Search

The output of bio-based polyvinyl alcohol (PVA) has been growing rapidly with a substantial increase of developments both in academic and industrial research areas in the past decade, which is due to its water solubility, plasticity, and degradability. However, PVA is highly flammable with a limiting oxygen index of only 19% owning to its inherent macromolecular structure composed of carbon, hydrogen, and oxygen atoms. The demand for flame retardancy of PVA has been increased rapidly and is generally satisfied by introducing flame retardants via chemical grafting, physical blending, and coating. This review summarizes the flame retardants applied in PVA and their influence on the flammability and mechanical properties of PVA materials. The type of flame retardant additives and their application technologies for various PVA products are presented in terms of various PVA products, such as films, aerogel, fibers, foams, and bulk composites. The films dominate the whole research of flame retardant PVA materials owing to their widespread application. The fire performance and flame retardant mechanism are compared and discussed. Additionally, PVA acted as an assistant agent in some polymeric flame-retardant formulations is also discussed and reviewed. [ABSTRACT FROM AUTHOR]

High efficient flame retardant surface treatment through a simple and universal strategy has attracted considerable interest. In this work, polyphosphonamide (PPA) was synthesized via an eco-friendly amine ester exchange reaction, and then the polydopamine-polyphosphonamide (PDA-PPA) coating was constructed by a mussel-inspired phenol-amine co-deposition on the surface of various substrates (cotton, polyethylene terephthalate, poly (lactic acid), polyamide, polypropylene fabrics, and flexible polyurethane foam). It was demonstrated that the PDA-PPA coating significantly improved the flame retardancy of the six substrates. For example, in the case of PDA-PPA coated cotton fabric sample, the limiting oxygen index was increased to 28.3%, the peak of heat release rate and total heat release was decreased by 70.6% and 48.2%, respectively. Especially in the vertical and horizontal burning tests, all PDA-PPA coated samples were self-extinguished and free of molten droplets. It was suggested that the PDA-PPA coating released P-containing radicals to capture active small free radicals and released non-combustible gases to dilute combustible volatiles in the gas phase. In addition, the coating showed excellent intumescent charring ability and promoted the char formation of all substates except polypropylene. Surprisingly, the coating also improved the breaking strength of the PDA-PPA coated fabric and the compressive stress of the PDA-PPA coated foam samples. It was believed that this work provides a scalable and promising strategy for preparing fire safety polymeric materials with a large specific surface area. [Display omitted] • Polyphosphonamide (PPA) was synthesized by an eco-friendly approach. • Polydopamine (PDA) -PPA coating was constructed on the surface of six substrates. • All PDA-PPA coated samples were self-extinguished and free of molten droplets. • The PDA-PPA coating exerted a comprehensive inhibition on combustion. • A facile, universal strategy for flame retardant surface treatment was proposed. [ABSTRACT FROM AUTHOR]

• By foam finishing with sodium polyborate, cotton fabric obtains good flame retardancy and maintains softness and breathability. • The flame retardant does not involve Cl or P-containing chemicals. • Foam finishing consume lower water or solvent than dip-padding finishing. The conventional process of imparting flame retardancy to cotton fabrics requires the consumption of large amounts of water, chemicals, and energy, which usually involves halogen-containing and phosphorus-containing chemicals. In this work, an eco-friendly sodium polyborate (SPB) foam was creatively introduced onto the cotton fabric surface by a bladed coater to improve the fire resistant performance. For the cotton sample with only 6.7% weight gain (WG) of SPB coating, the LOI value of cotton fabric (SPB treated cotton-1) was enhanced to 32.6% from 18.5%, the damaged length was decreased to 5.7 cm, and the sample self-extinguished in the vertical burning test. The peak of heat release rate value, total heat release value, and total smoke production (TSP) value decreased by 87.0%, 72.7%, and 22.2% respectively compared with those of the control sample. The TSP was further decreased by 80.6% when the WG of SPB was 16.7%. Besides, the SPB treated cotton showed enhanced antibacterial activities against S.aureus and E.coli. Particularly worth mentioning is in the SPB foam finishing procedure, no organic solvent and P or Cl-containing chemicals were involved, and the processing time was only around 3 min with obviously reduced water consumption, compared with dip-padding finishing. More importantly, SPB treated cotton kept good softness, whiteness, water vapor permeability, and air permeability. The SPB foam finishing in this work shows considerable potential in realize good flame retardancy on cotton fabrics by eco-friendly and high-efficient strategy. [ABSTRACT FROM AUTHOR]

