Cover Image, Volume 138, Issue 23

Abstract

This cover designed by Jingmiao Zhang and colleagues shows four kinds of agricultural waste particles such as (XS: OS/oilseed rape straw, RS/rice straw, WS/wheat straw and CS/corn stover). The image shows how they were used to reinforce agricultural waste liquefied polyol‐based polyurethane foam (XSPU). RS particles show great promoting ability and OS particles reveal complex influence, while WS and CS particles display mild effect on the foaming process. With 1% of OS, 6% of RS, 3% of WS or 1% of CS incorporating in matrix materials, the reinforced foams display applicable density, better physical and mechanical property, more uniform cellular structure, higher thermal stability and more excellent water absorption ability. Doi: https://doi.org/10.1002/app.50583

Stability and degradation of four agricultural wastes liquefied polyols based polyurethane foams

“…It indicated that CSPU showed the lowest thermal stability, while WSPU displayed the highest thermal stability. Because P‐CS had a lower hydroxyl number than the other three bio‐polyols 33 and less pMDI was needed when preparing CSPU at 1.5:1 of NCO/OH ratio. Therefore, the CSPU contained fewer urethane segments and its polymer chain appeared to be simpler than other foams and displayed weaker thermal stability.…”

“…The OS was obtained from Tohoku Agricultural Research Center (Iwate, Japan), while RS, WS, and CS were obtained from The University of Tokyo experimental farm. The XS was liquefied at 150°C for 40 min with 62.7 wt% polyethylene glycol 400 (PEG, Wako, AR) and 20.9 wt% ethylene glycol (EG, Wako, AR) as solvents, and 3 wt% sulfuric acid (Wako, AR) as a catalyst 33 . These P‐XSs were neutralized by 48% NaOH aqueous solution before subsequent application.…”

“…These P‐XSs were neutralized by 48% NaOH aqueous solution before subsequent application. The properties of P‐XS such as hydroxyl numbers and FTIR spectra were published in previous work 34 . The pMDI MR‐200 (30.99 wt% of NCO, 1.23 g/mL) was used as isocyanate, TEDA‐L33 (33% triethylenediamine and 67% dipropylene glycol, 1.03 g/mL) and TOYOCAT‐ET (70% 2‐dimethylaminoethyl ether and 30% dipropylene glycol, 0.90 g/mL) were used as catalyst, SH193 (polydimethylsiloxane backbone and polyethylene oxide co‐propylene oxide) was used as silicon surfactant and distilled water was used as blowing agent in PU foaming process, and they were supplied by Tosoh Corp.…”

“…A set of P‐XS/TEDA‐L33/TOYOCAT‐ET/SH193/water (100.0/3.5/0.5/1.0/3.0, based on weight) was added into a plastic cup (220 mL) and stirred rapidly to premix these materials sufficiently 3 . Then pMDI MR‐200 (kept the NCO/OH ratio at 1.5:1) 34 was added to the above mixture and all the feedstocks were stirred vigorously by a mechanical stirrer at 1000 rpm for 8 s. Then the plastic cup was allowed to rise at ambient temperature 20 ± 1°C for obtaining XSPU foam (Figure 1). The obtained foams were left for 24 h before being cut for follow‐up analysis.…”

“…The FTIR test was conducted on a Nicolet 6700 FTIR Spectrometer (Thermo Scientific, USA) by the potassium bromide tableting method 34 . The spectrometer was accessorized with a programmable temperature controller 0019‐019 (Spectra Tec.…”