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#0358


The Role of Kinetic Factors in the Formation of Network Polymers and Related Materials.

Tech Area / Field

  • CHE-POL/Polymer Chemistry/Chemistry

Status
8 Project completed

Registration date
12.01.1995

Completion date
23.12.1999

Senior Project Manager
Horowicz L

Leading Institute
Russian Academy of Sciences / Semenov Institute of Chemical Physics, Russia, Moscow

Collaborators

  • Dupont de Nemours, Germany, Bad Homburg\nDupont de Nemours, Belgium, Mechelen\nInstitut für Polymerforschung, Germany, Dresden\nUniversité Claude Bernard, France, Lyon\nInstitut National des Sciences Appliquées, France, Villeurbanne\nGeorgia Institute of Technology, USA, GA, Atlanta\nMichigan State University / Advanced Materials Engineering Experimental Station, USA, MI, Midland

Project summary

It is accepted that the structure and properties of polymers can be predicted quite accurately based on their molecular structure. Such forecasts are generally true when the process of the polymeric substance formation occurs under almost equilibrium conditions. These conditions are hardly available for actual polymer technologies. Numerous experimental results indicate that the rates of physical and chemical processes have essential and sometimes crucial influence on the final structure and properties of the crosslinked polymers.

Complication of topological structure leads to the expansion of the spectrum of structural relaxation times and causes continuous slowing down of free volume relaxation during thermosets cure. It can result in formation of polymer networks with uncompleted structural relaxation. Difficulties for relaxation of free volume increase drastically if it occurs in hindered conditions in presence of rigid filler in the curing system.

The role of kinetic factors in the formation of properties of crosslinked polymers is most pronounced when multicomponent mixtures of thermosets with additives are used, the process of curing being accompanied by phase transformations or evaporation of the solvent. Although a lot of such observations have been made, there are no systematic studies of the role of kinetic factors in the processes of crosslinked polymers formation.

The main objective of the project is the theoretical and experimental study of the role of kinetic factors in forming the structure and properties of crosslinked polymers based on multicomponent oligomeric systems

Initially compatible systems: thermoset-modifying additive, which undergo the phase decomposition during thermoset cure, have been chosen as the first group of objects. The character of spatial distribution of functional additives in polymer matrix often determines the operating properties of polymers (fracture toughness, stability to dynamic loading, catalytic, electrophysical, optical, and other properties). The second group of objects embraces multicomponent oligomeric systems, which include a solvent, filler and other additives. Studying the process of the curing of such systems will allow the process of coating formation to be characterized in details. The third group of objects is connected with the processes of formation of crosslinked polymer matrices by various mechanisms (polycondensation, ionic and radical polymerization). Studying the curing of these objects together with high-modulus fillers will elucidate the regularities of formation of fibrous composites and filled polymers.

So, the project envisages complex study of a series of physical (phase separation, evaporation of solvent, relaxation of volume) and chemical processes which take place simultaneously while complicated polymer systems are formed, and whose relative rates determine eventually the structure and properties of the polymer.


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