The incorporation of flame retardants (FRs) is often applied to reduce the fire risk of flexible polyurethane foam (FPUF), however, the addition of FRs usually brings mechanical loss, and the emigration of FRs during service life results in a decrease in flame retardancy. In this work, a hyperbranched FR (HPNP) containing nitrogen and phosphorous was synthesized via transesterification between dimethyl methyl phosphonate (DMMP) and triethanolamine. The distribution of HNPN in FPUF was simulated by the Materials Studio software. The flammability was characterized by the open flame test, horizontal combustion test, limiting oxygen index (LOI) and cone calorimeter test. The FPUF sample containing only 4 wt% HPNP self-extinguished immediately after the removal of the ignitor. For the FPUF containing 8 wt% HPNP sample, the LOI was increased to 26.3% from 17.9%. The total heat release and total smoke production were reduced by 65% and 75%, respectively compared to that of the control FPUF sample. More importantly, the radical trapping action in the gas phase and the charring promotion in the condensed phase were simulated and verified based on the experimental data. Furthermore, the interfacial energy calculation and molecular dynamics simulation suggested that the improved compatibility of FPUF/HPNP resulted in the superior durability of HPNP in FPUF. In addition, the FPUF samples containing HPNP also showed enhanced mechanical properties. It was expected the hyperbranched HPNP would be an ideal additive to produce flame retardant FPUF with excellent comprehensive performance. [Display omitted] • A hyperbranched flame retardant (HPNP) was synthesized by transesterification. • FPUF containing 8 wt%HPNP showed self-extinguish effect with an LOI of 26.3%. • Total smoke release of FPUF was greatly reduced by the presence of 8 wt% HPNP. • The addition of HPNP also enhanced the mechanical properties of FPUF. • The improved compatibility of HPNP and FPUF suppressed the emigration of HPNP. [ABSTRACT FROM AUTHOR]

It is still a big challenge for textile industry in improving fire resistance and reducing melt dripping with minimal loss on the physical properties of polyethylene terephthalate (PET) fabrics. In this work, a highly-effective hyperbranched flame retardant (DT) was first synthesized by ester exchange without using any organic solvent. Then, the DT foam was prepared and blade coated on PET fabric to improve the fire performance. The prepared PET fabric with only 2.7% weight gain of DT was self-extinguished and did not produce any molten dripping during the vertical flammable test. The peak heat release rate and total heat release of the PET fabric sample with 19.4% DT were decreased by 42.0% and 57.1%, respectively compared with that of the control PET. Besides, the as-prepared PET fabric sample showed better physical properties such as breaking strength, vapor permeability, air permeability, antistatic property, and softness than the control PET fabric sample. The DT foam finishing process did not involve any organic solvent and consumed less water and energy compared with conventional fabric treatments. It is expected that this work provides a facile and eco-friendly strategy for fabricating flame retardant PET fabric with excellent comprehensive performances. [Display omitted] • A hyperbranched flame retardant (DT) was synthesized by a solvent-free approach. • Flame retardant PET fabrics were prepared by sustainable foam finishing. • The PET fabric with 2.7% DT was self-extinguished and free of molten drops. • The treated PET fabric showed excellent physical properties. [ABSTRACT FROM AUTHOR]

