Articolele autorului SARBU ANDREI
Link la profilul stiintific al lui SARBU ANDREI

Study of polypyrrole functionalization parameters

The polypyrrole was functionalized by reaction with glutardialdehyde in order to insert further binding sites on the polymer surface for covalent immobilization of enzymes. Five parameters of functionalization reaction were studied: the catalyst (sulphuric acid) concentration, glutardialdehyde/water ratio, polypyrrole/functionalization solution ratio, temperature and time. The effect of each parameter was determined by keeping the other four constant.

Read more
New polymer inorganic-organic hybrids obtained through radical polymerization

New polymer inorganic-organic nanocomposites based on polyvinyl acetate were synthesized. Two types of compounds: mesoporous silica and a modified zeolite (HZSM-5) were used as inorganic matrix. The radical polymerization of the vinyl monomer took place in the pores of the inorganic structure. The raw materials were analyzed by chemical quantitative analysis and dynamic light scattering (DLS). In order to prove the nanocomposite obtaining, the final

Read more
Obtaining of Clinoptilolitic Extrudates for Environmental Applications. II. Statistical analysis of plasticizer and shear stress effects

A 2-way factorial design was used for the study of rheological properties of clinoptilolite pastes. For all clinoptilolite samples, studies were performed for 4 levels of plasticizer content in ceramic mixtures and 7 levels for shear rate variation, without replicates. The analysis of variance (ANOVA) was conducted with MathCAD software (version 14.0). Comparisons among treatments were analysed using Fisher’s least significant difference, with

Read more
Obtaining of Hydrotalcite-based Ceramic Monoliths Through Extruzion. The Investigation of the Effect of Additives on the Rheological Behaviour of the Ceramic Pastes

In this paper are presented the results of experimental research regarding the behaviour of ceramic pastes based on microcrystalline hydrotalcite [MII 1-xMIIIxOH)2]x+An-x/nmH2O, used for the preparation of monoliths with circular section through extrusion. The experimental studies regarding the rheological behaviour of hydrotalcite pastes lubricated with stearin shows that these materials have viscoplastic behaviour. Two rheological models are proposed

Read more
Polyphenol oxidase immobilizatization on functionalized polypyrrole

Polypyrrole (PPY) was functionalized by reaction with glutardialdehyde using sulphuric acid as catalyst. The samples of functionalized polypyrrole were then used for the covalent immobilization of polyphenol oxidase. The surface elemental composition of this enzyme was determined by X-ray Photoelectron Spectroscopy. FTIR spectrometry, Raman spectroscopy, Scanning Electron Microscopy and X-Ray Diffraction were used to prove polypyrrole functionalization

Read more
A2BA2 Block Copolymers of Poly(N-isopropylacrylamide) (A) and Poly(ethylene glycol) (B): Synthesis and Thermal Gelation Properties of Aqueous Solutions

A2BA2 block copolymers of poly(N-isopropylacrylamide) (A, PNIPAM) and poly(ethylene glycol) (B, PEG) were synthesized by SET-LRP for the first time. The 1H-NMR and GPC analyses showed that the block copolymers prepared had in average 3.5-3.8 PNIPAM arms/macromolecule and low polydispersities (Mw/Mn=1.25-1.35). The thermogelation behavior of their 20 wt% aqueous solutions was investigated by DSC, dynamic rheometry and the tube inversion method as

Read more
“Thermogelation properties of poly(N-isopropylacrylamide) – block – poly(ethyleneglycol) – block – poly(N-isopropylacrylamide) triblock copolymer aqueous solutions”
New method for silicon nitride synthesis via hybrid polymer nanocomposites
Proofs for molecular imprinting of an acrylic copolymer by phase inversion
Influence of the ultrasonic field on the template polymerization of acrylonitrile in inorganic structures