The influence of monomer structure on polypropylene modification in emulsion

1984 ◽  
Vol 49 (5) ◽  
pp. 1156-1166 ◽  
Author(s):  
Pavol Citovický ◽  
Darina Mikulášová ◽  
Jiří Mejzlík ◽  
Josef Majer ◽  
Viera Chrástová ◽  
...  
Keyword(s):  
Organic Liquid ◽  
Aqueous Emulsion ◽  
Heterogeneous Distribution ◽  
Solubility In Water ◽  
Chemically Modified ◽  
Heterogeneous Polymerization ◽  
Monomer Structure ◽  
Initiation Stage ◽  
Polypropylene Powder ◽  
Oxidized Polypropylene

Oxidized isotactic polypropylene powder is chemically modified by monomers of widely differing structure, the reaction being carried out at 30 °C in aqueous emulsion in the presence of a ferrous chelate as an activator. Apart from the polymer bonded to the polypropylene carrier also some homopolymer is formed simultaneously during this heterogeneous polymerization initiated by polypropylene peroxides. The mutual proportion and amount of the resulting polymers may be considerably influenced by the properties of the monomer used, such as by its partial or total solubility in water, its polarity and reactivity as well as by the substituent size. Moreover, the chelate and emulsifier type as well as the presence of organic liquid phase in the system play also an important role. The mechanistic discussion is focused to the early initiation stage of the polymerization. This period, together with the active participation of the monomer, is decisive for the formation of both polymer types produced in the system. The results obtained are in accordance with the observed heterogeneous distribution of -O-O- groups in oxidized polypropylene.

Mechanism and kinetics of grafting of polypropylene by water-soluble monomers in emulsion

1986 ◽  
Vol 51 (8) ◽  
pp. 1648-1655 ◽  
Author(s):  
Pavol Citovický ◽  
Darina Mikulášová ◽  
Emil Štaudner ◽  
Viera Chrástová ◽  
Jozef Beniska
Keyword(s):  
Liquid Phase ◽  
Acrylic Acid ◽  
Graft Polymerization ◽  
Reaction Order ◽  
Water Soluble ◽  
Aqueous Emulsion ◽  
Grafting Reaction ◽  
Mechanism And Kinetics ◽  
Polypropylene Powder ◽  
Kinetics Of

Oxidized isotactic polypropylene powder was grafted at 30 °C in aqueous emulsion with water-soluble monomers such as acrylic acid and acrylamide. The decomposition of the polypropylene -O-O- groups, initiating the graft polymerization, proceeds due mainly to the effect of the activator used, viz. a chelate of iron(II), and is favoured by the monomer and the necessarily present water-insoluble liquid phase. The grafting reaction order with respect to the concentration of the water-soluble monomer is 2 and higher. A mechanism and kinetics are suggested for the polypropylene grafting by these water-soluble monomers, involving the concept of presence of long-living radicals bonded to the solid polypropylene phase.

Heterogeneous distribution of AMPA glutamate receptor subunits at the photoreceptor synapses of rodent retina

2001 ◽  
Vol 13 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Iris Hack ◽  
Moritz Frech ◽  
Oliver Dick ◽  
Leo Peichl ◽  
Johann Helmut Brandstatter
Keyword(s):  
Glutamate Receptor ◽  
Heterogeneous Distribution

Binding of Tissue Plasminogen Activator to Vascular Grafts

1989 ◽  
Vol 61 (01) ◽  
pp. 131-136 ◽  
Author(s):  
Richard A Harvey ◽  
Hugh C Kim ◽  
Jonathan Pincus ◽  
Stanley Z Trooskin ◽  
Josiah N Wilcox ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Fibrinolytic Activity ◽  
Polymer Surface ◽  
Enzymic Activity ◽  
Vascular Prostheses ◽  
Chemically Modified ◽  
Insoluble Surfactant ◽  
Tissue Plasminogen

SummaryTissue plasminogen activator labeled with radioactive iodine (125I-tPA) was immobilized on vascular prostheses chemically modified with a thin coating of water-insoluble surfactant, tridodecylmethylammonium chloride (TDM AC). Surfactant- treated Dacron, polytetrafluoroethylene (PTFE), silastic, polyethylene and polyurethane bound appreciable amounts of 125I- tPA (5-30 μg 125I-tPA/cm2). Upon exposure to human plasma, the amount of 125I-tPA bound to the surface shows an initial drop during the first hour of incubation, followed by a slower, roughly exponential release with a t½ of appoximately 75 hours. Prostheses containing bound tPA show fibrinolytic activity as measured both by lysis of clots formed in vitro, and by hydrolysis of a synthetic polypeptide substrate. Prior to incubation in plasma, tPA bound to a polymer surface has an enzymic activity similar, if not identical to that of the native enzyme in buffered solution. However, exposure to plasma causes a decrease in the fibrinolytic activity of both bound tPA and enzyme released from the surface of the polymer. These data demonstrate that surfactant-treated prostheses can bind tPA, and that these chemically modified devices can act as a slow-release drug delivery system with the potential for reducing prosthesis-induced thromboembolism.

ROLE OF rhBMP-2 AND rhBMP-7 IN THE METABOLISM AND DIFFERENTIATION OF OSTEOBLAST-LIKE CELLS CULTURED ON CHEMICALLY MODIFIED TITANIUM SURFACES

2012 ◽  
pp. 141208072802005
Author(s):  
Fabiano Ribeiro Cirano ◽  
ADRIANE TOGASHI ◽  
MARCIA MARQUES ◽  
FRANCISCO PUSTIGLIONI ◽  
LUIZ LIMA
Keyword(s):  
Chemically Modified ◽  
Titanium Surfaces ◽  
Cells Cultured

Removal of nutrients from Organic Liquid Agricultural Waste using filamentous algae.

2020 ◽  
Author(s):  
Gonzalo Flores-Morales ◽  
Mónica Díaz ◽  
Patricia Arancibia-Avila ◽  
Michelle Muñoz-Carrasco ◽  
Pamela Jara-Zapata ◽  
...  
Keyword(s):  
Organic Waste ◽  
Low Cost ◽  
Organic Liquid ◽  
Agricultural Waste ◽  
Filamentous Algae ◽  
Tertiary Treatment ◽  
Nutrient Reduction ◽  
Algae Removal ◽  
Algae Growth ◽  
Waste Effluents

Abstract A feasibility analysis of tertiary treatment for Organic Liquid Agricultural Waste is presented using filamentous algae belonging to the genus Cladophora sp. as an alternative to chemical tertiary treatment. The main advantages of tertiary treatments that use biological systems are the low cost investment and the minimal dependence on environmental variables. In this work we demonstrate that filamentous algae reduces the nutrient load of nitrate (circa 75%) and phosphate (circa 86%) from the organic waste effluents coming from dairy farms after nine days of culture, with the added advantage being that after the treatment period, algae removal can be achieved by simple procedures. Currently, the organic wastewater is discarded into fields and local streams. However, the algae can acquire value as a by-product since it has various uses as compost, cellulose, and biogas. A disadvantage of this system is that clean water must be used to achieve enough water transparency to allow algae growth. Even so, the nutrient reduction system of the organic effluents proposed is friendly to the ecosystem, compared to tertiary treatments that use chemicals to precipitate and collect nutrients such as nitrates and phosphates.

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