Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM)

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Johannes Konnerth ◽  
David Harper ◽  
Seung-Hwan Lee ◽  
Timothy G. Rials ◽  
Wolfgang Gindl
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Surface Temperature ◽  
Cell Walls ◽  
Adhesive Contact ◽  
Wood Adhesive ◽  
Bond Line ◽  
Scanning Thermal Microscopy ◽  
Thermal Probe ◽  
Thermal Microscopy

Abstract Cross sections of wood adhesive bonds were studied by scanning thermal microscopy (SThM) with the aim of scrutinizing the distribution of adhesive in the bond line region. The distribution of thermal conductivity, as well as temperature in the bond line area, was measured on the surface by means of a nanofabricated thermal probe offering high spatial and thermal resolution. Both the thermal conductivity and the surface temperature measurements were found suitable to differentiate between materials in the bond region, i.e., adhesive, cell walls and embedding epoxy. Of the two SThM modes available, the surface temperature mode provided images with superior optical contrast. The results clearly demonstrate that the polyurethane adhesive did not cause changes of thermal properties in wood cell walls with adhesive contact. By contrast, cell walls adjacent to a phenol-resorcinol-formaldehyde adhesive showed distinctly changed thermal properties, which is attributed to the presence of adhesive in the wood cell wall.

scholarly journals Mapping thermal conductivity across bamboo cell walls with scanning thermal microscopy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Darshil U. Shah ◽  
Johannes Konnerth ◽  
Michael H. Ramage ◽  
Claudia Gusenbauer
Keyword(s):  
Thermal Conductivity ◽  
Cell Walls ◽  
Vascular Tissue ◽  
Thin Layers ◽  
Cellulose Microfibrils ◽  
Natural Material ◽  
Scanning Thermal Microscopy ◽  
Cell Axis ◽  
Thermal Microscopy ◽  
Fibre Cell

Abstract Scanning thermal microscopy is a powerful tool for investigating biological materials and structures like bamboo and its cell walls. Alongside nanoscale topographical information, the technique reveals local variations in thermal conductivity of this elegant natural material. We observe that at the tissue scale, fibre cells in the scattered vascular tissue would offer preferential pathways for heat transport due to their higher conductivities in both anatomical directions, in comparison to parenchymatic cells in ground tissue. In addition, the transverse orientation offers more resistance to heat flow. Furthermore, we observe each fibre cell to compose of up to ten layers, with alternating thick and thin lamellae in the secondary wall. Notably, we find the thin lamellae to have relatively lower conductivity than the thick lamellae in the fibre direction. This is due to the distinct orientation of cellulose microfibrils within the cell wall layers, and that cellulose microfibrils are highly anisotropic and have higher conductivity along their lengths. Microfibrils in the thick lamellae are oriented almost parallel to the fibre cell axis, while microfibrils in the thin lamellae are oriented almost perpendicular to the cell axis. Bamboo grasses have evolved to rapidly deposit this combination of thick and thin layers, like a polymer composite laminate or cross-laminated timber, for combination of axial and transverse stiffness and strength. However, this architecture is found to have interesting implications on thermal transport in bamboo, which is relevant for the application of engineered bamboo in buildings. We further conclude that scanning thermal microscopy may be a useful technique in plant science research, including for phenotyping studies.

Nano-Localized Thermal Analysis and Mapping of Surface and Sub-Surface Thermal Properties Using Scanning Thermal Microscopy (SThM)

2016 ◽  
Vol 22 (6) ◽  
pp. 1270-1280 ◽  
Author(s):  
Maria J. Pereira ◽  
Joao S. Amaral ◽  
Nuno J. O. Silva ◽  
Vitor S. Amaral
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Thermal Properties ◽  
Critical Role ◽  
Scanning Thermal Microscopy ◽  
Reliable Technique ◽  
Thermal Microscopy ◽  
Resistive Heater ◽  
Contrast Analysis ◽  
Conductivity Contrast

AbstractDetermining and acting on thermo-physical properties at the nanoscale is essential for understanding/managing heat distribution in micro/nanostructured materials and miniaturized devices. Adequate thermal nano-characterization techniques are required to address thermal issues compromising device performance. Scanning thermal microscopy (SThM) is a probing and acting technique based on atomic force microscopy using a nano-probe designed to act as a thermometer and resistive heater, achieving high spatial resolution. Enabling direct observation and mapping of thermal properties such as thermal conductivity, SThM is becoming a powerful tool with a critical role in several fields, from material science to device thermal management. We present an overview of the different thermal probes, followed by the contribution of SThM in three currently significant research topics. First, in thermal conductivity contrast studies of graphene monolayers deposited on different substrates, SThM proves itself a reliable technique to clarify the intriguing thermal properties of graphene, which is considered an important contributor to improve the performance of downscaled devices and materials. Second, SThM’s ability to perform sub-surface imaging is highlighted by thermal conductivity contrast analysis of polymeric composites. Finally, an approach to induce and study local structural transitions in ferromagnetic shape memory alloy Ni–Mn–Ga thin films using localized nano-thermal analysis is presented.

