The Thermal Degradation of Polymer Blends of Polyacrylonitrile

Samson, John Norman Reid (1975) The Thermal Degradation of Polymer Blends of Polyacrylonitrile. PhD thesis, University of Glasgow.

Abstract

The introductory chapter reviews both general aspects of polymer degradation and, in more detail, the relationships between the chemical structure and thermal stability of vinyl polymers. A brief description of polymer blends and their usage is given together with a survey of recent work upon the thermal behaviour of such systems. Chapter 2 summarizes the experimental aspects of the work. The first section deals with the preparation and purification of polymers used in subsequent chapters. The second part described the thermal analysis techniques and procedures which were used in examination of both polymers and polymer blends. The thermal degradation of polyacrylonitrile and of blends of polyacrylonitrile and polymethylmethacrylate is studied in detail in Chapter 3. The decomposition of polymethylmethacrylate is shown to undergo significant changes upon blending. The effect has been found to vary with blend composition and has been attributed to reaction with gaseous volatiles evolved from polyacrylonitrile decomposition. The rate of coloration and thermal degradation of nitrile polymers has been previously shown to be influenced by both the nature and amount of initiating structures either within the polymer chain or present as additives. In Chapter 4 the degradation of polyacrylonitrile in the presence of chlorinated polymers is found to be similarly influenced and in each system examined separation of the exothermic nitrile oligomerization process from chain scission reactions is evident. In Chapter 5 polyacrylonitrile blends containing polystyrene and polymethylacrylate are studied. Molecular mass results obtained after isothermal degradation of the blends reveal a reduction in chain scission which is consistent with a reduction in intermolecular chain transfer reactions between degrading polystyrene and polymethylacrylate. The thermal behaviour of both polymethacrylonitrile and blends of polyacrylonitrile and polymethacrylonitrile is examined in Chapter 6. The results of blend degradation indicate nitrile oligomerization to occur in polymethacrylonitrile accompanied by a reduction in the evolution of methacrylonitrile. A range of methylmethacrylate-methacrylamide copolymer compositions is discussed in Chapter 7. Thermal decomposition is shown to result in cyclization reactions between adjacent comonomer units which effectively reduces the methacrylate monomer yield. Similarities are drawn between copolymer behaviour and polymethylmethacrylate degradation in the presence of polyacrylonitrile.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Polymer chemistry
• Date of Award: 1975
• Depositing User: Enlighten Team
• Unique ID: glathesis:1975-78700
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Jan 2020 15:01
• Last Modified: 30 Jan 2020 15:01
• URI: https://theses.gla.ac.uk/id/eprint/78700