Masahiro Takatani

Cellulose esters as compatibilizers in wood/poly(lactic acid) composite

One of the important issues relevant to wood/plastic composite molding is the compatibility between hydrophilic wood and hydrophobic plastic. Polyolefins modified with maleic anhydride, which have been frequently used for wood and polyolefin composites, are not effective for poly(lactic acid) composites. Because compounds with both hydrophilic and hydrophobic groups are potential compatibilizers, cellulose esters of several carboxylic acids, RCOO-cellulose (R = CH3, C2H5, C3H7, C4H9, C5H11, C11H23), were synthesized and their effects as compatibilizers of wood/poly(lactic acid) composites (WPLC) were examined in this study. The mechanical properties of WPLC were improved with a small amount of added cellulose esters, especially cellulose butyrate or cellulose valerate. The relevant effect of added cellulose esters on the thermal properties of wood/PLA composite was analyzed by measuring dynamic viscoelasticity.

Fundamental studies on wood/cellulose-plastic composites: effects of composition and cellulose dimension on the properties of cellulose/PP composite

Although wood/cellulose-plastic composites (WPC) of low wood/cellulose content have been more accepted worldwide and are promoted as low-maintenance, high-durability building products, composites containing high wood/cellulose content are not yet developed on an industrial scale. In this study, flow properties, mechanical properties, and water absorption properties of the compounds of cellulose microfiber/polypropylene (PP) and maleic anhydride-grafted polypropylene (MAPP) were investigated to understand effects of the high cellulose content and the dimensions of the cellulose microfiber. The molding processes studied included compression, injection, and extrusion. It was found that fluidity is not only dependent on resin content but also on the dimension of the filler; fluidity of the compound declined with increased fiber length with the same resin content. Dispersion of the composite was monitored by charge-coupled device (CCD) microscope. Increasing the plastic content in the cellulose-plastic formulation improved the strength of mold in addition to the bond development between resin and filler, and the tangle of fibers. The processing mode affected the physicomechanical properties of the cellulosic plastic. Compression-molded samples exhibited the lowest modulus of rupture (MOR) and modulus of elasticity (MOE) and the highest water absorption, while samples that were injection-molded exhibited the highest MOR (70 MPa) and MOE (7 GPa) and low water absorption (2%).

Effect of Lignocellulosic Materials on the Properties of Thermoplastic Polymer/Wood Composites

Summary The effect of lignocellulosic materials on the board performance of thermoplastic polymer/wood composites was examined by using soft wood flours of 20 mesh- and 120 mesh-pass, steam-exploded beech flour, and two kinds of thermoplastic polymers, polyvinyl chloride and polystyrene. Steam-exploded wood flour was found to be one of the best lignocellulosic materials in terms of fracture strength and water resistance of the composite board. The properties of the composites are dependent not only on the lignocellulosic materials and polymers, but also on the average size of wood flour. Generally, a flour of 120 mesh pass gave composites of better performance than that of 20 mesh pass, but the tendency was reversed when steam-exploded beech flour was used.

Asymmetric syntheses of nitroalkanols using Pseudomonas sp. lipase: a proposal for the selection of the solvent system of lipase-catalyzed transesterification

Abstract By lipase-catalyzed stereoselective transesterification using Amano AK from Pseudomonas sp., nitroalcohols such as 1-nitro-2-butanol and 1-nitro-3-methyl-2-butanol were synthesized enantioselectively with enantiomeric ratios ( E values) of 20.9 and 12.5, respectively, in n -propyl ether. Various results were obtained during the lipase-catalyzed transesterification by changing the organic solvents that were used. The plots of the E values against the reciprocal of the dielectric constants ( e ) of the various organic solvents produced a bell-shaped curve which had a maximum E value for n -propyl ether (1/ e =0.3). The distance between the enzyme and the substrate might be changed in response to a change in the organic solvent.

The chemistry of zerumbone. Part 3: Stereospecific creation of five stereogenic centers by double Sharpless oxidation

Abstract The Sharpless asymmetric epoxidation was applied to zerumbol 2 in order to introduce chirality into the readily available achiral sesquiterpene zerumbone 1. Single bisepoxides (+)-3 and (−)-3 were obtained in nearly 100% enantiomeric purity, characterized as the unexpected all erythro configuration by X-ray analysis.

