| Phosphorus and nitrogen elements could be used as an environmentally friendly flame-retardant element because their products are less toxic and generate less smoking.Flame retardants containing phosphorus and nitrogen are usually called intumescent flame retardants.It could provide polymers with better flame retardancy than those composed of one element.The Mannich Reaction of phosphite esters is an important organic reaction with mild conditions and low cost,so it has a wide use in both basic research and commercial utilization.In this article three kinds of flame retardants for cotton were synthesized by formaldehyde,dimethyl phosphite and various ammonia/amine components according to the Mannich Reaction of phosphite esters.FR-1 containing hydroxyl group was prepared by choosing diethanolamine as amine components in the chapter two.DM508 etherified resin was used as a crosslinking agent and the flame resistant performance was discussed on cotton fabrics.The result showed that the damagedlength of fabric treated with FR-1 350g/L and DM508 80g/L was 8.3cm before laundering.The physical and mechanical property of fabric changed a little after finishing.But the flame resistant was nondurable.In the chapter three,a small molecular flame retardant(FR-2)containing amido was synthesized by formaldehyde,ammonia and dimethyl phosphite.The flame resistant performance and physical properties were also discussed on cotton fabrics. The studied systems was composed of flame retardant synthesized and two types of siloxane couplers including tetraethoxysilane(TEOS)andγ-glycidyloxypropyltrimet-hoxysilane (GPTMS).The process of long-lasting fire retardant technology,the technological conditions and the effect of fire retardant on cotton fabrics were introduced.The flame retardant properties of samples were evaluated by damagelength,the limiting oxygen index(LOI)values.Even after 30 times laundering the LOI values of these samples were all above 45%and 30%.The finishing systems endued cotton fabric with durable flame retardancy and there was non-formaldehyde couplers.Konwing from the chapter three that silanol generating after the hydrolysis of silane coupling agent was very reactive.Therefore a flame retardant(FR-3)containing siloxane groups was prepared withγ-aminopropyltriethoxysilane(APS)in the chaper four.As a result,the optimal finishing process of cotton fabric was as follows:flame retardant 350 g/L,pH value 8.0 around,curing 3 min at 165℃.Its limiting oxygen index(LOI)value was 28.3%after 10 times laundering,which promoted that the FR-3 could be considered as half-durable flame retardant.The chemical structures of the flame retardants were investigated by Fourier Transform Infrared Spectroscopy(FTIR)and elemental analysis.The flame retarded cotton fabrics were investigated by TGA-DTG and SEM.The TGA-DTG results reveled that the FRs decreased the initiate decomposition temperature of cotton fabric but enhanced its char residue at high temperature.SEM investigations revealed that the cotton treated by FR-2 and FR-3 respectively formed the continuous and close outer surface of the char layer during combustion,which acted as a good barrier to the transfer of heat and combustible gas between the flame zone and the substrate,and thus protected the underlying materials from further burning... |
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