Torque-rheometry investigation of model transreactions involving condensation polymers. I. Polyesters

The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, und...

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Bibliographic Details
Published in:Polymer engineering and science 2006-02, Vol.46 (2), p.139-152
Main Authors: Filippi, Sara, Madrigali, Laura, Polacco, Giovanni, Magagnini, Pierluigi, La Mantia, Francesco P., Acierno, Domenico
Format: Article
Language:English
Subjects:
Analysis
Applied sciences
Chemical properties
Chemical reactions and properties
Condensation
Degradation
Exact sciences and technology
Molecular weight
Organic polymers
Physicochemistry of polymers
Polyamides
Polyesters
Polyethylene terephthalate
Polymer blends
Properties
Structure
Torque
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Summary:The chemical transformations taking place when poly(ethylene terephthalate) (PET) or poly(ethylene naphthalate) (PEN) are blended in the melt with different low molar mass substances containing hydroxyl, carboxyl, or amine functional groups have been investigated as models of the transreactions, undergone by the polyesters in reactive blending operations. The polyester molecular weight changes caused by the alcoholysis, acidolysis, aminolysis, and esterolysis reactions have been monitored by torque‐rheometry, using a Brabender Plasticorder static mixer. The degradation of the polyesters by hydrolysis was also studied, under similar conditions, by the addition of a water‐releasing substance (wet polyamide‐6), and was shown to occur quite rapidly, although most of the added water was lost by flash vaporization caused by the high temperature of the polyester melt. It has been shown that the rate constants of the reactions leading to breakage of the inner ester bonds of the polyester macromolecules decrease in the following order: aminolysis (with aliphatic amines, either primary and secondary) > alcoholysis (with aliphatic alcohols) ≈ hydrolysis > acidolysis (with aromatic acids) ≥ acidolysis (with aliphatic acids) ≫ aminolysis (with aromatic amines) > alcoholysis (with phenols) ≫ esterolysis. POLYM. ENG. SCI. 46:139–152, 2006. © 2005 Society of Plastics Engineers
ISSN:0032-3888
1548-2634
DOI:10.1002/pen.20451