CN114112170A - Method for measuring internal air pressure of polymer foaming beads for wave-absorbing material - Google Patents
Method for measuring internal air pressure of polymer foaming beads for wave-absorbing material Download PDFInfo
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- CN114112170A CN114112170A CN202110987779.0A CN202110987779A CN114112170A CN 114112170 A CN114112170 A CN 114112170A CN 202110987779 A CN202110987779 A CN 202110987779A CN 114112170 A CN114112170 A CN 114112170A
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- 239000011324 bead Substances 0.000 title claims abstract description 61
- 229920000642 polymer Polymers 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 21
- 239000011358 absorbing material Substances 0.000 title claims abstract description 13
- 238000005187 foaming Methods 0.000 title abstract description 6
- 239000006260 foam Substances 0.000 claims abstract description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- 239000002184 metal Substances 0.000 claims description 8
- 238000003825 pressing Methods 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 5
- 239000007788 liquid Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims 1
- 239000002904 solvent Substances 0.000 claims 1
- 230000008859 change Effects 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 14
- 238000000465 moulding Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005303 weighing Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- -1 polypropylene Polymers 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000004445 quantitative analysis Methods 0.000 description 2
- 238000007493 shaping process Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000004794 expanded polystyrene Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002959 polymer blend Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
The invention discloses a method for measuring the internal air pressure of polymer foam beads for a wave-absorbing material, which provides a simple and convenient way for measuring and analyzing the internal air pressure of the polymer foam beads, so as to guide the forming and provide reference for operators to adjust prepressing parameters and steam forming parameters; the method can be basically used for measuring different regional environments and climate change and different types of polymer foaming beads. The method disclosed by the invention has relatively good universality, and the measured data of the air pressure in the polymer expanded beads are consistent with the estimated value of an operator with abundant experience.
Description
Technical Field
The invention relates to a method for measuring the air pressure in polymer foaming beads for a wave-absorbing material.
Background
The existing market has various wave-absorbing materials, wherein the electromagnetic wave absorber prepared by molding the expanded polymer beads has the advantages of uniform performance, easy control of molding size and structure, environment-friendly preparation process and the like. Expanded Polystyrene (EPS) and expanded polypropylene (EPP) are used in a wide range of applications in this field. Taking EPP as an example, when the EPP is molded, firstly, prepressing the EPP, then, on an EPP molding machine, after a movable mold and a fixed mold are closed, conveying the prepressed EPP beads into a mold cavity, introducing high-temperature steam with certain pressure from a steam pipeline on the mold to ensure that the beads expand again and are welded into a whole, stopping introducing the steam and removing the pressure of the mold, further expanding a foamed product to fill the whole mold cavity, introducing cooling water to cool the mold cavity and the foamed product, opening the mold when the stress of the mold cavity is reduced to a certain degree, ejecting a workpiece by an ejector rod, and then, putting the workpiece into a drying room to further dry moisture and shape.
Therefore, the currently common molding process for such expanded polymer beads is first pre-compaction. That is, the expanded polymer beads are sucked into an air pre-pressurizing tank, then a valve of the pre-pressurizing tank is closed, and then compressed air is introduced into the pre-pressurizing tank to carry out pressure loading according to a certain pressurizing program. After the operation of the procedure is finished, compressed air with certain pressure is stored in the expanded polymer beads; at this time, the air pressure stored inside the expanded polymer beads is important for molding. When the internal pressure is insufficient, the formed product is seriously shrunk, the size is difficult to control, the performance of the wave-absorbing material is influenced, and the appearance is easy to have defects so as to influence the apparent quality; when the internal pressure is high, the molding requires high steam pressure and a long water cooling time. This not only causes the energy consumption to be extravagant, still causes great damage to the mould, and the shaping cycle extension moreover influences production efficiency.
In addition, when expanded polymer beads of different types, different magnifications, or different molded articles are molded, the internal air pressure required for the expanded polymer is different. Also, the internal air pressure of the beads is sensitive to the environment, and the internal pressure of the expanded polymer beads in winter and summer is also very different for the same prepressing procedure. The prior production process usually depends on the experience of a forming technician to adjust the prepressing parameters.
Patent CN109883604B discloses an estimation method of the air pressure inside the polymer expanded beads, which quantitatively estimates the air pressure inside the expanded polymer and has certain guiding significance for the actual production. However, in the estimation process, the expanded polymer beads are deduced simply as a uniform close packing of spherical structures, which causes a relatively large deviation from the actual expanded polymer bead morphology. The expanded polymer beads used in practice have a substantially ellipsoidal or cylindrical form, and it is difficult to obtain a completely uniform bead size.
