Process for determining oxidation-dependent characteristics of similar plastic articles, as well as uses of the process and apparatus for performing the process on large injection moulded products, particularly bottle crates

摘要

The invention relates to a process for measuring the characteristics of test articles made from plastic, particularly polyethylene or polypropylene, to establish whether they are made from non-regenerated, regenerated or optionally a similar plastic which has been regenerated to a certain extent by the infrared spectrometric measurement of the transmission--absorption in the carbonyl group band range of the plastic. According to the invention, the transmission-- absorption is measured in the carbonyl group band range at least two different thicknesses of the same plastic and the thickness dependence of these measurements is used as a measurement criterion. The invention is more particularly used on bottle crates or other large injection moulded articles and can be used for classification preferably with sorting according to ageing criteria, also in the case of test articles made from regenerated material, as well as for the selection of old crates suitable for producing regenerated material. The invention also relates to infrared spectrometric means suitable for performing this process.