Search

A coated composite was prepared on polyester-cotton plain weave fabric, using PU2540 polyurethane as the matrix. The influences of the content of nickel powders on the dielectric constant (the real and imaginary parts and loss tangent value), reflection loss and shielding effectiveness of single-layer coated composites were mainly investigated. The results showed that within the frequency range of 1-1000 MHz, the value of the real part of the dielectric constant of the coated composites was the largest, and the polarisation ability with regard to electromagnetic waves was the strongest when the content of nickel powders was 40%. Within the frequency range of 15-225 MHz, the value of the imaginary part of the dielectric constant of the coated composites was the largest and the loss ability with regard to electromagnetic waves was the strongest when the content of nickel powders was 40%. Within the frequency range of 250-800 MHz, the loss tangent value of the dielectric constant of coated composites was the largest, and the attenuation ability with regard to electromagnetic waves was the strongest when the content of nickel powders was 40%. Within the frequency range of 1220-3000 MHz, the reflection loss value was the smallest when the content of nickel powders was 40%, and its absorption ability with regard to electromagnetic waves was the strongest. Within the frequency range of 760-3000 MHz, the shielding effectiveness of the coated composite was the largest when the content of nickel powders was 40%. [ABSTRACT FROM AUTHOR]

Graphite/talcum powder double-coated glass fibre felt composites were prepared using glass fibre felt as the base material, graphite as the surface absorbing agent, talcum powder as the underlying absorbing agent, epoxy resin E44 as the adhesive and low molecular 650 polyamide as the curing agent. The influences of the surface graphite content and underlying talcum powder content on the dielectric properties and conductivity of glass fibre felt composites were the main focus of the investigation. Results showed that when the frequency is less than 103 Hz, the values of the real and imaginary parts of the dielectric constant for double-coated glass fibre felt composites are largest when the surface graphite content is 50%. When the frequency is larger than 106 Hz, the value of the real part of the conductivity is largest when the graphite contents are 40% and 50%. When the frequency is less than 104Hz, the real part of the dielectric constant of the glass fiber mat composites is the largest when the talc content is 40%, and when talc content is 60%, the imaginary part of dielectric constant of glass fiber mat composites is the largest. The maximum loss tangent value for the composites occurs when the talcum powder content is 40%. When the frequency is larger, the value of the real part of the conductivity increases gradually. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the needle depth and frequency on the thermal insulation performance of pre-oxidised fibre felts was mainly investigated. The results showed that pre-oxidised fibre felts of a needle depth of 8 mm at a room temperature and working temperature of100-200 °C had the best thermal insulation performance, while fibre for those of different needle depths with increasing temperature, the steady-state temperature difference increased linearly. With an increasing needle frequency, the thickness and gram weight of the pre-oxidised fibre felts showed a decreasing trend, while the coefficient of thermal conductivity exhibited an increasing one. For pre-oxidised fibre felts of different needle frequencies with increasing temperature, the steady-state temperature difference showed a linearly increasing trend. [ABSTRACT FROM AUTHOR]

Firstly, the paper focused on the polyurethane foam soaking process with pyrrole solution, and discuss the estimated electro-mechanical properties of the modified PU foam. Secondly, scanning electron microscopy (SEM) micrographs were collected to understand the polypyrrole distribution inside the foam. The results show that the chemical polymerisation parameters needed to realise this amount of polypyrrole in the foam were 0.1 mol/L of pyrrole, a mole ratio of 1:2.25, an oxidation temperature of 12 ± 3 °C, and an oxidation time of 2 hours. SEM images of the samples prepared with the modified approach showed a continuous layer of about 10-15 μm thickness of the polypyrrole attached to the surface of the PU foam. [ABSTRACT FROM AUTHOR]

