Fengxiu Zhang

A plant-based reactive ammonium phytate for use as a flame-retardant for cotton fabric

A plant-based non-formaldehyde flame retardant containing high phosphorus ammonium phytate (APA) was synthesized for cotton fabric. The char length of treated cotton sample decreased to 31mm from the original 300mm. The LOI value of finished cotton fabric was as high as 43.2%, and after 30 laundering cycles, it still remained 30.5%, suggesting that APA could be used as an effective semi-durable flame retardant. The TG analysis in air demonstrated that the thermal oxidation stability of treated fabric was significantly improved. Cone calorimetry results showed that the peak heat release rate and total heat release of treated sample reduced obviously comparing with that of control sample. The SEM morphologies suggested that the APA molecule penetrated into the inner space of cotton fibers. FTIR spectra implied the APA molecule grafted onto cotton fibers. Then, the effective flame retardant APA has significant potential in practical application.

Mild surface modification of para-aramid fiber by dilute sulfuric acid under microwave irradiation

In aramid fiber-reinforced composites manufacturing, para-aramid fiber requires surface modification to improve its interfacial adhesion with matrix materials. In this study, aramid fiber was modified with dilute sulfuric acid, which was gradually concentrated under microwave irradiation. Results showed that the aramid fiber could be efficiently modified. Sulfonic acid groups were introduced on the surface of the aramid fiber, as confirmed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The breaking strength and thermal stability of the modified aramid fiber were not adversely affected. When the concentration of sulfuric acid was 30.0 g/L, the breaking strength of the aramid fiber remained at 90.7% of the original value, and the number of sulfonic acid groups of 1 g modified aramid fibers was 1.38 × 10–5 mol/g. Thermogravimetric and X-ray diffraction analyses showed that the main structure of the aramid fibers was not affected. The aramid fiber surface was not severely etched, as evidenced by scanning electron microscopy images. Therefore, this modifying method involving a gradual change in sulfuric acid concentration may be widely applied in many fields.

Anti-ultraviolet and anti-static modification of polyethylene terephthalate fabrics with graphene nanoplatelets by a high-temperature and high-pressure inlaying method

Grafting graphene on polyethylene terephthalate (PET) fibers requires a large number of environmentally harmful chemicals. In this study, a facile high-temperature and high-pressure method of inlaying graphene nanoplatelets was applied to fabricate anti-ultraviolet (UV) and anti-static graphene/PET composites. The resulting graphene-inlaid (GI) PET fabric, which showed excellent anti-ultraviolet and anti-static properties, was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform–infrared spectroscopy and X-ray diffraction. Results suggested that graphene had been inlaid into the PET fiber surface, and that the optimal inlaying conditions were as follows: inlaying temperature 200℃, inlaying pressure 15 MPa, and inlaying time 15 s. The UV protection factor of the GI PET fabric under optimal conditions could reach 50+ and was maintained at 50+ after 50 laundering cycles. The peak values of the static voltage and its half-time in the GI PET fabric could be reduced from 500.0 V to 10.0 V and from 7.39 s to 0.53 s, respectively, and the electrical resistivity of the GI PET fabric was 36.04 ± 0.14 kΩ.cm. The breaking strengths of the GI PET fabrics could be retained over 70.0% that of the pure PET fabric. The facile high-temperature and high-pressure inlaying method is an eco-friendly technique that requires very few chemicals, except for ethyl alcohol.

A new acrylamide- glyoxal-based, formaldehyde-free elastic and stiffness finishing process for silk fabric

A new formaldehyde-free reagent based on acrylamide and glyoxal was synthesized to improve the elasticity, stiffness, and weight gain of silk fabric. The finishing process could be completed rapidly in 20 seconds. The results showed that the elasticity, stiffness, and weight gain of silk fabric were efficiently improved. The stiffness was improved from 0.03 to 0.88 N·m, the delayed crease recovery angle was increased from 240° to 288.6°, and the weight gain could reach 18.1%. The finished silk fabrics were durable. The breaking strength and tear strength were substantially increased, and the whiteness of the silk was well maintained. Scanning electron microscopy revealed that the surface of the finished silk remained smooth. Fourier transform infrared spectroscopic analysis indicated the finishing reagent reacted on the silk, and X-ray diffraction analysis indicated that a new crystalline phase formed during the finishing process.

Facile fabricate a bioinspired Janus membrane with heterogeneous wettability for unidirectional water transfer and controllable oil–water separation

A novel smart Janus membrane for unidirectional water transfer and oil–water separation is facilely fabricated by coating graphene nanoplatelets (GNs) onto one side of polyethylene terephthalate (PET) fabric through high-temperature and high-pressure method and subsequently grafting phosphoric acid (HP) into the other side of PET fabric. Results suggest that the prepared HP–PET–GNs Janus membrane with heterogeneous surface wettability attributed to the hierarchical structure of membrane shows special unidirectional water transfer property. The water droplet can penetrate across the membrane from the GNs-coated (hydrophobic) side to the HP-grafted (hydrophilic) side, and be blocked to pass through the membrane from hydrophilic side to hydrophobic side. Moreover, the HP–PET–GNs Janus membrane is found to have the maximum water flux and separation efficiency of 2073 ± 207 Lm−2h−1 and 99.5 ± 0.2% for methylbenzene–water mixture, and the maximum oil flux and separation efficiency of 3113 ± 52 Lm−2h−1 and 99.6 ± 0.1% for carbon tetrachloride–water mixture, respectively. The water separation efficiency and oil separation efficiency could arrive at 99.0 ± 0.1 and 99.3 ± 0.2% even after 10 separation cycles, respectively. It is revealed that the obtained Janus membrane has excellent separation capability for separating the layered oil–water mixtures and possesses wonderful recyclability.

