| Moisture wicking textiles with outstanding directional water transport performance can provide comfortable protection.The studies achieved good results in improving the directional water transport performance.But liminations such as poor breathability & moisture permeability,and low abrasion-resistance & flexibility still remain.Besides,The mechanism optimization of directional water transport textiles are only studied by the wetting property.The relationship between porous structures and transfer performance lacks mechanism analysis.Therefore,in order to meet the requirement of moisture permeability & breathability,abrasion-resistance,flexibility of functional directional water transport membranes,a novel micro/nanofibrous composite membrane was successfully fabricated by using needle punch-hot press,electrospining,and modification technology.The structure and wettability gradient of the composites membranes was optimized.The key technology of preparation protective and comfortable directional water transport membranes was broken.The as-prepared composite membrane with outstanding performance.Furthermore,the directional water transport mechanism of membranes with various wettability and structure design was explored.It provides a theoretical and practical fundation for the design protective and comfortable composites.The research contents are summarizeds as follows:(1)Needle punch/coating microfibrous membranre was processed combing needle punch-hot press and modification technique(spray coating and knife over roll coating).The hot press method was used to form the bonding point and improve the mechanical strength/abrasion resistance.The influence between the modification method/gradient stucture and directional water transport,moisture permeable & breathable,flexible and abrasion resistant properties of the microfibous membranes was explored.The results shows that wettability driving force is the key factor.On the other hand,TPU membrane has better mechanical performance and abrasion resistance.(2)Inspired by the directional water transport phenomenon and multi-layered structure in nature.A novel multi-layer gradient and honeycomb nanonets/ sandwich nanofibrous composite membrane were fabricated by using electrospinning and in-situ polymerization.The influence between the wettability/stucture design and the properties of the nanofibrous membranes was studied.The results showed that honeycomb nanonets significantly increased the pore size and decreased the transport resistance.Meanwhile,the subsequent sandwich composite membrane has the outstanding comfortable performance.It is worth noting that the air permeability up to2 order of magnitudes higher than that of the commercial membrane.(3)A gradient composite needle punch/hot press-electrospinning micro/nano structure composite membrane was fabricated by incorporating the advantages of micro/nanofibrous membrane.The influence between the micro/nano gradient structure on property was studied.The results showed that the obtained micro/nanofibrous composites retained the robust abrasion resistance of microfibrous composite membranes and excellent flexibility of nanofibrous composite membranes.The oneway transport index R could up to 712.6450 %.In addition,a plausible mechanism was proposed to explain the transport of air,water vapor and liquid.The results confirmed that the air flow accordeds with the Darcy’s law.The WVT rate was accord with Fick’s Law.Of note,the directional water transport performance was affect by the polymer type.The driving force in various microchannels is different.The microchannels from small to large shows the maximal driving force and minimal resistant force.The above findings provide a theoretical basis for the design and application of micro/nano multiscale composites.In the end,the theoretical and experimental guidance was provided for the structural optimization of directional water transport porous materials. |
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