A novel polyurethane prepolymer as toughening agent: Preparation, characterization, and its influence on mechanical and flame retardant properties of phenolic foam

Abstract

A novel phosphorus-and silicon-containing polyurethane prepolymer (PSPUP) was synthesized by the chemical reaction of phenyl dichlorophosphate with hydroxy-terminated polydimethylsiloxane (HTPDMS) and subsequently with toluene-2,4-diisocyanate. The structure of PSPUP was confirmed by Fourier transform infrared spectroscopy and 1 H nuclear magnetic resonance. Afterward, a series of phenolic foams (PF) with different loadings of PSPUP toughening agent were prepared. The apparent density and scanning electron microscopy results showed that the addition of PSPUP can increase the apparent density of phenolic foam. The compressive, impact and friability test results showed that the incorporation of PSPUP into PF dramatically improved the compressive strength, impact strength, and reduced the pulverization ratio, indicating the excellent toughening effect of PSPUP. The limiting oxygen index of PSPUP modified phenolic foams remained a high value and the UL-94 results showed all samples can pass V0 rating, indicating the modified foams still had good flame retardance. The thermal properties of the foams were investigated by thermogravimetric analysis under air atmosphere. Moreover, the thermal degradation behaviors of the PF and PSPUP/PF were investigated by real-time Fourier transform infrared spectra.

Synthesis of Boron-Containing Toughening Agents and Their Application in Phenolic Foams

“…, and the weight loss may be due to the dehydration of further curing from 100 to 200°C, 15 and degradation of surfactant (Tween 80). 22 The third step happens from 400 to 800°C and is caused by the decomposition of phenolic resin with a T max (the peak temperature in the DTG curve) of 471°C…”

Thermal degradation study of pure rigid polyurethane in oxidative and non-oxidative atmospheres

“…Rigid PU (RPU), one of the most common PU form, could be achieved by excessive addition of isocyanates compared with polyols. RPU foam finds applications in building construction mainly as sandwich structures with its good performances on mechanical strength, aging durability, water resistance, and thermal insulation behaviors [1]. However, the fatal flammability of RPU prevents its widespread application especially when some fire disasters occurred, such as Shanghai Jing'an District fire, resulting in 58 people dead and at least 70 injured [2,3].…”

Phenolic foams toughened with crosslinked poly (n‐butyl acrylate)/silica core‐shell nanocomposite particles

“…Polyurethane foam and polystyrene foam are widely used in thermal insulation materials for buildings. However, due to their high flammability, replacing them with phenolic foams is a common trend . Due to its low thermal conductivity, excellent flame‐retardant performance, affordable cost, high dimensional stability, low generation of toxic gas and no dripping during combustion, phenolic foam has been extensively studied in recent years .…”