Promotion effect of NP fire retardant pre-treatment on heat-treated poplar wood. Part 2: hygroscopicity, leaching resistance, and thermal stability

Abstract

In continuation of the previous study concerning the effects of a combined treatment of wood with nitrogen-phosphorus (NP) fire retardant and heat treatment (HT), the hygroscopicity, leachability, thermal stability, Fourier transform-infrared (FT-IR) spectra, and X-ray diffraction (XRD) properties of Populus beijingensis W.Y. Hsu have been investigated. The wood samples were impregnated with 10% NP fire retardant solution and exposed to HTs at 140°C–160°C for 30 min. HT of NP treated wood reduced the moisture absorption and enhanced the leaching resistance of NP and improved the thermal stability. The HT decomposes the NP and the acidity of these degradation products has a dehydration effect on the wood polysaccharides, and the number of hydroxyl groups in wood decreased substantially. The crystallinity index of the NP-impregnated and heat-treated wood also increased. The post low-temperature HT enhanced the fixation of the NP fire retardant and hydrophobicity of the NP-treated wood.

Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 1: Compression Recovery and Flammability

“…The reason is that the HT increased the hydrophobicity and the TM process further enhanced the surface density of WHT-TM. The compression stability of WHT-TM samples remarkably enhanced due to the NP pre-treatment and the acceleration effect of NP on wood thermal degradation during the thermo-densification process [29,33]. When compared with that of WTM, the HDfs value was 31.60% higher and the Tr value decreased from 26.65% to 6.07%.…”

“…Then, they were divided into six groups (Table 1), each comprised of 15 samples. The NP impregnation and HT conduction protocols were kept the same as in former studies [29,33]. Samples in groups W NP-TM , W TM , and W HT-TM were pre-heated using a thermo-compressor (MLG68-S, Zhengzhou, China) for 5 min, then thermo-mechanically pressed to 14 mm final thickness using a stopper for 20 min at constant temperature.…”

“…The first cluster was separated into two subgroups (Figure 5d). The compression recovery improvement of the W NP-TM could elucidate that the NP fire retardant acts as an acid accelerator, which could intensify the effectivity of HT [29,33], as the W HT-TM and W NP-TM are classified into the same subgroups.…”

Evaluation of ultrasonic-assisted dyeing properties of fast-growing poplar wood treated by reactive dye based on grey system theory analysis

“…The broad peak that occurs at 3400-3200 cm −1 was associated with -OH stretching in hydroxyl groups originating mainly from cellulose [36]. The absorption at 1740 cm −1 was due to C=O stretching of xylan [37]. The peak at 1034 cm −1 was attributed to C-O-C stretching of aliphatic ether bond [4].…”

Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 2: Dynamic Wettability and Bonding Strength

“…Our research group attempted to enhance the leachability and hygroscopicity of NP, as well as smoke development during burning [16]. Recent studies revealed that NP also has an intensification effect on high-temperature (HT) treatment of wood [17,18]. In Part 1 of this study, it was reported that the combined process of using NP fire retardant and TM methods improved compression recovery and combustion safety.…”