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A method for measuring transverse relaxation rate of wood cell wall pore surface

A technology of transverse relaxation rate and measurement method, which is applied in the field of determination of transverse relaxation rate of wood cell wall pore surface, can solve the problems of long test time, large deviation of measurement results, and low efficiency

Active Publication Date: 2022-07-29
INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the gas adsorption method has a long test time, high energy consumption and low efficiency
The time-domain NMR method needs to select a standard sample that is similar to the wood pores and has a known average pore size to calibrate the surface relaxation rate of the wood pores, and then obtain the conversion coefficient between the T2 distribution and the pore size to determine the pore size distribution, while the standard sample cannot Accurately reflect the wood pores, so there is still a large deviation in the measurement results

Method used

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  • A method for measuring transverse relaxation rate of wood cell wall pore surface
  • A method for measuring transverse relaxation rate of wood cell wall pore surface
  • A method for measuring transverse relaxation rate of wood cell wall pore surface

Examples

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Embodiment 1

[0077] The method for determining the transverse relaxation rate of the pore surface of the wood cell wall described in this embodiment includes the following steps:

[0078] (1) Select the wood sample for thermogravimetric analysis, and determine the heat treatment temperature to be 200 °C to prevent the heat treatment temperature from being too high to damage the chemical components of the cell wall of the wood sample and affect the determination of cell wall pores;

[0079] (2) Heat-treating the wood sample, drying the wood sample at 105°C until it is absolutely dry, and recording the mass m a =0.885g, then under nitrogen protection, the temperature was increased to 200°C at a programmed rate of 5°C / min, and then kept for 5 hours to obtain a heat-treated sample. The mass of the heat-treated sample was m b =0.878g, mass loss rate (m a -m b )×100% / m a = 0.791%, controlled within the range of 0-1%, to prevent heat treatment from damaging the chemical components of the cell ...

Embodiment 2

[0122] The method for measuring the transverse relaxation rate of the pore surface of the wood cell wall described in this example is the same as the method in Example 1, except that in step (11), the starting point and the ending point of the part with the same slope in the curve 2 are selected as the curve 2 The data between each node comes from the same type of pore system; by comparing curve 2 and curve 3, the distribution nodes of curve 2 correspond to the same d on curve 3 N2 The data points are used as the distribution nodes of curve 3;

[0123] The distribution nodes of curve 2 in this embodiment are: figure 2 In the middle curve 2, the remaining nodes except the second and third distribution nodes (arranged in the order of nitrogen adsorption pore size from small to large) are not shown in additional drawings in order to save space. Through weighted linear regression, the values ​​of Q and K corresponding to the nitrogen adsorption pore size and nuclear magnetic por...

Embodiment 3

[0127] The method for measuring the transverse relaxation rate of the pore surface of the wood cell wall described in this example is the same as the method in Example 1, except that in step (11), the starting point and the ending point of the part with the same slope in the curve 3 are selected as the distribution of the curve 3 nodes, the data between each node comes from the same type of pore system; the distribution nodes of curve 3 in this embodiment do not include figure 2 The 7th, 8th, and 9th distribution nodes of curve 3 in the middle (arranged in ascending order of nitrogen adsorption aperture), other distribution nodes are the same as those in Example 1. To save space, no additional drawings are added.

[0128] Through weighted linear regression, the values ​​of Q and K corresponding to the nitrogen adsorption pore size and nuclear magnetic pore size between each distribution node are determined, and the surface transverse relaxation rate ρ of the cell wall pores of...

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Abstract

The invention relates to a method for measuring the transverse relaxation rate of a pore surface of a wood cell wall, which comprises the following steps: (1) sequentially performing heat treatment and water-saturated treatment on a wood sample to obtain a water-saturated sample; (2) using time-domain nuclear magnetic resonance Spectrometer is used to measure the transverse relaxation time distribution curve of the saturated sample, and curve 1 is obtained; (3) the wood sample after the measurement in step (2) is dried to absolutely dry, and then the gas adsorption pore size is measured, and curve 2 is obtained; (4) Calculate based on the data of curve 1 and curve 2 to obtain the transverse relaxation time value corresponding to the gas adsorption aperture under the same cumulative distribution frequency, and obtain curve 3; (5) Combine curve 2 and curve 3 to obtain the wood test. The distribution nodes of different pore systems within the pore size range of the cell wall of the sample are determined, the conversion coefficients between the nodes are determined, and the surface transverse relaxation rates of the different pore systems of the cell wall of the wood sample are determined.

Description

technical field [0001] The invention belongs to the technical field of wood cell wall pore detection, in particular to a method for measuring the transverse relaxation rate of the wood cell wall pore surface. Background technique [0002] Wood is an important material, which occupies an important position in national production and life, and is widely used in building materials, furniture, environmental protection, energy, chemical industry and other fields. Due to its natural growth characteristics, wood can form a natural organic composite material with distinct structural layers and orderly structure, with a fine hierarchical porous structure. Scholars at home and abroad divide wood pores into macroscopic (macropores), mesoscopic (mesoporous) and microscopic pores (micropores). pit pores and microfibril gaps. The pores of the wood cell wall play an important role in the properties of wood and in the processing and utilization of wood. It not only has a great impact on w...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N24/08G01N15/08G01N1/44
CPCG01N24/08G01N15/088G01N15/0893G01N1/44
Inventor 金枝付跃进陈倩曾珍胡生辉
Owner INST OF WOOD INDUDTRY CHINESE ACAD OF FORESTRY
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