Electrostatic charge generation and buildup during contact and frictional electrification of woven textile fabrics

411-419Woven textile fabrics of cotton, polyester, nylon and polypropylene have been tested for contact and frictional electrification under similar experimental conditions. These fabrics are contacted and rubbed with steel and polytetrafluoroethylene (PTFE) for investigating electrostatic charge generation and dissipation properties between polymer-metal and polymer-polymer materials. Measurements have been made for the charge buildup after first initial contact/rubbing; the charge buildup during 50 contact/rubbing cycles; and the half-life discharge time. It is observed that the charge generation during rubbing and contact with steel is less than that with PTFE. It is also observed that the samples charged by rubbing decay quickly as compared to the contact charged samples. The findings indicate that with a few exceptions, the charge magnitude and polarity follow the triboelectric series

Electrostatic charge generation and buildup during contact and frictional electrification of woven textile fabrics

Woven textile fabrics of cotton, polyester, nylon and polypropylene have been tested for contact and frictional electrification under similar experimental conditions. These fabrics are contacted and rubbed with steel and polytetrafluoroethylene (PTFE) for investigating electrostatic charge generation and dissipation properties between polymer-metal and polymer-polymer materials. Measurements have been made for the charge buildup after first initial contact/rubbing; the charge buildup during 50 contact/rubbing cycles; and the half-life discharge time. It is observed that the charge generation during rubbing and contact with steel is less than that with PTFE. It is also observed that the samples charged by rubbing decay quickly as compared to the contact charged samples. The findings indicate that with a few exceptions, the charge magnitude and polarity follow the triboelectric series

Improving high-altitude UV–Vis resistance of PBO braided tendons of NASA’s super pressure balloons

Super pressure balloons (SPBs) are used by the National Aeronautics and Space Administration (NASA) for ultra-long duration ballooning (ULDB) missions which carry various scientific explorations to support space and earth sciences research activities. The resistance to photo-degradation of load-bearing braided tendons of SPBs is critical to the success of ULDB missions. Recognizing the critical need to improve UV and visible light (UV–Vis) protective performance of p-phenylene-2, 6-benzobisoxazole (PBO) braids, North Carolina State University and NASA’s Balloon Program collaborated to investigate the effectiveness of sheath extrusion method in improving the UV–Vis resistance of tendons. This study included two PBO tendon types – 48,000 (48k) denier tendons and 72,000 (72k) denier tendons. Using a sheath extrusion method, the tendons were covered with UV protective sheath of low-density polyethylene containing two types of UV inhibitors – TiO2 rutile nanoparticles and PolyOne PE White CC®. Bare and sheathed tendons were subjected to artificial UVB exposure in the lab as well as to both high altitude and ground exposure during flight missions conducted by NASA. Protection against radiation exposure was evaluated by determining the loss of tensile strength after exposure. UV–Vis protection of tendons improved with an increase in sheath thickness as well as UV inhibitor content in the sheath. The results also showed that 72k denier braids had higher resistance against UV degradation compared to 48k denier braids. In-flight exposure results confirmed the comparative UV protective performance of tendons exposed to accelerated artificial UVB exposure in lab. 72k denier tendon covered with sheath containing 10% PE White CC® (sheath thickness of 0.37 mm) experienced the lowest strength loss among all tendon samples to high-altitude exposure during flight missions. The study has also utilized UV–Vis transmittance of the sheath covering the braids as a method of evaluating the performance of the protective sheaths

Development of UV protective electrospun layers for high performance fibres for high altitude applications

121-125In this study, a range of lightweight UV protective layers has been developed from electrospun polyurethane loaded with different amount of rutile TiO2 nanoparticles using electrospinning with variable speed drum (collecting surface). To assess the degree of protection of the manufactured layers, a braid from Zylon fibres has been sheathed with the protective layers of different weight per braid unit length and the strength of yarns raveled from the braids is measured. The strength retention after exposure to artificial UV rays in Atlas Weatherometer for six days is used as a measure of the degree of sheath protection. Electrospun polyurethane layers loaded with 1% of TiO2 with weight of 2.29 g/m braid, processed at high speed collector (87.7 m/min), provide the highest protection among the developed electrospun polyurethane layers. </span

