CN113618855A - Bionic wood-based humidity indicator and preparation method thereof - Google Patents

Bionic wood-based humidity indicator and preparation method thereof Download PDF

Info

Publication number
CN113618855A
CN113618855A CN202110769632.4A CN202110769632A CN113618855A CN 113618855 A CN113618855 A CN 113618855A CN 202110769632 A CN202110769632 A CN 202110769632A CN 113618855 A CN113618855 A CN 113618855A
Authority
CN
China
Prior art keywords
wood
active layer
bionic
layer
passive layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202110769632.4A
Other languages
Chinese (zh)
Other versions
CN113618855B (en
Inventor
詹天翼
刘治廷
吕建雄
彭辉
陈凯文
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nanjing Forestry University
Original Assignee
Nanjing Forestry University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nanjing Forestry University filed Critical Nanjing Forestry University
Priority to CN202110769632.4A priority Critical patent/CN113618855B/en
Publication of CN113618855A publication Critical patent/CN113618855A/en
Application granted granted Critical
Publication of CN113618855B publication Critical patent/CN113618855B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27D—WORKING VENEER OR PLYWOOD
    • B27D1/00—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring
    • B27D1/04—Joining wood veneer with any material; Forming articles thereby; Preparatory processing of surfaces to be joined, e.g. scoring to produce plywood or articles made therefrom; Plywood sheets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D21/00—Measuring or testing not otherwise provided for

Abstract

The invention discloses a bionic wood-based humidity indicator which comprises an active layer and a passive layer, wherein an adhesive is arranged between the active layer and the passive layer, the active layer and the passive layer are both wood laminates, and the deformation of the active layer along the longitudinal direction is larger than that of the passive layer. The invention discloses a preparation method of a bionic wood-based humidity indicator, which comprises the following steps: determining the curvature change range of the bionic wood-based humidity indicator according to the humidity range of the actual use condition; determining the initial water content and the thickness proportion of an active layer and a passive layer in the indicator according to the curvature change range; respectively preparing an active layer and a passive layer; humidifying the active layer and the passive layer respectively to enable the active layer and the passive layer to reach the initial water content; and gluing the active layer and the passive layer, and carrying out hot pressing to prepare the bionic wood-based humidity indicator. The bionic wood-based humidity indicator prepared by the invention only adopts wood and adhesive as raw materials, has low cost, simple process steps and high production efficiency, and the indicating method is sensitive, efficient and simple and can be used repeatedly.