scholarly journals Scanning Thermal Microscopy of Ultrathin Films: Numerical Studies Regarding Cantilever Displacement, Thermal Contact Areas, Heat Fluxes, and Heat Distribution

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 491
Author(s):  
Christoph Metzke ◽  
Fabian Kühnel ◽  
Jonas Weber ◽  
Günther Benstetter
Keyword(s):  
Thermal Properties ◽  
Ultrathin Films ◽  
Hexagonal Boron Nitride ◽  
Thermal Contact ◽  
Heat Transfer Process ◽  
Heat Propagation ◽  
Heat Fluxes ◽  
Detailed Knowledge ◽  
Scanning Thermal Microscopy ◽  
Thermal Microscopy

New micro- and nanoscale devices require electrically isolating materials with specific thermal properties. One option to characterize these thermal properties is the atomic force microscopy (AFM)-based scanning thermal microscopy (SThM) technique. It enables qualitative mapping of local thermal conductivities of ultrathin films. To fully understand and correctly interpret the results of practical SThM measurements, it is essential to have detailed knowledge about the heat transfer process between the probe and the sample. However, little can be found in the literature so far. Therefore, this work focuses on theoretical SThM studies of ultrathin films with anisotropic thermal properties such as hexagonal boron nitride (h-BN) and compares the results with a bulk silicon (Si) sample. Energy fluxes from the probe to the sample between 0.6 µW and 126.8 µW are found for different cases with a tip radius of approximately 300 nm. A present thermal interface resistance (TIR) between bulk Si and ultrathin h-BN on top can fully suppress a further heat penetration. The time until heat propagation within the sample is stationary is found to be below 1 µs, which may justify higher tip velocities in practical SThM investigations of up to 20 µms−1. It is also demonstrated that there is almost no influence of convection and radiation, whereas a possible TIR between probe and sample must be considered.

Thermal conductivity of SiO2 films by scanning thermal microscopy

1999 ◽  
Vol 245 (1-3) ◽  
pp. 203-209 ◽  
Author(s):  
S Callard ◽  
G Tallarida ◽  
A Borghesi ◽  
L Zanotti
Keyword(s):  
Thermal Conductivity ◽  
Scanning Thermal Microscopy ◽  
Thermal Microscopy ◽  
Sio2 Films

Thermal probe self-calibration in ac scanning thermal microscopy

2004 ◽  
Vol 35 (3-6) ◽  
pp. 305-314 ◽  
Author(s):  
M. Chirtoc ◽  
X. Filip ◽  
J.F. Henry ◽  
J.S. Antoniow ◽  
I. Chirtoc ◽  
...  
Keyword(s):  
Scanning Thermal Microscopy ◽  
Thermal Probe ◽  
Thermal Microscopy ◽  
Self Calibration

Thermal Aspects of Grinding: The Effect of the Wheel Bond on Heat Transfer to an Abrasive Grain

1991 ◽  
Vol 113 (4) ◽  
pp. 395-401 ◽  
Author(s):  
M. W. Harris ◽  
A. S. Lavine
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Heat Conduction ◽  
Beneficial Effect ◽  
Surface Temperature ◽  
Thermal Damage ◽  
High Thermal Conductivity ◽  
Abrasive Grain ◽  
Grain Surface

Heat generated during grinding can cause thermal damage to the workpiece and wheel. It is therefore important to understand the thermal aspects of grinding. This paper addresses heat conduction into the wheel, by considering a single abrasive grain in contact with the workpiece. In particular, the effect of the bond material on conduction into the grain is investigated. The results for the grain surface temperature are given in terms of parameters describing the geometry and thermal properties of the grain and bond. The beneficial effect of a high thermal conductivity for both the grain and the bond is clearly demonstrated.

Characterization of the thermal conductivity of insulating thin films by scanning thermal microscopy

2013 ◽  
Vol 44 (11) ◽  
pp. 1029-1034 ◽  
Author(s):  
Séverine Gomès ◽  
Pascal Newby ◽  
Bruno Canut ◽  
Konstantinos Termentzidis ◽  
Olivier Marty ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Scanning Thermal Microscopy ◽  
Thermal Microscopy
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