On the importance of the permeability test of the

2022-08-17
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The importance of overall packaging permeability test (Part 1)

preface

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with the acceleration of the pace of life, people increasingly realize the importance of packaging for food, medicine, electronics and other products. Whether in the international or domestic market, the increasing expectation of product shelf life makes the barrier requirements of packaging materials higher and higher. In order to select suitable packaging materials and predict the shelf life of products, manufacturers should pay attention to testing the permeability of the overall packaging. Choosing a high barrier material does not necessarily mean that the overall package made of it also has high barrier. This paper illustrates the importance of the permeability test of the whole package with an example of the material selection of the milk powder packaging bag

experimental design and test methods

a company produces infant milk powder with a package size of 20cm x 10cm x 6cm. Because milk powder is easy to deteriorate in the presence of oxygen or water vapor, high-performance barrier materials must be used. They asked MOCON to measure and evaluate the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) of barrier materials with five multilayer structures (see Table 1). The samples used are packaging bags and sheet samples cut from the packaging bags. These bags have been filled with milk powder and have been transported after packaging

table 1 Sample structure and number

sample number

material structure

1

Pet/Al/nylon/LLDPE

2

Pet/Al/PE

3

Pet/Al/petmet/PE

4

Pet/Al/nylon/PE

5

Pet/PE (extruded)/Al/PE (extruded)ded)/pe

considering that the product is put on the market in tropical areas, the oxygen permeability and moisture permeability test conditions are determined as set out in Table 2

Table 2 Test conditions and test purposes

test items

test conditions

test instruments

bag oxygen permeability

(CC/m2 day)

temperature: 37C

tested object: 100% O2 with 90% RH

carrier gas: dry nitrogen

MOCON ox tran 2/61

film oxygen permeability

(CC/m2 day y)

temperature: 37C

tested object: 100% O2 with 90% RH

carrier gas: dry nitrogen

MOCON ox tran 2/21

bag moisture permeability

(gm/PKG * day)

temperature: 37C

tested object: 100% RH water vapor

carrier gas: dry nitrogen

MOCON permatran w 3/31

film moisture permeability

(GM/m2 day)

temperature: 37C

tested object: 100% RH water vapor

carrier gas: dry nitrogen

MOCON permatran w 3/31

the oxygen permeability experiment of sheet samples is carried out in the oxygen permeability tester ox-tran of American MOCON company? Model 2/21 (ASTM d-3985 and ASTM f-1927) system. OX-TRAN? Model 2/21 complies with ASTM d3985. The experimental process follows the principle of isobaric method. The sample is separated into two independent air flow systems in the ventilation chamber. On one side is the gas to be tested that further improves the product quality (it can be pure oxygen or mixed gas containing oxygen, and the relative humidity can be set), and on the other side is flowing nitrogen to keep the oxygen content at zero. The total pressure on both sides of the sample is equal, but the partial pressure of oxygen is different. Under the effect of the concentration difference of oxygen, oxygen penetrates the film. The oxygen molecules through the film are carried by the nitrogen gas flow and sent to the electric quantity analysis sensor (special Coulomb sensor). The electric quantity analysis sensor can accurately measure the amount of oxygen contained in the nitrogen gas flow, so as to calculate the oxygen transmittance of the material. It is suitable for testing high barrier film materials or packages. The instrument accurately controls the temperature, relative humidity and pressure in the whole test process. It has two test chambers, which can measure two samples or two package samples at the same time

the oxygen permeability test of packaging bags is conducted in the United States mo14. Tortuosity: qb/t 2803 ⑵ 006 tortuosity measurement method of rigid plastic pipes ox-tran? Model 2/61 (ASTM d3985 and ASTM f-1927) system. Its operating principle is similar to that of ox-tran? Model 2/21 is the same, but its structural design is more suitable for the determination of packaging. It has six test chambers, and six samples can be measured at the same time each time

the moisture permeability experiment of sheet samples is carried out in permatranw, a water vapor permeability tester of MOCON company in the United States? 3/31 (in accordance with ASTM f-1249). The experimental process follows the principle of isobaric method. One side of the sample is set with different relative humidity, and the other side is purged and kept dry by flowing nitrogen. Water vapor molecules penetrate from the high humidity side to the low humidity side, and then the carrier gas is sent to the special pressure regulation infrared sensor, which receives water vapor and converts it into electrical signal output. The instrument generates any relative humidity in the range of 35% to 90% RH by pressure regulation, or 100% RH. It is suitable for testing high barrier film materials or packages. The instrument accurately controls the temperature, relative humidity and pressure in the whole test process. It has two test chambers, which can measure two samples or two package samples at the same time

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