نتایج جستجو برای: polymer degradation

تعداد نتایج: 240989  

2008
Mikkel Jørgensen Kion Norrman Frederik C. Krebs

Polymer and organic solar cells degrade during illumination and in the dark. This is in contrast to photovoltaics based on inorganic semiconductors such as silicon. Long operational lifetimes of solar cell devices are required in real-life application and the understanding and alleviation of the degradation phenomena are a prerequisite for successful application of this new and promising techno...

2015
Wangtong He Xuejia Ding

In recent years, because of the advantage of radiation technology-low energy, clean, environmental protection, etc., so that the use of radiation technology for polymer synthesis or processing research continues to heat up; however polymer materials irradiated via high-energy radiation prone to produce free group or to react with atomic oxygen in the air, resulting in the material cracking, cro...

2012
Uttiya Dey Naba Kumar Mondal Kousik Das Shampa Dutta

Inertness and indiscriminate uses as well as growing water and land pollution problems have lead to concern about plastics. Present paper investigates the possibility of plastic degradation by microbes isolated from forest soil and automobile washout sludge. The in-vivo degradation was studied by litter bag experiment by taking 1 g of each plastic and buried under forest soil and automobile was...

2017
Pierre Gilormini Emmanuel Richaud Jacques Verdu Pierre GILORMINI Emmanuel RICHAUD Jacques VERDU

A statistical theory was proposed for the degradation (random scission of chains) of a network having f-functional nodes in the case where all chains contain equireactive groups and a chain scission event does not create new groups or suppress more than one group. Closedform relations were established between the conversion ratio of the degradation process and the crosslink density. Emphasis wa...

Journal: :Brazilian dental journal 2007
Cláudio Maniglia-Ferreira Guilherme Bönecker Valverde João Batista Araújo Silva Regina Célia Monteiro de Paula Judith Pessoa Andrade Feitosa Francisco José de Souza-Filho

This in vivo study investigated the time of degradation of root filling material (trans 1,4-polyisoprene) retrieved from endodontically treated teeth and correlated the occurrence of degradation with the longevity of endodontics. Thirty-six root-filled teeth with different filling times (2 to 30 years) and with and without periapical lesions were selected. All teeth presented clinical indicatio...

2017
Vinay Mohan Pathak

Inertness and the indiscriminate use of synthetic polymers leading to increased land and water pollution are of great concern. Plastic is the most useful synthetic polymer, employed in wide range of applications viz. the packaging industries, agriculture, household practices, etc. Unpredicted use of synthetic polymers is leading towards the accumulation of increased solid waste in the natural e...

2013
D. M. Correia J. Padrão L. R. Rodrigues F. Dourado S. Lanceros-Méndez V. Sencadas

The thermal and hydrolytic degradation of electrospun gelatin membranes cross-linked with glutaraldehyde in vapor phase has been studied. In vitro degradation of gelatin membranes was evaluated in phosphate buffer saline solution at 37 oC. After 15 days under these conditions, a weight loss of 68 % was observed, attributed to solvation and depolymerization of the main polymeric chains. Thermal ...

2013
Emad Yousif Raghad Haddad

Exposure to ultraviolet (UV) radiation may cause the significant degradation of many materials. UV radiation causes photooxidative degradation which results in breaking of the polymer chains, produces free radical and reduces the molecular weight, causing deterioration of mechanical properties and leading to useless materials, after an unpredictable time. Polystyrene (PS), one of the most impor...

2005
Joris Wieme M. F. Reyniers

The physical properties of the polymer product determine to a large extent its processability and applications. A large number of properties are directly related to the molecular mass distribution (MMD) of the polymer product. Besides the MMD, the polymer microstructure also plays an important role and influences to a large extent the thermal stability of the polymer product. Most of the therma...

Journal: :Asian Journal of Applied Sciences 2011

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