CONTENTS &
ABSTRACTS
In
English. Summaries in Estonian
Proceedings of the Estonian Academy of Sciences.
Chemistry
Volume 55 No. 2
June 2006
Special issue
on polymer science
Foreword;
59–60
Andres Öpik
Activation
of cellulose-based carriers with pentaethylene-hexamine;
61–69
Jolita Aniulyte, Jolanta Bryjak, and
Jolanta Liesiene
Abstract. A method for the activation of a cellulose-based matrix resulting in obtaining active primary amino groups via a long spacer arm was developed. The method is based on coupling pentaethylenehexamine (PEHA) to the polymeric matrix through epoxy groups. It was shown that modification of cellulose with PEHA is a straightforward and convenient procedure that has the advantages of high coupling efficiency. The primary amino group density on the carrier surface can be easily adjusted by changing the content of epoxy groups in the matrix or by altering the amount of PEHA in the reaction mixture.
The lectins Concanavalin A and Wheat Germ Agglutinin were employed as ligands for the immobilization onto the PEHA-activated carrier using glutaraldehyde. It was shown that the spacer arm affected ligand coupling kinetics as well as the chromatographic behaviour of the adsorbents obtained. Covalent immobilization of enzyme glucoamylase on PEHA-activated cellulose was done. It was found that covalent binding via glutaraldehyde offers satisfactorily stable and active preparations.
Key words: cellulose activation, spacer arm, lectin-affinity adsorbents, enzyme immobilization.
Tselluloosipõhiste
kandjate aktiveerimine pentaetüleenheksamiiniga
On uuritud tselluloosipõhiste kandjate aktiveerimist pika vahelüli kaudu primaarsete aminorühmadega, milleks pentaetüleenheksamiin (PEHA) on epoksürühmade abil seotud polümeerse maatriksi külge. Ligandid on immobiliseeritud PEHA-aktiveeritud kandjale glutaaraldehüüdiga ja saavutatud kromatograafiaks vajalik statsionaarse faasi püsivus.
Biobased polymer compsites for films and
coatings; 70–77
Dace Erkske, Ilze Viskere, Anda Dzene, Velta Tupureina,
and Ludmila Savenkova
Abstract. Heterogeneous multicomponent biocomposites were elaborated on the basis of biodegradable polymer polyhydroxybutyrate through incorporation of additives of distinctive chemical nature (plasticizers, renewable fillers, compatibilizers). Plasticized polyhydroxybutyrate solutions were used as continuous matrices for the formation of films and paper coatings. Mechanical, thermal, hygroscopic, and barrier properties and biodegradation of the obtained materials were evaluated in terms of application as biodegradable packaging.
Key words: biocomposites, polyhydroxybutyrate (PHB), starch, biodegradation, water vapour permeability, hygroscopic properties.
Biopolümeersed
komposiidid kiledeks ja kateteks
Keemiliselt olemuselt eristuvate manuste (plastifikaatorid, täiteained, ühildajad) lisamisel biolagunevate polümeeride polühüdroksübutüraadile on välja töötatud heterogeenne multikomponentne biokomposiit. Plastifitseeritud polühüdroksübutüraadi lahuseid on kasutatud kui pidevat maatriksit kilena ja paberi katmisel. Saadud materjalidele on määratud nende mehaanilised, termilised, hügroskoopsed, isoleerivad ja biolagunevad omadused, milliseid on hinnatud nende rakendatavuse järgi biolaguneva pakkematerjali valmistamisel.