Development of fully bio-based composite: Wood/cellulose diacetate/poly(lactic acid) composite

Within the framework of an establishment of a sustainable recycling society, the utilization of bio-based materials, such as wood, chitin and protein should be promoted. In this context, research on wood/plastic composites (WPC) has increased rapidly. In WPC, wood acquires one of the important characteristics of plastics: easy molding. In the development on WPCs in the past, plastic material was based on fossil resources, such as polyolefine, as a matrix. In recent years, poly(lactic acid) (PLA) has attracted attention as a substitute of fossil plastic in application fields, such as medical devices, electronic products and automotive applications (Reed and Gilding 1981; Mochizuki 2006). PLA was also suggested as a WPC matrix to prepare fully bio-based composites (Mochizuki 2006; Serizawa et al. 2006). Mathew and Oskman (2006) and Mathew et al. (2005) suggested that the addition of wood filler improved tensile and storage moduli of PLA films, but these authors found that the tensile strength and elongation at break were lower than those of neat PLA film without filler. The mechanical properties of wood/PLA composites (Takatani et al. 2007) were also studied. It was demonstrated that the modulus of elasticity (MOE) of such composites (weight ratio of wood/PLA, 80/20) was 1.5 times larger than a neat PLA board, although the modulus of rupture (MOR) and water resistance of the composite decreased in the presence of wood filler. When hydrophilic wood and hydrophobic plastic are mixed, the interfacial adhesion of the materials does not develop well, because of the poor compatibility of the components. A composite with poor mechanical property and water resistance is the result. There is a patent on PLA modified with maleic anhydride (MAPLA) claiming improved properties of wood/ PLA composite (Shiraishi and Ueda 2005). However, Plackett (2004) found that the addition of MAPLA decreased the tensile strength of jute/PLA composite (Plackett 2004). Huda et al. (2006) investigated the effect of maleic anhydride polypropylene (MAPP) in wood/PLA composite and reported that the addition of 5% MAPP decreased the MOR of wood/PLA composite. Lee et al. (2004) reported that the modified bamboo fiber with maleic anhydride increased the melt viscosity of bamboo fiber/PLA mixture and a composite with improved tensile strength was obtained. In our previous study, we reported the effect of cellulose esters as new additives for wood/PLA composite to make fully bio-based composites (Takatani et al. 2007). The addition of only 2% cellulose esters of C2–C6 carboxylic acids improved the storage modulus and MOR of wood/PLA composites. The effects were dependent on the length of acyl carbon chains of cellulose esters. Although the addition of cellulose esters improved the water resistance of composites, a small amount of addition up to 8% did not satisfy the practical purpose. The Japanese Industrial Standard (JIS A5741, 2006) requires: MOR )20 MPa, water absorption (WA) -10%, linear expansion (LE) -3% after 24 h soaking in water at room temperature. One of the important drawbacks of PLA as matrix of WPC is that the composite shows low water resistance, because polyester is inferior to polyolefin with regard to water resistance. In this paper, the preparation of a fully bio-based wood filler/PLA composite is addressed. This consists of wood flour and cellulose diacetate (CDA) with improved water resistance and complies with the industrial standard, JIS A5741.

Development of room-temperature curing aqueous emulsion-type acrylic adhesive I: effect of monomer composition on the initial adhesive strength

For the purpose of developing a new aqueous emulsion-type adhesive for wood or paper use that does not release formaldehyde or volatile organic solvents, a honeymoon-type acrylic adhesive was examined. An adhesive system consisting of acrylic monomers copolymerized with functional monomers and a cross-linking agent was selected for the purposes of increasing initial adhesive strength and ensuring room-temperature curing. The initial adhesive strength increased by the use of cross-linkers such as dihydrazides and also polymeric methylene diphenyl diisocyanate (pMDI). Thus an adhesive with reasonable to good initial adhesive strength and room-temperature curing was obtained. The effect of pMDI on the initial adhesive strength was not significant and decreased when the amount of acrylamide in a copolymer was high.

Isolation of hemicellulose from a sorghum, Andropogon sorghum Brot, Kumadake no. 263, and determination of its constituent sugars.

Hemicellulose was isolated from the stem of sorghum, Andropogon sorghum Brot, Kumadake no. 263, and the constituent sugars of this isolate were determined. The xylose concentration in the hemicellulose of SV263 was extremely high.

Thermosetting Adhesive Based on Tannin and Poly(N-Hydroxymethyl Acrylamide)

A thermosetting adhesive consisting of tannin and poly(N-hydroxymethylacrylamide) was studied. This adhesive is an environmentally friendly one using only water as the solvent and is partly based on a natural product. It showed good bonding strength and water resistance for a wood product although those properties were lower than the level of phenol-formaldehyde resin.

Performance of phenol-formaldehyde based wood adhesives containing steam exploded beech flour

The effect of adding steam exploded beech flour (SE) to phenol-formaldehyde (PF) wood adhesive was examined. The viscosity of formulations prepared from SE and PF did not show significant time-dependent change, but showed a sharp decrease in response to an increase of rotatory shear speed. The tensile shear strength of a 3-ply veneer board bonded with a SE/PF formulation exceeded that of the PF-bonded sample with up to 60% replacement of PF by SE. A similar result was obtained in wood failure of the tensile test. Chemical analyses showed that little hemicellulose remained in SE. As lignin extracted from SE was not an effective additive for PF, these results suggest that the improved performance of the SE/PF adhesives results from the physical, rather than the chemical nature of the additive.