Steel slag waste combined with melamine pyrophosphate as a flame retardant for rigid polyurethane foams

The rigid polyurethane foam (PU) is a versatile material, used especially for construction and household applications. The current situation demands a facile, cost-efficient, and greener approach for developing the polyurethanes from bio-derived materials. In this study, we present a novel bio-polyol synthesized using carvone, an extract from caraway, spearmint, or dill seeds via facile thiol-ene reaction. Our one-step reaction uses a UV irradiation to allow the room temperature conversion of the carvone to a high purity bio-polyol, as confirmed from the standard analytical characterizations. The hydroxyl number of 365 mg KOH/g close to its theoretical limit confirms the high conversion yield of the polyol for rigid PU synthesis. To overcome the flammability issues in PU, expandable graphite (EG) powder was used as an additive flame-retardant during the synthesis step. The resulting foams with EG maintained the uniform closed cell structure (>95%) with a high compression strength of 175 kPa. The addition of EG in PU results in the formation of a protective char layer during the flammability test and reduces the weight loss from 40.70% to 3.55% and burning time from 87 to 11 s. Our results confirm that the carvone-based polyol can be a novel alternative to the petroleum polyols for an industrial-scale application.

https://www.mdpi.com/2311-5629/6/2/27/pdf

Expendable Graphite as an Efficient Flame-Retardant for Novel Partial Bio-Based Rigid Polyurethane Foams

A novel bio-based polyol was synthesized using corn oil and 2-mercaptoethanol via thiol-ene reaction as an alternative to petroleum-based polyol for the synthesis of polyurethane foams. The polyol was analyzed using wet chemical techniques to obtain hydroxyl number and viscosity. Infrared spectroscopy and gel permeation chromatography were used to confirm the structural properties of the foams. Flame-retardant polyurethane foams were prepared by the addition of different concentrations of dimethyl methyl phosphonate (DMMP) in final foam composition. The effect of DMMP on the thermo-mechanical properties of the polyurethane foams was analyzed. The TGA analysis showed improved stability of the final char with addition of DMMP in the foams. All the foams maintained a well-defined cellular structure and over 95% of closed cell content. The horizontal burning test showed reduced burning time and weight loss from 115 s and 38 wt.% for the neat foams, to 3.5 s and 5.5 wt.% for DMMP-containing foams (1.94 wt.% P). The combustion test using cone calorimeter showed a considerable reduction in heat release rate and total heat release. Thus, our study shows that corn-oil based polyol can be used to produce renewable polyol for industrially producible rigid polyurethane foams. The addition of a small amount of DMMP could result in a significant reduction in the flame-retardant properties of the polyurethane foams.

Novel Biobased Polyol Using Corn Oil for Highly Flame-Retardant Polyurethane Foams

A novel compound (bis(3-hydroxyaminophenyl) phenyl phosphine oxide) (BHAPPO) was synthesized as a flame retardant based on bisphosphoramide structure. Rigid polyurethane foam (RPUF) formulations were prepared with different BHAPPO and ammonium polyphosphate (APP) content to investigate both flame retardant property of BHAPPO and the possible synergistic effect of BHAPPO and APP against RPUFs. FT-IR, 1H-NMR and 31P-NMR spectroscopy analysis confirmed the expected structure of BHAPPO. Flame retardancy and thermal degradation behavior of RPUFs were determined by limiting oxygen index (LOI) test and thermogravimetric analysis (TGA). The flame retardant property of novel BHAPPO against the prepared RPUF samples was confirmed. The synergetic effect of BHAPPO and APP combination both on reducing the flammability and enhancing the char formation of RPUFs was also confirmed with a dependence on their ratio. The compatibility effect of BHAPPO on mechanical and morphological properties of RPUFs was also investigated by compression test and SEM analysis. Fire behaviors and the effect of using flame retardant additives in polyurethane foam were investigated using a cone calorimeter. Carbon dioxide amount was found lower for flame retardant PU foam.

Synthesis and characterization of phosphorus-based flame retardant containing rigid polyurethane foam

Polyurethane (PU) foams physically modified by two additive phosphorous flame retardants (FR)—phenol isobutylenated phosphate or phenol isopropylated phosphate, and chemically reinforced by functionalized 1,2-propanediolizobutyl POSS (PHI-POSS) have been synthesized and investigated towards thermal and mechanical properties, as well as flammability behaviour. The foamed PU hybrid materials were prepared in a two-step process using a polyether polyol and polymeric 4,4′-diphenylmethane diisocyanate. On the basis of the obtained results of mechanical properties, thermal insulation, thermal stability and flammability investigations, the influence of the applied additives—including POSS nanoparticles, on the rigid polyurethane foams was determined. The analysis of thermogravimetric and microcalorimetry data revealed an improved resistance to burning of the PU foams containing hybrid reactive (POSS)/additive (phosphate) FR systems, as evidenced by reduced rate of heat release. Importantly, mechanical properties tests showed that incorporation of bulky silsesquioxane nanoparticles to polyurethane structure via covalent bonds strengthens the foam integrity.

