Lists
Lists
McKee, John Wason (2005) An investigation into the blending of poly(ethylene naphthalate) and poly(ethylene terephthalate) using single stage injection stretch blow moulding. Doctoral thesis, London Metropolitan University.
PEN and PEN PET blended polymers provide an opportunity for injection stretch blow moulders to produce containers with a superior oxygen transmission barrier and thermal properties to those provided by PET. Research undertaken on PET has provided knowledge of the typical processing conditions and design parameters required to produce bottles and wide mouth containers, however, there is evidence that indicates that PEN does have different process parameters and product design requirements. The research currently published being based on the two stage injection moulding process, and focussing on the use of homopolymer PEN, or PEN copolymers where the naphthalate fraction of the blend is between 15 and 30%. There has been little research published on blends with naphthalate mole fractions above 30%, and less on the single stage blow mould process. There is little evidence of research to produce wide mouth jars or containers.
This research has focussed on producing containers using single stage injection blow moulding equipment, and manufactured from homopolymer PEN and blending PEN with PET by using naphthalate copolymer resins. Two specific product designs have been chosen with prototype single cavity injection and blow moulding tooling produced. Both tooling concepts are commercial developments with identified end uses destined for the consumer market. The first container was a single serve beer can for a boutique beer, the second a tomato sauce bottle. In both cases the cost of the PEN at $USS/lb inhibited the products progressing beyond in-house product trialling and evaluation. Both products were successful from a product performance and material composition perspective.
Design criteria for preform and blow mould tooling and the processing parameters for differing naphthalate mole fractions have been produced. For the single stage process the preform to blow mould relationship differs from that of published two stage literature. The oxygen barrier was found to have a synergistic relationship with the naphthalate mole fraction, the improvement in oxygen barrier being greater than the actual mathematical improvement made by increasing the naphthalate mole fraction. Analysis using NMR of samples produced with differing cooling conditions indicated that the resulting composition between naphthalate, terephthalate and ethylene glycol can be manipulated. An investigation into the structure of samples produced yielded little information on the actual morphology of PEN PET blends.
 |
View Item |