| Polyester-cotton fabric which combines the strengths of polyester and cotton,like breathability,comfort,dimensional stability,smooth,etc,is popular in various fields such as clothing,furniture decoration,transportation.However,the flammability of polyester-cotton fabric poses a heavy fire hazard,which limits its further applications.Therefore,it is of great practical significance to apply flame-retardant treatment on polyester-cotton fabric.In addition,polyester-cotton fabric with single flame-retardant function fails to meet the complex needs of all walks of life.Especially,flame-retardant polyester-cotton fabric endowed with waterproof and self-cleaning functions,as well as improved wash durability,would possess extensive applications.In this thesis,after summarizing the research of flame-retardant finishing of fabrics,to overcome the shortcomings of traditional flame-retardant finishing methods of polyester-cotton fabric,such as poor wash durability and poor efficiency,a novel layer-by-layer self-assembly based coating technique was proposed to prepare flame-retardant polyester-cotton fabric.Meanwhile,metal-organic coordination crosslinking and hydrophobic treatments were applied to improve the wash durability of the flame-retardant coatings.Scanning electron microscopy(SEM),thermogravimetric analysis(TGA),horizontal flame test,and laundrying test were conducted to evaluate the properties of coated polyester-cotton fabric such as morphology,thermal stability,flame retardancy and hydrophobic properties,and study the related flame-retardant and superhydrophobic mechanism.The main research work of this thesis is listed as follows:1.Firstly,hypophosphorous acid modified chitosan(PCS)was synthesized.Then,PCS and polyethyleneimine(PEI)were used as polyanion and polycation,respectively,to construct PCS/PEI coating on the polyester-cotton fabric through electrostatic interaction in a layer-by-layer self-assembly way.TGA results showed that the thermal stability and char residue of the polyester-cotton fabric at high temperature were significantly enhanced aftter the treatment of PCS/PEI coating,compared with the untreated polyester-cotton fabric.Horizontal flame test revealed that the untreated one burned completely with 115 s of flame and 234 s of smoldering.In contrast,after the treatment of 20 bilayers of PCS/PEI coating,the flame self-extinguished only after 33 s and the smoldering phenomenon disappeared,indicating that the PCS/PEI coating imparted good flame-retardant properties to the polyester-cotton fabric.Moreover,SEM and Raman characterizations were conducted to evaluate the morphology and structure of char residues.Significant intumescent char layers were observed on the PCS/PEI coated fabric,which was expected to prevent the volatilization of combustible gases and transfer of oxygen and heat,thus achieving the flame-retardant effect.2.In an effort to improve the wash durability of the flame-retardant co,ating prepared via layer-by-layer self-assembly technique,diethylenetriamine penta methylene phosphonic acid(DTPMP)and ferric ion(Fe3+)were deposited on the polyester-cotton fabric through coordination cross-linking interaction to form DTPMP/Fe3+coating.DTPMP which contains phosphate groups and N-C-P structure,played a good role of intumescent flame effect during the combustion process.SEM results showed that the polyester-cotton fabric was uniformly coated by DTPMP/Fe3+coating with a large number of micro/nano-sized protrusions on the surface.The results of horizontal flame test revealed that,the polyester-cotton fabric modified by 5 bilayers of DTPMP/Fe3+ coating self-extinguished after only 4 s,exhibiting excellent flame-retardant effect.The results of micro-scale combustion calorimetry showed that,compared with the untreated polyester-cotton fabric,the peak of heat release rate of the 5 bilayers of DTPMP/Fe3+coating modified one was reduced by 27.1%and the total heat release was reduced by 30.4%,indicating the excellent flame-retardant effect of DTPMP/F33+ coating.In addition,since metal-organic coordination interactions are mostly stronger than electrostatic interactions,compared with the PCS/PEI coating fabricated through electrostatic interaction,DTPMP/Fe3+ coating exhibited improved wash durability.After two cycles of standard laundrying test,self-extinguishing effect was still achieved for the 5 bilayers of DTPMP/Fe3+ coating modified polyester-cotton fabric,whereas the 20 bilayers of PCS/PEI coating modified one burned completely.3.In an effort to further improve the wash durability of the flame-retardant coating and expand the application of polyester-cotton fabric,superhydrophobic flame-retardant polyester-cotton fabric was fabricated.Three low surface energy materials including polydimethylsiloxane(PDMS),1H,1H,2H,2H-perfluorodecyltrimethoxysilane(PFDS),and polyvinylidene fluoride-hexafluoropropylene(PVDF-HFP)were applied to modify the hierarchically rough surface of the DTPMP/Fe3+ coating.The water contact angle of DT/Fe-8BL@PDMS which was coated with 8 layers of DTPMP/Fe3+and 2 wt%PDMS reached 155.60° and exhibited excellent self-cleaning performance.Under the same conditions,the water contact angle of DT/Fe-8BL@PFDS and DT/Fe-8BL@PVDF-HFP was 158.7° and 150.8°,respectively.Moreover,after 15 cycles of laundrying test or 30 cycles of abrasion test,the water contact angle of DT/Fe-8BL@PDMS remained larger than 140°,while the water contact angle of DT/Fe-8BL@PFDS and DT/Fe-8BL@PVDF-HFP was less than 140°.This indicated that DT/Fe-8BL@PDMS exhibited better wash durability and abrasion resistance,which was due to that PDMS film has better film-forming ability and mechanical properties than PFDS and PVDF-HFP.In addition,DT/Fe-8BL@PDMS still exhibited self-extinguishing performance in horizontal flame test even after 12 cycles of laundrying test,indicating that the wash durability of flame-retardant DTPMP/Fe3+ coating was improved greatly by PDMS treatment. |
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