ADVANCED BIO-FRIENDLY POLYMERS
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ADVANCED BIO-FRIENDLY POLYMERS Jaroslav Mosnáček
description
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. - PowerPoint PPT Presentation
Transcript of ADVANCED BIO-FRIENDLY POLYMERS
ADVANCED BIO-FRIENDLY POLYMERS
Jaroslav Mosnáček
What is degradation of polymers?
• Any 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.
• 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
Mode of initiation of degradation
Thermal* Photo (light induced)*
Biological*Chemical (Hydrolytic)*
MechanicalHigh Energy Radiation
*Will be discussed
MECHANISTIC ASPECT OF POLYMER DEGRADATIONMECHANISTIC ASPECT OF POLYMER DEGRADATIONChain scission
Random Chain scission (Hydrocarbons)
Mode of Initiation
Thermal
Norrish Type (I, II) chain scission (SSR) Photochemical
Enzymatic or hydrolytic attack of esters, amides and glucosides (SSR) Biological/hydrolytic
Random scisson
+. .
+ +
Alkanes Alkenes Alkadienes
SSR= Single step reaction
Norrish I and II
MECHANISTIC ASPECT OF POLYMER DEGRADATIONMECHANISTIC ASPECT OF POLYMER DEGRADATIONMode of InitiationSide Chain elimination
Solvolysis (Hydrolysis) of ester linkage (SSR) Chemical (hydrolytic)
Elimination of HCl (PVC) (CR) Thermal
SSR= Single step reaction CR = Chain reaction
H
Cl
Cl
H
H
Cl
Cl
H
H
Cl
Cl
H
H
Cl
Cl
H
H
Cl
- HCl
Polyene
Side Chain Elimination
Aromatics
PVC
O
On
S
OO
O
mO
O
S
O
On
S
OOH
O
mO
O
S
O
On
S
OOH
OH
mO
S
H
OH
poly(acrylic acid-block vinyl acetate)
poly(acrylic acid-block-vinyl alcohol)
poly(tert-butyl acrylate-block-vinyl acetate)
Hydrolysis of ester linkages
MECHANISTIC ASPECT OF POLYMER DEGRADATIONMECHANISTIC ASPECT OF POLYMER DEGRADATIONMode of Initiation
Oxidation
Depolymerization
Cross-linking
Thermal
Thermal, Photochemical,Mechanical, Chemical
Typical for Poly(methyl methacrylate and mainly for other acrylate based polymers
COOR
COOR
COOR
COOR
COOR
COOR
COOR
COOR
.
+ COOR.COO
COOR
COOR
COOR
COOR Monomer
PP with OxygenBeta-scission of tertiary alkoxy radicals