• Two reactive flame retardants were obtained through transesterification. • The flame retardants improved the flame retardancy of rigid polyurethane foam. • The mechanical properties and low heat conductivity were well maintained. The reactive type flame retardants have been applied in rigid polyurethane foams (RPUF) owing to their excellent durability and minimal negative effect on the physical properties, however, their flame retardant efficiency cannot meet the requirements in many practical application scenarios. In this work, two reactive-type flame retardants with several hydroxyl groups were synthesized by a solvent-free transesterification between erythritol and dimethyl methyl phosphonate (DMMP), and they were then introduced into RPUF by reacting with isocyanate respectively. The flammability of the as-prepared RPUF samples was evaluated by limiting oxygen index (LOI) and cone calorimeter tests. With the presence of 10 phr as prepared flame retardant, the LOI value of RPUF was improved from 18.3% to 29.8%, and the peak heat release rate (pHRR) and total heat release (THR) were reduced by 31.4% and 47.8% respectively in contrast to that of control RPUF. Furthermore, the compressive strength and thermal conductivity of RPUF containing reactive flame retardants were similar to those of control RPUF. This study provides an innovative method for the clean production of commercial RPUF with fire safety by using a modified phosphorus ester. [ABSTRACT FROM AUTHOR]

Flexible polyurethane foam (FPUF) is widely used in our life, but it is inherent flammable. The demand for environmental-friendly multi-functional FPUF has been increasing rapidly in the last decade. In this work, a novel bio-based flame retardant coating was constructed by chemically reacting sodium alginate (OSA) and polydopamine (PDA) on the FPUF, followed by depositing nanorod-like β-FeOOH molecules through complexation reaction to form a biomimetic structure. The limiting oxygen index of the coated FPUF samples reached 25.5%. The peak heat release rate was reduced by 45.0%, and the smoke density of the coated sample was decreased by 69.1% compared to that of the control FPUF sample. It was proposed that the OSA-PDA-β-FeOOH decomposed during combustion to promote the formation of compact crosslinked char and released inert gases to dilute the combustible gases, and the β-FeOOH transferred to Fe 2 O 3 to settled the smoke particles reducing the smoke release. Furthermore, the coating with shark skin like structure endowed FPUF antibacterial ability because of its good superoleophobicity underwater. This work provided a novel strategy to construct a biomimetic multifunctional coating on the FPUF. [Display omitted] • A biobased coating was constructed on flexible polyurethane foam (FPUF). • The coating with a biomimetic structure improved the flame retardancy of FPUF. • The LOI of the coated FPUF reached 25% after washing and/or abrasion. • The coating decreased the peak smoke density of FPUF by 68.5%. • FPUF with superoleophobicity underwater showed antibacteria for cleaning application. [ABSTRACT FROM AUTHOR]

• Phosphorylated histidine-amino triazine-diaminopropane (PHTD) copolymer was synthesized and used as bifunctional additives of flame retardant and binder. • PHTD can improve the flame retardancy and smoke suppression of EPS foams significantly. • The hard shell formed by PHTD can improve the compressive strengths of EPS foams. A novel intumescent flame retardant, phosphorylated histidine-amino triazine-diaminopropane (PHTD) was synthesized and utilized as both a flame retardant and a binder addition. Flame retardant expanded polystyrene (EPS) foams containing PHTD was successfully prepared by coating method. The limited oxygen index (LOI) and vertical burning (UL-94) tests were used to determine the flammability of EPS/PHTD composite foams, and an apparent flame retardant effect could be obtained with up to 28.8% LOI value and UL-94 V-0 rating when 41.9 wt.% PHTD was added. The cone calorimetric test results showed that the treat EPS sample showed significantly depressed peak heat release rate (pHRR) by 74.9% and peak smoke production rate (pSPR) by 77.3%. Additionally, the flame retardant could be evenly coated on the surface of EPS beads. Even though part of the foam was damaged, it could still keep good flame retardant performance. Furthermore, the thermal conductivity of coated foam was not affected and remained at a comparatively low level, and the compressive strength was increased by 20.0%. [ABSTRACT FROM AUTHOR]