PE-LLD, PE-LD, PE-HD
Packaging material
Measuring cells: DSC820
Pan: Aluminum 40 µl, hermetically sealed
Sample preparation: Samples cut out of the films
DSC measurement: Heating from 30 °C to 160 °C, cooling to 30 °C, then heating to 160 °C, all steps with heating or cooling rates of 10 K/min
Atmosphere: Nitrogen, 50 cm3/min
DSC is specified in the USP for the physical testing of polyethylene containers: the quality of packaging material is of decisive importance for the protection of raw materials and end products. In particular, primary packaging material i.e. packaging material that comes into direct contact with the product must be perfect as far as quality is concerned, must satisfy the specified requirements and must not react with the material that it is designed to protect. The first heating run serves to eliminate any (unknown) thermal history so that samples of different quality can be properly compared with each other in the second heating run. The melting peak maximum and the crystallinity (calculated from the heat of fusion), are used as quality criteria.
The crystallinity of a sample is determined by comparing its measured heat of fusion with that of 100% crystalline PE which is assumed to have a heat of fusion of 290 J/g. This is demonstrated as example with one of the curves.
Sample | Heating run 1 Peak, °C |
Crystallinity, % | Heating run 2 Peak, °C |
Crystallinity, % |
PE-LD | 113.7 | 37.9 | 116.5 | 40.2 |
PE-HD | 132.9 | 64.5 | - | - |
PE-LLD | 109.6 | 31.7 | 109.8 | 31.4 |
Using DSC, the samples can be distinguished from each other without any difficulty. The method is very suitable for rapid quality control purposes.
Quality Control, PE Films | Thermal Analysis Application No. HB838 | Application published in METTLER TOLEDO TA Application Handbook Pharmaceuticals