthalate) composites modified with nanoscale titanium dioxide particles (nano-TiO2). The nano-TiO2 was pretreated by a dry coating method, with aluminate coupling agent as a functional grafting additive. The agglomeration resistance was evaluated, which exhibited significant improvement for the modified nanoparticles. Then, the effects of the modified nano-TiO2 on the crosslinking and ageing-resistant properties of the composites were studied. With a real-time Fourier transform infrared (FT-IR) measurement, the nano-TiO2 displayed promoting effect on the crosslinking of polyester resin with triglycidyl isocyanurate (TGIC) as crosslinking agent. Moreover, the gloss retention, colour aberration and the surface morphologies of the composites during accelerated UV ageing (1500 hours) were investigated. The results demonstrated much less degree of ageing degradation for the nanocomposites, indicating an important role of the nano-TiO2 in improving the ageing-resistant properties of synthetic polymer composites.