Modeling and simulation for correlations of polyethylene (PE) characteristics and final properties for individual products / Modelagem e simulação para correlação entre as caracteristicas do polietileno (PE) com as propriedades finais dos artefatos produzidos na industria

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

A great challenge related to polymers research has been the development of relations enabling prediction of polymer final properties according to the initial operational conditions - either during the polymerization process or the transformation process phases. These relations can be utilized to optimize the operational conditions of transformation systems and to produce devices with specified end-use properties. The first step for this is the information about the relationship s between end-use and intrinsic properties, while the second step is to correlate operation conditions with intrinsic properties of the resins. So, the main objective of the present work is to built-up empirical models to predict end -use properties of polyethylene (PE) resins as functions of its intrinsic properties and still correlate qualitatively these properties. Due to several types of polyethylene resins that are present in the market, the resins studied were separated in groups in accord to the final application of each ones. The research was carried out to evaluate the most important properties for each final application. Then, equations were found for each resins group, including the following classes of properties: mechanical, thermical, optical, contact surface, rheological and morphological properties. Intrinsic properties selected to characterize the resins were fluidity index (FI), which is opposite related to viscosity and molecular weight of the resin; stress exponent (SE) / expansion ratio (SR), which is a measure of the non-Newtonian character of the polymer melt and may be used to evaluate the processability of the polymer resin; and density, which is directly related with resins degree of crystallinity. Among the existing intrinsic properties, that ones which were selected exert, generally, a significant influence on the polymers properties, as well as being easily measurable in the industrial environment. Beyond an extensive literature revision, a previous statistic analysis of the correlations between variables was carried out, and then the input variables were chosen for each model. For two of six resins groups studied, the SE / SR properties were not used as a model input because these properties is not measured or meaningful for the greater part of the resins from those groups. It is important emphasize that the additives can exert considerable influence about end-use properties of polymers, thus, the additives influence makes even more complex the learning about a polymer final properties forecast from the operational conditions of the polymerization systems. However, a control of the additives amount and quality was not possible and a research including comprehensively the additives influence on polymers performance properties remaining beyond the scope of this work. In the curse of this research, a large number of experiments were carried out, embracing twenty seven properties and forty six resins, totalizing approximately eight hundred and seventy experimental results (Appendix I), and each experimental value presented represents a mean of the obtained results for five samples of each kind of resin. In general, models developed are able to reproduce and predict experimental data within experimental accuracy

ASSUNTO(S)

polietileno - propriedades mecanicas correlation final properties polietileno - propriedades termicas modelagem modeling intrinsic properties polyrthylene correlação (estatistica) polietileno - propriedades oticas

ACESSO AO ARTIGO

Documentos Relacionados