6533b7d2fe1ef96bd125f4db
RESEARCH PRODUCT
Correlation between processability and properties of a high density polyethylene by a rheological approach
Paolo MarianiFrancesco MenconiFrancesco Paolo La MantiaG. Cariannisubject
chemistry.chemical_classificationExtrusion mouldingMaterials sciencePolymers and PlasticsRheometerOrganic ChemistryPolymerPolyethyleneCondensed Matter PhysicsViscoelasticitychemistry.chemical_compoundchemistryRheologyPolymer chemistryMaterials ChemistryHigh-density polyethylenePhysical and Theoretical ChemistryElastic modulusdescription
The thermal-oxidative and thermal-mechanical stability of high density polyethylene (chromium based catalyst technology) was examined at many different temperatures using a rheological approach. The changes in molecular structure, which take place during processing, have been studied using a Clextral co-rotating twin-screw extruder in comparison with dynamic measurements performed with a rotational rheometer under definite conditions of temperature, strain and frequency and in presence of air. In order to evaluate the degradation response, an investigation of elastic modulus G' as a function of frequency ω on the residual sample after ageing has been carried out. The molecular weight increase, probably due to the formation of small amounts of long chain branching, is clearly observed through the growth of the elastic properties, mainly at low frequencies (i.e. high relaxation times). The stabilised polymer shows a less pronounced tendency towards degradation, even if a critical temperature (240 °C) has been found at which antioxidant has not any effect in avoiding degradation.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2002-07-01 | Macromolecular Chemistry and Physics |