Wood-fiber reinforced polylactide is a biodegradable composite where both fibers and matrix are from renewable resources. When designing new materials of this kind, it is useful to measure the influence of fiber–matrix interface properties on macroscopic mechanical properties. In particular, a quantitative measure of the dynamic stress transfer between the fibers and the matrix when the material is subjected to cyclic loading would simplify the development of wood-fiber composites. This is obtained by comparing the mechanical dissipation of the composite with a value predicted by a viscoelastic micromechanical model based on perfect interfacial stress transfer. The loss factors predicted by the model are 0.12 and 0.16 at dry and humid conditions, respectively, which amount to 63 and 66% of the experimentally determined values. For Young's moduli the predicted values are 1.01 and 0.88 GPa, which correspond to 92% of the experimentally determined values. The mismatch between the predicted and experimental values may be attributed to imperfect interfaces with restrained stress transfer. Loss factors are also determined for specific molecular bonds using dynamic Fourier transform infrared (FT-IR) spectroscopy. These values show the same trends with regard to moisture content as the macroscopically determined loss factors.
Nabi Saheb, D. and Jog, J.P. (1999). Natural Fiber Polymer Composites: A Review , Advances in Polymer Technology, 18(4): 351–363 .
2.
Bledzki, A.K. and Gassan, J. (1999). Composites Reinforced With Cellulose Based Fibers , Progress in Polymer Science, 24(2): 221–274 .
3.
Rydholm, S.A. (1967). Pulping Processes, Interscience Publications, New York , pp. 42–69.
4.
Gamstedt, E.K. , SjoÖholm, E. , Neagu, R.C. , Berthold, F. and Lindstrom, M. (2002). Effects of Fibre Bleaching and Earlywood-Latewood Fractions on Tensile Properties of Wood–Fibre Reinforced Vinyl Ester, In: Lilholt, H. (ed.), The 23rd Risø International Symposium on Materials Science: Sustainable Natural and Polymeric Composites – Science and Technology, Roskilde, pp. 185–196.
5.
Auras, R. , Harte, B. and Selke, S. (2004). An Overview of Polylactides as Packaging Materials , Macromolecular Bioscience, 4(9): 835–864 .
6.
Oksman, K. and Selin, J.-F. (2004). Plastics and Composites from Polylactic Acid, In: Wallenberger, F.T. and Weston, N. (eds), Natural Fibers, Plastict and Composites, pp. 150–165, Kluwer Academic Publishers, Boston .
7.
Correêa, C.A. , Razzino, C.A. and Hage, E. Jr. (2005). Dynamic Mechanical Thermal Analysis of Interface Adhesion in Wood-plastic Composites, In: The 8th International Conference on Woodfiber-Plastic Composites, Madison, USA, pp. 179–184.
8.
Kubaàt, J. , Rigdahl, M. and Welander, M. (1990). Characterization of Interfacial Interactions in High Density Polyethylene with Glass Spheres Using Dynamic-mechanical Analysis , Journal of Applied Polymer Science, 39(7): 1527–1539 .
9.
Hashin, Z. (1990). Thermoelastic Properties of Fiber Composites with Perfect Interface , Mechanics of Materials, 8(4): 333–348 .
10.
Nairn, J.A. (2005). Generalized Shear-lag Analysis Including Imperfect Interfaces, Advanced Composite Letters (in press).
11.
Hashin, Z. (1991). Composite Materials with Viscoelastic Interphase: Creep and Relaxation , Mechanics of Materials, 11(2): 135–148 .
12.
Weir, N.A. , Buchanan, F.J. , Orr, J.F. , Farrar, D.F. and Boyd, A. (2004). Processing, Annealing and Sterilisation of Poly-L-lactide , Biomaterials, 25(18): 3939–3949 .
13.
Kasuga, T. , Maeda, H. , Kato, K. , Nogami, M. , Hata, K. and Ueda, M. (2003). Preparation of Poly(lactic acid) Composites Containing Calcium Carbonate (Vaterite) , Biomaterials, 24(19): 3247–3253 .
14.
Mezghani, K. and Spruiell, J.E. (1998). High Speed Melt Spinning of Poly(L-lactic acid) Filaments , Journal of Polymer Science: Part B: Polymer Physics, 36(6): 1005–1012 .
15.
Garlotta, D. (2001). A Literature Review of Poly(lactic acid) , Journal of Polymers and the Environment, 9(2): 63–84 .
16.
AÅkerholm, M. , Berthold, F. , LindstroÖm, M. and Salmeàn, L. (2005). Dynamic FT-IR Spectroscopy – A Suitable Tool For Fibre-Matrix Interfacial Characterisation of Wood Fibre Composites? In: Pre-Symposium on Chemistry and Performance of Composites Containing Wood and Natural Plant Fibres at the 59th Appita Annual Conference and Exhibition, New Zealand, pp. 95–100.
