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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymers and the environment 1 (1993), S. 241-245 
    ISSN: 1572-8900
    Keywords: Degradation ; biodegradation ; starch-filled ; polyethylene ; prooxidant ; autoxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Preheated14C-labeled LDPE-films with 15% corn starch and a proxidant formulation [masterbatch (MB)] incubated in aqueous solutions with fungi at ambient temperature are about three times more susceptible to biodegradation than the corresponding preheated pure LDPE as observed by liquid scintillation counting (LSC). The inbuilt induction time before autoxidation commences can be shortened by initial heating. Preheated LDPE-MB materials biodegrade about five times faster than nonheated ones. After 1 year of biodegradation of nonheated LDPE-MB, sporadic increases in the evolution of14CO2 have been noted, showing that the induction time may be running toward and end.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8900
    Keywords: LDPE ; biodegradation ; molecular weight changes ; degradation products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The molecular weight changes in abiotically and biotically degraded LDPE and LDPE modified with starch and/or prooxidant were compared with the formation of degradation products. The samples were thermooxidized for 6 days at 100°C to initiate degradation and then either inoculated with Arthobacter paraffineus or kept sterile. After 3.5 years homologous series of mono- and dicarboxylic acids and ketoacids were identified by GC-MS in abiotic samples, while complete disappearance of these acids was observed in biotic environments. The molecular weights of the biotically aged samples were slightly higher than the molecular weights of the corresponding abiotically aged samples, which is exemplified by the increase in $$\overline M _n$$ from 5200 g/mol for a sterile sample with the highest amount of prooxidant to 6000 g/mol for the corresponding biodegraded sample. The higher molecular weight in the biotic environment is explained by the assimilation of carboxylic acids and low molecular weight polyethylene chains by microorganisms. Assimilation of the low molecular weight products is further confirmed by the absence of carboxylic acids in the biotic samples. Fewer carbonyls and more double bonds were seen by FTIR in the biodegraded samples, which is in agreement with the biodegradation mechanism of polyethylene.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8900
    Keywords: Poly(ε-caprolactone ; poly(lactic acid) ; processing additives ; biodegradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Melt-pressed films of polycaprolactone (PCL) and poly(lactic acid) (PLA) with processing additives, CaCO3, SiO2, and erucamide, were subjected to pure fungal cultures Aspergillus fumigatus and Penicillium simplicissimum and to composting. The PCL films showed a rapid weight loss with a minor reduction in the molecular weight after 45 days in A. fumigatus. The addition of SiO2 to PCL increased the rate of (bio)erosion in A. fumigatus and in compost. The use of a slip additive, erucamide, was shown to modify the properties of the film surface without decreasing the rate of bio(erosion). Both the rate of weight loss and the rate of molecular weight reduction of PCL increased with decreasing film thickness. The addition of CaCO3 to PLA significantly reduced the thermal degradation during processing, but it also reduced the rate of the subsequent (bio)degradation in the pure fungal cultures. PLA without additives and PLA containing SiO2 exhibited the fastest (bio)degradation, followed by PLA with CaCO3. The degradation of the PLA films was initially governed by chemical hydrolysis, followed by an acceleration of the weight change and of the molecular weight reduction. PLA film subjected to composting exhibits a rapid decrease in molecular weight, which then remains unchanged during the measurement period, probably because of crystallization.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1395-1405 
    ISSN: 0887-624X
    Keywords: polyanhydride ; oxepan-2,7-dione ; ring-opening polymerization ; crosslinking ; degradation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinked poly(adipic anhydride) has been obtained in this study of the synthesis of a rapidly hydrolyzable crosslinked polymer system. The thermal, mechanical, and degradative behavior was markedly affected by the ratio of reactants, using 0-50 mol % of the crosslinking agent. Optimum properties were reached at 20-30 mol %. Methylene segment crosslinks were obtained by copolymerizing oxepan-2,7-dione (adipic anhydride) with 1,2,7,8-diepoxy-octane. The crosslinking reaction resulted in polyester bonds but the material had a significant amount of poly(adipic anhydride) homosequences. These are crucial for a rapid degradation. The network formation is dependent on the functionality of the reactants, on the reactivities of the functional groups and on the reaction pathways. In this study, the most important factor affecting the structure of main chains is the higher reactivity of the anhydride compared to that of the epoxide leading to homopolymer sequences. This was also evident in the model reaction between oxepan-2,7-dione and 1,2-epoxybutane. The initial degradation profile of the crosslinked polymer corresponds to the linear counterpart of the polymer. The remaining polyester network has a longer degradation rate. © 1996 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1635-1649 
    ISSN: 0887-624X
    Keywords: poly(1,5-dioxepan-2-one) ; crosslinking ; bis(∊-caprolactone) ; swelling behavior ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(lactones) may be crosslinked by ring-opening polymerization of the corresponding cyclic esters in the presence of tetrafunctional bis(∊-caprolactone). The homopolymer of 1.5-dioxepan-2-one (DXO) has poor mechanical properties but also some very good properties, such as biocompatibility and degradability. Crosslinking of degradable polymer based on the poly(ether-ester) DXO was performed with crosslinkers having the same reactivity as the monomer. 2,2-Bis(∊-caprolactone-4-yl)propane (BCP) and bis(∊-caprolactone-4-yl) (BCY) with tetrafunctionalities were synthesized from the corresponding diols and then used as comonomers during the polymerization of DXO. The comonomers showed the same reactivity to the initiator, stanneous 2-ethylhexanoic acid, as DXO and perfectly random crosslinked films were obtained. The crosslinked films showed a high degree of swelling already at 2-3 mol % BCP or BCY. The BCP crosslinker was somewhat less soluble in DXO at lower temperatures, but all BCP was soluble at 180°C. These polymeric films were elastic with no crystallinity and the Tg values increased from -39°C for pure DXO to -35°C for BCP crosslinked films and -21°C for BCY crosslinked ones. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1635-1649, 1997
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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