Development of analysis method for determining PP/PE blends ratios with analytical devices and investigation of its accuracy

At the beginning of the plastics industry, mostly single-component (with a polymeric structure in its composition) polymer materials were used in manufacturing. Changing needs and expectations make these single-component structures insufficient in many applications. Because while some features of the same product are very good in a certain application, some features are very weak. This either shortens the life of the product or limits the use of that plastic materials. By mixing polymer materials with different properties, new polymer material mixtures with much superior properties have been started to be produced. These mixtures can be made in two different ways as chemical and physical mixtures. Of these, chemical mixtures are mixtures based on monomers, and they are made in the form of macromolecules consisting of two or more different monomers in the polymerization process, and these polymers are called copolymers. Alloys of polymers obtained by mixing polymers with different macromolecules within each other on a macromolecular basis. These alloys are physically mixed at the macromolecular level and have long been applied in the manufacturing industry for a variety of reasons. PP and PE ratios in polypropylene (PP) and polyethylene (PE) blends, which are among the most widely used blends, affect both process parameters and final product properties. Knowing both the granular PP/PE mixtures and the PP/PE mixture ratios in the final product is essential for both adjusting the process parameters and predicting the product behavior in the usage environment. Identification of PP and PE can be done by analytical methods such as Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), as well as by their hot solubility in xylene solvent. There is no method for making ratio separation in both analytical methods and solution method. Although it is foreseen to make this distinction in the ISO 1833-23 method, it is not used by any laboratory since the method has not been published. This study was initiated with the foresight that a method for rate determination could be developed by utilizing the difference in thermal behavior, which is the most important distinguishing feature of PP and PE. In this study, it is aimed to determine the ratio from the melting peak area enthalpy energy difference by making the polymer separation from the melting temperature difference of both polymers. Enthalpy energies of PP and PE were measured using DSC device by working with samples with known PP/PE ratios. The regression equation was obtained by performing a regression analysis between the measured energy and the ratios. Since the equation with a high coefficient of 0.98 for the R2 of the regression equation was created, a test method with high accuracy was created. By using this equation obtained, it has been proved by trial measurements that the ratio determination of the samples with unknown ratios becomes possible. The ratios of materials with 30%PP- 70%HDPE and 60%PP-40%HDPE mixture were found as 27%-73% and 59%-41% with the equation obtained. The ±3% deviation obtained was below the 5% deviation, which is the acceptable limit specified in the TS EN ISO 1833-1 standard.