The Structure And Performance Of STF Capsule Multi-stage Cushioning Composite Material For The Protection Of The Elderly

In this paper,a kind of multi-stage cushion and energy-absorbing textile composite material is designed for the protection of senior people from falling down.The mechanical protective properties of the material are also discussed.Inspired by the structure of grapefruit skin,the structure of multistage cushion composite material designed in this paper is: STF capsule with shear thickening liquid(STF)as core material is added to the polyurethane foam,and spacer woven fabric is added to both sides of the foaming polyurethane.In the preparation process of composite materials,the improvement of multistage buffering performance of materials was discussed and optimized,including preparation of STF,encapsulation of STF,polyurethane foaming and addition of fabric,so as to effectively protect from the impact force received after falling.Through SEM observation on the STF capsules,the results confirmed that STF capsules have double-layer and internal porous core-shell structure,which can be mixed in polyurethane foam to form a Pomelo-like peel structure that can effectively increase the buffer performance.Through the TGA curve,it can be observed that STF capsules successfully encapsulated appeared good thermal stability,which is stable below 226 ?.STF capsules with different particle sizes were prepared by controlling the inner diameter of the inject needle.The experimental results showed that the 1.83 mm capsule had the highest STF content,the highest compression energy and the highest sustained release speed,as well as good thermal stability and mechanical properties.Then the resulted STF capsules were mixed into foamed polyurethane(STF-CPCM)and tested by SEM,FTIR,TG,compression and dynamic impact.SEM showed that PU65 had the maximum pore diameter and wall thickness.FTIR test results confirmed that STF capsules did not react with polyurethane.TGA results showed that PU75 had a maximum residual mass of 11.47%.Compression test results show that PU65/30 has the maximum compression energy up to 1.985 MPa;Under the impact of 20 J energy,PU75 has the maximum buffer response.PU75/40 has the best buffer performance among samples with different mass fraction STF capsules.Then,the buffering properties of foaming polyurethane coated warp knitted spacer fabric(SC/PU/ Spacer)composites were studied.The results showed that the cushioning performance of the spacer fabric increased: the compression energy of 4-W/STF/PU was 5.65 times that of P-PU,and the maximum impact value of 4-W/STF/PU decreased by 848 N compared with P-PU.This study provides a reference for the development of protective equipment for the elderly.