/pdf/1-2-propanediolizobutyl-poss-as-a-co-flame-retardant-for-13rh67ufm9.pdf

1,2-Propanediolizobutyl POSS as a co-flame retardant for rigid polyurethane foams

A novel Flame-Retardant N-(P,P′-diphenyl) phosphorus-based-(3-triethoxysilicon) propylamine (DPTP) was synthesized in this study. The impact of DPTP on the mechanical properties, thermal stability, and flame retardancy of rigid polyurethane foam (RPUF) was studied. The addition of DPTP to RPUF can significantly reduce the undesirable thermal effects and smoke density during combustion, as well as increasing the limiting oxygen index. Compared with pure RPUF, the peak heat release rate of RPUF containing 10 phr of DPTP decreased by 39.4%, while its peak smoke production rate decreased by 49.9%. However, it was also found that the addition of DPTP reduced the compressive strength of RPUF.

/pdf/environmentally-friendly-flame-retardant-and-its-application-1r43rld8lx.pdf

Environmentally Friendly Flame-Retardant and Its Application in Rigid Polyurethane Foam

Intumescent flame retardant functional silicate and preparation method thereof

The invention discloses a reaction type phosphorus-nitrogen fire retardant and a synthesizing method of the reaction type phosphorus-nitrogen fire retardant. The synthesizing method comprises the following steps: adding a diamido compound into a reaction container containing solvents, adding an acid-binding agent, then adding phosphorus chlorine compound or phosphorus oxychloride compound, stirring uniformly, adjusting the temperature to 50 DEG C-90 DEG C, and reacting for 5-15h at constant temperature; filtering, washing a filter cake with water repeatedly and filtering or dissolving the filter cake with a strong-polarity solvent, and drying to obtain the reaction type phosphorus-nitrogen fire retardant. According to the reaction type phosphorus-nitrogen fire retardant and the synthesizing method of the fire retardant, the synthesizing method is simple, is free of complicated aftertreatment and is easy to implement; and the reaction type phosphorus-nitrogen fire retardant is high in thermal stability, active amido functional groups contained in molecules of the fire retardant have chemical bonding with polymer or polymer raw materials, so that the reaction type phosphorus-nitrogen fiber retardant can be mixed with substrate materials, and can be applied to polymers with various substrate materials.

Reaction type phosphorus-nitrogen fire retardant and synthesizing method thereof

As a biodegradable thermoplastic, polylactic acid (PLA) shows great potential to replace petroleum-based plastics. Nevertheless, the flammability and brittleness of PLA seriously limits its use in emerging applications. This work is focused on simultaneously improving the flame-retardancy and toughness of PLA at a low additive load via a simple strategy. The PLA/MKF/NTPA biocomposites were prepared by incorporating alkali-treated, lightweight, renewable kapok fiber (MKF) and high-efficiency, phosphorus-nitrogenous flame retardant (NTPA) into the PLA matrix based on the extrusion–injection molding method. When the additive loads of MKF and NTPA were 0.5 and 3.0 wt%, respectively, the PLA/MKF/NTPA biocomposites (PLA3.0) achieved a rating of UL-94 V-0 with an LOI value of 28.3%, and its impact strength (4.43 kJ·m−2) was improved by 18.8% compared to that of pure PLA. Moreover, the cone calorimetry results confirmed a 9.7% reduction in the average effective heat of combustion (av-EHC) and a 0.5-fold increase in the flame retardancy index (FRI) compared to the neat PLA. NTPA not only exerted a gas-phase flame-retardant role, but also a condensed-phase barrier effect during the combustion process of the PLA/MKF/NTPA biocomposites. Moreover, MKF acted as an energy absorber to enhance the toughness of the PLA/MKF/NTPA biocomposites. This work provides a simple way to prepare PLA biocomposites with excellent flame-retardancy and toughness at a low additive load, which is of great importance for expanding the application range of PLA biocomposites.

/pdf/preparation-and-mechanism-of-toughened-and-flame-retardant-3kkfuzyq.pdf

Preparation and Mechanism of Toughened and Flame-Retardant Bio-Based Polylactic Acid Composites

Radiative cooling is an effective technology with zero energy consumption to alleviate climate warming and combat the urban heat island effect. At present, researchers often use foam boxes to isolate non-radiant heat exchange between the cooler and the environment through experiments, so as to achieve maximum cooling power. In practice, however, there are challenges in setting up foam boxes on a large scale, resulting in coolers that can be cooled below ambient only under low convection conditions. Based on polymer materials and nano-zinc oxide (nano-ZnO, refractive index > 2, the peak equivalent spherical diameter 500 nm), the manufacturing process of heat pump film (HPF) was proposed. The HPF (4.1 mm thick) consists of polyethylene (PE) bubble film (heat transfer coefficient 0.04 W/m/K, 4 mm thick) and Ethylene-1-octene copolymer (POE) cured nano-ZnO (solar reflectance ≈94% at 0.075 mm thick). Covering with HPF, the object achieves 7.15 °C decreasing in normal natural environment and 3.68 °C even under certain circumstances with high surface convective heat transfer (56.9 W/m2/K). HPF has advantages of cooling the covered object, certain strength (1.45 Mpa), scalable manufacturing with low cost, hydrophobic characteristics (the water contact angle, 150.6°), and meeting the basic requirements of various application scenarios.

/pdf/a-scalable-heat-pump-film-with-zero-energy-consumption-1qc10djk.pdf

A Scalable Heat Pump Film with Zero Energy Consumption

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