The present invention overcomes the above disadvantages, and can measure the internal air pressure of any form of expanded polymer beads by a simple operation. And the density of the polymer or the polymer blend is not required to be measured in advance, so that the air pressure in the foaming polymer can be accurately measured, and the method has a strong guiding significance for actual operation.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defect that the internal air pressure of the expanded polymer bead in the prior art has no simple quantitative analysis method to guide the forming of the wave-absorbing material, and provides a method for measuring the internal air pressure of the expanded polymer bead for the wave-absorbing material.
In order to solve the technical problems, the invention provides the following technical scheme:
a method for measuring the air pressure inside polymer expanded beads for wave-absorbing materials comprises the following steps:
A. taking a 1000mL wide-mouth measuring cup, the qualitym 1 (unit g);
B. opening the air pre-pressing tank, quickly taking out about 500mL of the pre-pressed polymer foam beads from the air pre-pressing tank, placing the pre-pressed polymer foam beads in the wide-mouth measuring cup in the step A, and weighing the massm 2 ；
C. Pour volume V into Wide-mouthed measuring cup in B1Alcohol (in mL) and known by volume as V2The metal mesh sheet completely presses down the polymer foam beads to dip into the alcohol, and the liquid scale V in the measuring cup at this time is read3；
D. Taking out the alcohol and the metal mesh sheet in the measuring cup B, putting the residual wide-mouth measuring cup and the polymer foam beads into a drying oven with the temperature of 70-80 ℃ for baking for several hours until the weight of the wide-mouth measuring cup is constant at normal temperaturem 3 ；
D. Recording ambient temperatureT(unit is in degree C);
e: then, the measured internal air pressure of the pre-compacted polymer foam beads is:
the above equation is derived by using an ideal gas equation, also called ideal gas law or Clappelon equation, which is used to describe the ideal gas state change law. The functional relationship between the mass M (molar mass M), the quantity n of substance, and the state variables pressure p, volume V, and absolute temperature T of an ideal gas is:
pV = mRT/M = nRT formula, R is the gas constant.
For mixing ideal gases, the pressure p is the partial pressure of the component partsp 1、p 2、p 3… …, the amount of substance n being the sum of the amounts of the constituent substances, such that:
the two equations are the equation of state of the ideal gas and the mixed ideal gas, can be obtained by the gas law strictly followed by the ideal gas, and can also be derived by the gas dynamic theory according to the micro model of the ideal gas. When the pressure is below several atmospheric pressures, various actual gases approximately follow an ideal gas state equation, the lower the pressure is, the better the equation conformity is, and the extreme condition that the pressure tends to zero is strictly followed.
The invention has the following beneficial effects: the invention can accurately measure the internal air pressure of any form of expanded polymer beads. Therefore, the method provides a simple and convenient way for quantitative analysis to guide the forming, and basically can be used for measuring different regional environments, climate change and different types of polymer foaming beads.
Detailed Description
The following description of the preferred embodiments of the present invention is provided for the purpose of illustration and description, and is in no way intended to limit the invention.
Example 1
A method for measuring the air pressure inside an EPP bead for a wave-absorbing material comprises the following steps:
A. taking a 1000mL wide-mouth measuring cup with the mass of 15.23 g;
B. opening an air pre-pressing tank, quickly taking out about 500mL of pre-pressed polymer foam beads from the air pre-pressing tank, placing the pre-pressed polymer foam beads in the wide-mouth measuring cup in the step A, and weighing 35.84g of mass;
C. pour a volume of 300mL of alcohol into the wide-mouth beaker in B and immerse the polymer foam beads into the alcohol completely under pressure from a metal mesh sheet of known volume of 20.5mL, read the liquid mark 721.3mL in the beaker at this time;
D. taking out the alcohol and the metal mesh sheet in the measuring cup in the step B, and putting the residual wide-mouth measuring cup and the polymer foam beads into a drying oven with the temperature of 80 ℃ for baking for 4 hours until the weight of the wide-mouth measuring cup is constant to 35.12g at normal temperature;
D. recording the environmental temperature to be 26.3 ℃;
e: then, the measured internal air pressure of the pre-compacted polymer foam beads is:
calculated, pre-pressing according to the pre-pressing program to obtain an internal pressure of the EPP beads of 2.60 bar.
Wangzhi, having a 12-year EPP bead formation experience. According to experience, the internal air pressure estimation value of the EPP beads obtained by the prepressing program by the master is 2.5-2.8 bar, which is consistent with the data obtained by the testing method of the invention.
