In the quality control of recycled plastic materials, the laboratory tensile test is of great importance

When we approach the production of a plastic product , we need to collect a series of information regarding the quality and characteristics of the recycled raw material that we need to use.

It is necessary to acquire certain data on the composition of the raw material, through laboratory tests such as DSC, density, fluidity, the presence of fillers, humidity and others, but there is also information regarding the mechanics of the material Before.

These help us know how the finished product will behave when subjected to mechanical stresses, such as traction, bending, shear or compression.

Every time we apply a force to a body it tends to deform, sometimes even imperceptibly to the human eye, as a response to the stress received. If the body returns to its primary condition at the end of the stress, this deformation is defined as elastic.

In this type of deformation, all the work done to deform the piece is stored in the form of elastic energy which is then returned once the stress has been eliminated.

Laboratory tests are used to understand in advance, i.e. before the product is made, what the elastic behavior of the body will be and what its mechanical limits will be.

However, it must be kept in mind that the behavior of a real material can be different from the ideally elastic one: the presence of large deformations leads in fact to a plastic response of the material.

But how does a tensile test on a specimen of recycled plastic material take place in the laboratory?

First of all, it is necessary to create specimens according to current regulations, which will have a typical dog bone shape, and will have precise geometric and dimensional parameters.

The prepared samples, obtained by injection moulding, according to the UNI EN ISO 527 standard , must be free from torsion and must have pairs of parallel surfaces, edges free of incisions, defects, surface depressions or burrs, with a total length of 149 mm . and a thickness of 4 mm.

The laboratory machine, represented by a strain gauge , will graphically and analytically measure the deformation of the sample subjected to examination and will give us indications of the future behavior of the product we would like to create.

This data, together with the other indispensable indicators, gives us an in-depth picture of the type of raw material we will use and will help us make any corrections both on the mixture and, possibly, on the production process.

Category: news - technical - plastic - recycling - tensile test - quality