Preparation
of chitosan powder and investigation of its properties;
78–84
Marianna Laka and Svetlana Chernyavskaya
Abstract. For the preparation of chitosan powder, the thermocatalytic destruction method developed in our earlier works was applied. Chitosan samples obtained from exoskeletons of crustaceans with a molecular weight of 500 kDalton, deacetylation degree 80% and with a molecular weight of 900 kDalton, deacetylation degree 70% were investigated. For these samples, optimal thermocatalytic treatment conditions for partial destruction of chitosan, which was controlled from the change in intrinsic viscosity, to the levelling-off degree of polymerization (LODP) were developed. In our case, LODP was ~ 140 units. The destructed chitosan was dissolved in water and precipitated with adding a definite amount of NaOH. The precipitated chitosan was washed off, dried at 60 °C, and ground in a ball mill. As a result, a cream-like powder was obtained, whose major part of particles had sizes of 1–15 mm. The properties of the obtained powder were investigated by the microscopic, X-ray diffraction, IR spectroscopic, and physico-chemical methods.
Key words: chitosan, deacetylation degree, intrinsic viscosity, levelling-off degree of polymerization, thermocatalytic destruction.
Kitosaanpulbri saamine
ja selle omaduste uurimine
Kitosaanpulbri saamiseks on kasutatud termokatalüütilist osalise lagundamise meetodit. Optimaalsete lagundamistingimuste leidmiseks on kontrollitud kitosaaniproovide piirviskoossuse muutust kuni polümerisatsiooni tasakaaluni. Saadud pulbri omadusi on uuritud mikroskoopiliste, röntgenidifraktsiooni-, IP-spektroskoopia- ja füüsikalis-keemiliste meetoditega.
Synthesis
and properties of cross-linked poly(ester urethanes) from poly(lactide) triols
and poly(caprolactone) diols; 85–92
Brigita Lazdina, Uldis Stirna, Velta Tupureina, Anda Dzene,
and
Irina Sevastyanova
Abstract. Segmented polyurethanes, whose soft segments were formed by poly(caprolactone) diols with the average molecular weight (Mn) ranging from 400 to 2700 and hard segments by poly(lactide) triols with a Mn of 600–3000, and 1,6-hexamethylenediisocyanate and 4,4’-methylene bis(cyclohexyl) diisocyanate were studied. For poly(lactide) triol and poly(caprolactone) diol synthesis, glycerol and 1,4-butane diol, respectively, were used as D,L-lactide and e-caprolactone polymerization initiators. The effect of a change in the soft segment content on the properties of polyurethanes at a constant value of molecular weight between cross-links was investigated. The obtained polyurethanes have an amorphous or semicrystalline structure with a minor phase separation degree. Varying the Mn of poly(lactide) and poly(caprolactone) blocks as well as their ratio in the structure, polyurethanes with different tensile, thermal, and biodegradation properties were obtained.
Key words: segmented poly(ester urethanes), poly(caprolactone) diols, poly(lactide) triols, glycerol, tensile properties, thermal properties.
Polü(laktiid)trioolidest
ja polü(kaprolaktoon)dioolidest ristseotud polü(esteruretaanide) süntees ja
omadused
On sünteesitud polüuretaanid, mille pehmed plokid on moodustunud polü(kaprolaktoon)dioolide ja kõvad polü(laktiid)trioolide reaktsioonil erinevate diisotsüanaatide ja initsiaatoritega. On määratud pehmete ja kõvade plokkide arvkeskmise molaarmassi mõju polüuretaanide erinevatele omadustele.
Bating
of pelts after deliming with peracetic acid; 93–100
Justa Širvaitytė, Virgilijus
Valeika, Kęstutis Beleška, and
Violeta Valeikienė
Abstract. The bating of pelts after using peracetic acid for deliming was studied. It was established that the commonly used enzymes, which are active in alkaline media, acted weakly in such pelts: they did not remove scud and hair remnants from the grain of pelt satisfactorily. Enzyme preparations LITHUDAC L and Novo Bate WB, which are active in acid media, can be used for bating such pelts. These enzymes clean the grain of pelt well and do not affect the collagen of pelt markedly.
Key words: pelt, bating, acid medium, enzymes.
