Simulations of the injection stretch-blow moulding process have been developed for the manufacture of poly(ethylene terephthalate) bottles using the commercial finite element package ABAQUS/standard. Initially a simulation of the manufacture of a 330 mL bottle was developed with three different material models ( hyperelastic, creep, and a non-linear viscoelastic model (Buckley model)) to ascertain their suitability for modelling poly(ethylene terephthalate). The Buckley model was found to give results for the sidewall thickness that matched best with those measured from bottles off the production line. Following the investigation of the material models, the Buckley model was chosen to conduct a three-dimensional simulation of the manufacture of a 2 L bottle. It was found that the model was also capable of predicting the wall thickness distribution accurately for this bottle. In the development of the three-dimensional simulation a novel approach, which uses an axisymmetric model until the material reaches the petaloid base, was developed. This resulted in substantial savings in computing time. PRC/1657
Simulations of various stretch blow and blow moldings of axisymmetric PET bottles has been carried out using ABAQUS. A creep constitutive model with material data developed for a thermoforming process was used in the finite element analysis. Simulations using shell and solid elements were compared with experimental moldings. The creep material model, when combined with solid elements and a very high coefficient of friction, provided the best predictions for bottle side wall thickness, strains, blowing pressure, and general material movement. It was found that, using ABAQUS, the predicted wall thickness distribution of the material in an injection blow molded bottle agreed well with the values obtained using commercial process conditions. © 1998 John Wiley & Sons, Inc. Adv Polym Techn 17: 339–352, 1998
Technological advances in protein biochemistry now enable researchers to modify the structure of peptides to enable them to possess self-assembling properties, forming hydrogels at low concentrations. Peptides can be altered further to provide multifunctional characteristics, for example, to demonstrate antimicrobial properties. The aim of this article is to investigate the in vivo toxicity and antimicrobial properties of a low molecular weight (naphthalene-2-ly)acetyl-diphenylalanine-dilysine-OH (NapFFKK-OH) peptide hydrogel using an innovative waxworm (Galleria mellonella) model, as an alternative to mammalian/vertebrate testing. NapFFKK-OH hydrogels did not demonstrate any observable in vivo toxicity or death in G. mellonella larvae over 5 days at concentrations studied (≤2% w/v). A dose-dependent log 10 reduction in viable (CFU/mL) Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria implicated in nosocomial infections was observed over 72 h. NapFFKK-OH was especially effective against in vivo infection models of S. aureus with a significant 4.4 log 10 CFU/mL reduction in viable bacteria at 2% w/v after 72 h. Our results show G. mellonella to be a useful model for preliminary determination of in vivo toxicity and antimicrobial efficacy profiles of novel nanomaterials, including peptide-based hydrogels. This contributes to the 3R principles of animal testing, reduction, refinement, and replacement. The results also show NapFFKK-OH to be a promising alternative to standardly employed antimicrobials with the potential to be utilized as a novel therapeutic in the treatment and prevention of hospital infections.
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