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Blister Packaging is used in a number of industries. For each application, there is a specific quality requirement. However, its use in the medicine and pharma industry requires one of the most stringent quality parameters. Let us examine these requirements from the perspective of medicine industry.

Solid medicine is the primary subject of blister packaging. The container should keep the active substances inside the medications from evaporating, leaking, or leaking out into the environment. Under the influence of pressure variations, volatile medicinal substances can disintegrate inside the packaging material and diffuse to the outside. The solid drug's fragrant or volatile constituents, for example, would evaporate and pass through the materials.

The package, on the other hand, should protect the drugs within from direct contact with air, moisture, foreign matter, and microorganisms. The air contains oxygen, moisture, a huge number of microorganisms, and foreign stuff. When such substances are introduced into pharmaceutical packages, they cause oxidation, hydrolysis, degradation, pollution, and fermentation.

Because the PTP aluminium foil, PVC sheets, and PVC/PVDC laminated sheets used in blister packaging will come into close contact with medications, material testing is very important. Appearance, barrier property, tensile strength, impact resistance strength, thermal tensile ratio and other mechanical characteristics, as well as hygiene indices, are among the testing items, each of which has its testing procedures and standards (or manufacturer's standards). The most significant blister package testing items will be discussed next.

1. Barrier property testing:

The most important aspect of blister package testing is the barrier property test. Oxygen transmission rate testing and water vapour transmission rate testing are two types of blister barrier property testing. The oxygen transfer rate of aluminium foil is not tested according to the norms. Due to the tight association between this index and the number of pinholes, if this number meets the requirements in the standards, the oxygen transmission rate can meet the consumption requirement. Aluminium and PVC both have strong barrier characteristics in real-world applications. As a result, while acquiring instruments, great precision should be considered. Testing technologies for oxygen and water vapour transmission rates have become more widely used. The next sections will focus on the testing technology for the barrier property of entire blisters. When assessing the barrier property of the entire blister, we employ a specifically developed apparatus to prepare the blister specimen. For oxygen transmission rate testing, the equal pressure method is used, and for water vapour transmission rate testing, the sensor method is used. During the testing process, the flow velocity should be adjusted carefully to avoid affecting the specimen's condition as a result of the large gas quantity change and the resulting dramatic pressure shift inside the blister. To expand the testing scope, the blister testing fixtures can also be used to test capsules or other tiny containers.

2. Heal seal strength testing:

Sealing performance is a key index for the practicality of blister packages, just as it is for other types of packages, and heat seal strength is a significant testing item for sealing performance. Heat seal strength testing is required for blister packages, whether they are made of aluminium foil and PVC sheet or aluminium foil and PVC/PVDC laminated sheet. The following is the heat seal strength testing procedure: Choose appropriate heat seal parameters based on the specific testing standards; heat-seal a piece of PVC sheet or a piece of PVC/PVDC laminated sheet (to stack the adhesive side of the aluminium layer with the PVC sheet) at the size of 100mm100mm with a heat sealer; then cut the specimen with a width of 15mm, and choose three pieces from the middle part to perform 180°peeling with a tensile tester (peeling speed based on the specific

3. Thermal Tensile Ratio Testing:

The thermal tensile ratio is an important testing item for PVC sheet or PVC/PVDC laminated sheet; it's defined as the size changes after enduring a specific temperature for a specific period, and it's the percentage ratio of the spot distance variation to the starting spot distance. The test should be performed under YBB00292004, Thermal Tensile Ratio Test Method. Cut two square pieces from the sheet, each having a 120mm1mm side. Carve two vertical lines, AB (lengthwise) and CD (crosswise), with a spot distance of 100mm1mm, across the middle point; then carve at the top of those two lines; measure the lengths of AB and CD accurately and calculate the arithmetic mean value. Place the square pieces on the glass or metal panels so that they do not deform freely. Place the square pieces horizontally in a heater set to 100°C1°C for 10 minutes, then remove to cool to room temperature, accurately measure the lengths of AB and CD, and determine the arithmetic mean values. The thermal tensile ratio must be within 6% of the specified value, according to the requirements.

4. Impact Resistance Strength Testing:

Press forming is a crucial step in the blister package manufacturing process. As a result, determining the impact resistance strength of the PVC sheet or PVC/PVDC laminated sheet is critical. The testing should be done with a falling ball impact tester. Cut five specimens with a length of 150mm and a breadth of 50mm from a given amount of products. Place the specimens in a 232°C/505% RH atmosphere for 4 hours, and then perform the tests in the same setting.

Place the specimens at a distance of 100mm apart on the falling ball impact tester. The PVDC layer should be facing upwards on PVC/PVDC laminated sheets. As shown in the table, choose the steel ball and the height of the falling ball. The steel ball floats easily between the spaces in the middle. Both lengthwise and crosswise, the damage should be no more than two pieces.