The heat transmission through a fabric during the measurement of thermal resistance was simulated by a novel heterogeneous model that was constructed according to the structure of ThermolabII Tester KES-F7. In this model, the heat transmissions along the longitudinal and transverse directions of yarn were treated independently. The material constants of fabrics, such as mass density, specific heat, thermal conductivity and thickness, were used as parameters for simulation in this fabric model. The validity of this model was then confirmed by the high consistency between the heat flux obtained from experiment and simulation, with the average difference ratio lower than 5%. The simulation results suggested that the guard area could effectively reduce the horizontal heat leakage from the test plate when the experimental fabric was thin. Only less than 8% of heat leaked in the one-layer case, while the leakage was significantly aggravated when more layers of fabric were stacked, resulting in the considerably lower thermal insulation achieved in both experiment and simulation compared with that in real fabrics. The temperature distribution in the model also implied that the longitudinal and transverse thermal conductivity of yarn exerted great effect on the heat leakage during the measurement. Moreover, for multilayers consisting of different fabrics, the laying sequence could obviously influence the heat leakage and, consequently, change the obtained thermal resistance.
The wearability of braided harness cord was studied by measuring the tensile properties of worn ones with a universal electronic strength tester and wearing test device developed in our laboratory. The abrasion mechanism of harness cord was investigated, and the fractured schematic diagram was proposed according to the morphology observed by a hand USB microscope and scanning electron microscope. The results indicated the abrasive action could significantly reduce the tensile properties of harness cord, and a negative linear correlation between the tensile properties and the abrasive times was observed. The morphology suggested the fractured process of harness cord could be divided into five stages: surface abrasion of sheath fibers, partial breakage of sheath fibers, structure failure, full breakage of sheath fibers, and breakage of core fibers. In addition, the fibers in harness cord presented different fracture types due to the combined effect of external friction, bending, stretching, and fatigue during the wearability test.
Super-hydrophobic fabrics have shown great potential during the last decade owing to their novel functions and enormous potential for diver’s applications. Surface textures and low surface energy coatings are the keys to high water repellency. However, the toxicity of nanomaterials, long perfluorinated side-chain polymers, and the fragile of micro/nano-texture lead to the super-hydrophobic surfaces are confined to small-scale uses. Thus, in this article, a stable polydimethylsiloxane (PDMS)-coated super-hydrophobic poly(ethylene terephthalate) (PET) fabric (PDMS-g-PET) is manufactured via dip-plasma crosslinking without changing the wearing comfort. Benefiting from the special wrinkled structure of PDMS film, the coating is durable enough against physical abrasion and repeated washing damage, which is suffered from 100 cycles of washing or 500 abrasion cycles, and the water contact angle is still above 150°. This study promotes the way for the development of environmentally friendly, safe, and cost-efficient for designing durable superhydrophobic coatings for various practical applications.
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