Nanoindentation for Characterizing Wood & Related Systems

Transcription

1 Nanoindentation for Characterizing Wood & Related Systems Johannes Konnerth and Wolfgang Gindl Institute of Wood Science and Technology BOKU University - Vienna Institute of Wood Science and Technology I Johannes Konnerth

2 Nanoindentation basic principle DSI depth sensing indentation Pmax hmax under load h0 after load 2

3 Nanoindentation tips Microscope images Berkovich Three-sided pyramidal tip Conospherical tip 3

4 Nanoindentation data analysis load P depth h 2 h 2 1 W v 3 h 1 W p S W e depth h t 1 t 2 time t 4

5 Nanoindentation data analysis H E r E P A 1 = 2 π S A m ν 1 + ν = r E m Ei C IT max = Hardness = h 2 h 1 h 1 material i indenter Reduced Modulus of Elasticity Oliver & Pharr (1992) Indentation Creep E i =1140GPa Poisson s ratio ν i =0.07 5

6 Nanoindentation sample preparation - surface roughness Indenter Indenter Surface Surface 6

7 Nanoindentation Sample preparation a b 15 2 c e d f g

8 Nanoindentation on Wood Scales in Wood-Adhesive bonds 5 mm 50 mm 50 µm 5 µm 8

9 Mechanical properties of Adhesive Films Tensile Test macro ESPI 9

10 Mechanical properties of Adhesives in the bond line 50 µm 10

11 Mechanical properties of Adhesives 10 MUF R 2 = E bond line-ni (GPa) 6 4 PVAc PUR PRF Epoxy Polyester 2 PP E film-macro (GPa) 11

12 Mechanical properties of Adhesives Nanoindentation Deformation Work W elastic W plastic W viscoelastic Work [Joule 1E-12] EP MUF PEst PRF PP PUR PVAc 12

13 Mechanical properties of Adhesives Nanoindentation Creep C IT EP MUF PEst PRF PP PUR PVAc 13

14 Wood cell walls in the Interphase region 50 µm 14

15 Wood cell walls in the Interphase region interphase cell walls 0.70 interphase cell walls 25 reference cell walls reference cell walls Reduced Elastic Modulus [GPa] Hardness [GPa] N= PUR PRF MUF PVAc PUR PRF MUF PVAc PUR PRF MUF PVAc 15

16 Melamine-modified spruce wood Melamine-modified Hardness (GPa) N = 8 Reference 17 Melamine-treated Reference Elastic modulus (GPa) N = 8 Reference 17 Melamine-treated 16

17 Cell wall micromechanics Lignin content (%) N = 20 LW_0 20 EW_0 20 LW_20 20 OW_35 20 CW_50 41 CCML Hardness (GPa) Type of sample N = LW_0 EW_0 LW_20 OW_35 CW_50 CCML Type of sample Elastic modulus (GPa) N = LW_0 EW_0 LW_20 OW_35 CW_50 CCML Type of sample 17

18 Cell wall micromechanics Elastic modulus Ex (GPa) Invalid! P y x Micro-fibrils Microfibril angle ( ) 18

19 Fibers 19

20 Cell wall micromechanics Cellulose fibers Modulus of elasticity (GPa) Viscose fibers Lyocell fibers Bocell fibers Unoriented cellulose films Oriented cellulose films Nanoindentation data Gindl and Schöberl, unpublished <sin²θ> 20

21 Elastic modulus (GPa) Elastic modulus Hardness Distance (µm) Hardness (GPa) 21

22 Wood cell walls in the Interphase region Nanoindentation-Mapping Wood Mapping area Adhesive 22

23 Wood cell walls in the Interphase region Nanoindentation-Mapping increasing E-modulus increasing E-modulus 23

24 Influence of tip geometry and Micro Fibril Angle on measurements A-A MFA Berkovich indent B-B - MFA A Berkovich indent A Wood cell wall celllumen cellulosemicrofibrils B B 24

25 New Tip geometry Berkovich 142,3 100nm tip radius Er [GPa] Cone 60, 150nm 25

26 Publications related to Nanoindentation Gindl W, Gupta HS, Grunwald C (2002) Lignification of spruce tracheid secondary cell walls related to longitudinal hardness and modulus of elasticity unsing nano-indentation, Canadian Journal of Botany-Revue Canadienne de Botanique, 80, 10, Gindl W, Gupta HS (2002) Cell-wall hardness and Young s modulus of melamine-modified spruce wood by nano-indentation, Composites Part A: Applied Science and Manufacturing, 33, 8, Gindl W, Gupta HS, Schoberl T, Lichtenegger HC, Fratzl P (2004) Mechanical properties of spruce wood cell walls by Nanoindentation, Applied Physics A: Materials Science & Processing, 79, 8, Gindl W, Schoberl T (2004) The significance of the elastic modulus of wood cell walls obtained from nanoindentation measurements, Composites Part A: Applied Science and Manufacturing, 35, 11, Gindl W, Schoberl T, Jeronimidis G (2004) The interphase in phenol-formaldehyde and polymeric methylene diphenyl-di-isocyanate glue lines in wood, International Journal of Adhesion and Adhesives, 24, 4, Konnerth J, Jäger A, Eberhardsteiner J, Müller U, and Gindl W (2006) Elastic properties of adhesive polymers, Part II: Polymer films and bond lines by means of nanoindentation. Journal of Applied Polymer Science, 102, 2, Konnerth J, Gindl W (2006) The interphase in wood-adhesive bond lines by nanoindentation. Holzforschung, 60, Gindl W, Konnerth J, Schoberl T (2006) Nanoindentation of regenerated cellulose fibres. Cellulose, 13, 1, 1-7 Gindl W, Schoberl T, Keckes J (2006) Structure and properties of pulp fibre-reinforced composite with regenerated cellulose matrix, Applied Physics A: Materials Science & Processing, 83, 1, Konnerth J, Valla A, Gindl W (2007) Nanoindentation-mapping of a wood-adhesive bond. Applied Physics A: Materials Science & Processing, DOI: /s y 26

27 Johannes Konnerth and Wolfgang Gindl BOKU - University of Natural Resources and Applied Life Science Vienna - Austria Department of Material Science and Process Institute of Wood Science and Technology 27