17.
Brinson, L.C. and Lin, W.S. (1998). Comparison of Micromechanics Methods for Effective Properties of Multiphase Viscoelastic Composites , Composite Structures, 41(3–4): 353–367 .
18.
Kostopoulos, V. and Korontzis, D.T. (2003). A New Method for the Determination of Viscoelastic Properties of Composite Laminates: A Mixed Analytical-experimental Approach , Composites Science and Technology, 63(10): 1441–1452 .
19.
Melo, J.D.D. and Radford, D.W. (2003). Viscoelastic Characterization of Transversely Isotropic Composite Laminae , Journal of Composite Materials, 37(2): 129–145 .
20.
Adams, R.D. and Bacon, D.G.C. (1973). Effect of Fibre Orientation and Laminate Geometry on the Dynamic Properties of CFRP , Journal of Composite Materials, 7: 402–428 .
21.
Hashin, Z. (1979). Analysis of Properties of Fiber Composites with Anisotropic Constituents , Journal of Applied Mechanics, 46(3): 543–550 .
22.
Hashin, Z. and Rosen, B.W. (1964). The Elastic Moduli of Fiber-reinforced Materials , Journal of Applied Mechanics, 31: 223–232 .
23.
Tucker, C.L. and Liang, E. (1999). Stiffness Predictions for Unidirectional Short-fiber Composites: Review and Evaluation , Composites Science and Technology, 59(5): 655–671 .
24.
Chandra, R. , Singh, S.P. and Gupta, K. (2002). Micromechanical Damping Models for Fiber-reinforced Composites: A Comparative Study , Composites Part A, 33(6): 787–796 .
25.
Lu, W. , Carlsson, L.A. and Andersson, Y. (1995). Micro-model of Paper. Part 1: Bounds on Elastic Properties , Tappi, 78(12): 155–164 .
26.
Kellog, R.M. and Wangaard, F.F. (1969). Variation in the Cell-wall Density of Wood , Wood and Fiber Science, 1: 180–204 .
27.
Lee, I. , Kim, B.N. and Koo, K.N. (1994). Dynamic Characteristics of Thermoplastic Composite Laminates , Composites, 25(4): 281–286 .
28.
Neagu, R.C. , Gamstedt, E.K. and LindstroÖm, M. (2005). Influence of Wood-fibre Hygroexpansion on the Dimensional Instability of Fibre Mats and Composites , Composites Part A, 36(6): 772–788 .
29.
Woodings, C. (2000). New Developments in Biodegradable Nonwovens, In: EDANA's 2000 Nonwovens Symposium, Prague.
30.
Hedenqvist, M. (2002). Mechanical Properties of Polymers; Viscoelastic Properties, KTH, Stockholm .
31.
Best, D.J. and Rayner, J.C.W. (1987). Welch's Approximate Solution for the Behrens–Fisher Problem , Technometrics, 29(2): 205–210 .
32.
Bancroft, T.A. and Han, C.P. (1981). Statistical Theory and Inference in Research, Vol. 39, Marcel Dekker, New York , pp. 264–266.
33.
Fellers, C. , Andersson, H. and Hollmark, H. (1986). The Definition and Measurement of Thickness and Density, In: Bristow, J.A. and Kolseth, P. (eds), Paper Structure and Properties, pp. 151–167, Marcel Dekker, New York .
34.
Noda, I. (1990). Two-dimensional Infrared (2D IR) Spectroscopy: Theory and Applications , Applied Spectroscopy, 44(4): 550–561 .
35.
Noda, I. , Dowrey, A.E. and Marcott, C. (1983). Dynamic Infrared Linear Dichroism of Polymer Films Under Oscillatory Deformation , Journal of Polymer Science: Polymer Letters Edition, 21: 99–103 .
36.
Marcott, C. , Dowrey, A.E. and Noda, I. (1994). Dynamic Two-dimensional IR Spectroscopy , Analytical Chemistry, 66(21): 1065–1075 .
37.
AÅkerholm, M. and Salmeén, L. (2004). Softening of Wood Polymers Induced by Moisture Studied by Dynamic FTIR Spectroscopy , Journal of Applied Polymer Science, 94(5): 2032–2040 .
38.
Halpin, J.C. and Kardos, J.L. (1976). The Halpin–Tsai Equations: A Review , Polymer Engineering and Science, 16(5): 344–352 .
39.
Bledzki, A.K. , Reihamane, S. and Gassan, J. (1996). Properties and Modification Methods for Vegetable Fibers for Natural Fiber Composites , Journal of Applied Polymer Science, 59: 1329–1335 .
40.
Zadorecki, P. and Flodin, P. (1986). Properties of Cellulose-polyester Composites , Polymer Composites, 7(3): 170–175 .
