Transport in oriented bottles made from polyester resin

Abstract

Oxygen permeation has been measured in flat sheet as a function of degree of orientation, and oxygen and water transport have been measured in oriented polyester bottles. O2 permeability in flat sheets decreases gradually with orientation on either side of an abrupt decrease by about a factor of 2 after moderate orientation. The bottles tested were all more highly oriented than that critical decree; no significant effect of orientation on water or O2 transport in bottles could be found. Only container intrinsic viscosity (IV) (which is determined by molecular weight, and is therefore a convenient measure of polymer degradation) was significantly related to the transport properties of the bottles. It was found that O2 transport is increased with increasing IV while H2O transport decreased. The explanation for these seemingly contradictory data can be found in the chemistry of degradation of the polyester.

Improving oxygen barrier properties of poly(ethylene terephthalate) by incorporating isophthalate. I. Effect of orientation

“…The larger amount of isophthalate that would be required to significantly impact gas permeability would also reduce T g 1 and could affect processing performance. High orientation and strain‐induced crystallization induced by the stretch‐blow molding process impart good gas barrier to PET bottles 4. The possibility exists that significant levels of isophthalate would adversely affect orientation and crystallization.…”

Crystallinity and oxygen transport properties of PET bottle walls

“…Poly(ethylene terephthalate) (PET) is widely used in bottles for food and beverage packaging. High orientation and strain‐induced crystallization imparted by the stretch–blow molding process give the bottle improved oxygen barrier over unoriented, amorphous PET 1. Efforts to quantify biaxial orientation reveal complex orientation patterns in the bottle and strong orientation gradients through the bottle wall 2.…”

Morphology‐permeability relationships in biaxially oriented Pet films: A relationship between oxygen permeability and PROF

“…( l -X c ) ( 7 ) Equation ( 7 ) reflects the dependency on percent crystallinity and factors governing the state of the amorphous phase. Normally, the gas permeability and water vapor is correlated with percent crystallinity, and factors affecting diffusion of gases, from the amorphous phase.…”