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Stretch Blow Molding (stretch + blow_molding)

Distribution by Scientific Domains
Polymers and Materials Science100%

Selected Abstracts

Visualization study and analysis on preform growth in polyethylene terephthalate stretch blow molding

JOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007
Han-Xiong Huang
Abstract In stretch blow molding (SBM) process, the preform growth during the stretching and blowing is critical to the thickness distribution and properties of the final bottle. Whereas the thickness distribution is one of the most important criteria in the production of bottles. So this work focused on the polyethylene terephthalate (PET) preform growth using a transparent mold, through which the instantaneous images of the preform in the stretching and blowing stage were captured. By changing the delay time of the preblow, the three preform growth types, referred to as dolphin, sandpile, and two-bubble, were observed. The longitudinal and hoop stresses acting on the preform segment during the stretching and blowing were analyzed. Two parameters, on which the longitudinal and hoop stresses depend, respectively, were defined. Then combining the geometry and sizes of the preform, the stresses and temperature distribution on it, and the stress,strain curves of the PET material used, the cause for different preform growth types was systematically analyzed. On the basis of preform growth types, the thickness distributions of the bottles obtained under different delay times of the preblow were explained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 564,573, 2007 [source]

An inverse estimation of initial temperature profile in a polymer process

POLYMER ENGINEERING & SCIENCE, Issue 1 2008
Ali A. Ranjbar
Since one of the most important parameter in polymer processing such as injection stretch blow molding is temperature distribution in the thickness direction, an inverse method has been applied to estimate this profile. This process comprises of four steps. In the first step the preform is injection molded, and in the second and third step it is stretched by a rod to its final length and then inflated and in the last step it is discharged from the mold. In such kind of polymer flows viscous dissipation plays a remarkable role in the evolution of temperature profile. Some theoretical temperature profile has been applied to confirm the validation of the inverse algorithm. Different solution techniques are applied in this article to the inverse problem under consideration, namely: the conjugate gradient and Levenberg,Marquardt method. After the preform is injection molded, which is the first step, it is removed from the mold, which corresponds to time t = 0. At this moment an infrared camera is used to record the surface temperature of the preform with a certain time step. With regard to variation of thermal properties with temperature, the inverse problem becomes nonlinear. These experimental data provided by the infrared camera are then used to estimate the temperature profile at the end of injection process before stretching and inflation took place. POLYM. ENG. SCI., 48:133,140, 2008. © 2007 Society of Plastics Engineers [source]

Stress,strain behavior as related to surface topography and thickness uniformity in uni- and biaxially stretched PVDF/PMMA blends

POLYMER ENGINEERING & SCIENCE, Issue 12 2007
Xixian Zhou
The influence of blend composition and processing conditions on the surface roughness and thickness uniformity of PVDF/PMMA blends were investigated in uniaxial and biaxial deformation mode for PVDV and PVDF/PMMA blends 70/30, 55/45, and 40/60 wt%. The addition of PMMA retards the thermal crystallizability of the blends and this allows rapid solidification into films with little or no crystallinities. Such precursors with lowered crystallinity were found to be easily uni- and biaxially stretched into uniform and transparent films in the temperature range between the glass transition temperature and cold crystallization temperature where they exhibit strain hardening. Thus, these blends are suitable for processes such as tenter frame biaxial stretching, double bubble film blowing, and stretch blow molding where they will exhibit good transparency and thickness uniformity. POLYM. ENG. SCI., 47:2110,2117, 2007. © 2007 Society of Plastics Engineers [source]