Coating of textile fabrics with poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS) is one of the methods used for obtaining functional or smart applications. In this work, we prepared PEDOT:PSS polymer with certain additives such as polyethylene glycol, methanol (MeOH), and ethylene glycol on polyester fabric substrates by a simple immersion process. Surface resistance was measured and analyzed with analysis of variance to determine the coating parameters at 95% confidence level. Fourier transform infrared (FTIR) analysis and scanning electron microscopy (SEM) study of the samples were performed. Contact angle and washing fastness measurements were conducted, to observe the wettability and washing fastness of the samples, respectively. Surface resistance values were decreased by a factor of 100, due to conductive enhancers. As the immersion time and temperature condition varies, surface resistance showed no difference, statistically. FTIR analysis supports the idea that the mechanism responsible for the conductivity enhancement is the partial replacement of PSS from PEDOT chain by forming a hydrogen bond with hydroxyl ion (OH) of the conductive enhancers. A SEM images showed that PEDOT:PSS is well distributed to the surface of the fabrics. Contact angle measurements showed morphology change in the samples. The conductivity was reasonably stable after 10 washing cycles. Altogether, an effective simple immersion of coated polyester fabric is presented to achieve functional textiles that offer a broad range of possible applications.
This study presents the mechanical properties of weft knitted sandwich fabrics (bursting strength) and the effect of the raw materials used. Two types of fabrics, with and without reinforcing yarns, were analysed. To determine the influence of the raw material type, a combination of three structure variants were obtained by changing the position in the structure architecture of two types of raw material: Kevlar® and linen yarns. Each of these variants was studied at three levels of density, given by the position of the quality cam, in order to determine the influence of this parameter. Tests were organised in two stages: the first concerned the bursting behaviour of single layer fabrics, and the second considered the study of more layers of sandwich fabrics with different orientation. Satisfactory results were obtained after this study regarding the possibility of replacing the high-performance yarns with natural ones.
This paper proves in theoretical and experimental terms the availability for scientific research of the active electrical power absorbed by a CNC machining centers during a transient regime of the spindle motor (start/stop on 10,000 rpm) electrically supplied by an AC/AC converter. A simple computer assisted experimental setup (with transformers placed on the electrical supply system of the converter, signals acquire system) and processing procedures are used in order to produce a correct approach of spindle motor and converter behaviour concluded in condition monitoring and diagnosis. Some relevant results were obtained in description of active electrical power (energy) absorption during acceleration and negative power absorbed during deceleration by electrical braking, in the description of instantaneous power constituents (voltage and current) and evolution in frequency domain by fast Fourier transform. An experimental approach on energy conversion efficiency (converter input electrical energy into output mechanical energy of spindle motor) was done. As an interesting topic for future, these research achievements are available in the research of mechanical loading (torque) during cutting processes (cutting tool and process condition monitoring).
This paper proposes a study in theoretical and experimental terms focused on the vibration beating phenomenon produced in particular circumstances: the addition of vibrations generated by two rotating unbalanced shafts placed inside a lathe headstock, with a flat friction belt transmission between the shafts. The study was done on a simple computer-assisted experimental setup for absolute vibration velocity signal acquisition, signal processing and simulation. The input signal is generated by a horizontal geophone as the sensor, placed on a headstock. By numerical integration (using an original antiderivative calculus and signal correction method) a vibration velocity signal was converted into a vibration displacement signal. In this way, an absolute velocity vibration sensor was transformed into an absolute displacement vibration sensor. An important accomplishment in the evolution of the resultant vibration frequency (or combination frequency as well) of the beating vibration displacement signal was revealed by numerical simulation, which was fully confirmed by experiments. In opposition to some previously reported research results, it was discovered that the combination frequency is slightly variable (tens of millihertz variation over the full frequency range) and it has a periodic pattern. This pattern has negative or positive peaks (depending on the relationship of amplitudes and frequencies of vibrations involved in the beating) placed systematically in the nodes of the beating phenomena. Some other achievements on issues involved in the beating phenomenon description were also accomplished. A study on a simulated signal proves the high theoretical accuracy of the method used for combination frequency measurement, with less than 3 microhertz full frequency range error. Furthermore, a study on the experimental determination of the dynamic amplification factor of the combination vibration (5.824) due to the resonant behaviour of the headstock and lathe on its foundation was performed, based on computer-aided analysis (curve fitting) of the free damped response. These achievements ensure a better approach on vibration beating phenomenon and dynamic balancing conditions and requirements.
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