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Properties of rigid polyurethane foam with added walnut shell powder modified with ammonium polyphosphate

delete2026-07-25
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PRE
AI
X
Xu Zhang *
韩蕊 (Rui Han)
Z
Zhi Wang *
H
Hua Xie
DOI:10.1007/s10570-026-07153-6delete
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Abstract

Abstract

En 中文
Rigid polyurethane foam (RPUF) was prepared with walnut shell powder as the carbon source and ammonium polyphosphate (APP) as the acid source. Its thermal stability, flame retardancy, and mechanical properties were investigated by thermogravimetric analysis, cone calorimetry, scanning electron microscopy (SEM) analysis, limiting oxygen index (LOI) test, and compression test. The result showed that the foam with 5 wt.% of walnut shell and 10 wt.% APP (RPUF-W5APP10.0) had the highest thermal decomposition temperature and activation energy (E). It showed that the addition of APP improved the thermal stability of the RPUF. RPUF-W5APP10.0 had the lowest peak heat release rate (PHRR) and total heat release (THR), which were 57.98 and 38.74% lower than the foam without APP (RPUF-W5APP0) at 25 kW/m2. It also exhibited the highest LOI (24.4%) and UL-94 rating (V-0). In addition, RPUF-W5APP10.0 had the lowest peak smoke production rate (PSPR) of 0.0050 m2/s and total smoke release (TSR) of 43.29 m2/m2. SEM and Raman analyses revealed that RPUF-W5APP10.0 had the densest and most structurally intact char layer. The mechanical properties and thermal insulation of RPUF-W5APP10.0 were far superior to RPUF-W5APP0. The study provides a useful reference for the expansion of the flame-retardant field of bio-based RPUF.
Keywords:
Walnut shell
Rigid polyurethane foam
Ammonium polyphosphate
Thermal stability
Flame retardancy

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Cellulose cover
Cellulose
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4.8
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