In this paper, an orthogonal experiment of 3 factors and 3 levels was firstly designed to prepare PAN pre-oxidised fibre felts with good thermal insulation properties; the range method was used to analyse the result of the orthogonal experiment, and finally the tensile properties and thermal stability were tested. Finally, pre-oxidised fibre felt composites for the coating of silica aerogel were prepared using the coating process to compound silica aerogel on re-oxidised fibre felts. Firstly, the influence of the content of silica aerogel on the heat insulation performance of the coated composite materials was analysed, and then a test of the coefficient of thermal conductivity, an experiment on the back temperature, and characterisations of the tensile properties and thermal stability of the composite coating of pre-oxidised fibre felt composites of the coating of silica aerogel were carried out. Results showed that through analysis of the orthogonal experiment, we can state that the best preparation process of pre-oxidised fibre needled felts was as follows: needle number - 2, needle depth - 8 mm, and needle frequency - 140 times/min. The transverse tensile strength of PAN pre-oxidised fibre needled felts prepared by crossly webbing of PAN pre-oxidised fibres was superior to the longitudinal tensile strength; thermogravimetric analysis showed that the pre-oxidised fibre needled felts had excellent thermal stability. The coefficient of thermal conductivity of the aerogel coating of the composites firstly decreased and then increased with an increase in the content of aerogel. Coated composites had the lowest coefficient of thermal conductivity when the aerogel content was 4% wt. At temperatures of 100 °C, 150 °C and 200 °C, the heating rate of the transient-state back temperature and the steady-state average temperature were both the lowest when the aerogel content was 6% wt. [ABSTRACT FROM AUTHOR]

The impact of the mass percentage of PAN-based pre-oxidised fibre felt in a composite material and of the curing temperature on the composite material's mechanical properties were studied in order to optimise the preparation method of epoxy resin composite material. The results showed that when the dosage of PAN-based pre-oxidised fibre felt was 15% of the mass of epoxy resin and the curing temperature was 170 °C, the tensile and bending properties of the composite materials produced were the best. This study has addressed the absence of reports on this type of composite material, and is expected to lead to the development of applications for this new type of composite material. [ABSTRACT FROM AUTHOR]

A type of cationic decolourising agent was prepared and applied to printing and dyeing wastewater treatment. The effects of the concentration of the decolourising agent, the pH value and stirring speed on decolourisation efficiency were studied. The results show that the optimum decolourisation process of the decolourising agent is determined as follows: at room temperature, a dosage of the decolourising agent of 7 mg/l, pH =7.0, and a stirring speed of 150 rpm. The decolourising agent applied to decolourise a direct dye, strong acid dye, weak acid dye and reactive dye in simulated wastewater showed high decolourisation efficiency in all cases. The range of decolourisation efficiency from the highest to lowest is as follows: direct dye, weak acid dye, strong acid dye, and reactive dye. [ABSTRACT FROM AUTHOR]

The influence of the yarn fineness and stitch length of polyester knitted fabrics on the dielectric constant was investigated by the single factor test method. As a result of the investigation, polyester knitted fabric parameters were chosen so as to obtain a polyester knitted fabric with the maximum real part and imaginary part of the dielectric constant. The results show that when the yarn fineness is 59 tex and the mark of the stitch length is 75, the polyester knitted fabric displayed the maximum real part and imaginary part of the dielectric constant. Finally, the polyester knitted fabric with these parameters had good microwave absorbing properties. [ABSTRACT FROM AUTHOR]

Flexible polypyrrole coated fabric composites with good dielectric properties were produced using pyrrole as a monomer by in-situ polymerisation on polyester fabric. Initially, the influence of the pyrrole concentration, temperature and time on the dielectric constant of the real and imaginary parts, the loss tangent, and the surface resistance of the composites were investigated. Subsequently, exterior morphologies was analysed. The results show that the pyrrole concentration, the reaction temperature and time had a significant influence on the real and imaginary parts of the dielectric constant, the loss tangent, and the surface resistance of the composites. The polypyrrole composites produced show good performance in terms of dielectric properties and electrical conductivity. In the 0-106 Hz frequency range, the values of the real and imaginary parts of the dielectric constant of the 0.8mol/l group are both at their largest. Moreover, the value of the surface resistance of the 0.8 mol/l group is at its smallest, and the value of the surface resistance of the 0.2 mol/l group is at its largest, which is 12 times the value given by the 0.8 mol/l group. Values of the real and imaginary parts of the dielectric constant, and the loss tangent for the experimental group produced by polymerisation at ambient temperature are at their largest, which is superior to the other groups. The value of the surface resistance for the experimental group produced at ambient temperature is at its smallest and the electrical conductivity is at its strongest; the higher the reaction temperature, the larger the value of the resistance. The various dielectric properties of the 150 min group are better than for the other groups. [ABSTRACT FROM AUTHOR]

