Glass-polymer Composites Research Articles

Surface molecular degradation of 3D glass polymer composite under low earth orbit simulated space environment

Epoxy resin reinforced with 3D parabeam glass fibre was subjected to low earth orbit (LEO) simulation conditions comprising ultra high vacuum, temperature cycling (TC), and ultraviolet (UV) radiation and atomic oxygen (AO) bombardment. Inspection of the same composite using only a selection of these hazardous conditions provided comparison measures to identify the effect of each condition on the surface degradation of the resin composite. Each of the individually selected conditions showed a different degradation mechanism that is accelerated by the presence of other conditions. X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and scanning electron microscopy (SEM) were used to provide surface information. The resin composite samples suffered surface oxidation that increased the oxygen content to 17.24% in comparison with the untreated sample (only 14.2%). The samples that were treated with AO showed higher C–O and C O functional groups on the surface in comparison with the rest of the samples (as indicated by XPS). Molecular information (from ToF-SIMS) showed that surface oxidation differs with different conditions and in comparison with the use of all conditions. All treated samples were shown to suffer significant chain scission and loss of volatiles as a result of the LEO conditions. The extent of the chain scission reaction for each condition can be indicated by the extent of the reduction of the relative concentration of the aliphatic hydrocarbon ions. The relative intensity of the C 4H 11N 4O 2 + ion showed that AO bombardment accelerated the oxidation of the surface. The AO effect is doubled when UV and TC are also present. SEM results indicated that sample surfaces were eroded and roughened upon exposure to LEO conditions. Presence of AO and UV in the LEO conditions introduced white deposits onto the surface, believed to be crosslinked formations.

Lasing efficiency of dyes incorporated into a nanoporous glass-polymer composite

We have used microsecond coherent pumping to study the lasing efficiency of active elements based on a nanoporous glass-polymer composite activated by organic dyes, as a function of the spectral composition of the pump within the main absorption band of the dye. We have shown that under the indicated excitation conditions, the lasing efficiency can exceed 40% and can be comparable with the lasing of liquid elements.

The Bending Strength of Medium Density Fibreboard (MDF) from Different Ratios of Kenaf and Oil Palm Empty Fruit Bunches (EFB) Admixture for Light Weight Construction

The use of alternative materials from agriculture and plantation bio-mass has widely been researched especially for use in bio-composites. These bio-mass have been used in flour form as fillers, in fibre form as reinforcements and in both flour and fibre forms as bulking agents. These bio-mass not only enhanced the composites but also help to reduce the burden on natural fibres from the forests. Furthermore, these bio-mass fibres can be used as an alternative or supplementary raw material in composites such as fibre glass-polymer composites by replacing part of the synthetic fibres, if not all, depending on the final application of the finished composites. Combining one material with other materials provides a strategy for producing advanced composite materials that take advantage of the properties especially bending strength of both types of resources. It allows the researcher to design materials based on end-use requirements within a framework of cost, availability, recyclability, energy use, and environmental considerations. This paper reports on the bending strength of MDF from kenaf, oil palm EFB, and from admixtures of EFB and kenaf in different ratios. Production of composite material from these diversified resources will not only help to reduce the pressure on natural forests, it is also an alternative to overcome waste disposal problems in palm oil industries. The results indicate that kenaf and EFB could be mixed to produce MDF. The panel produced can be used for furniture components such as table tops and shelves, wall partitions and door panels.

Relation between spectral and lasing properties for dyes of different classes

The lasing efficiency and the service life of pyrromethene and phenalemine dyes doped to nanoporous glass-polymer composites are studied upon monochromatic laser pump. The absorption and luminescence spectra of these dyes are investigated. The spectral parameters of the dyes determining their lasing efficiency are found from the analysis of their spectra and lasing characteristics, and the dyes are classified according to their lasing efficiency. A correlation between the lasing efficiency and the service life of laser elements is also established.

