Abstract: A collapse resistant polyester container is provided for hot fill applications employing product fill temperatures up to about 190.degree. F. (87.8.degree. C.) or more. The container has at least one region which is thermoelastically deformable inwardly after the container is hot filled and sealed to offset the pressure forces which tend to collapse the container as the contents cool and create an internal vacuum. The thermoelastic region is preferably formed in a two step molding process in which the region is formed and heat set at a first position and then reformed outwardly to a second position and cooled in that position.

Abstract: In forming hollow, molecularly oriented articles having a substantially oval or substantially equilateral triangular cross section from thermoplastic preforms by a method which includes distending the preforms in a mold while at molecular orientation temperature, the improvement providing improved material distribution in regions furthest from the axes of the articles when the thermoplastic is moldable polyalkylene terephthalate having an inherent viscosity of at least 0.55 which involves limiting the corner definition ratio to between about 3 to about 9 and the circular deviation ratio to no greater than about 2.4 at the cross section during distension and controlling axial and maximum radial stretch of the preforms within predetermined limits.

Abstract: A collapse resistant polyester container is provided for hot fill applications employing product fill temperatures up to about 190.degree. F. (87.8.degree. C.) or more. The container has at least one region which is thermoelastically deformable inwardly after the container is hot filled and sealed to offset the pressure forces which tend to collapse the container as the contents cool and create an internal vacuum. The thermoelastic region is preferably formed in a two step molding process in which the region is formed and heat set at a first position and then reformed outwardly to a second position and cooled in that position.

Abstract: In forming hollow, molecularly oriented articles having substantially rectangular cross sections from thermoplastic preforms by a method which includes distending the preforms in a mold while at molecular orientation temperature, the improvement providing improved material distribution in regions furthest from the central axes of the articles (e.g. in the corner areas) when the thermoplastic is moldable polyalkylene terephthalate having an inherent viscosity of at least 0.55 which involves limiting the corner definition ratio to between about 2 to about 14 and the circular deviation ratio to no greater than about 2.4 at the cross section during distension and controlling axial and maximum radial stretch of the preforms within predetermined limits.

Abstract: In forming hollow, molecularly oriented articles having a substantially oval or substantially equilateral triangular cross section from thermoplastic preforms by a method which includes distending the preforms in a mold while at molecular orientation temperature, the improvement providing improved material distribution in regions furthest from the axes of the articles when the thermoplastic is moldable polyalkylene terephthalate having an inherent viscosity of at least 0.55 which involves limiting the corner definition ratio to between about 3 to about 9 and the circular deviation ratio to no greater than about 2.4 at the cross section during distension and controlling axial and maximum radial stretch of the preforms within predetermined limits.

Abstract: In forming containers from injection molded preforms of thermoplastic material such as nitrile-based polymers by a process which includes heating the preforms to orientation temperature followed by distension to container form in a mold, the improvement providing reduced thickness variability in lower portions of the containers which involves controlling preform shrinkage during such heating to between about 4 to 15% of the initial length for nitrile materials by maintaining the ratio of average thickness to inside preform surface area within defined limits and then axially and radially stretching such preforms during distension to predetermined levels. Nitrile preforms convertible to such improved quality containers have values of between about 0.005 to 0.011 inch.sup.-1 for the aforementioned ratio.

Abstract: In forming containers from injection molded preforms of thermoplastic material such as nitrile-based polymers by a process which includes heating the preforms to orientation temperature followed by distension to container form in a mold, the improvement providing reduced thickness variability in lower portions of the containers which involves controlling preform shrinkage during such heating to between about 4 to 15% of the initial length for nitrile materials by maintaining the ratio of average thickness to inside preform surface area within defined limits and then axially and radially stretching such preforms during distension to predetermined levels. Nitrile preforms convertible to such improved quality containers have values of between about 0.005 to 0.011 inch.sup.-1 for the aforementioned ratio.

Abstract: Hollow articles such as bottles and containers are formed from tubular, elongated injection molded preforms made of thermoplastic material and having a finished neck portion adjacent an open end and a closed end body portion which method comprises annealing said preform by heating the portion of the preform body adjacent the neck to a temperature just below or about the Tg (glass transition temperature) for such material while maintaining the remainder of the preform body at a significantly lower temperature, for a sufficient time to essentially relieve the internal stresses in said body portion adjacent the neck, such annealing step being applied prior to the thermoforming of said preform into the hollow article.