Effect of compression on hydroscopicity of extracted Chinese fir heartwood

In order to clarify the effects of extraction and compression on the hydroscopicity of wood, Chinese fir （Cunninghamia lanceolata Hook.） heartwood samples with or without extraction were radially or tangentially compressed under water-saturated condition at room temperature. Warm water and 1% sodium hydroxide were used as different solutions for extraction. Water absorption capacity and moisture adsorption isotherms of the compressed samples were then tested. The fractal dimension of internal wood surfaces （Dfs） was calculated based on adsorption isotherms by FHH equation. Results showed that in both compressed groups, the hydroscopicity of samples extracted by sodium hydroxide solution improved greatly, while that of samples extracted by warm water changed little, compared with that of water-saturated samples. Recovery of set and the change of hydroscopic environment inside wood were main reasons for the difference of water absorption among water-saturated samples and samples extracted with warm water and sodium hydroxide solution. The swelling rate of samples extracted by sodium hydroxide solution significantly increased. Moreover, the swelling rate in the tangential direction of tangentially compressed samples was obviously higher than that in radial direction of radially compressed ones. Dfs values of woods extracted by warm water and sodium hydroxide solution decreased by 0.002 and 0.007 in a radially compressed group and by 0.013 and 0.013 in a tangentially compressed group, compared to those of water-saturated one. Therefore, the conclusion can be made that the extraction and compression treatments used in this study have no obvious effects on internal wood surface.

PREPARATION AND CHARACTERIZATION OF MEDICAL HYDROSCOPIC POLYURETHANE

A series of uncharged, anionic, cationic, and heparinized polyetherurethanes(PEUs) was synthesized. The soft segments of these PEUs were respectively obtained by polyte-tramethylene oxide of molecular weight 1000 (PTMO-1000), polythylene glycol of molecularweight 1000 (PEG-1000), PEG-4000, and the mixture of PEG-4000 with PTMO-1000 orPEG-1000. The hard segments consisted of 4,4’ -methylene diphenylene diisocyanate (MDI)which was extended with ethylenediamie (ED), 1,4Mbutanediol (BD), N-methyldiethanolamine(MDEA), or L-Sodium α,ε-diaminocaproate (SDAC), respectively. The chemical structure of different PEUs was confirmed by nuclear magnetic resonance. Waterabsorptions were measured. The results showed that the ionic, heparinized PEUs, and the PEUscontained PEG-4000 as soft segments have higher water absorptions than ordinary PEUs. ThePEUs based mainly on PEG-4000 as soft segments are a kind of high hydroscopic polymer mate-rials, and their hydroscopicity increases with PEG-4000 in soft segment.

Acoustical Properties of Acetylated Wood

Many of the traditional woods used for musical instruments have been selected not only for their natural beauty but for the high content of waxes and resins that help increase water repellency of the wood but have little or no effect on stabilizing dimensions or vibrational properties. Moisture changes have a great negative effect on both the musical quality of wooden musical instruments and limit the length of time they can be played without loss of musical quality. It is possible to stabilize both the wood and the vibrational properties by chemically modifying the wood. One technology that can do this is the reaction of wood with acetic anhydride. Acetylation of wood slightly increases density, and slightly （about 5%） reduces both sound velocity and sound absorption when compared to unreactedwood. Acetylation does not change the acoustic converting efficiency. Acetylation reduces the amount of moisture in the cell wall decreasing the effect of moisture on the viscose properties of wood. This allows a wooded musical instrument to be played longer without having to let it dry out. This gives an instrument made from acetylated wood a greater range of moisture conditions it can be played in without losing tone quality. Acetylation also greatly stabilizes the physical dimensions of the wood. The major effect of acetylation of wood, therefore, is to stabilize acoustic properties. The technology can be applied to almost any wood though more easily to permeable types so non-traditional wood species can be used. A violin, a piano soundboard, a guitar, a recorder, a bagpipe chanter, and trumpet and trombone mouthpieces have been made using acetylated wood with very positive results. Several more wooden instruments made from acetylated wood are presently being made for further testing and early market development.