No abstract

Cotton fabric, as an important material, is suffering from some defects such as flammability, easy pollution and so on; therefore, it is important to make a flame-retardant and superhydrophobic modification on cotton fabric. In this study, we demonstrated a preparation of high-efficiency flame-retardant and superhydrophobic cotton fabric with double coated construction by a simple multi-step dipping. First, the fabric was immersed in branched poly(ethylenimine) (BPEI) and ammonium polyphosphate (APP) water dispersions successively, and then immersed in polydimethylsiloxane (PDMS)/cellulose nanocrystals (CNC)-SiO2 toluene dispersion to form a BPEI/APP/PDMS/CNC-SiO2 (BAPC) composite coating on the surface of the cotton fabric. Here, the hydrophobic modified CNC-SiO2 rods were used to construct the superhydrophobic layer and the BPEI/APP mixture was used as the flame-retardant layer, as well as SiO2 particles which could further improve the flame-retardant effect. PDMS was mainly used as an adhesive between the BPEI/APP layer and the CNC-SiO2 layer. The resulting cotton fabric shows outstanding flame-retardant properties, in that the value of oxygen index meter (LOI) reaches 69.8, as well as excellent superhydrophobicity, in that the water contact angle (WCA) is up to 156.6°. Meanwhile, there is a good abrasion resistance, the superhydrophobicity is not lost until the 16th abrasion cycles and the flame retardant retains well, even after 100 abrasion cycles in an automatic vertical flammability cabinet under a pressure of 8.8 kPa.

Lignin nanospheres could be taken main structural materials and cellulose nanocrystals as a reinforcer for preparation of superhydrophobic surfaces with good robustness and long UV resistance.

No abstract

To improve on the poor strength and flame retardancy of a chitosan (CS)-based functional film, cellulose nanofiber (CNF) was taken as the reinforced material and both ammonium polyphosphate (APP) and branched polyethyleneimine (BPEI) as the flame-retardant additives in the CS matrix to prepare the CS/CNF/APP/BPEI composite film by simple drying. The resulting composite film showed good mechanical strength, with a tensile strength reaching 71.84 Mpa due to the high flexibility of CNF and the combination of CS, CNF and BPEI through strong hydrogen bonding interactions. The flame retardant-performance of the composite film greatly enhanced the limit oxygen index (LOI), up to 32.7% from 27.6% for the pure film, and the PHRR intensity decreased to 28.87 W/g from 39.38% in the micro-scale combustion calorimetry (MCC) test due to the ability of BPEI to stimulate the decomposition of APP, releasing non-flammable gases such as CO2, N2, NH3, etc., and forming a protective phosphating layer to block the entry of O2. Based on the good flame retardancy, mechanical strength and transparency, the CS/CNF/APP/BPEI composite film has a great potential for future applications.