Description

Bionic wood-based humidity indicator and preparation method thereof
Technical Field
The invention relates to the technical field of wood bionics, in particular to a bionic wood-based humidity indicator and a preparation method thereof.
Background
In the long evolution process of nature, the tissue structure of plants evolves to adapt to climate change. The leaves are stretched in rainy days to absorb water and closed in dry days to reduce loss; the opening degree of the pine nut shell scales changes according to the change of humidity; the wheat and awns are drilled into soil gaps along with the periodic change of humidity in the day and night alternating process; when the bean pods are dehydrated and contracted, the two bean pods are reversely bent to form a spiral shape, so that ejection of the seeds is realized. These behaviors that rely on humidity to actively change shape are high-level survival strategies for plants.
Wood is a capillary limited expansion colloidal material that is hygroscopic because the chemical components of the cell wall contain polar groups. When the air humidity is low, the wood is desorbed, and the internal moisture is diffused to the air; when the air humidity is high, the wood is subject to sorption, absorbing moisture from the air. During sorption or desorption, wood dimensions change, i.e. drying shrinkage and swelling. As an anisotropic material, the wood has different dry shrinkage and wet expansion in different directions, and the dry shrinkage and wet expansion amount in the transverse direction (radial direction and chord direction) is far larger than that in the longitudinal direction. The dry shrinkage and wet expansion may cause defects of cracking, warping and the like of the wood, so that the control of the dry shrinkage and wet expansion of the wood and the improvement of the dimensional stability of the wood are always important fields of wood modification.
Conventional wetness indicators include wet and dry bulb thermometers, hair hygrometers, lithium chloride hygrometers, and the like. The dry-wet bulb thermometer consists of two identical thermometers, one of which is a dry bulb thermometer and the other is a wet bulb thermometer. The temperature indication of the wet bulb thermometer is lower than that of the dry bulb thermometer by utilizing moisture evaporation, so that the relative humidity of air is obtained according to the difference of the wet bulb thermometer and the dry bulb thermometer, but the humidity indicator has low indicating efficiency, is insensitive and is easily influenced by wind speed, so that the indicating accuracy is influenced; the hair hygrometer measures the air humidity by using the change of the length or the volume of the hair after moisture absorption, but has the defects of lagging induction change, easy dust accumulation and unsuitability for long-term repeated use; lithium chloride or aluminum oxide is used as a humidity meter, and humidity is measured according to capacitance and resistance changes after the metal film absorbs water, but the cost is high.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects of the prior art and provide the bionic wood-based humidity indicator and the preparation method thereof, the raw materials of the prepared bionic wood-based humidity indicator are only wood and adhesive, the cost is low, the process steps are simple, the production efficiency is high, the indication method is sensitive, efficient and simple, the indicator can be repeatedly used, and multiple indications can be performed in the humidity range.
In order to solve the technical problems, the invention provides a bionic wood-based humidity indicator which comprises an active layer and a passive layer, wherein an adhesive is arranged between the active layer and the passive layer, the active layer and the passive layer are both made of wood laminates, and the longitudinal deformation of the active layer is larger than that of the passive layer.
In the double-layer structure, a certain difference exists in the longitudinal dimension change of the control active layer and the control passive layer. However, the active layer and the passive layer are bonded into a whole by the adhesive, so that the indicator bends to coordinate the size change difference of the active layer and the passive layer. When the humidity is increased, the indicator bends towards one side of the passive layer; when the humidity is reduced, the bend is restored toward the active layer side.
The invention also provides a preparation method of the bionic wood-based humidity indicator, which comprises the following steps:
determining the curvature change range of the bionic wood-based humidity indicator according to the humidity range of the actual use condition;
determining the initial water content and the thickness proportion of an active layer and a passive layer in the indicator according to the curvature change range;
respectively preparing an active layer and a passive layer;
humidifying the active layer and the passive layer respectively to enable the active layer and the passive layer to reach the initial water content;
and gluing the active layer and the passive layer, and carrying out hot pressing to prepare the bionic wood-based humidity indicator.
Preferably, the humidity range of the actual using condition is 5-99% relative humidity.
Preferably, the curve of the bionic wood-based humidity indicatorThe rate variation range is-15 to 10 μm-1。
Preferably, the initial water content of the active layer and the passive layer is 0%, 12% or 30%.
Preferably, the humidity conditioning conditions of the active layer and the passive layer are 0%, 69% or 100%.
Preferably, the thickness of the active layer and the passive layer is 20-200 μm, and the ratio of the thickness of the active layer to the thickness of the passive layer is 0.1-10.
Preferably, the length direction of the active layer is the axial direction of the fir wood, the rigidity of the active layer is 10000MPa, the length direction of the passive layer is the radial direction of the fir wood, and the rigidity of the passive layer is 800 MPa.
Preferably, the adhesive is phenolic resin adhesive, and the adhesive application amount is 150-200 g/m2。
Preferably, the hot pressing temperature is 140-160 ℃, the hot pressing time is 1-5 min, and the hot pressing pressure is 0.1-0.3 MPa.
The invention achieves the following beneficial effects:
(1) compared with other humidity indicators, the bionic wood-based humidity indicator prepared by the invention only adopts wood and adhesive as raw materials, and has the advantages of low cost, simple process steps and high production efficiency;
