Case Studies
Industry Case Studies – Characterisation and Analysis
Case Study No.1
Decision is made to investigate the use of regrind in a product where impact is critical.
How was it resolved?
Testing of manufactured product for MFR (melt flow rate) and impact strength with various levels of regrind compared to original virgin material properties. Shelf-life ageing comparison (or accelerated weathering if outdoor product) followed by impact strength to review degradation affects.
Case Study No.2
New product is to be used outdoors and mechanical property retention is critical.
How was it resolved?
Accelerated weathering followed by tensile testing.
Case Study No.3
Biodegradable film needs to remain strong for two months but weaken and fail within four months.
How was it resolved?
Accelerated weathering followed by puncture resistance at intervals equivalent to 2 & 4 months real-time use.
Case Study No.4
Product is cracking during sub-assembly.
How was it resolved?
Solvent immersion test to check for residual stress. Review of manufacturing conditions, specifically any parameter that affects cooling rates.
Case Study No.5
Contamination issue: the client sent one sample of their product with particulate on the bottom of the container.
How was it resolved?
Samples were isolated and cleaned in Class 100 Clean Air Centre. FTIR and DSC were applied to determine the material types. The client checked their materials list and equipment associated with this product. The PTFE source was determined to have come from a stirring bar used during manufacture of the solution. Once the material had been positively identified I asked the client to send the suspect contamination sources for exact comparative analysis. FTIR confirmed stirring bar FTIR spectrum was chemically identical to the contamination. DSC confirmed that the stirrer bar material was identical by matching both material Tm and DeltaH values.
Case Study No.6
Product development issue: the client had been buying a film product and they approached the MRI and asked us to deformulate the product for them.
How was it resolved?
Light Microscopy demonstrated a three-layer structure. FTIR was used to type the materials.The PVC layer needed to be investigated further:
For Plasticiser Content by Solvent Extraction. Extractable Plasticiser Content = 27% For Plasticiser Type by GCMS of the Extractant Solution. The main Plasticiser Type was determined to be di-n-octyl phthalate, by GCMS
Case Study No.7
Processing issue: a batch of parts was cracking in service after normal pressure was put on the end of the part.
How was it resolved?
GPC was used to compare both ‘good’ and ‘bad’ samples. Therefore we looked at the process and decided to look at the moisture content of the pre-processed material:
Using Karl Fischer Coulometry we determined that the material had not been dried sufficiently. This then led to the materials’ molecular weight being affected during processing causing the material in the part to be weakened.
Case Study No.8
Recycling issue: a manufacturer using regrind polyethylene material experienced difficulties with contamination of screen plates within an extruder.
How was it resolved?
The problem was thought to be caused by contamination of the regrind feedstock. The MRI was requested to identify the contaminant and to determine the source of contamination if possible. Debris from the screen plates was examined under an optical microscope. It was determined that the contamination was not compatible with the matrix and could be removed easily. FTIR determined that the materials present were PET-based.
