Abstract:

Objective Polyester/cotton (T/C 65/35) fabrics have been widely used in both clothing and industrial fields, because of their great moisture absorption and breathability associated with cotton fibres and good mechanical property provided by polyester fibres. However, T/C fabrics are extremely flammable and hard to be flame-retardant, because the special ″scaffolding effect″ of polyester and cotton can arise violent flame, large amount of heat and copious smoke. Therefore, T/C fabrics used in public places such as curtains, need to meet the flame-retardant requirements to can reduce the fire risk.

Method To prepare polyester/cotton (T/C,65/35) fabrics that are flame-retardant and meet practical application requirements, chitosan (CS) and γ-piperazinyl propylmethyl dimethoxy silane (GP-108) were utilized to prepare flame-retardant T/C fabrics through one-step dip-coating method, and the micromorphology, thermal stability, flame retardancy, tensile strength, flame-retardant mechanism and whiteness of T/C fabrics and flame-retardant T/C fabrics were studied.

Results The results showed that PCS/GP coatings successfully formed a film on the surface of T/C fabrics and enveloped both polyester and cotton fibers. T/C-PCS/GP exhibited a typical thermal degradation process of polyester-cotton fabrics with char residues value of 28.5% retained at 700 ℃, indicating that the PCS/GP coatings improved the thermal stability of flame-retardant T/C fabrics in the high temperature zone. The LOI value of T/C-PCS/GP was increased to 26.5%, achieving self-extinguishing during the vertical flame test(VFT). The scanning electron microscopy (SEM) photos of char residues after VFT showed that PCS/GP eliminated the scaffolding effect of polyester-cotton fabrics. The peak heat release rate and fire growth index of T/C-PCS/GP were decreased by 20% and 40% respectively compared with those of T/C fabrics, indicating a significant reduction in fire hazard. The SEM pictures of char residues after CCT showed that polyester in T/C fabrics was completely melted, while T/C-PCS/GP kept the original shape of fibers and presented perfect intumescent flame-retardant char layers. T/C-PCS/GP underwent the thermal degradation processes in advance compared with T/C fabrics, because of the catalysis effect of phosphoric acid. However, T/C-PCS/GP released less volatiles at the maximum thermal degradation temperature and barely no gas products release during the high temperature zoon. T/C-PCS showed decreased tensile strength compared with T/C, while owing to the addition of GP-108, T/C-PCS/GP obtained better tensile strength compared with T/C-PCS. Meanwhile, the use of GP-108 solved the yellowing problem of T/C-PCS and increased the whiteness of T/C-PCS/GP.

Conclusion The results showed that an eco-friendly flame-retardant coating had deposited on the surface of T/C fabrics which presented ideal flame retardancy, mechanical property and whiteness. PCS/GP coatings are capable of endowing T/C fabrics with great flame retardancy through establishing instrument flame-retardant char layers after heating. Fortunately, T/C-PCS/GP showed decreased fire hazard. For the utilization of GP-108, the damage of tensile strength associated with PCS had been avoided and the whiteness of T/C-PCS/GP was better than that of T/C-PCS. The design of PCS/GP was hopeful to provide more stratagems for the intumescent flame-retardant system with environmental materials. Meanwhile, the application of silane agent solved the decreasing tensile strength and whiteness owing to PCS. This work was lack of analysis containing the original properties of T/C, such as hand feeling, which played a key role on the practical application of flame-retardant T/C.

Key words: polyester/cotton blended fabric, flame-retardant finishing, chitosan, intumescent flame retardant system, silane coupling agent