(2) the bionic wood-based humidity indicator prepared by the invention has sensitive, efficient and simple indicating method;
(3) the wood-based humidity indicator can be used repeatedly and can indicate for multiple times in a humidity range;
(4) the bionic wood-based humidity indicator prepared by the invention has the advantages of adjustable breadth size, beautiful finished product and various forms.
Drawings
FIG. 1 is a schematic representation of an exemplary indication of a wood-based wetness indicator provided in accordance with an embodiment of the present invention;
FIG. 2 is a graph showing the relationship between the curvature of a wood-based humidity indicator and the ambient humidity in various embodiments;
FIG. 3 is a graph of curvature of an absolute dry wood-based wetness indicator versus the ratio of active and passive layer thicknesses;
FIG. 4 is a graph of curvature of an oven-dried wood-based moisture indicator as a function of moisture content of the active and passive layers.
Detailed Description
The present invention will be further described with reference to the following examples. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a bionic wood-based humidity indicator comprises an active layer 1 and a passive layer 2, an adhesive 3 is arranged between the active layer 1 and the passive layer 2, the active layer 1 and the passive layer 2 are both wood laminates, and the active layer 1 deforms more than the passive layer 2 along the longitudinal direction. In the double-layer structure, there is a difference in controlling the longitudinal dimensional change of the active layer 1 and the passive layer 2. However, since the active layer 1 and the passive layer 2 are integrally bonded by the adhesive 3, the indication is that the bending occurs in accordance with the difference in the dimensional changes of the active layer 1 and the passive layer 2. When the humidity increases, the indicator bends toward the passive layer 2 side; when the humidity is reduced, the bending is restored toward the active layer 1 side.
Example 1
A bionic wood-based humidity indicator is prepared by the following steps:
step one, determining the actual humidity change range as follows: 50% -90%.
Step two, determining the curvature change range of the wood-based humidity indicator to be-3 μm according to the humidity change range of the step one-1~3μm-1。
Step three, determining the initial water content of the active layer to be 12% and the initial water content of the passive layer to be 0% according to the curvature variation range of the step two;
and step four, determining the thickness of the active layer to be 100 μm and the thickness of the passive layer to be 50 μm according to the curvature variation range of the step two.
And step five, according to the initial water content in the step three, the humidity adjusting condition of the active layer is 100%, and the humidity adjusting condition of the passive layer is 0%.
And step six, gluing the active layer and the passive layer which are subjected to the step three to the step five, and assembling in parallel. The glue application amount is 150g/m2。
And step seven, hot pressing. The hot pressing temperature is 140 ℃, the hot pressing time is 5min, and the hot pressing pressure is 0.1 MPa. And after the hot pressing is finished, obtaining the bionic wood-based humidity indicator.
Example 2
A bionic wood-based humidity indicator is prepared by the following steps:
step one, determining the actual humidity change range as follows: 30% -75%.
Step two, determining the curvature change range of the wood-based humidity indicator to be-1 μm according to the humidity change range of the step one-1~4μm-1。
Step three, determining the initial water content of the active layer to be 30% and the initial water content of the passive layer to be 0% according to the curvature variation range of the step two;
and step four, determining the thickness of the active layer to be 150 μm and the thickness of the passive layer to be 100 μm according to the curvature variation range of the step two.
And step five, according to the initial water content in the step three, the humidity adjusting condition of the active layer is 100%, and the humidity adjusting condition of the passive layer is 0%.
And step six, gluing the active layer and the passive layer which are subjected to the step three to the step five, and assembling in parallel. The glue application amount is 200g/m2。
And step seven, hot pressing. The hot pressing temperature is 150 ℃, the hot pressing time is 3min, and the hot pressing pressure is 0.2 MPa. And after the hot pressing is finished, obtaining the bionic wood-based humidity indicator.
Example 3
A bionic wood-based humidity indicator is prepared by the following steps:
step one, determining the actual humidity change range as follows: 10% -90%.
Step two, determining the curvature change range of the wood-based humidity indicator to be-2 μm according to the humidity change range of the step one-1~6μm-1。
Step three, determining the initial water content of the active layer to be 30% and the initial water content of the passive layer to be 30% according to the curvature variation range of the step two;
and step four, determining the thickness of the active layer to be 100 μm and the thickness of the passive layer to be 100 μm according to the curvature variation range of the step two.
And step five, according to the initial water content in the step three, the humidity adjusting condition of the active layer is 100%, and the humidity adjusting condition of the passive layer is 100%.
And step six, gluing the active layer and the passive layer which are subjected to the step three to the step five, and assembling in parallel. The glue application amount is 170g/m2。
And step seven, hot pressing. The hot pressing temperature is 160 ℃, the hot pressing time is 4min, and the hot pressing pressure is 0.3 MPa. And after the hot pressing is finished, obtaining the bionic wood-based humidity indicator.
Example 4
A bionic wood-based humidity indicator is prepared by the following steps:
step one, determining the actual humidity change range as follows: 40% -60%.
Step two, determining the curvature change range of the wood-based humidity indicator to be-1 μm according to the humidity change range of the step one-1~4μm-1。
Step three, determining the initial water content of the active layer to be 30% and the initial water content of the passive layer to be 12% according to the curvature change range of the step two;
