Research on properties of rigid polyurethane foam with heteroaromatic and brominated benzyl polyols

Synergistic Effect of APP and TBC Fire-Retardants on the Physico-Mechanical Properties of Strandboard

This study explored the feasibility of fabricating fire-retardant strandboard with low mechanical properties deterioration to the physico-mechanical properties. A hybrid fire-retardant system of ammonium polyphosphate (APP) and 1,3,5-tris(2,3-dibromopropyl)-1,3,5-triazinane-2,4,6-trione (TBC) was investigated. Thermogravimetric analysis results show that both APP and TBC enhance the thermal stability and incombustibility of wood strands. An infrared spectrum was applied to investigate the effect of flame retardants on the curing behaviors of polymeric diphenylmethane diisocyanate (PMDI) resin. Based on the results of limiting oxygen index (LOI) and Cone calorimetry (CONE), APP and TBC both lead to a higher fire retardancy to strandboard. It is worth mentioning that the two flame retardants lead to evidently differential influences on the modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), and water-soaking thickness swelling (TS) properties of strandboard. Hence, a hybrid flame retardant is prominent in manufacturing strandboard with both good fire retardant and satisfying physico-mechanical properties.

Study on the Structure-Property Dependences of Rigid PUR-PIR Foams Obtained from Marine Biomass-Based Biopolyol

The paper describes the preparation and characterization of rigid polyurethane-polyisocyanurate (PUR-PIR) foams obtained with biopolyol synthesized in the process of liquefaction of biomass from the Baltic Sea. The obtained foams differed in the content of biopolyol in polyol mixture (0–30 wt%) and the isocyanate index (I_ISO = 200, 250, and 300). The prepared foams were characterized in terms of processing parameters (processing times, synthesis temperature), physical (sol fraction content, apparent density) and chemical structure (Fourier transform infrared spectroscopy), microstructure (computer microtomography), as well as mechanical (compressive strength, dynamic mechanical analysis), and thermal properties (thermogravimetric analysis, thermal conductivity coefficient). The influence of biopolyol and I_ISO content on the above properties was determined. The addition of up to 30 wt% of biopolyol increased the reactivity of the polyol mixture, and the obtained foams showed enhanced mechanical, thermal, and insulating properties compared to foams prepared solely with petrochemical polyol. The addition of up to 30 wt% of biopolyol did not significantly affect the chemical structure and average cell size. With the increase in I_ISO, a slight decrease in processing times and mechanical properties was observed. As expected, foams with higher I_ISO exhibited a higher relative concentration of polyisocyanurate groups in their chemical structure, which was confirmed using principal component analysis (PCA).

Recycled polyethylene terephthalate and aluminum anodizing sludge-based boards with flame resistance

The objective of this study was to utilize polyethylene terephthalate (PET) and aluminum anodizing sludge (AAS) to produce fire-resistant polyurethane (PU) boards of different densities. Boards with 10%, 20%, 30%, 40% and 50% PET waste as a replacement for the PU raw material were prepared with the addition of 20% aluminum sludge. The products were checked by scanning electron microscopy (SEM) to show that the addition of residues modified the morphology of the alveoli and reduced the compressive strength of the rigid foams. The boards showed combustion deceleration up to flame extinction in the flammability test (UL94) because of the presence of the AAS. The influence of the fillers on the combustion of the specimens without and with 50% PET was observed through SEM images of the preserved and burnt regions of the materials. A reduction in the direct production costs of all the sheets was measured and reached close to 70% in the case of the board with the highest amount of added residues. Therefore, as a way to save natural resources and become more sustainable, it is suggested that the civil construction industry consider the addition of these residues as part of its formulations.

Structure and Flame-Retardant Actions of Rigid Polyurethane Foams with Expandable Graphite

In this paper, rigid polyurethane foams that were filled with expandable graphite (RPUF/EG) composites were prepared by the liquid blending method, and then the structure and flame retardancy performance of materials were investigated through optical microscope, scanning electron microscope, limit oxygen index, cone calorimeter, thermogravimetric analysis coupled to fourier transform infrared spectrum, and X-ray photoelectron spectroscopy. The results showed that a large number of EG could be good to the exhibition of flame retardancy of RPUF, where the optimal material was found at loading 15 phr EG that showed an increased limit oxygen index value and a decreased calorific or fuming value. TGA coupled FTIR and XPS revealed that EG could disassembled before RPUF under heating treatment, and it could form a pyknotic and enahnced residual carbon layer on RPUF surface after the fire, which restricted the transfer of gas, like oxygen or heat into PU matrix, finally resulting in the promotion of flame retardancy of RPUF.