Durability of Glass Polymer Composites Subject to Stress Corrosion

Although it is well known that moisture ingress in glass fiber reinforced polymers~GFRP! enhances the phenomenon of stress corrosion cracking in the fibers, and that this reaction is likely to proceed more rapidly at the weakest sites in the glass fiber surface, a fundamental law that would permit the valid extrapolation of stress rupture curves to long service lives is yet to be developed. As a result, design guidelines for glass fiber reinforced polymers components have been developed mainly on a prescriptive rather than of a perfor- mance basis. Based on the well established knowledge on the chemical behavior of glass and, in particular, that of glass flaws, a model that combines fracture mechanics, shear lag theory, and a probability model for flaw size is developed to describe the behavior of GFRP composites. The predicted results, although limited to rather idealized situations, are very encouraging. They suggest that, with only modest assumptions about material properties, it is possible to obtain mechanisms of GFRP breakdown, which correspond with observed experimental behavior.

Preparation and Characterization of Lithium Ion Conducting Glass–Polymer Composites

Abstract Glass–polymer composite electrolytes of high lithium ion conducting oxysulfide glass and the comb-shaped poly(oxyethylene) polymer (TEC-19) were prepared. The conductivity of the composite with 2 vol% TEC-19 doped with LiClO4 was 1 × 10−3 at 100 °C and 3 × 10−5 S cm−1 at 30 °C. The composite exhibited a 4 V stable potential window versus Li+/Li.

Development of new near-infrared filters based on the “sandwich” polymer-chalcogenide glass-polymer composites

A new generation of filters are presented that are ideal for blocking visible light while passing near-infrared ra- diation. These filters are based on the novel use of selenium-based chalcogenide glasses with a low softening point on the one hand, and thermoplastic polymers on the other hand. A technology was developed that allows ''sand- wich'' structures to be obtained, which include thin layers of polymers and chalcogenide glasses. The technology permits the cutoff edge of filters to be controlled with high accuracy. This can be done either by varying components of the ''sandwich'' or by varying the thickness of the chalcogenide glass layer. © 2001 Society of Photo-Optical Instrumentation Engineers.

Electrochemical Properties of GeS2‐Based Glass‐Polymer Composite Electrolytes for Lithium‐Ion Batteries

Electrochemical properties of glass‐polymer composite (GPC) electrolytes, consisting of 0.4 glass and polymer, have been investigated using impedance spectroscopy and four‐probe dc measurements. Results indicate that the GPC electrolyte with 13 vol % polymer exhibits conductivity of at room temperature, and at 80°C. Further, the GPC electrolyte is more stable against than against Li. The interfacial resistance of a GPC/ interface remains constant at 80°C for 250 h. The cycling behavior of a cell consisting of carbon as the negative electrode and as the positive electrode showed that the capacity decreased from an initial value of 110 to 100 mAh/g after 50 cycles.

Preparation and electrochemical properties of glass-polymer composite electrolytes for lithium batteries

Electrochemical behavior of a new class of glass-polymer composites (GPC), consisting of (100− x) vol% (0.56Li 2S·0.19B 2S 3·0.25LiI) glass and x vol% (P(EO) 6·LiN(CF 3SO 2) 2) polymer with x = 7, 13 and 25, has been investigated in cells with different electrodes. Results show that the addition of the polymer to the glass powder increases not only the mechanical flexibility but also the ionic conductivity. The combination of impedance spectroscopy and 4-probe dc measurements indicates that the GPC with x = 13 vol% polymer exhibits the highest lithium ion conductivity, varying from 3 × 10 −4 Ω −1 cm −1 at room temperature to 1.4 × 10 −3 Ω cm −1 at 80 °C. In addition, the GPC electrolytes with x = 13 vol% seem to be relatively stable against Li, Li x Mn 2O 4, and carbon electrodes, since interfacial impedances between the electrolyte and the electrode materials are relatively constant at 70 °C for up to 375 hours.

New polyaniline/porous glass composite

In this work we report the preparation of a glass-polymer composite, obtained by the in situ oxidative polymerization of aniline, in the pores of Porous Vycor Glass (PVG). A piece of PVG was added to acid aniline solution. PVG adsorbs aniline via an ion-exchange process (H + from PVG porous surface/C 6H 5NH 3 +). The impregnated PVG was added to a (NH 4) 2S 2O 8 acid solution. The glass gradually went to dark green with the formation of polyaniline in its conducting form, the emeraldine salt. The counter-anions are the SiO − groups on the pores surface of the glass, as confirmed by 29Si-CP-MAS-NMR. Addition of the composite to an NH 4OH solution leads do a change from dark green to dark blue (emeraldine base), and this process is reversible.