and step four, determining the thickness of the active layer to be 60 μm and the thickness of the passive layer to be 40 μm according to the curvature variation range of the step two.
And step five, according to the initial water content in the step three, the humidity adjusting condition of the active layer is 100%, and the humidity adjusting condition of the passive layer is 69%.
And step six, gluing the active layer and the passive layer which are subjected to the step three to the step six, and assembling in parallel. The glue application amount is 185g/m2。
And step seven, hot pressing. The hot pressing temperature is 150 ℃, the hot pressing time is 4min, and the hot pressing pressure is 0.2 MPa. And after the hot pressing is finished, obtaining the bionic wood-based humidity indicator.
Example 5
A bionic wood-based humidity indicator is prepared by the following steps:
step one, determining the actual humidity change range as follows: 35% -85%.
Step two, determining wood according to the humidity change range in the step oneThe range of curvature variation of the humidity indicator was-3 μm-1~7μm-1。
Step three, determining the initial water content of the active layer to be 12% and the initial water content of the passive layer to be 12% according to the curvature change range of the step two;
and step four, determining the thickness of the active layer to be 25 μm and the thickness of the passive layer to be 25 μm according to the curvature variation range of the step two.
And step five, according to the initial water content in the step three, the humidity adjusting condition of the active layer is 69%, and the humidity adjusting condition of the passive layer is 69%.
And step six, gluing the active layer and the passive layer which are subjected to the step three to the step five, and assembling in parallel. The glue application amount is 190g/m2。
And step seven, hot pressing. The hot pressing temperature is 145 ℃, the hot pressing time is 3min, and the hot pressing pressure is 0.2 MPa. And after the hot pressing is finished, obtaining the bionic wood-based humidity indicator.
Fig. 2 shows the change of curvature of the wood-based hygrometer of each embodiment during the change of ambient humidity. It can be seen from the figure that in either embodiment, the curvature is approximately linear or exponential with respect to ambient humidity. Namely, the curvature and the ambient humidity have a one-to-one correspondence relationship, but the numerical value of the curvature and the variation amplitude along with the relative humidity of each embodiment have differences. The value of the curvature is related to the total thickness of the wood-based wetness indicator and the ratio of the thicknesses of the active and passive layers. The magnitude of the change in curvature with relative humidity is related to the moisture content of the active/passive layers. Fig. 3 shows the curvature of the absolute dry wood-based gauge as a function of thickness ratio for different total thicknesses. As can be seen from the figure, the absolute value of the absolute dry curvature decreases with increasing thickness ratio and decreases with increasing total thickness. FIG. 4 is a graph showing the variation of the curvature variation range of the active/passive layer under different water content conditions. Therefore, according to the actual humidity change range, a better curvature change range, a corresponding thickness ratio and an initial water content can be determined.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The bionic wood-based humidity indicator is characterized by comprising an active layer and a passive layer, wherein an adhesive is arranged between the active layer and the passive layer, the active layer and the passive layer are both wood laminates, and the active layer deforms longitudinally to be larger than the passive layer.
2. The method for preparing the bionic wood-based humidity indicator according to claim 1, which is characterized by comprising the following steps:
determining the curvature change range of the bionic wood-based humidity indicator according to the humidity range of the actual use condition;
determining the initial water content and the thickness proportion of an active layer and a passive layer in the indicator according to the curvature change range;
respectively preparing an active layer and a passive layer;
humidifying the active layer and the passive layer respectively to enable the active layer and the passive layer to reach the initial water content;
and gluing the active layer and the passive layer, and carrying out hot pressing to prepare the bionic wood-based humidity indicator.
3. The preparation method of the bionic wood-based humidity indicator according to claim 2, wherein the humidity range of actual use conditions is 5-99% relative humidity.
4. The preparation method of the bionic wood-based humidity indicator according to claim 2, wherein the curvature variation range of the bionic wood-based humidity indicator is-15-10 μm-1。
5. The method of claim 2, wherein the active layer and the passive layer have an initial water content of 0%, 12% or 30%.
6. The method for preparing a bionic wood-based humidity indicator according to claim 5, wherein the humidity conditioning conditions of the active layer and the passive layer are 0%, 69% or 100%.
7. The method for preparing a bionic wood-based humidity indicator according to claim 2, wherein the thicknesses of the active layer and the passive layer are 20-200 μm, and the ratio of the thicknesses of the active layer and the passive layer is 0.1-10.
8. The method as claimed in claim 2, wherein the active layer has an axial stiffness of 10000MPa, and the passive layer has a radial stiffness of 800 MPa.
9. The preparation method of the bionic wood-based humidity indicator according to claim 2, wherein the adhesive is phenolic resin adhesive, and the adhesive application amount is 150-200 g/m2。
10. The preparation method of the bionic wood-based humidity indicator according to claim 2, wherein the hot pressing temperature is 140-160 ℃, the hot pressing time is 1-5 min, and the hot pressing pressure is 0.1-0.3 MPa.
CN202110769632.4A 2021-07-07 2021-07-07 Bionic wood-based humidity indicator and preparation method thereof Active CN113618855B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110769632.4A CN113618855B (en) 2021-07-07 2021-07-07 Bionic wood-based humidity indicator and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110769632.4A CN113618855B (en) 2021-07-07 2021-07-07 Bionic wood-based humidity indicator and preparation method thereof