An eco-friendly intumescent flame retardant with high efficiency and durability for cotton fabric

The eco-friendly flame-retardant I-type ammonium polyphosphate (I-type APP) has poor water solubility and poor durability when applied to textiles, limiting its application in the textile industry. In this study, we resolve I-type APP solubility in water and then improve its durability for cotton fabric. The resolvable APP was grafted onto cotton fabrics by the P–O–C bonds. The limiting oxygen index (LOI) values of the 30% APP-treated cotton fabric was 50.1%; after 50 laundering cycles (LCs), the LOI values still retained 28.5%. No after-flame and after-glow were observed in the vertical burning test. These experimental results imply that the APP-treated cotton fabrics have high flame retardancy and excellent durability. Scanning electron microscopy showed that the surfaces of cotton fabric before and after treatment were similar and no material was deposited on the surface. X-ray diffraction analysis demonstrated that the crystal structures of the APP-treated cotton were almost unaffected. The thermogravimetric (TG) and TG-infrared (IR) analysis indicated that the treated cotton produced phosphoric acid or polyphosphoric acid during thermal decomposition to promote the dehydration and carbonization of cellulose in favor of char form. The results of the microcalorimetry indicated that the total heat release and the peak of the heat release rate of the treated cotton were significantly lower than those of the control cotton. The whiteness indexes, tensile strengths and bending lengths of the APP-treated cotton fabric showed that it still maintained good physical properties.Graphical abstract

Straightforward one-step solvent-free synthesis of the flame retardant for cotton with excellent efficiency and durability

A flame retardant, ammonium salt of 1-hydroxyethylidene-1,1-diphosphonic acid (AHEDPA), was synthesized by a facile one-step methodology and was proven to have achieved remarkable improved flame retardancy of cotton with exceptional durability because AHEDPA with functional groups PO-(NH4+)2 could react with OH of cellulose to form new POC bonds characterized by Fourier transform infrared (FT-IR) spectra, which further verify that AHEDPA was chemically bound to cotton instead of as additive or mixing into polymer. Combustion behaviors of the control and treated cotton were assessed by cone calorimetry, vertical flammability and limiting oxygen index (LOI) tests. The cone calorimetry results display that the peak heat release rate (PHRR) and total heat release (THR) of cotton fabric treated by 30% AHEDPA were reduced up to 95% and 68%, respectively, compared with those of control cotton. No after-flame and after-glow phenomena for treated cotton were observed in vertical flammable test. LOI test evinces that the cotton fabric treated with 30-40 % AHEDPA could be used as a durable flame retardant fabric with a LOI value of 26.2-29.5% after 50 laundering cycles. Thermogravimetric (TG) data both in nitrogen and in air atmosphere reveal that the AHEDPA treated cotton notably increased the char yield by catalyzing dehydration of cellulose, thus protecting the underlying matrix from heat and fuel. The efficient and durable flame retardant for the AHEDPA by the one-step synthesis method has great development prospects in industrial.

A novel reactive anti-ultraviolet finishing of cotton fabric based on N-dihydroxy ethylene cyanoguanidine

This study reports a novel ultraviolet (UV) absorber, N-dihydroxy ethylene cyanoguanidine (NDEC), which was synthesized from dicyandiamide and glyoxal. The NDEC compound was characterized by Fourier-transform infrared spectrum and nuclear magnetic resonance. NDEC was grafted onto cotton fabric through covalent bonding by the pad–dry cure method. The optimal finishing conditions were that the mass concentration of NDEC was 5 g/L, baking time 240 s and temperature 140℃. The UPF value of cotton fabric treated under optimal finishing conditions reached 50+ and was minimally reduced (to 47) after 50 laundry cycles. The breaking strength and thermostability of the original cotton fabric were preserved after treatment. Successful grafting of – C≡N and –C=N groups onto the treated fabric was confirmed in the Fourier-transform infrared spectrum. Meanwhile, the finished cotton fiber remained smooth, as confirmed by scanning electronic microscopy.

A novel method to bind soybean protein onto the surface of poly(ethylene terephthalate) fabric

In this study, –NH2 groups were introduced to a poly(ethylene terephthalate) (PET) fabric to make the fabric hydrophilic and, then, soybean protein was bonded on the surface of the modified PET fabric to obtain a soybean protein/PET composite fabric. The –NH2 groups allowed the soybean protein to be firmly bonded on the surface of the modified PET fabric. Scanning electron microscopy images showed that the surface of each modified PET fiber had a small number of grooves and that there was a thin film on each soybean protein/PET fiber. Attenuated total reflectance Fourier transform infrared spectra demonstrated that the nitrated and reduced PET fibers were introduced –NH2 groups and that there were –CO–NH– groups on the surface of soybean protein/PET fibers. X-ray photoelectron spectroscopy analyses showed that there was a nitrogen element on the modified PET fibers. The X-ray diffraction patterns suggested that the crystal structures of the modified fibers did not change significantly during the modification processes. The thermogravimetry results showed that the thermal stability of soybean protein/PET fiber kept well. The wearability tests indicated that the breaking strength and elasticity of the original fabric were well retained by the modified fabrics. The soybean protein/PET fabric had good levels of hydrophilicity and softness when the binding rate was below 3.0%.