Example 2
A method for measuring the air pressure inside Expanded Polyethylene (EPE) beads for wave-absorbing materials comprises the following steps:
A. taking a 1000mL wide-mouth measuring cup with the mass of 15.23 g;
B. opening an air pre-pressing tank, quickly taking out about 500mL of pre-pressed polymer foam beads from the air pre-pressing tank, placing the pre-pressed polymer foam beads in the wide-mouth measuring cup in the step A, and weighing 29.95g of the pre-pressed polymer foam beads;
C. pour a volume of 300mL of alcohol into the wide-mouth beaker in B and immerse the polymer foam beads into the alcohol completely under pressure from a metal mesh sheet of known volume of 20.5mL, at which time the liquid scale in the beaker is read at 660.7 mL;
D. taking out the alcohol and the metal mesh sheet in the measuring cup in the step B, and putting the residual wide-mouth measuring cup and the polymer foam beads into a drying oven with the temperature of 70 ℃ for baking for 3 hours until the weight of the wide-mouth measuring cup is constant to 29.12g at normal temperature;
D. recording the environmental temperature to be 25.9 ℃;
e: then, the measured internal air pressure of the pre-compacted polymer foam beads is:
calculated, precompressed according to the precompression program described above, resulting in an internal pressure of the EPE beads of 3.22 bar.
Cao has a 15-year EPE bead formation experience. According to experience, the estimated value of the internal air pressure of the EPE bead obtained by the Cao master through the prepressing program is 3.0-3.5 bar, which is consistent with the data obtained by the testing method of the invention.
The data determined in examples 1-2 are consistent with the predictions made by an experienced molding technologist. Can be used to guide the shaping of the beads.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. A method for measuring the air pressure in polymer expanded beads for wave-absorbing materials is characterized by comprising the following steps:
A. taking a 1000mL wide-mouth measuring cup with mass m1(unit g);
B. opening the air precompression tank and rapidly removing the precompressed polymer foam beads therefromAbout 500mL, put into the wide-mouth measuring cup in the step A, and weigh the mass m2；
C. Pour volume V into Wide-mouthed measuring cup in B1Alcohol (in mL) and known by volume as V2The metal mesh sheet completely presses down the polymer foam beads to dip into the alcohol, and the liquid scale V in the measuring cup at this time is read3；
D. Taking out the alcohol and the metal mesh sheet in the measuring cup in the B, putting the residual wide-mouth measuring cup and the polymer foam beads into a drying oven at 70-80 ℃ for baking for several hours until the weight of the wide-mouth measuring cup is constant to m at normal temperature3；
D. Record ambient temperature T (in ℃);
e: then, the measured internal air pressure of the pre-compacted polymer foam beads is:
2. the method for estimating the internal pressure of polymer expanded beads according to claim 1, wherein in the step B, the temperature of the air to be pressurized into the preliminary pressing tank is room temperature.
3. The method for measuring the air pressure inside the polymer cell beads for the wave-absorbing material according to claim 1, wherein the temperature of the oven in the step D is adjusted according to the tolerance temperature of different polymers, so that the polymer cell beads are preferably easy to dry the surface solvent and ensure that the polymer is not decomposed or separated out by heating.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110987779.0A CN114112170A (en) | 2021-08-26 | 2021-08-26 | Method for measuring internal air pressure of polymer foaming beads for wave-absorbing material |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110987779.0A CN114112170A (en) | 2021-08-26 | 2021-08-26 | Method for measuring internal air pressure of polymer foaming beads for wave-absorbing material |
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| CN114112170A true CN114112170A (en) | 2022-03-01 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116195671A (en) * | 2021-11-30 | 2023-06-02 | 内蒙古伊利实业集团股份有限公司 | Ice cream filling method suitable for different pressure environments and ice cream production process |
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|---|---|---|---|---|
| JPH01136729A (en) * | 1987-11-25 | 1989-05-30 | Yoshihiko Seki | Detecting device of foaming pressure in expansion molding machine |
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| CN111363285A (en) * | 2020-04-20 | 2020-07-03 | 无锡敬仁电子材料科技有限公司 | Preparation method of PMI high-temperature-resistant wave-absorbing material |
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-
2021
- 2021-08-26 CN CN202110987779.0A patent/CN114112170A/en active Pending
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| US20120065286A1 (en) * | 2010-09-10 | 2012-03-15 | Lifoam Industries | Process for enabling secondary expansion of expandable beads |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116195671A (en) * | 2021-11-30 | 2023-06-02 | 内蒙古伊利实业集团股份有限公司 | Ice cream filling method suitable for different pressure environments and ice cream production process |
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