SynopsisThe complex piezoelectric constant (d = d'id"), elastic constant (c = c' + ic"), and dielectric constant (6 = E'if") were measured at a frequency of 10 Hz over the temperature range from -150 to 50°C and for a range of hydration up to 0.26 g/g for decalcified bone and up to 0.084 g/g for bone. For decalcified bone, t' and t " increased with increasing hydration with a deflection at the critical hydration h, = 0.08 g/g; d' at -150°C increased below h, but decreased above h, with increasing hydration; c' increased below -60°C but decreased above -60°C with increasing hydration; and the peak temperatures oft", d " , and c" below -50°C agree with each other and decreased with increasing hydration with a deflection at h,. For bone, similar hydration and temperature dependences were observed for t and c. However, the dependence of d on hydration and temperature was different from that of decalcified bone, reflecting a two-phase structure consisting of collagen fibers and mineral hydroxyapatite. The critical hydration for bone was 0.04 g/g.

SynopsisThe interaction of water with wood, such as bamboo and cedar, is investigated by measuring their complex piezoelectric, dielectric, and elastic constants between -150 and 150O C at 10 Hz.Bamboo and cedar are found to have two hydration-dependent elastic loss peaks, one is observed at about -looo C and the other at about -40° C. The former loss peak is due to the adsorbed water in the hydration range between 0 and 4% moisture content (MC) and the latter to the adsorbed water above 4% MC.These two types of water are considered bound on different sites in the regions around crystalline cellulose, where molecules of one type associate with each other and molecules of the other are unassociated.We consider that the piezoelectric polarization of wood is attributed to the rotation of hydroxyl groups in the crystal lattice of cellulose. The piezoelectric constants are observed to decrease but the elastic and dielectric constants to increase with increasing hydration.The effect of adsorbed water on elastic losses in bamboo and cedar are found to be similar to that in collagenous substances.

To investigate actions of water in keratin, the piezoelectric, dielectric, and elastic constants are measured at 10 Hz, at temperatures between -160 and 150 degrees C, and at various hydration levels. From changes in the piezoelectric, dielectric, and dynamic mechanical parameters with moisture content (m.c.), we have identified three regimes (I, II, and III) in the hydration of water for keratin. At high hydration (21% m.c.) around 0 degree C, the piezoelectric constants for keratin steeply decrease with increasing temperature. This may be attributed to interfacial polarization which is strongly related to self-associated water molecules (particularly regime III water) just around crystalline helical regions which can exhibit the stress-induced, i.e., piezoelectric, polarization and may be attributed to electrode polarization induced by the increase of mobile ions in the amorphous matrix region, some of which would be released from their trapped states just around the piezoelectric phase by the regime III water. With increasing hydration, the elastic constants for keratin are found to increase below -70 degrees C and decrease above -70 degrees C. This suggests a viscoelastic transition of the keratin structure due to bound water (regime II water). The piezoelectric, dielectric, and elastic loss peaks are found at around -120 degrees C for hydrated keratin, believed to be due to tightly bound water (regime I water), which acts only to stiffen the keratin structure. The adsorption regions of water in keratin are discussed by a piezoelectric two-phase model, which consists of piezoelectric and nonpiezoelectric phases. It is proposed that water molecule would at least adsorb in the nonpiezoelectric phase.

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ABSTRACT:A comparison is made of the second and the fourth moments of the end-to-end distances of several broken chain models with those of continous stiff chains. A shift factor f is introduced in such a way that n= fLD, where n is the degree of polymerization in the broken chain, L is the contour length and LID is the mean square end-to-end distance in the limit of the long stiff chain. A single f-value is found to yield a good coincidence of both the second and the fourth moments of the end-to-end distance of the broken chain with those of the stiff chain. Values of the shift factor f which make the best coincidence of the conformations of the broken chains and the stiff chain are 1.66 for the freely rotating chain, 10.49 for the polymethylene chain and 9.18 for the chain with independent hindrance-potentials of the polymethylene type.KEY WORDS Stiff Chain I Wormlike Chain I Broken Chain I Conformation I Characteristic Ratio I Second and Fourth Moments of End-to-End Distance 1 Shift Factor I The conformation of long flexible polymers is adequately represented by a Gaussian distribution in the absence of the excluded volume of the chain elements. This Gaussian conformation is the asymptotic one in the limit of a long Markovian chain; 1 ' 2 the mean square end-to-end distance