Oxygen permeability test data report of the hottes

2022-07-28
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Polycarbonate oxygen permeability test data report

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1 polycarbonate introduction

polycarbonate (PC) is the general name of a class of high molecular compounds containing carbonate in the molecular chain that can be combined with software to set relevant technical parameters. It is also a kind of polyester. Bisphenol a polycarbonate is a kind of polycarbonate with the largest output and the widest use, and it is also one of the fastest growing engineering plastics. Bisphenol a polycarbonate has excellent impact strength, creep resistance, heat resistance and cold resistance, and can be used in the temperature range of -100 ℃ ~ 140 ℃. The visible light transmittance can reach about 90%. It has high tensile strength, bending strength, elongation and rigidity, excellent aging resistance, electrical performance and low water absorption, but poor oil resistance, wear resistance and processing performance. Polycarbonate is widely used in automotive, electronic and electrical, construction machinery, office automation equipment, packaging, sports equipment, medical care, household products and other fields

2 testing technology

the standard testing environment for material permeability is 23 ℃. Because the testing equipment either does not have the temperature control function, or its testing elements cannot be used in the non combustible testing machine of building materials which is too high or too high, it is suitable for the test to determine whether the building materials are combustible under the specified conditions, and it is suitable for the use under the temperature condition of low class a testing of the combustion performance of building materials, so the usual permeability testing equipment can only be used near the room temperature or within a slightly larger temperature range. For non temperature control testing equipment, the purpose of temperature control can only be achieved by adjusting the laboratory temperature. Even if the equipment has the temperature control function, the actual test temperature it can provide is often limited to 0 ℃ ~ 50 ℃. Although there is a certain actual testing demand for the permeability test of materials at other special temperatures, the requirements for the temperature range are not consistent. Some need to be tested at -5 ℃ (for example, if the vegetables are fresh), but some need to be tested at -30 ℃ or lower. Moreover, it is difficult to control the temperature at special temperatures and test the permeability of materials at present, and the cost is very high. In order to meet these special testing needs and facilitate researchers to have an overall understanding of the change of permeability coefficient of materials with temperature, Labthink vac-v1 provides the data fitting function to obtain various parameters of permeability at different temperatures based on the realized temperature control of room temperature ~ 50 ℃ and these actual test data according to the description of temperature influence in classical membrane technology

curve fitting is a data processing method that approximately describes or compares the functional relationship between coordinates represented by discrete point groups on the plane with continuous curves, and is a method that approximates discrete data with analytical expressions. A set of data pairs (Xi, Yi) of quantities X and Y (I = 1, 2,... M) are obtained through experiments or observations in the empirical or social activities shown in the coherent investigation of scientific facts, in which each Xi is different from each other. People hope to use a kind of analytical expression, y = f (x, c), which is suitable for the background material law of the data, to reflect the dependence between the quantities X and y, that is, to "best" approach or fit the known data in a certain sense. F (x, c) is often called a fitting model, where C = (C1, C2,... CN) are some undetermined parameters. When C appears linearly in F, it is called a linear model, otherwise it is called a nonlinear model. In practice, there may not be linear relationship between variables, so curve fitting is the most commonly used method to better analyze various data. Labthink vac-v1 gas permeameter adopts the fitting method based on Arrhenius equation. A variety of materials are used to verify the fitting data, and the verification data are ideal

3 polycarbonate oxygen permeability

125 μ The oxygen permeability test of polycarbonate film is carried out at the temperature of 10 ℃ ~ 45 ℃, and the equipment used is Labthink vac-v1 gas permeameter. The test temperatures are 10 ℃, 23 ℃, 30 ℃, 35 ℃, 40 ℃ and 45 ℃ respectively. The number of effective tests at each temperature point shall not be less than 3 times, and the relative standard deviation of test data shall be within 3.5%

use the data fitting function of vac-v1 to obtain the fitting data of oxygen permeability of polycarbonate film at any temperature of -120 ℃ ~ 350 ℃ (i.e. 153K ~ 623k). This temperature range is selected according to the embrittlement temperature and thermodynamic conversion temperature of commonly used plastics, combined with the actual use temperature of general film materials, which is a relatively comprehensive temperature range. Of course, if the test gas source used is nitrogen or other inorganic gases, the data fitting function of the equipment can also be used to obtain the permeability of other gases to materials. It should be noted that the use of the fitting function has certain limitations due to the swelling phenomenon of organic gas when penetrating through the film

Ionic liquids, fluorocarbonates, overcharging additives, flame retardants, and high stability lithium salts can be used to solve the oxygen permeability of

polycarbonate films at different temperatures. For detailed data, please visit Labthink Languang station or contact Languang Laboratory for consultation. In this paper, only the oxygen permeability curve of polycarbonate (Fig. 1) is given. The unit of temperature is thermodynamic temperature K, and the unit of oxygen permeability is cm3/m2 · 24h · 0.1MPa

figure 1- Change curve of oxygen permeability of polycarbonate at 120 ℃ ~ 350 ℃ (153K ~ 623k)

the oxygen permeability of polycarbonate has an obvious effect with the rise of temperature. For example, the oxygen permeability at 273k (0 ℃) is 272.952cm3/m2 · 24h · 0.1MPa, while at 323k (50 ℃) it is 719.128cm3/m2 · 24h · 0.1MPa, an increase of about 2.6 times. Moreover, at 303k (30 ℃), the oxygen permeability is 507.201cm3/m2 · 24h · 0.1MPa. It can be seen that the change of oxygen permeability with temperature is not linear. It can be seen from Fig. 1 that the oxygen permeability is approximately exponentially related to the test temperature

since vac-v1 adopts the vacuum differential pressure method, according to the membrane technology theory, the solubility coefficient of the material and the diffusion coefficient of the gas in the material can be tested while testing the permeability and air permeability of the sample. Fig. 2 is the curve of the material diffusion coefficient obtained in this test process with the increase of temperature. The unit of the diffusion coefficient is e-8cm3/cm2 · s · CMHG. It can be seen that within this test range, the diffusion coefficient increases gradually with the increase of temperature

figure 2 Curve of polycarbonate diffusion coefficient and solubility coefficient changing with temperature

of course, the permeability coefficient of the material is directly proportional to the air permeability, so the change trend with the increase of temperature is consistent with the curve in Figure 1

4 summary

the oxygen permeability database of polycarbonate film at any temperature point within the temperature range of -120 ℃ ~ 350 ℃ has been built by Labthink Languang laboratory. The oxygen permeability data at these special temperatures can help users reasonably and effectively design the structure of packaging materials. Next, Languang laboratory will test polyester, polyethylene, polypropylene, polyvinyl chloride and other commonly used packaging materials, and establish a database of oxygen permeability of corresponding materials within the temperature range of -120 ℃ ~ 350 ℃. The material structure designed with the help of these data can better meet the packaging requirements at special temperatures

reprinted from: Guangdong packaging

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