مدلسازی فرآیند فیلم دمیده: تجزیه و تحلیل انتقال حرارت و توسعه خواص فیزیکی پلیمر در بلوری
Abstract: Various aspects of modeling the blown film process is presented in this work. In particular, experimental and theoretical analysis of the heat transfer and its effect on the film properties were discussed. A novel experimental technique to measure the heat transfer coefficient was developed. It was found that the heat transfer coefficient goes through a maximum at the curvature. This is in direct contrast with the existing heat transfer models. Further heat transfer from the bubble was explained based on our cooling air velocity measurements. Results indicated that the boundary layer thins out near the curvature, resulting in high heat transfer at the curvature. Application of a two dimensional heat transfer model along with viscoplastic elastic constitutive equation was also presented. This is based on a two phase model. A numerical simulation was also performed for modeling the blown film process. The results are in good agreement with the experimental observations. An attempt was made to correlate the film properties with the process variables. Strain and strain rate were used as correlating variables. Reasonable correlations were achieved for tensile and impact properties, but tear properties do not correlate well. Based on this analysis, it was concluded that it is difficult to single out or a isolate a variable for the purposes of correlation because of the complex interaction of the processing variables. Two or more correlating variables are needed.