| In this decade,the demands of energy saving,diverse personal thermoregulation requirements,the emergence of wearable electronics along with smart textiles give rise to the resurgence of personal thermal management(PTM)technologies.PTM including personal cooling,heating and thermoregulation,are far more flexible and extensive than the traditional air/liquid cooling garments for the human body.Recently,many new advanced materials and strategies have been developed in this decade,promoting the thermoregulation performance and the wearing comfort of PTM simultaneously.Unfortunately,reported techniques to fabricate such thermal management materials often suffer from the low fabrication efficiency and high cost,which are definitely obstacles to large-scale and cost-effective production and application.Inspired by polar bears’ hollow hairs and porous structure commonly in nature and life,the thermoplastic polypropylene(PP)and high-density polyethylene(HDPE)were respectively used as polymer matrix,thermoplastic polyoxyethylene(PEO)was used as dispersion phase.A facile,low-cost,efficient,and large-scale method was developed successfully to fabricate porous materials for personal thermal management.More importantly,it is a solvent-free processing and environmentally friendly method to prepare porous materials.The main results of the research are as follows:(1)Firstly,high-density polyethylene(HDPE)/polyoxyethylene(PEO)fiber with different draw ratios were continuously fabricated by extrusion molding.Subsequently,polyethylene microfibrilar bundles(PMBs)containing oriented mircrofibrils were obtained after the PEO phase was leached from the HDPE/PEO fibers.This paper systematically studies the effect of draw ratio on morphology,porosity and thermal insulation property,as well as personal thermal management.The as-pared PMBs is composed of interconnected mircrofibrils which aligned along the extrusion direction.Interestingly,there are many oriented microchannels between the neighboring mircrofibrils.Such oriented mircrofibrils endowed PMBs with outstanding mechanical property.Compared with commercial cotton textiles,the fabrics woven by PMBs show outstanding thermal insulation property in any temperature condition.Meanwhile,larger draw ratio is helpful to enhance thermal insulation property.Finally,the applications of PMBs in personal thermal management under different circumstance were discussed.The results showed that PMBs fabric can not only prevent the loss of human body heat to realize passive heating in indoor circumstance,but also can insulate the direct sunlight radiation to avoid the excessive rise of skin temperature and improve sweat evaporation efficiency to realize personal cooling in outdoor circumstance.(2)The PP/(PP/PEO)/PP composites were prepared by the conventional polymer melt processing methods of “trilayered blow molding”.The as-prepared PP/(PP/PEO)/PP(PPE)composites were consisting of three layers,whose middle layer is PP/PEO phase,and the outer layer and inner layer are PP phase.Subsequently,the PP/PMBs/PP(PM)film was fabricated by leaching PEO phase from the PPE blend.The influence of weight ratio on the microstructure and thermal insulation properties also were discussed.The result indicates that weight ratio has an important effect on the microstructure and thermal insulation properties of PM film.When the weight ratio of PEO is 70 wt%,the microfibrils in PM-70 film become more smaller and uniform,therefore PM-70 film presents the best thermal insulation property with thermal conductivity 0.05 W/mk.In addition,the hydrophobicity and selective adsorption of the PM film has been studied.The results show that the PM film had outstanding hydrophobicity,PP/PMBs/Ethanol(PM/E)film was fabricated after the adsorption of organic solvent.Compared with PM film,PM/E film shows obvious improvement in transparency and thermal insulation property and has outstanding dynamic reliability,which can adapt to the change of external temperature,has a great potential in thermal management. |
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