Confidence intervals of long-term prediction and synthesis of creep compliance prediction estimates for expanded polystyrene (EPS) under permanent compressive stress

• Published in: Polymer testing Vol. 27; no. 6; pp. 688 - 697
• Main Authors: Gnip, I.Y., Vaitkus, S., Keršulis, V., Vėjelis, S.
• Format: Journal Article
• Language: English
• Published: Kindlington Elsevier Ltd 01.09.2008; Elsevier
• Subjects: Applied sciences; Cellular; Confidence interval prediction; Creep compliance; Exact sciences and technology; Expanded polystyrene (EPS); Forms of application and semi-finished materials; Permanent compressive stress; Polymer industry, paints, wood; Synthesis of predictions; Technology of polymers; Synthesis of predictions; Permanent compressive stress; Creep compliance; Confidence interval prediction; Expanded polystyrene (EPS); Statistical analysis; Theoretical study; Mechanical properties; Compressive strength; Cellular plastic; Long term; Modeling; Confidence interval; Creep curve; Styrene polymer; Plastics
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2008.04.008

The results obtained in investigating creep behaviour of expanded polystyrene (EPS) with a density of 16.5–33 kg/m 3, subjected to long-term compressive stress σ c, making 0.25 and 0.35 of stress corresponding to 10% relative deformation of the test specimens, are presented. The overall period of the direct long-term experiment was 3–4 years. Confidence interval prediction of creep compliance for the period of 50 years in the future was based on extrapolation of creep formation approximated by power and exponential regression equations which were reduced to a linear form by taking logarithms. The consistency (agreement) of particular confidence interval predictions was demonstrated and the synthesis (integration) of these extrapolation-based predictions was made. The results of synthesized predictions are presented. The dependence of the prediction estimates of creep compliance (creep strains) of expanded polystyrene on its density, permanent compression stress and time of prediction was determined.