Nobuo Shiraishi

Water‐absorbing polyurethane foams from liquefied starch

Water-absorbing polyurethane foams were prepared from liquefied starch polyols and diphenylmathane diisocyanate (MDI) by using a cell-opening foaming surfactant. The liquefied starch polyols were obtained by the liquefactions of starch in the presence of polyethylene glycol-dominant reaction reagents by using sulfuric acid as a catalyst under either a refluxing condition or a reduced-pressure condition. The influences of the liquefaction conditions on the properties of the liquefied starch polyols were investigated, taking into account the requirements for preparing appropriate polyurethane foam. Feasible formulations for the preparation of the water-absorbing foams were proposed and the properties of the foams obtained were investigated.

The Preparation and Flow Properties of HC1 Catalyzed Phenolated Wood and its Blends with Commercial Novolak Resin

Phenolation of birch wood meal was carried out in the presence of HCl catalyst by using a reflux condenser system. The effects of reaction time, HCl catalyst concentration, and phenol/wood ratio on the phenolation extents were determined as a function of liquefaction temperatures covering 60, 90, 120, and 150°C. It was revealed that among the reaction parameters, the reaction temperature had the greatest influence on the residual rate and the amounts of combined phenol. Although the optimum reaction temperature which gave sufficient amounts of combined phenol was found to be 120°C, the residual rates obtained at 150°C were however lower than those for 120°C. It was also found that the flow temperature of the phenolated wood increased with an increase in the amount of combined phenol. In order to improve the thermoflowability, as one of the trials, commercial novolak resin was mixed with the phenolated woods in several different ratios. By this blending with novolak resin, the flow temperatures of the phenolated woods could be reduced to a certain extent.

Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 1. Identification of the Reaction Products

Summary Guaiacylglycerol-β-guaiacyl ether (GG) was used as a lignin model compound to study the liquefaction reaction mechanism of lignin in the presence of phenol under the catalysis of several typical acids such as sulfuric, phosphoric and oxalic acids. The reaction products were isolated by silicagel column chromatography and high performance liquid chromatography (HPLC). The structures of the obtained compounds were identified by means of GC-MS, 1H-NMR, 13C-NMR, 1H-1H COSY, HMBC and HMQC. As a result, about 30 compounds were obtained as the main reaction products. It was found that their structural characteristics were significantly different from those yielded at the non-catalyzed liquefaction (Lin et al. 1997a), and independent on the acid species. The dominant products were guaiacylglycerol-α-phenyl-β-guaiacyl ethers, followed by guaiacol, triphenylethanes, diphenylmethanes, benzocyclobutanes and phenylcoumarans. The structural characteristics and yields of these main reaction products indicated that condensation between phenol and GG in its C-α and further cleavages in both the β-O-4 linkage and Cβ–Cγ bonding could be the dominant reaction pathways.

Liquefaction of corn bran (CB) in the presence of alcohols and preparation of polyurethane foam from its liquefied polyol

Liquefied corn bran (CB)-based polyol was obtained by the liquefaction of CB in the presence of a poly(ethylene glycol) (PEG400)/glycerol mixed solvent. The effects of liquefaction parameters on the degree of liquefaction were evaluated. The catalyst content and solvent/CB ratio have a greater influence on the percent residue than does the reaction temperature. Polyurethane foams were successfully prepared from the liquefied CB-based polyol. Molecular weights of CB-based polyol have no effect on the reaction time, and its hydroxyl numbers and viscosities were suitable for the preparation of foam. Furthermore, the acid value increased to about 34 during the liquefaction. The densities and mechanical properties of the foams showed comparable values to those of conventional polyurethane foams. The amount of additive (PCL303) in the liquefied CB-based polyol had a significant effect on the properties of the resulting foams.

Liquefaction Mechanism of β-O-4 Lignin Model Compound in the Presence of Phenol under Acid Catalysis. Part 2. Reaction Behaviour and Pathways

Summary By means of high performance liquid chromatography (HPLC) and gel permeation chromatography (GPC), the yields of the main reaction products and the polymeric portion formed in the reaction of guaiacylglycerol-β-guaiacyl ether (GG) under various acid-catalyzed conditions were quantified as a function of reaction time. Based on their forming sequence and reaction behavior, as well as their structural characteristics, an acid-catalyzed reaction mechanism of GG with phenol was proposed.

Thermoplasticization of cellulose acetates by grafting of cyclic esters

A plasticization method for cellulose acetates (CAs) based on the selective grafting of ε‐caprolactone (CL) and L-lactide (LACD) has been developed. The selective‐grafted products could be prepared by ring opening polymerization in the melt state at 140°C using stannous octoate as catalyst, where CAs with remaining hydroxyl groups worked as initiator. Plasticization of CAs by this selective grafting can solve the problem encountered in the previous reports (Yoshioka et al., 1996, 1998) that the bleeding of unreacted monomers and homo‐oligomers from the inside of molded articles to their surface was often found. By using adequate reaction conditions, the grafting reaction proceeded rapidly and could be completed within 10–30 min. LACD is grafted more rapidly than CL onto CAs, producing relatively rigid and brittle products in the earlier stages and elastomer‐like ones in the later stages. Transparent amorphous molded articles were obtainable depending on the reaction conditions. The analysis of the structure of the grafted side chains by means of high resolution NMR spectroscopy showed that, although the grafted side chains are composed of large amounts of ε‐oxycaproyl or lactidyl block polymer portions depending on the reaction conditions, a large amount of randomly polymerized parts coexist in the grafted chains, which confer high thermoplasticity, elasticity and amorphous nature to the grafted products obtained.

Preparation and characterization of the phenolated wood using hydrochloric acid (HCl) as a catalyst

SummaryBirch (Betula maximowicziana Regel) wood meal was liquefied in the presence of phenol using hydrochloric acid (HCl) as a catalyst at a temperature of 150 °C for 2 h in an autoclave. It was found out that HCl acid could be used as an effective catalyst for the hydroxy phenylation of wood under the experimental conditions. In this study the effect of the concentration of the acid catalyst and the phenol-to-wood ratio on the liquefaction were investigated. The results showed that the phenol-to-wood ratio and the concentration should be increased to a certain degree in order to achieve a less residual rate and sufficient amount of combined phenol. The phenolated woods had apparent flow temperatures in the range of 134.4 to 199.8 °C, being higher than that of a commercial novolak resin. Furthermore, increases in the HCl concentration during liquefaction reaction led to increase in the apparent flow temperature of the resulting phenolated woods. However, the changes in the liquid ratio did not bring about evident changes. The relationship between shear stress (τ) and shear rate

Liquefaction Mechanism of Lignin in the Presence of Phenol at Elevated Temperature without Catalysts. Studies on ß-O-4 Lignin Model Compound. II. Reaction Pathway

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