A literature survey of the influence of preform reheating and stretch blow molding with hot mold process parameters on the properties of PET containers. Part I

Abstract

The paper presents a wide analysis of the literature on the modified blow molding process with simultaneous stretching of PET material for storing hot filled drinks. The hot fill process is an inexpensive conventional filling technology for high-acidity products (pH < 4.5). It allows certain drinks (sensitive beverages such as fruit and vegetable juices, nectars, soft drinks, vitaminized water) to be stored at ambient temperature without the need for chemical preservatives. The primary feature of the bottles used in the hot fill process is their temperature stability, i.e. the ability to retain the shape of the bottle at the filling temperature. From a mechanical point of view, the thermal stability of PET [poly(ethylene terephthalate)] bottles manufactured by the ISBM (injection stretch blow molding) process is determined by the mechanical and thermal response of the blown preforms. From a microscopic point of view, the strongest influences on the mechanical and thermal properties of PET bottles are the orientation and crystallization processes. From a technological point of view, the properties of PET bottles after manufacture by the stretch blow molding process is mainly determined by the initial structure of the PET preform, the geometry and temperature distribution of the preform, the geometry of the blow mold, the temperature of the blow mold and its distribution in various parts of the mold and technological parameters of the blow molding process.

Blowing Kinetics, Pressure Resistance, Thermal Stability, and Relaxation of the Amorphous Phase of the PET Container in the SBM Process with Hot and Cold Mold. Part II: Statistical Analysis and Interpretation of Tests

“…In summary, because of the contraction occurring, there is no clear correlation between the amount of oriented amorphous phase and the pressure resistance. The analysis of the literature shows that, with the reduction of the oriented amorphous phase, the mechanical strength of the material decreases [ 3 , 4 ], but, according to Formula (3), with the decrease in volume (due to shrinkage), the mechanical strength increases. To determine such correlations, it would be necessary to study the relationship between the degree of orientation of the amorphous phase and the pressure resistance with the elimination of shrinkage.…”

“…A broad review of the literature on the SBM process with cold and hot molds is presented in other articles [ 1 , 2 , 3 , 4 ]. The first part of the paper contains a literature analysis, the purpose of the research together with a description of the methodology of experimental research and its results [ 5 ].…”

Blowing Kinetics, Pressure Resistance, Thermal Stability, and Relaxation of the Amorphous Phase of the PET Container in the SBM Process with Hot and Cold Mold. Part I: Research Methodology and Results

“…A broad review of the literature on the SBM process with cold and hot molds is presented in other articles [ 3 , 4 , 5 , 6 ]. For analyzing the impact of changes in the SBM process parameters on the packaging properties, many testing methods have been developed, including tests directly related to the entire SBM process and tests related to individual components of the SBM process (i.e., PET material testing, blowing air flow testing, heat flow testing).…”