Introduction

SPHEREX AMC is a company which produces master batches like modifying agents for the plastics industry to facilitate production of plastic films. One of these master batches is under development to improve its thermal stability because customers could have problems if the product oxidizes, in particular during process. The goal of this study was to find a new composition and, if it necessary, new conditions to obtain a product with better stability. In order to do this, we used a reference product which allowed us to increase our master batch stability. To analyze this leading product, tests were carried out with a DSC (Differential Scanning Calorimetry) to identify components and to compare stability between samples.

Experimental conditions

The goal of the first part of this experiment was to compare the stability of our product with the stability of the leading product. To achieve this, a DSC OIT (Oxidative Induction Times) was performed. This test was used to compare and evaluate the stability of our formulation. In a classic way, analyses with DSC OIT are usually done with oxygen flow in order to boost oxidation but this test was performed under atmospheric conditions. The only difference was the oxidation time which was longer but we wanted to compare the results carried out on the same conditions.
The product was maintained at 190°C and the time necessary to get the oxidation (exothermic reaction) was measured. The SPHEREX sample and the sample of reference were tested and the analyses showed that the SPHEREX product had a time of oxidation shorter than the other sample. As a result the product was not stabilized enough, so we had to prepare a new formulation with more stabilizer which gave better thermal stability to the SPHEREX master batch.
A traditional DSC test was also performed to identify components which could improve properties of the product. By analyzing the leading product, we obtained a melting point of the polymer near 120°C, which is characteristic of linear polyethylene and not of classic polyethylene used in our formulation.

Results

To validate this new formulation by taking into account the results of these analyses, this formulation will be extruded and the same DSC OIT test as the one we done previously will be performed in order to obtain results close to those for the leading product.

Conclusion

The DSC OIT test was used during our development but this method will also be used for quality control when master batch stability is critical.

DSC OIT Analysis on the leading product

SPHEREX AMC
ZI de Chavanon
43120 Monistrol sur Loire

SECRETARY
Catherine BEKHALED