Improvement of Barrier Properties of Poly(Ethylene Terephthalate)with Nanoclay
Bibliographic record
Abstract
RESUME Le polyethylene terephtalate (PET) comme polymere d’ingenierie semi-cristallin trouve enormement d’applications dans l’industrie des emballages. Cependant, pour certaines applications comme celles des boissons gazeuses et des bieres, diminuer sa permeabilite au gaz, autrement dit augmenter ses proprietes barrieres, demeure un defi considerable. L’introduction de feuillets de nano-argile de silicate en tant que phase impermeable dans la matrice polymere devient ainsi une alternative interessante. Le melange a l’etat fondu et la polymerisation in situ sont des techniques generalement utilisees pour produire des nano-composites de PET. La premiere methode reste cependant preferable car elle presente des avantages economiques et environnementaux, puisqu’elle ne necessite pas la presence de solvants ni de monomeres. Dans la premiere phase de la presente etude, les nano-composites de PET (NCPs) ont ete prepares en utilisant differentes argiles organiquement modifiees. La compatibilite avec la matrice, ainsi que la stabilite thermique de l’ensemble, jouent un role preponderant dans l’evolution morphologique des NCPs. Dans la deuxieme phase, des films minces de NCP ont ete produits avec succes par extrusion suivi d’un etirage. L’effet de l’incorporation des argiles sur les proprietes mecaniques, barrieres, thermiques et optiques des produits finaux a ete etudie. Aussi, l’importance de la cristallinite lors de la solidification en sortie d’extrusion et l’influence de la presence des argiles sur le degre de cristallinite en conditions isothermes comme non-isothermes ont ete investiguees.----------ABSTRACT Polyethylene terephthalate (PET), as a semi crystalline engineering polymer, is used extensively in packaging applications. However, gas permeability is a challenge in some applications such as soft drinks and beers. The introduction of layered silicate nanoclay, as an impermeable nanoparticle phase in a polymer matrix, is an attractive approach to enhance gas barrier properties. Melt compounding and in situ polymerization are the main techniques employed to produce PET nanocomposites. The former is the preferred method for preparation of polymer nanocomposites, which has environmental and cost advantages, due to the absence of solvents and monomers. In the first phase of this work, PET clay nanocomposites (PCN) were prepared using different types of organo-modified clay, including ammonium, phosphonium and imidazolium surfactants. Both compatibility and thermal stability play an important role in morphological development of PCNs. In the second and main part of this project, PCN thin films were prepared successfully, using cast film extrusion. The effect of incorporated clay on mechanical, barrier, thermal and optical properties of the products was studied. Incorporating 3 wt% Cloisite30B into PET matrix, led to 23% reduction in oxygen permeability and 20% improvement in tensile modulus. The effect of processing conditions, including screw profile, screw speed and feeding rate, on properties of PCN films were also studied. It was found that screw speed and, accordingly, applied shear has stronger effect on barrier and mechanical properties of the final products than feeding rate (residence time). At the highest screw speed, 27% and 30% improvement in barrier properties and tensile modulus were achieved, respectively.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".