What is meant by hydrolytic degradation?
Hydrolytic Degradation: This process occurs in polymers that are watersensitive active groups, especially those that take a lot of moisture. Polymers that have an ability for hydrolytic destruction usually have heteroatoms in the main or side chain.
How is polyester degraded?
Condensation polymers like polyesters, polyamides, polyurethanes and polycarbonates can be degraded by hydrolysis of their carbonyl groups, to give lower molecular weight molecules.
What makes polycaprolactone biodegradable?
Biodegradation of Biopolymers PCL is a synthetic polyester that is partially crystalline, having a low melting point (60°C) and a glass transition temperature of −60°C. PCL can be readily degraded by lipases and esterases of the microorganism [55].
What is oxidative degradation of polymers?
Oxidative degradation involves the disintegration of macromolecules by the action of oxygen on the substrate (oxidation). Free radicals are formed which react with oxygen-producing oxy- and peroxy-radicals. As a result of oxidation, the mechanical properties and utility of the polymer are significantly reduced.
What is photolytic degradation?
Photolytic degradation of drugs. Drug stability can be ad. versely affected by pho tochemical reactions. Light- sensitive drugs darken or become discolored when exposed to natural or artifi cial light.
What is hydrolytic degradation of polymers?
In hydrolytic degradation, polymer bonds react with water molecules, break up, and produce new chain ends. The original chains break up into smaller segments, resulting in polymer degradation. Most chemical groups that react with water contain O, N, S, P, and other non-carbon atoms.
What are the four main ways to degrade material?
Degradation Mechanisms
- microstructural and compositional changes,
- time-dependent deformation and resultant damage accumulation,
- environmental attack and the accelerating effects of elevated temperature, and.
- synergistic effects among the above.
How does polycaprolactone degrade?
Polymers containing ester groups, such as PCL, are susceptible to degradation through hydrolysis [40]. This may proceed through chemical or enzymatic pathways, with variable kinetics for each mechanism occurring under different conditions.
How long does it take polycaprolactone to decompose?
It takes more than a year for polycaprolactone to degrade noticeably, and the total degradation time is up to 4 years. PCL is biodegraded by bacteria and fungi. In the human body, degradation is a two-step process. During the first year, ester groups are hydrolytically cleaved.
How are polymers decomposed?
Polymer degradation can generally be classified into two mechanisms: hydrolysis and oxidation. Hydrolysis is thus defined as the reaction with water where the water molecules lead to cleavage of chemical bonds within a material. In many ways hydrolysis is often seen as the opposite of condensation.
How do polymers oxidize?
Oxidative degradation is usually initiated when polymer chains form radicals, either by hydrogen abstration or by homolytic scission of a carbon-carbon bond. This can occur during manufacture, processing or during service when exposing the polymer to light or heat.
What is photolytic degradation explain its prevention?
Photodegradation is the alteration of materials by light. Photodegradation does not apply to how materials may be aged or degraded via infrared light or heat, but does include degradation in all of the ultraviolet light wavebands.
What are the biodegradable uses of polycaprolactone?
Polycaprolactone (PCL) is a biodegradable polymer that is widely utilized for biomedical applications, as well as for environmentally sustainable packaging.
What is the thermal degradation temperature of polycaprolactone?
It is stable over its melt processing temperature range for days, and exhibits significant and rapid thermal degradation at temperatures in excess of 170 °C [ [7], [8], [9], [10] ].
What kind of polymer is ε-caprolactone ( PCL )?
Poly ( ε -caprolactone) (PCL) is a slow-degrading aliphatic polyester and a widely-utilized polymer for biomaterial and sustainable packaging applications.
How does the degradation of polymers take place?
Environmental degradation of polymers occurs primarily through the actions of microorganisms such as fungi, bacteria, and algae [ 1 ], while oxidative, enzymatic, and pH-related catalysis of hydrolysis drives the process in a physiological environment.