Toornaha pehmendamine
pärast peräädikhappega töötlemist
On uuritud toornaha
pehmendamist peräädikhappega töötlemise järel. On selgitatud, et tavaliselt
kasutatavad ensüümid, mis on aktiivsed leeliseses keskkonnas, ei eemalda
karvade kõrvaldamisel allesjäänud karvajäänuseid. Sellise toornaha
pehmendamiseks saab kasutada ensüümpreparaate LITHUDAC L ja Novo
Bate WB, mis on aktiivsed happelises keskkonnas. Need ensüümid puhastavad
naha põhjalikult ega mõju märgatavalt naha kollageenile.
Structure
and properties of polyurethane foams obtained from rapeseed oil polyols;
101–110
Uldis Stirna, Irina Sevastyanova,
Maria Misane, Ugis Cabulis,
and Ilze Beverte
Abstract. By transesterifying rapeseed oil with triethanolamine or glycerol, polyols with a hydroxyl number of 290–310 mg KOH/g were synthesized. water-blown rigid polyurethane foams (PUFs) with an isocyanate index of 150–250 were obtained from rapeseed oil polyols. Studies on the effect of the concentration of potassium oleate, the cyclotrimerization catalyst of isocyanate groups, on the conversion degree of isocyanate groups were carried out using FTIR spectroscopy. The optimal physical and mechanical properties of the obtained PUFs were achieved at an isocyanate index of 150–200. water-blown PUFs from rapeseed polyols, in contrast to water-blown PUFs from petrochemical polyols, are characterized by quite high hydrophobicity.
Key words: water-blown polyurethane foams, rapeseed oil polyols, isocyanate index, physical properties, mechanical properties.
Rapsiõli
polüoolidest saadud polüuretaanvahtude struktuur ja omadused
Kasutades puhumisagendina vett, on rapsiõli transesterdatud polüoolidest saadud erineva isotsüanaatrühmade sisaldusega vahtpolüuretaanid, millele on määratud füüsikalis-mehaanilised omadused. Optimaalse isotsüanaatrühmade sisaldusega vahtudele on iseloomulik kõrge hüdrofoobsus.
Properties of CuInS2 free surface
and the effect of conductive polymer layers on these properties;
111–119
Anatoly
Verbitsky, Yaroslav Vertsimakha, Petr Lutsyk, Sergei Studzinsky, Sergei
Bereznev, Julia Kois, Andres Öpik, and
Enn Mellikov
Abstract. The influence of thin conductive polymer layers on the surface photovoltage of CuInS2 (CIS) layers prepared using the so-called CISCuT method was studied. The deposition of poly(3,4-ethylenedioxythiophene) films on the free surface of CIS resulted in a small decrease in the height of the potential energetic barrier and in an increase in the efficiency of charge carriers transport through the CIS/polymer interface. The change of photovoltaic properties resulting from the polymer deposition on the free surface of CIS was also analysed for the carbazole polymers. Our results confirm the possibility of using the conductive polymer films as organic buffer layers in complete cell structures for photovoltaic cells based on the inorganic photoabsorber CIS.
Key words: CuInS2, photovoltaic structure, conductive polymer, interface.
Elektrit juhtiva
polümeerkile mõju CuInS2 pinna omadustele
On
uuritud EJP-kile mõju CISCuT-meetodil valmistatud CuInS2 (CIS) fotovoltomadustele.
On selgunud, et polü(3,4-etüleendioksütiofeen)- (PEDOT-)kile sadestamine CIS-i
pinnale alandab CIS/EJP ülemineku potentsiaalibarjääri kõrgust, soodustades
laengukandjate liikumist. On uuritud ka CIS-i struktuuri fotovoltomaduste
muutust C12H9N-i sadestamisel CIS-i pinnale. Töö
tulemused kinnitavad EJP-kilede kasutamise võimalikkust “puhverkihina”
fotovolthübriidsetes struktuurides koos CIS-i fotoabsorberkihiga.
Copyright
Transfer Agreement; 120