Search results for "engineering.material"
showing 10 items of 2352 documents
Water sorption isotherms of molecularly imprinted polymers. Relation between water binding and iprodione binding capacity
2017
International audience; Molecularly imprinted polymers are often used in aqueous medium in order to recognize specifically a target molecule. The molecular recognition is usually based on hydrogen bonding. In this case, water molecule presents a serious competition towards the target molecule. In this study, the water sorption by molecularly imprinted polymers was studied in aqueous medium. The molecularly imprinted polymers were specific for iprodione fungicide and were prepared using a 24 full factorial experimental design. They were synthesized using EGDMA or TRIM as crosslinker, methacrylamide or styrene as functional monomer and using bulk or precipitation polymerization. The water sor…
Optimization of synthesis of a titaniumcatalyst supported on alumina for synthesis of ultra-high molecular-weightpolyethylene (UHMWPE)
1994
Ethylene polymerized under low pressure over a catalytic system (modified Аl2Оз/ТlСl4 + AlEt2Cl) yields UHMWPE. Alumina gel chlorinated and calcined (above 773 K) was used as a catalyst carrier. The effect of the main variables of carrier chlorination (concentration of HCl, chlorination time and temperature) and of the calcination temperature on activity of the catalytic system was investigated. A mathematical method of planning experiments and evaluating experimental results was used in order to improve both the analysis of the conditions of the preliminary modification of the support and their optimization. Relationships between the surface properties of the alumina carrier and the activi…
An assembly of organic-inorganic composites using halloysite clay nanotubes
2018
Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with specific functionalities. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting supramolecular and covalent interactions resulting in controlled colloidal stability adjusted to the solvent polarity. The functionalized halloysite nanotubes can be employed as reinforcing filler for polymers as well as carriers for the sustained release of active molecules, such as antioxidants, flame-retardants, corrosion inhibitors, biocides and drugs. The tubular morphology makes halloysite a perspective template for core-shell metal supports for mesoporous catalysts. The cataly…
Melt stabilisation of high-density film-grade polyethylene
2001
The thermoxidative degradation of a high-density polyethylene stabilised either with standard and novel kinds of antioxidants was examined at many different temperatures. The aim of this work was to investigate the degradation response (crosslinking or chain-breakage) on the polyolefin molecular structure in terms of low shear rate melt viscosity increment and oxidation induction time both studied through steady and dynamic shear flow tests performed in a rotational rheometer. Lactone type antioxidants, especially the one containing P-EPQ phosphite component, exhibit the lowest thermoxidative degradation at high temperatures. Vitamine E, used in blend with a phosphite, appears to be a good …
pH-Responsive protein nanoparticlesviaconjugation of degradable PEG to the surface of cytochromec
2020
Proteins represent a versatile biopolymer material for the preparation of nanoparticles. For drug delivery applications an acid-triggered disassembly and payload release is preferred. Herein, we present a protein nanoparticle system based on cytochrome c, which is surface-modified with acid-degradable polyethylene glycol (PEGylation). pH-Sensitivity was obtained through vinyl ether moieties distributed in the polyether backbone. When PEGylated, cytochrome c shows a different solubility behaviour in organic solvents, which allows for particle preparation using an emulsion-based solvent evaporation method. The resulting particles are stable under physiological conditions but degrade at acidic…
An immunoassay for terbutryn using direct hapten linkage to a glutaraldehyde network on the polystyrene surface of standard microtiter plates.
2001
2-Aminobutylamino-4-ethylamino-6-isopropylamino-1,3,5-triazine (ABA-atrazine) has been synthesized and used as a coating hapten in an immunoassay with a monoclonal antibody against terbutryn. Coating was achieved by covalently linking ABA-atrazine to a glutaraldehyde polymer network directly bound to the polystyrene surface of a standard 96-well microtiter plate. The assay was carefully optimized. In particular, the coating hapten concentration had a strong effect on the ELISA sensitivity. By including a pre-incubation step a low test midpoint (IC50-value) of 0.130 microg L(-1) was achieved. As far as we are aware this is the most sensitive ELISA for terbutryn yet reported. The coating-hapt…
Illustrating the processability of magnetic layered double hydroxides: layer-by-layer assembly of magnetic ultrathin films.
2013
We report the preparation of single-layer layered double hydroxide (LDH) two-dimensional (2D) nanosheets by exfoliation of highly crystalline NiAl-NO3 LDH. Next, these unilamellar moieties have been incorporated layer-by-layer (LbL) into a poly(sodium 4-styrenesulfonate)/LDH nanosheet multilayer ultrathin film (UTF). Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible light (UV-vis), and X-ray diffraction (XRD) profiles have been used to follow the uniform growth of the UTF. The use of a magnetic LDH as the cationic component of the multilayered architecture enables study of the resulting magnetic properties of the UTFs. Our magnetic data show the appearance of spontaneous …
Investigations of polymerizable multilayers as gas separation membranes
1985
Abstract Polymerizable Langmuir—Blodgett (LB) multilayers of several diacetylenic amphiphiles were investigated on gas-permeable, polymeric supports. Macroscopically homogeneous multilayer films of hexacosa-10,12-diynoic acid and pentacosa-10,12-diyne phosphonate could be built up on polypropylene and polytetrafluoroethylene materials. As shown by scanning electron microscopy, the microscopic homogeneity of the built-up multilayers was mainly controlled by the surface structure of the support material, whereas the chemical nature of the support and photopolymerization of the layers did not affect the high order of the films. Such LB multilayers deposited on porous support materials are able…
The role of filler type in the photo-oxidation behaviour of micro- and nano-filled polypropylene
2011
The rising interest in polymer nanocomposites leads also to an increasing concern for their photo-oxidation resistance. The main properties and photo-oxidation behaviour of polypropylene-based microcomposites and nanocomposites were investigated. The results show that the use of nanosized calcium carbonate may lead to a higher photo-oxidation rate than that of pristine polypropylene, in a way that is comparable to organo-modified nanoclays. It is also observed that nanosized calcium carbonate causes higher photodegradation rates than microsized calcium carbonate. The main reasons for the increased photo-oxidation rates when using organo-modified nanoclays include the presence of iron ions, …
“Effect of Filler Type and Processing Apparatus on the Properties of the Recycled “Light Fraction” from Municipal Post-Consumer Plastics”
2001
Plastic waste or scraps are generated from two main sources: industrial wastes and post-consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post-consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post-consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous …