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  • 1995-1999  (4)
  • 1
    ISSN: 1572-8900
    Keywords: PHBV ; polyacrylate ; reactive blending ; biodegradation ; properties
    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 biodegradability of a multicomponent system based on biotechnological occurring polyester (poly(β-hydroxybutyrate-co-β-hydroxyvalerate) (PHBV)) with inclusion of acrylate elastomer (polybutylacrylate) (PBA) was investigated. A bacterium which produced extracellular enzymes that degrades PHBV even when blended with PBA was isolated and tentatively designated asAureobacterium saperdae. It was observed, by morphological investigation, that, while the bacterial degradation was permitted for PBA content of 20% by weight, it was inhibited for PBA content of 30%, owing to the occurrence of a rubbery layer that prevents to the bacteria an easy accessibility in the PHBV-rich regions. In fact, owing the bacterial growth, only PHBV was metabolized, whereas no degradation of PBA was detected for blend samples. It was confirmed that the degradation proceeded via surface erosion of PHBV also in the blends. Finally, mechanical tests on PHBV/PBA specimens as a function of degradation extent have shown different behavior of the blends at different the PBA content. Thermal analysis of blends and PHBV has been reported, too
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(L-milchsäure) ist ein biokompatibler, semikristalliner, thermoplastischer Polyester mit ungünstigen mechanischen Eigenschaften. Daher wurde in einem “reactive blending”-Prozeß ein Acrylkautschuk, n-Butylacrylat, mittels einer Suspensionspolymerisation in Wasser auf in einem organischen Lösungsmittel gelöste Poly(L-milchsäure) gepfropft. Die gebildeten Copolymeren konnten isoliert und durch NMR-Spektroskopie und DSC-Messungen charakterisiert werden. Die Untersuchung der mechanischen Eigenschaften ergab keine befriedigenden Ergebnisse, weil die Kautschukphase wahrscheinlich aus viskosen linearen Makromolekülen besteht und daher keine elastischen Eigenschaften besitzt. In weiteren Arbeiten soll der Syntheseweg so modifiziert werden, daß durch den Einbau von Diacrylaten eine zumindest partielle Vernetzung der Kautschukphase erreicht wird.
    Notes: Poly(L-lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n-butyl acrylate, via water suspension polymerization onto poly(L-lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross-linked.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 39 (1996), S. 191-204 
    ISSN: 0959-8103
    Keywords: Biopol ; polybutylacrylate ; polycaprolactone ; reactive blending ; melt-mixing ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Multicomponent polymeric systems containing Biopol as one of the phases are described as obtained according to two different procedures: radical polymerization of an acrylic polymer in the presence of Biopol, and melt-mixing of Biopol with polycaprolactone in the presence of peroxide. The decomposition of peroxide causes, in both cases, the formation of intergrafted species responsible for interfacial activity and compatibilization. The results of chemical, chemical-physical, morphological and mechanical tests, confirming the occurrence of such interactions, are reported.
    Additional Material: 14 Ill.
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  • 4
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(β-hydroxybutyrate) (PHB) is a biotechnologically produced polyester, highly crystalline, totally biodegradable with low versatility in mechanical properties. To overcome this problem we performed a reactive blending procedure with a glassy acrylic polymer, poly(methyl methacrylate) (PMMA), via water suspension polymerisation of the acrylic monomer precursor onto poly(β-hydroxybutyrate). It was possible to isolate the co-polymeric phase formed between the two polymers and to characterize it using NMR and differential scanning calorimetry (DSC) techniques. Fracture tests on the blends gave a satisfactory response: in fact the Critical Energy Release Factor (Gc) calculated by Linear Elastic Fracture Mechanism (LEFM) theory of a PHB/PMMA 70/30 wt/wt blend is less than two times larger than that of neat PHB.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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