Problem: Brittleness of packaging material
A plastic product, which was originally intended as packaging material, turned out to be brittle and therefore unsuitable for this purpose. To determine the cause, a comprehensive Dry and thermal characterization carried out to the transition temperatures and enthalpies of the material.
Strategy: Step-by-step material analysis
To resolve the issue, a step-by-step examination procedure used to determine the thermal properties of the plastic and its crystallinity.
Step 1: Material determination using FTIR spectroscopy
In the first step, the plastic was FTIR spectroscopy analyzed. It turned out that it was amorphous PET (PET-A) acted without additional Metal powders, oxides & compunds or additives.
Step 2: Characterization using Differential Scanning Calorimetry (DSC)
In the next step, the plastic was Differential scanning calorimetry (DSC) The results showed a high degree of crystallinity on 48%, and it was found that the plastic above the glass transition temperature (Tg) recrystallized.
Interim result: cause of brittleness
The low one cooling rate in the manufacturing process was the reason why the crystallization of the PET was not sufficiently suppressed. This led to an increased degree of crystallinity, which brittleness of the material.
Step 3: Optimizing the cooling rates
To solve the problem, the optimal cooling rate identified on the source material. A temperature-time kinetics which showed that a cooling rate of at least 30 K/min is necessary to to reduce the degree of crystallization and toughness of the material.
Final report: Optimization of the process
The final report recommended either cooling the material more quickly or Glycol-modified PET (PET-G) which is better suited for the intended purpose due to its lower tendency to crystallize.