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degradation injectable polymers Address for correspondence: Pathiraja A Gunatillake CSIRO Molecular Science Bag 10 Clayton South MDC Vic 3169 Australia Telephone number: 61 3 9545 2501 E-mail: Thilak Gunatillakecsiro au Introduction Biodegradable synthetic polymers offer a number of ad-vantages over other materials for developing scaffolds in tissue engineering The key advantages
Abstract This study evaluates the degradation of six different elastomeric polymers used for O-rings: EPDM FEPM type I- and II-FKM FFKM and FSR in five different simulated geothermal environments at 300 C: 1) non-aerated steam/cooling cycles 2) aerated steam/cooling cycles 3) water-based drilling fluid 4) CO 2-rich geo-brine fluid and 5) heat–cool water quenching cycles
Polymers with controlled biomedical degradation characteristics can be used as an important part of tissue engineering and drug delivery therapies Many types of natural and synthetic biodegradable polymers have been investigated for medical and pharmaceutical applications
colour of polymers The degradation occurs due to changes accompanying with the main backbone or side groups of the polymer Degradation is a chemical process which affects not only the chemical composition of the polymer but also the physical parameters such as colour of the polymer chain conformation molecular weight molecular weight distribution crystallinity chain flexibility cross
Unfortunately all polymers- painted or not- are vulnerable to environmental forces that can cause polymer degradation What Causes Polymers to Degrade? Because of their composition polymers tend to break down faster than the surrounding metal body panels when exposed to certain elements like sunlight air pollution road tar oxygen grime and oil
Biodegradable polymers can be tailored for controlled degradation through numerous functional groups including esters amides anhydrides and others Among these polyesters synthesized from lactide 1 and glycolide 2 shown in Figure 1 are of particular interest because they are well tolerated in biological systems and display distinct tunable physicochemical and mechanical properties
Biodegradable polymers can be tailored for controlled degradation through numerous functional groups including esters amides anhydrides and others Among these polyesters synthesized from lactide 1 and glycolide 2 shown in Figure 1 are of particular interest because they are well tolerated in biological systems and display distinct tunable physicochemical and mechanical properties
Detailed examples of enzymatic degradation of polymers are illustrated from current scientific literature with the discussion on various factors that can influence the degradation In addition different techniques that are generally applied to assess the degradation process as well as degradation products have been described Finally a special emphasis is given to the investigation of the
Degradation in Dielectric Polymers Using In Situ Electroluminescence Electrical treeing which causes tiny dendritic hollow channels generated inside solid dielectrics is typically regarded as an irreversible degradation and usually results in catastrophic breakdown Here usingin situ electroluminescence during electrical treeing autonomous self-healing of electrical degradation in
Thermal and Oxidative Degradation of Polymers In recent decades synthetic polymeric materials be- cause of their unique physical properties have rapidly replaced more traditional materials such as steel and nonferrous metals as well as natural polymeric materi-als such as wood cotton and natural rubber However one weak aspect of synthetic polymeric materials com-pared with steel and
POLYMERS AND THEIR ENVIRONMENTAL DEGRADATION Prof Norman Billingham University of Sussex Brighton Polymers "I am inclined to think that the development of polymerization is perhaps the biggest thing chemistry has done where it has had the biggest effect in everyday life The world would be a totally different place without artificial fibres plastics elastomers etc Even in the field
Polymer degradation and aging is one of the most daunting obstacles to the long-term use of polymeric materials Therefore the degradation of PLA/PGA polymers in the presence of basic drugs depends on a number of parameters ie base catalysis neutralisation of carboxyl end groups porosity size and dimension of devices load and morphology of incorporated compounds All these factors
In recent years biodegradable polymers have become the hot topic in people's daily life with increasing interest and a controllable polymer biodegradation is one of the most important directions for future polymer science This article presents the main preparation methods for biodegradable polymers and discusses their degradation mechanisms the biodegradable factors recent researches and
BIODEGRADABLE POLYMERS - authorSTREAM Presentation Poly ε caprolactone: Poly ε caprolactone semi-crystalline polymer slower degradation rate than PLA remains active as long as a year for drug delivery Biodegradation: Occurs in two phases: First phase: hydrolytic chain scission of the ester linkage Second phase: decrease in the rate of chain scission and onset of weight loss due to