Publications (2)

Publication Number Publication Date
CN113618855A true CN113618855A (en) 2021-11-09
CN113618855B CN113618855B (en) 2022-07-01

Family

ID=78379212

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110769632.4A Active CN113618855B (en) 2021-07-07 2021-07-07 Bionic wood-based humidity indicator and preparation method thereof

Country Status (1)

Country Link
CN (1) CN113618855B (en)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102001114A (en) * 2010-09-17 2011-04-06 南京林业大学 Method for manufacturing curved laminated veneer lumber
CN102554990A (en) * 2012-01-20 2012-07-11 汕头市宜华家具有限公司 Wood drying method
CN103072159A (en) * 2013-01-28 2013-05-01 南京工业大学 Prestressed laminated wood with creep resistant deformation performance, and preparation method and use thereof
CN108908567A (en) * 2018-06-19 2018-11-30 温州职业技术学院 A kind of wood-bending equipment
CN109352767A (en) * 2018-12-17 2019-02-19 宜华生活科技股份有限公司 Bending of solid wood processing method with directional curvature function
CN110216753A (en) * 2019-07-23 2019-09-10 张树彬 A kind of big plate benging equipment of solid wood
PL3071912T3 (en) * 2013-11-18 2020-06-15 Coldbay Ab A method and system for drying wood in a drying compartment

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102001114A (en) * 2010-09-17 2011-04-06 南京林业大学 Method for manufacturing curved laminated veneer lumber
CN102554990A (en) * 2012-01-20 2012-07-11 汕头市宜华家具有限公司 Wood drying method
CN103072159A (en) * 2013-01-28 2013-05-01 南京工业大学 Prestressed laminated wood with creep resistant deformation performance, and preparation method and use thereof
PL3071912T3 (en) * 2013-11-18 2020-06-15 Coldbay Ab A method and system for drying wood in a drying compartment
CN108908567A (en) * 2018-06-19 2018-11-30 温州职业技术学院 A kind of wood-bending equipment
CN109352767A (en) * 2018-12-17 2019-02-19 宜华生活科技股份有限公司 Bending of solid wood processing method with directional curvature function
CN110216753A (en) * 2019-07-23 2019-09-10 张树彬 A kind of big plate benging equipment of solid wood

Also Published As

Publication number Publication date
CN113618855B (en) 2022-07-01

Similar Documents

Publication Publication Date Title
Stamm et al. Thermodynamics of the Sweeling of Wood
Barzegar et al. Experimental evaluation of the performances of cellulosic pads made out of Kraft and NSSC corrugated papers as evaporative media
CN105067682A (en) Flexible capacitive humidity sensor and preparation method thereof
Franco et al. Influence of water and air flow on the performance of cellulose evaporative cooling pads used in Mediterranean greenhouses
Vinha Hygrothermal performance of timber-framed external walls in Finnish climatic conditions: A method for determining the sufficient water vapour resistance of the interior lining of a wall assembly
CN113618855B (en) Bionic wood-based humidity indicator and preparation method thereof
Vailati et al. Upscaling of wood bilayers: design principles for controlling shape change and increasing moisture change rate
CN201716128U (en) Temperature measuring device for outer surface of high-speed aircraft
CN108254317A (en) A kind of fiber bragg grating temperature sensor in non-grid region coating polyimide
CN106182223B (en) The excessively curved correction forming method of variable cross-section arc glue laminated wood member
Schwab et al. Predictions for the increase in pressure and water content of vacuum insulation panels (VIPs) integrated into building constructions using model calculations
Pelliccia et al. Characterisation of wood hygromorphic panels for relative humidity passive control
Zarr et al. Heat and moisture transfer in wood-based wall construction: Measured versus predicted
CN104634691A (en) Experiment device for accurately measuring relatively large evaporation from water surface under solar irradiation
CN106046216B (en) A kind of high-temp resisting high-humidity resisting wetness sensitive polymer and preparation method thereof and the capacitance sensor being prepared into based on wetness sensitive polymer
CN206832386U (en) A kind of assembled resistance strain gage
CN2101237U (en) Thermophilic high molecular humidity sensitive element
CN103331982B (en) A kind of production technology of aluminum foil composite paper
CN201583213U (en) Engineering plastic film substrate strain gauge
AL-ISMAILI Simple Iterative Approach Temperature for
CN207730649U (en) A kind of fiber bragg grating temperature sensor in non-grid region coating polyimide
Walton Moisture diffusion in the cured burley tobacco leaf
Bianconi et al. Hygroscopic Coffer
Exner-Kittridge Closure to “case study on the accuracy and cost/effectiveness in simulating reference evapotranspiration in West-Central Florida” by Michael Grant Exner-Kittridge and Mark Cable Rains
CN212780612U (en) Temperature and humidity measuring device

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant