Publications by authors named "Chaojun Wan"

Article Synopsis
  • A new organic-inorganic biomass composite aerogel was created using materials like glucomannan, isocyanate, and water glass, utilizing a freeze-drying method.
  • The aerogel exhibits an interpenetrating network structure and demonstrates impressive mechanical properties, including a compressive strength of 4.751 MPa and high thermal stability due to the inclusion of boron ions.
  • This composite aerogel offers an eco-friendly solution for insulation in low-energy buildings, with optimal insulation thickness between 40-60 mm, significantly reducing heat release rates.
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Supramolecular flame retardants have attracted increasing attention recently due to their simple and eco-friendly preparation process. In this study, a novel flame retardant HEPFR was prepared using supramolecular self-assembly technology between piperazine and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP). It was introduced into polyvinyl alcohol (PVA) matrix to form PVA/HEPFR composite film.

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Flame retardant treatment of epoxy resins (EP) to reduce their flammability for extending their range of applications attracts considerable attention. However, the synthesis process of conventional flame retardants is complicated and involves organic hazardous solvents. Meanwhile, how to ensure both the flame-retardant and mechanical properties is a long-standing and actual difficult problem.

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At present, biomass foamlike materials are a hot research topic, but they need to be improved urgently due to their defects such as large size shrinkage rate, poor mechanical strength, and easy hydrolysis. In this study, the novel konjac glucomannan (KGM) composite aerogels modified with hydrophilic isocyanate and expandable graphite were prepared by a facile vacuum freeze-drying method. Compared with the unmodified KGM aerogel, the volume shrinkage of the KGM composite aerogel (KPU-EG) decreased from 36.

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Rigid polyurethane foam (RPUF) is one of the best thermal insulation materials available, but its flammability makes it a potential fire hazard. Due to its porous nature, the large specific surface area is the key factor for easy ignition and rapid fires spread when exposed to heat sources. The burning process of RPUF mainly takes place on the surface.

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In this study, a novel hyperbranched phosphorus/nitrogen-containing flame retardant (HPNFR) was facilely synthesized via the transesterification reaction of dimethyl methylphosphonate and tris (2-hydroxyethyl) isocyanurate and characterized successfully by H NMR and FTIR. The sample with 4 wt% HPNFR can achieve V-0 rating in UL-94 test and possess a LOI value as high as 34.5%.

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The current study aims at comparatively investigating the effect of apparent density on flame retardancy, thermal degradation and combustion behaviors of rigid polyurethane foam (RPUF), RPUF/ expandable graphite (EG) and RPUF/ ammonium polyphosphate (APP). A series of RPUF, RPUF/EG and RPUF/APP samples with different apparent densities (30, 60 and 90 kg/m³) were prepared. The flame retardancy, thermal degradation, and combustion behaviors of each sample were investigated.

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Hypothesis: Organic foamy materials possess good thermal insulation properties and inorganic materials are non-combustible. Hence, it is possible to develop a kind of organic-inorganic lightweight thermal insulation materials with excellent fire safety.

Experiments: Hollow glass microsphere (HGM), as one kind of lightweight noncombustible inorganic material, was chosen as the filling material.

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