Abstract
In this work, the self‐assembled lignin‐based flame retardant (LMA) was grafted with γ‐aminopropyltriethoxysilane (APTES) to obtain a novel type of silicon‐containing intumescent flame ...retardant (LK), which can be applied on polypropylene (PP) to obtain flame retardant PP (PP‐LK). Furthermore, low cost flame retardant PP biocomposite (PP/M/L) with high lignin content were prepared by compounding lignin, LK and PP. The developed PP‐LK and PP/M/L exhibited significant excellent flame retardancy, smoke suppression and mechanical properties. In particular, the UL‐94 test achieved V‐0, and the limit oxygen index (LOI) increased from 17.9% of PP to 28.3% of PP‐LK, and 27.2% of PP/M/L, respectively. Meanwhile, tensile strength and Young's modulus increased by 6.3% and 19.64% for PP‐LK and PP/M/L, respectively. Especially, the tensile strength of PP with 15% LK and 25% lignin achieved 30.88 MPa, and the Young's modulus reached 1415 MPa. The excellent carbonization properties of PP‐LK illustrated that the lignin component of LK had excellent carbonization ability. The prepared LK provided a novel strategy to improve the fire safety and cost of PP, and wide the applications of lignin.
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•A novel multi-functional polymeric curing agent for epoxy resin.•Efficient curing ability, good flame retardancy, and high transparency.•The mechanisms of flame retardance and ...transparence.
Traditional cured epoxy resin (EP) usually loses its transparency once it encounters the requirement of flame retardance. To obtain the EP with simultaneous excellent transparency and flame retardancy, a novel multi-functional polymeric curing agent named DPPEI was synthesized via a reaction between diphenylphosphinic chloride (DPPC) and polyethylenimine (PEI) in this work. Different measurements confirmed that the DPPEI was prepared successfully. After incorporation of the DPPEI into EP, the cured EP (DPPEI-EP) material with simultaneous excellent transmittance and flame retardancy was obtained after a mild curing process. The transmittance of the resulting DPPEI-EP was kept at about 90% in the visible region at a loading of 35 wt% DPPEI, meanwhile, the DPPEI-EP sample with the thickness of only 1.6 mm passed the V-0 rating in vertical burning test, had no dripping, and achieved the limiting oxygen index of 29.8%. In combustion test, both total heat release and total smoke production of the DPPEI-EP containing 30 wt% DPPEI were respectively greatly decreased by 69.5% and 78.3% compared with the corresponding value of the reference sample PEI-EP, showing high flame-retarding and smoke-suppressing efficiency. The transparent and flame-retardant mechanisms of DPPEI-EP were investigated insightfully through different tests. All these results demonstrate that the DPPEI is a novel multi-functional polymeric curing agent for EP, which has efficient curing ability and meanwhile endows the cured EP with simultaneous excellent flame retardancy and transparency.
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•Tailored hybrid designed with MOF, PBA layer and PDA as linker between the two.•Hierarchical structure equipped with target function by interfacial interaction.•The hybrids impart EP ...with significantly enhancement flame retardancy.•Hybrids simultaneously decrease release of toxic gases, such as CO to Epoxy.
With the aim of achieving fire safe epoxy (EP), a hierarchical hybrid (UiO66-PDA-PBA) was designed with metal-organic framework (MOF, UiO-66) as the core structure, self-assembled prussian blue analogues (PBA) as surface layers, and polydopamine (PDA) as the link between the two. The tailored hierarchical structure equipped with target functions enabled the enhancement of the intrinsic fire retardancy of the inner UiO-66, through the significant interfacial catalytic effect. The results demonstrated that with the addition on of 3% UiO66-PDA-PBA, EP composites exhibited a 50% decrease in peak heat release rate (pHRR) and a 66% decrease in production of carbon monoxide (COP), accompanied with the suppression of smoke. Meanwhile, the adequate characterizations showed that the interfacial catalyst of nickel species derived from PBA exhibited high activity transforming into residue with a polyaromatic structure and exhibited catalytic oxidation effect for CO through Py-GC-MS and XRD results. The interfacial engineering between this hierarchical fire retardant and polymer may enhance quality of the char residue, which attributed to the ability for efficient catalytic effect, thus enhancing the fire safety of EP. In perspective, constructing the structure tailored hierarchical fire retardants with target functions is an effective means of achieving fire safety in epoxy.