The response of polymer optical fiber (POF) to cyclic loading for the application of a POF sensor for automotive seat occupancy sensing

The goal of this research aimed to develop an accurate and reproducible textile-based optical fiber sensor for automotive seat occupancy. In our previous publication, the response of perfluorinated (PF) graded index (GI) polymer optical fibers (POFs) (62.5/750 and 62.5/490m) to bending and tensile loading was investigated. In this study, the response of the PF GI POFs to cyclic loading was investigated. The repeated loading and unloading the POF sensor would experience due to car vibrations and multiple uses by seat occupants, might cause fatigue failure to the POF sensor. The results showed that the Cytop-1 did not show any permanent deformation up to 500 cycles at strain rates 4 and 60mm/min at a gage length of 76.2mm in its elastic sensitive strain region. The Cytop-2 showed permanent deformation at 3.5% strain after 500 cycles at a gage length of 76.2mm. Thus, the Cytop-1 was found out to be more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to the Cytop-2. In this study, a theoretical approach of the behavior of PF GI POF to cyclic loading was also provided

The response of polymer optical fiber (POF) to bending and axial tension for the application of a POF sensor for automotive seat occupancy sensing

The automotive industry is a promising area for innovations in the field of polymer optical fiber (POF) sensors as the industry currently uses the POF mostly for data transmissions. Since an optical fiber sensor has a high bandwidth, is small in size, is lightweight, and is immune to electromagnetic interference, it offers higher performance than that of its electrical-based counterparts such as the strain gage, elastomeric bladder, and resistive sensor systems. This enhanced performance makes an optical fiber sensor a suitable material for sensing seat occupancy for improved safety features in automobiles. The overall goal of this research is to develop a textile-based optical fiber sensor for automotive seat occupancy with high accuracy and reproducibility. In this study, the bending and tensile loading responses of POF were investigated, where two perfluorinated (PF) graded index (GI) POFs with two different core/cladding diameters, 62.5/750 and 62.5/490m, were used. The bending loss and the light attenuation against the applied axial stress were measured by a photon counting optical time-domain reflectometer. The critical bending diameters were analyzed: Cytop-1 (62.5/750m)38.10mm, Cytop-2 (62.5/490m)44.45mm. Furthermore, the elastic sensitive strain regions (x), where the stress-induced loss was recoverable, of the POFs at a 76.2mm gage length at a strain rate of 4mm/min were determined: Cytop-1: 3%x3.5%, Cytop-2: 3.1%x3.3%. The Cytop-1 was found to be less sensitive to bending and to have greater elastic sensitive strain range relative to the Cytop-2. In this study, a theoretical approach of the PF GI POF behavior to bending and axial tension was provided. The results demonstrated the feasibility of POFs as optical fiber sensors for automotive seat occupancy sensing

A textile- based optical fiber sensor design for automotive seat occupancy sensing

In our previous publications, the response of perfluorinated (PF) graded index (GI) POFs (62.5/750, 62.5/490m) to bending, tensile loading, and cyclic loading was investigated. The results showed that Cytop-1 (62.5/750m) was more appropriate to be used as an optical fiber sensor for automotive seat occupancy sensing relative to Cytop-2 (62.5/490m). In this study, a textile-based optical fiber sensor was designed and the effect of automotive seat covering including face material and foam backing on a sensor's performance was analyzed. The pressure interval under which the proposed POF sensor design could perform well was found to be between 0.18 and 0.21N/cm(2), where PF GI POF (62.5/750m) was used as the POF material. The responses of the sensor in this interval were observed to be accurate and reproducible. The face fabric structure and the thickness of foam backing were not found to be significant factors to change the sensor response. Artificial neural network (ANN) was used for data analysis, and Qwiknet (version 2.23) software was used to develop ANNs. According to the results of Qwiknet, the prediction performances for training and testing data-sets were 75 and 83.33%, respectively