Sökning: "degradation environment"

Visar resultat 1 - 5 av 353 avhandlingar innehållade orden degradation environment.

1. 1. Environmentally Degradable Polyethylene : Effects of Additives and Environment on the Degradation and Degradation products

   Författare :Farideh Khabbaz; KTH; []
   Nyckelord :LDPE; polyethylene; oxidative degradation; photo-oxidation; thermo-oxidation; degradation products; photosensitisers; pro-oxidant; starch; master-batch; gas chromatography mass-spectrometry; GC-MS; solid phase microextraction; SPME;

   Sammanfattning : This thesis summarises and compares the influences ofdifferent additives (photosensitisers, pro-oxidants, abiodegradable filler) on blown low-density polyethylene (LDPE)films during photo- and thermal degradation with respect tochemical changes in the polymer matrices and identifieddegradation products. Additives studied were irondimethyldithiocarbamate (FeDMC), nickel dibutyldithocarbamate(NiDBC), carbon black, starch, a pro-oxidant that consisted ofmanganese stearate together with styrene butadiene rubber (SBR)or natural rubber (NR) and a master batch containing linearLDPE, starch and pro-oxidant. LÄS MER

3. 2. Chemical Pollutants Released to the Marine Environment by Degradation of Plastic Debris

   Författare :Berit Gewert; Matthew MacLeod; Magnus Breitholtz; Merle Plassmann; Martin Wagner; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Plastic; microplastic; degradation; leachates; weathering; photo-oxidation; marine environment; toxicity; Applied Environmental Science; tillämpad miljövetenskap;

   Sammanfattning : Since the beginning of the mass production in the 1940s, plastic has been manufactured in quickly increasing amounts. Plastic debris accumulates in the environment and lately much attention has been drawn to the pollution in the world’s oceans. LÄS MER

4. 3. Controlling Polylactide Degradation through Stereocomplexation and Lactic Acid Based Additives

   Författare :Sofia Regnell Andersson; Minna Hakkarainen; Ann-Christine Albertsson; Marek Kowalczuk; KTH; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Polylactide; stereocomplex; plasticizer; degradation; degradation products; ESI-MS;

   Sammanfattning : The successful use of degradable materials in new applications depends on our ability to control the degradation process. A number of aspects need to be evaluated including degradation rate, the onset of degradation and the nature, formation and release of degradation products. LÄS MER

5. 4. Interactions between polymers and the environment

   Författare :Nazanin Alipour; Mikael S. Hedenqvist; Antal Boldizar; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Deltamethrin; piperonyl butoxide; polyethylene; migration; multilayer film; EVOH; n-hexane; crystallization; mechanical properties; X-ray scattering; swelling; larvae; protein; lipid; moisture sorption; release; nanoclay; polypropylene; degradation; Fiber- och polymervetenskap; Fibre and Polymer Science;

   Sammanfattning : This dissertation addresses the structure and properties of a number of polymer-based materials when they come into contact with specific environments. The first part describes the migration and depletion of active substances from insecticide-impregnated polyethylene sheets in water and air at different humidity levels and higher temperatures. LÄS MER

7. 5. Degradation Pathways of Dimethylmercury in Natural Waters

   Författare :Johannes West; Sofi Jonsson; Andrew Graham; Elena Gorokhova; Bridget Bergquist; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mercury; Marine; Degradation; Methylmercury; Aquatic; Environmental Sciences; miljövetenskap;

   Sammanfattning : Mercury (Hg) is a naturally occurring toxic trace metal whose release into the environment has been (and still is) exacerbated by human activities. The bioavailability of Hg is tied to its chemical speciation, with monomethylmercury (MMHg) being the primary form of Hg that bioaccumulates and biomagnifies. LÄS MER