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ADVANCED BIO-FRIENDLY POLYMERS

ADVANCED BIO-FRIENDLY POLYMERS. Jaroslav Mosn áček. What is degradation of polymers?. A ny change of the polymer properties relative to the initial, desirable properties. In this sense, "degradation" is a generic term for any number of reactions which are possible in a polymer.

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ADVANCED BIO-FRIENDLY POLYMERS

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  1. ADVANCED BIO-FRIENDLY POLYMERS Jaroslav Mosnáček

  2. What is degradation of polymers? • Anychange of the polymer properties relative to the initial, desirable properties. • In this sense, "degradation" is a generic term for any number of reactions which are possible in a polymer. • These reactions, in turn, lead to a change in the physical and optical properties of the polymer. • It is accompanied with change in molar mass of the polymers

  3. Mode of initiation of degradation Thermal* Photo (light induced)* Biological* Chemical (Hydrolytic)* Mechanical High Energy Radiation *Will be discussed

  4. MECHANISTIC ASPECT OF POLYMER DEGRADATION Mode of Initiation Chain scission RandomChain scission (Hydrocarbons) Thermal Norrish Type (I, II) chainscission (SSR) Photochemical Enzymatic or hydrolytic attack of esters, amides and glucosides (SSR)Biological/hydrolytic Norrish I and II SSR= Single step reaction

  5. MECHANISTIC ASPECT OF POLYMER DEGRADATION Mode of Initiation Side Chain elimination Solvolysis (Hydrolysis) of ester linkage (SSR) Chemical (hydrolytic) Thermal Elimination of HCl (PVC) (CR) Hydrolysis of ester linkages SSR= Single step reaction CR = Chain reaction

  6. MECHANISTIC ASPECT OF POLYMER DEGRADATION Mode of Initiation Thermal Depolymerization Typical for Poly(methyl methacrylate and mainly forother acrylate based polymers Cross-linking Thermal, Photochemical, Mechanical, Chemical Oxidation PP with OxygenBeta-scission of tertiary alkoxy radicals

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