Aging of Polymers the irreversible change in the properties of polymers under the action of among other factors heat oxygen sunlight ozone and ionizing radiation Depending on the factor the aging will be of the thermal oxidative light ozone or radiation type Aging occurs during the storage and treatment of polymers as well as during the
Aging of Polymers the irreversible change in the properties of polymers under the action of among other factors heat oxygen sunlight ozone and ionizing radiation Depending on the factor the aging will be of the thermal oxidative light ozone or radiation type Aging occurs during the storage and treatment of polymers as well as during the
The oxidative and thermal degradation of polymers has very important implications on their suitability for particular end-user applications Particularly in relation to their physical properties and the lifetime over which the manufactured article retains these properties after which they become unsuitable for purpose
stabilization of polymers under irradiation environments thus has become a key issue in the extensive and still growing use of radiation processing in polymer processing and modification During the last decade a number of meetings have been organized under the auspices of the IAEA in order to elaborate recent developments in the application of radiation chemistry in polymer based industries
Polymer Degradation and Stability deals with the degradation reactions and their control which are a major preoccupation of practitioners of the many and diverse aspects of modern polymer technology Deteriorative reactions occur during processing when polymers are subjected to heat oxygen and mechanical stress and during the useful life of the materials when oxygen and sunlight are the
Polymers from biomass are of prime concern and are the cornerstone in terms of various applications such as biofuels biomedical and biocomposite applications Recently concerns on the environmental pollution and exhaust of natural resources caused by the nonbiodegradable petroleum-based plastics materials have attracted attention on the development of environmentally benign polymers for
Controlling degradation requires understanding of many different phenomena including chemical mechanisms the influence of polymer morphology the complexities of oxidation chemistry and the effects of stabilisers fillers and other additives This book offers a wealth of information for polymer researchers and processors requiring an understanding of the implications of thermal degradation
Research highlights Degradation of semiconducting polymers was accelerated by concentrated sunlight Acceleration factors exceeding 100 were obtained compared to 1 sun illumination Acceleration factors in the range 19–55 at 100 suns were found for 5 polymers The method can be used as an accelerated lifetime test for polymer stability screening
stabilization of polymers under irradiation environments thus has become a key issue in the extensive and still growing use of radiation processing in polymer processing and modification During the last decade a number of meetings have been organized under the auspices of the IAEA in order to elaborate recent developments in the application of radiation chemistry in polymer based industries
Linear high molecular weight polymers undergo central scission in strong flows due to buildup of stress from fluid drag An alternative to linear architecture is the star branched polymer that shows higher shear stability against such scission We consider two six-arm star polymers differing in the connectivity of the arms at the core The first is a fused-core star PMMA where the arms are
Degradation of polymers can be carried out by heat radiation or biochemical treatment The radiant energy may be high-energy radiation from gamma rays ion beams and electrons or even low-energy radiation from ultraviolet (UV) light UV stabilizers added to polymer products reduce the rate of degradation Chemical degradation results from treatment with chemicals such as acids and alkalis
Thermal degradation of polymers is molecular deterioration as a result of overheating At high temperatures the components of the long chain backbone of the polymer can begin to be broken (chain scission) and react with one another to change the properties of the polymer Thermal degradation can present an upper limit to the service temperature of plastics as much as the possibility of
We will also review the chemistry of the polymers including synthesis and degradation describe how properties can be controlled by proper synthetic controls such as copolymer composition highlight special requirements for processing and handling and discuss some of the commercial devices based on these materials POLYMER CHEMISTRY Biodegradable polymers can be either natural or synthetic
Degradation of PCL Polycaprolactone belongs to a family of polymers called polyesters Degradation of PCL occurs by random hydrolytic secession of its ester linkages Ester linkages are very susceptible to hydrolysis The rate of hydrolysis is modulated by the crystallinity and hydrophobicity of the monomer components of the polymer chain
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