A higher rPET share can affect colour, material variability, mechanical performance and barrier properties. The direction and size of the changes depend on the recyclate and manufacturing process. The percentage alone cannot predict bottle performance.
The rPET percentage is only one variable
Two bottles containing the same proportion of rPET can have different properties if they use different recyclate quality, preform geometry, blow-moulding settings or processing histories.
Feedstock quality is fundamental
The behaviour of rPET is influenced by intrinsic viscosity, thermal and hydrolytic degradation, contamination, colour, moisture, and the quality of decontamination and material preparation.
Mechanical properties
Mechanical performance can change because of differences in molecular weight, crystallinity and material orientation during blow moulding. There is no universal linear rule that more rPET means less strength. The result depends on the combined material, process and design.
Colour and appearance
rPET may increase yellow, grey or greenish tones and variation between batches. Manufacturers therefore control feedstock colour, preform characteristics and the permitted tolerances of the finished product.
Barrier performance
Oxygen or other gas transmission depends on more than the rPET proportion. Wall thickness, crystallinity, material orientation, bottle geometry and test conditions also matter. A reliable assessment therefore requires measurements on the actual packaging.
Processing
PET is sensitive to moisture and thermal history. Inadequate drying or excessive thermal exposure can reduce performance whether the feedstock is virgin or recycled.
How should the effect of rPET be assessed?
A useful approach is to compare packaging series produced under controlled conditions at different rPET levels. Evaluate weight and wall thickness, mechanical resistance, colour, barrier properties and variation between samples together.
The key conclusion
rPET content is an important material parameter, but it should not be the only explanation for packaging performance. A sound assessment brings together feedstock data, processing conditions, design information and test results.