•In-situ coprecipitation modified APP (Fe/Zn-LDH@APP) was prepared.•Heat release and smoke production of Fe/Zn-LDH@APP were greatly decreased.•Fe/Zn-LDH@APP improved the mechanical performance of ...EP.•Fe/Zn-LDH@APP exerted the synergistic catalytic effect during combustion of EP.
Inspired by the in-situ coprecipitation technology, Fe/Zn-layered double hydroxides (Fe/Zn-LDH) doped ammonium polyphosphate (APP) was prepared for high fire-safety epoxy resins (EP). The investigation on the chemical composition and micromorphology of Fe/Zn-LDH@APP confirmed the uniform deposition of Fe/Zn-LDH on the surface of APP. The results showed that EP containing 4 wt% Fe/Zn-LDH@APP exhibited the highest LOI of 29.4% and passed the UL-94 V0 level. Additionally, compared to neat EP, the peak of heat release rate, peak of smoke production rate, and the fire growth rate decreased by 66.4%, 48.4%, and 80.7%. The greatly enhanced flame retardancy of EP was contributed to the highly synergistic charring catalysis via abundant interfacial contact sites. Moreover, the mechanical performance of Fe/Zn-LDH@APP/EPs were slightly affected due to the improved interfacial interaction of Fe/Zn-LDH@APP. Generally, this work exploited a tactful strategy to construct LDH doped APP hybrid material, and presented the potential application in industry.
A novel multifunctional organic–inorganic hybrid was designed and prepared based on ammonium polyphosphate (APP) by cation exchange with diethylenetriamine (DETA), abbreviated as DETA-APP. Then ...DETA-APP was used as flame-retardant curing agent for epoxy resin (EP). Curing behavior, including the curing kinetic parameters, was investigated by differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). The flame retardance and burning behavior of DETA-APP cured EP were also evaluated. The limiting oxygen index (LOI) value of DETA-APP/EP was enhanced to 30.5% with only 15 wt % of DETA-APP incorporated; and the UL-94 V-0 rating could be easily passed through with only 10 wt % of the hybrid. Compared with DETA/EP, the peak-heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak-smoke production release (SPR) of DETA-APP/EP (15 wt % addition), obtained from cone calorimetry, were dropped by 68.3, 79.3, 79.0, and 30.0%, respectively, suggesting excellent flame-retardant and smoke suppression efficiency. The flame-retardant mechanism of DETA-APP/EP has been investigated comprehensively. The results of all the aforementioned studies distinctly confirmed that DETA-APP was an effective flame-retardant curing agent for EP.
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•A common and facile method was revealed to fabricate multifunctional flame-retardant cotton fabric using ammonium phosphate as cross-linker.•Superior flame retardancy and ...antibacterial performance could be achieved via a one-pot process.•The modified cotton fabric presented exceptional washing durability and well-preserved the whiteness, air permeability and hand feeling.
