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Materials 2016, 9(12), 1020; doi:10.3390/ma9121020

Viscoelastic Properties of the Chinese Fir (Cunninghamia lanceolata) during Moisture Sorption Processes Determined by Harmonic Tests

1
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China
2
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, China
3
College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China
*
Author to whom correspondence should be addressed.
Academic Editor: George Papanicolaou
Received: 25 September 2016 / Revised: 23 November 2016 / Accepted: 5 December 2016 / Published: 17 December 2016
(This article belongs to the Section Biomaterials)
View Full-Text   |   Download PDF [2876 KB, uploaded 17 December 2016]   |  

Abstract

Measured by harmonic tests, the viscoelastic properties of Chinese fir during moisture sorption processes were examined under three relative humidity (RH) modes: RHramp, RHisohume, and RHstep. The stiffness decreased and damping increased as a function of the moisture content (MC), which is presumed to be the effect of plasticization and an unstable state. The increasing damping was associated with the breaking of hydrogen bonds and the formation of free volume within polymer networks. The changes of loss modulus ratio at 1 and 20 Hz, E1Hz/E20Hz, proved the changing trend of the unstable state. Higher ramping rates aggravated the unstable state at the RHramp period, and higher constant RH levels provided more recovery of the unstable state at the RHisohume period. Changes of viscoelastic properties were associated with RH (varied or remained constant), and the application of Boltzmann’s superposition principle is a good approach to simulate viscoelasticity development. View Full-Text
Keywords: Chinese fir; sorption; viscoelasticity; harmonic test; mode of RH increment; plasticization effect; unstable state Chinese fir; sorption; viscoelasticity; harmonic test; mode of RH increment; plasticization effect; unstable state
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Zhan, T.; Lu, J.; Jiang, J.; Peng, H.; Li, A.; Chang, J. Viscoelastic Properties of the Chinese Fir (Cunninghamia lanceolata) during Moisture Sorption Processes Determined by Harmonic Tests. Materials 2016, 9, 1020.

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