Time dependent behavior of flax/starch composites

J. Varna (Corresponding Author), E. Spārniņš, R. Joffe, Kalle Nättinen, Johanna Lampinen

Research output: Contribution to journalArticleScientificpeer-review

13 Citations (Scopus)

Abstract

The time-dependent mechanical response of flax fiber-reinforced thermoplastic starch matrix composite and neat starch is analyzed. It is demonstrated that the response is highly sensitive to the relative humidity (with specific saturation moisture content in the composite) and special effort has to be made to keep it constant. It was found that the accumulation of micro-damage and the resulting reduction of the elastic modulus in this type of composite is limited. The highly nonlinear behavior of composites is related to the nonlinear viscoelasticity and viscoplasticity. These phenomena are accounted for by simple material models, as suggested in this study. The stress-dependent nonlinearity descriptors in these models are determined in creep and strain recovery tests at low as well as by high stresses.
Original languageEnglish
Pages (from-to)47-70
JournalMechanics of Time-Dependent Materials
Volume16
Issue number1
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

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Flax
Starch
Composite materials
Viscoplasticity
Viscoelasticity
Thermoplastics
Atmospheric humidity
Creep
Moisture
Elastic moduli
Recovery
Fibers

Cite this

Varna, J., Spārniņš, E., Joffe, R., Nättinen, K., & Lampinen, J. (2012). Time dependent behavior of flax/starch composites. Mechanics of Time-Dependent Materials, 16(1), 47-70. https://doi.org/10.1007/s11043-011-9156-7
Varna, J. ; Spārniņš, E. ; Joffe, R. ; Nättinen, Kalle ; Lampinen, Johanna. / Time dependent behavior of flax/starch composites. In: Mechanics of Time-Dependent Materials. 2012 ; Vol. 16, No. 1. pp. 47-70.
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Varna, J, Spārniņš, E, Joffe, R, Nättinen, K & Lampinen, J 2012, 'Time dependent behavior of flax/starch composites', Mechanics of Time-Dependent Materials, vol. 16, no. 1, pp. 47-70. https://doi.org/10.1007/s11043-011-9156-7

Time dependent behavior of flax/starch composites. / Varna, J. (Corresponding Author); Spārniņš, E.; Joffe, R.; Nättinen, Kalle; Lampinen, Johanna.

In: Mechanics of Time-Dependent Materials, Vol. 16, No. 1, 2012, p. 47-70.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Varna, J.

AU - Spārniņš, E.

AU - Joffe, R.

AU - Nättinen, Kalle

AU - Lampinen, Johanna

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Y1 - 2012

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AB - The time-dependent mechanical response of flax fiber-reinforced thermoplastic starch matrix composite and neat starch is analyzed. It is demonstrated that the response is highly sensitive to the relative humidity (with specific saturation moisture content in the composite) and special effort has to be made to keep it constant. It was found that the accumulation of micro-damage and the resulting reduction of the elastic modulus in this type of composite is limited. The highly nonlinear behavior of composites is related to the nonlinear viscoelasticity and viscoplasticity. These phenomena are accounted for by simple material models, as suggested in this study. The stress-dependent nonlinearity descriptors in these models are determined in creep and strain recovery tests at low as well as by high stresses.

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DO - 10.1007/s11043-011-9156-7

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