Many factors were needed to be considered to prepare pre-oxidised fibre felts with excellent heat insulation performance, and different production processes showed differences in the heat insulation performance of pre-oxidised fibre felts. In order to probe into the influence of the production process on the heat insulation performance of materials, a large number of experiments were needed to be carried out. For needle-punched nonwoven pre-oxidised fibre felts, web features, needle characteristics and the needle process will all affect the structure of pre-oxidised fibre felts, thus bringing a major influence on the heat insulation performance of pre-oxidised fibre felts. In this paper, the influence of the needle number on the heat insulation performance of pre-oxidised fibre felts was mainly studied. Results showed that an increase in the needle number will cause a decrease in the thickness and gram weight of pre-oxidised fibre felts, and a weakening trend in the heat insulation performance of pre-oxidiaed fibre felts with an increasing needle number at room temperature and at 100-200 °C was shown. Moreover when the needle number was 1 and 2, the pre-oxidised fibre needled felts had good heat insulation performance, and for pre-oxidized fibre felts at different needle numbers with increasing temperature, the temperature difference in a steady state increased linearly. [ABSTRACT FROM AUTHOR]

Initially waste feather protein was used to prepare a reactive cationic crosslinking modified agent, WLS, as a starting material which was used to prepare a quaternary ammonium type cationic environment-friendly fixing agent (named WLSPR) for dyeing cotton fabric with reactive dyes after solid colour processing. In this paper, the degree of staining on white cloth from colored cloth after a soaping process was assessed (by determination of the K/S value) as well as the washing fastness etc. as the evaluation indices. The optimum synthetic conditions of fixing agent WLSPR were determined, and the structure and properties of the additives characterised. The results show that the maximum absorption wavelength of the cationic protein fixing agent WLSPR is 195nm. Synthesis of the environment-friendly fixing agent WLSPR using optimum conditions can reduce white staining during soap washing, effectively improving the cotton fabric in terms of colour fastness to washing and rubbing fastness. Based on infrared spectral characterisation, it was confirmed that the protein-based cationic auxiliary additives were synthesised. [ABSTRACT FROM AUTHOR]

Self-cleaning polyester fabrics were prepared by a simple gas phase deposition procedure in which a layer of polydimethylsiloxane nanofilaments was grown onto textile fibers. Superhydrophobic and self-cleaning properties, tensile breaking strength, mechanical stability and permeability of polyester fabrics were investigated. The results showed that the fabrics deposited had superhydrophobicity, and the contact angle and sliding angle of the fabric surface were 159° and 1.7°, respectively. The self-cleaning test showed that dust particles adhere to rolling water and shed from the surface of polyester fabric, leaving an extremely clean surface. In addition, the polyester fabric deposited still has excellent breaking strength and permeability. This approach is simple, inexpensive and has little effect on the mechanical properties of the fabric. [ABSTRACT FROM AUTHOR]

Sparse coding is currently an active topic in signal processing and pattern recognition. MetaFace Learning (MFL) is a typical sparse coding method and exhibits promising performance for classification. Unfortunately, due to using the l1-norm minimization, MFL is expensive to compute and is not robust enough. To address these issues, this paper proposes a faster and more robust version of MFL with the l2-norm regularization constraint on coding coefficients. The proposed method is used to learn a class-specific dictionary for facial expression recognition. Extensive experiments on two popular facial expression databases, i.e., the JAFFE database and the Cohn-Kanade database, demonstrate that our method shows promising computational efficiency and robustness on facial expression recognition tasks. [ABSTRACT FROM AUTHOR]

In this paper, the influence of fabric structure, weft density, end spacing and yarn fineness on the dielectric constant of polyester woven fabrics was studied. The results show that at low frequencies, the dielectric constant of fabric was clearly affected by the processing parameters; when the organisation of the fabric is plain i.e. the warp density is 140/10 cm, weft density 140/10 cm and yarn linear density 32 tex, the absorbing performance of polyester woven fabrics is at its best. At higher frequencies, the effect of the varying parameters on the dielectric constant of the fabrics can be neglected. Polyester woven fabrics have better EM absorbing properties for these parameters. This study offers a new theoretical basis for the development of EM absorptive fabrics. [ABSTRACT FROM AUTHOR]