Ammonium phosphates have been proven to be efficient and durable flame retardants for cellulose fabric. However, a facile process for their multifunctional flame-retardant modification has not yet been reported. In order to achieve this goal, we synthesized an ammonium diphosphate of ethylene glycol (AP) and used it as a crosslinker to fabricate flame-retardant and antibacterial cellulose fabric with a dihydroxyl N-halamine precursor (BD) via a one-pot process. The AP/BD modified fabric exhibited superior flame retardancy, with a LOI value of 32.9% and self-extinguishing behavior at only 11.0% weight gain. The heat release was significantly inhibited, with an 81% reduction in peak heat release rate (PHRR) and a 60% reduction in total heat release (THR). Furthermore, the modified fabric maintained its self-extinguishing properties even after undergoing 50 washing cycles, demonstrating excellent washing durability with a LOI value of 30.5%. In addition to its outstanding flame retardancy, the AP/BD modified fabric also displayed excellent biocidal efficacy due to the formation of N-Cl bonds through simple bleaching treatment. All inoculated bacteria were killed within just 5 min of contact without any noticeable dissolution occurring. Moreover, the oxidative chlorine that acted as an antibacterial factor could be recharged after long periods of storage and washing. Importantly, no significant changes in whiteness, air permeability or hand feeling were observed after the AP/BD modification process. Therefore, this work presents a common and facile approach for preparing highly-efficient flame-retardant cellulose fabrics with multifunctionality.
We found in our previous study that ethylenediamine- or ethanolamine-modified ammonium polyphosphates could be used alone as an intumescent flame retardant for polypropylene (PP), but their ...flame-retardant efficiency was not very high. In this present work, a novel highly-efficient mono-component polymeric intumescent flame retardant, piperazine-modified ammonium polyphosphate (PA-APP) was prepared. The oxygen index value of PP containing 22 wt % of PA-APP reached 31.2%, which increased by 58.4% compared with that of PP with equal amount of APP, and the vertical burning test (UL-94) could pass V-0 rating. Cone calorimeter (CC) results indicated that PP/PA-APP composite exhibited superior performance compared with PP/APP composite. For PP containing 25 wt % of PA-APP, fire growth rate (FGR) and smoke production rate (SPR) peak were reduced by 86.4% and 78.2%, respectively, compared with PP blended with 25 wt % APP. The relevant flame-retardant mechanism of PA-APP was investigated by Fourier transform infrared spectroscopy etc. The P–N–C structure with the alicyclic amine was formed during the thermal decomposition of piperazine salt (−NH2 +–O–P−), and the rich P–N–C structure facilitated the formation of stable char layer at the later stage, consequently improving the flame-retardant efficiency of APP.
•A new quaternary ammonium ionic liquid was synthesised and used to strip montmorillonite.•An environmentally friendly composite hydrogel has successfully prepared.•The composite hydrogel efficiently ...removes cationic dyes (MB, RhB), anionic dyes (MO, IC) and 4-nitrophenol.•The adsorption mechanisms involve electrostatic interactions and hydrogen bonding.•Selectivity and circulation experiments revealed the practical application of adsorbent.
Herein, quaternary ammonium ionic liquids (DM) with different chain lengths was successfully synthesised for the removal of sodium montmorillonite (MMT) and a composite hydrogel (DMCHA) was prepared. The hydrogel was used for the synergistic removal of organic pollutants such as cationic dyes (methylene blue: MB, rhodamine B: RhB), anionic dyes (methyl orange: MO, indigo red: IC) and nitrobenzene compounds (4-nitrophenol: 4-NP) from wastewater. Notably, the maximum adsorption amounts of MB, MO, IC and RhB were 349.68, 325.42, 306.08 and 332.85 mg/g, respectively, at 298.15 K. The reduction of 4-NP by composite hydrogels loaded with Ni-NPs showed excellent catalytic performance (Kapp = 0.17). The adsorption process of DM16CHA on dyes conforms to the Langmuir model, obeys the proposed first-order model of intraparticle diffusion, and is spontaneous and heat-absorbing. Selectivity experiments with mixed dyes solutions indicate promising applications for DM16CHA. The adsorption mechanism of DM16CHA on the four dyes was mainly based on electrostatic and hydrogen bonding interaction. The cyclic adsorption experiments showed that DM16CHA has excellent recyclability. Furthermore, DM16CHA has excellent antimicrobial and mechanical properties that endow the gel-based adsorbent with contamination resistance and durability. The DM16CHA provides an economical, efficient, green and promising strategy for industrial wastewater treatment and environmental protection.
