1,721,105 research outputs found
Adhesion of UV-curable resins containing alkoxysilane monomers on glass surfaces
No full textA study of UV curable systems containing different alkoxysilane monomers coated on glass surfaces was performed with the aim of deeping the knowledge of the mechanism of adhesion between the two phases. Different amounts of monomerscontaining alkoxysilane groups
(methacryloiloxypropyltrimethoxysilane, MEPTS, and mercaptopropyltrimethoxysilane, MPTS) were introduced in a typical epoxy—acrylic resin network by means of UV curing technique and linked to the network through copolymerization (MEPTS) or chain transfer (MPTS) reaction.
After UV curing, the formation of adhesion bonds. between the polymer network and the glass surface was investigated at 100°C and at room temperature. Higher adhesion values and faster bonding formation were obtained by using MPTS monomer with respect to MEPTS. In order to obtain more information about these systems, some XPS analyses on both the sides of the films and on the bulk were performed. Differences in the. atomic content on the two sides of the films are evidenced and discussed. Wetting tension measurements are in agreement with XPS analysis results. On the basis of the surface analyses data, the adhesion results obtained In the presence of the
two alkoxysilane monomers are attributed to the different network structures and crosslinking densities
Studio mediante analisi DSC della copolimerizzazione in massa dell'N-vinilpirrolidone con dialchil-maleati o fumarati
No full textL'analisi termica differenziale si presenta ccm una tecnica interessante per lo studio della copolimerizzazione radicalica in massa di questi monomeri fornendo utili informazloni sulla cinetica della reazione, sulla conversione a polimero e sulla reattività relativa dei monomeri
maleici e fumarici. Questa tecnica inoltre si presenta estremamente flessibile potendosi operare sia in condizioni isoterme che con scansione di temperatura in presenza di iniziatori termolabili o anche con reazione iniziata per via fotochimica
Polymer-metal adhesion promoters in UV curable coatings
Full text linkDifferent types of acrylic monomers containing functional groups able to improve adhesion on steel substrates were prepared and introduced in a typical UV curable epoxy-acrylic system based on a bisphenol-A-diglycidyl-ether diacrylate with a reactive diluent mixture. The adhesion properties of the films obtained after UV curing were measured and related to the presence of different types of functional groups in the resin. Monomers like esters of phosphoric acid with hydroxy-alkyl-acrylates, adducts of hydroxy-alkyl-acrylates on 2-methyl-2,5-dioxo-1-oxa-2-phospholane, acrylic and methacrylic acids and their esters containing free carboxylic groups were taken into account. The results obtained show that the adhesion properties depend on the type of functional group present and on the structure of the monomer. Humidity and solvent resistance tests were performed on film containing the additives homogeneously mixed or added as a thin layer on the substrate surface. The results obtained in the different conditions are reported and discussed
Factors influencing the adhesion properties of radiation curable coatings on different substrates
No full textThe adhesion properties of UV-curabIe coatings based on a typical epoxy acrylate resin, modified by the presence of different reactive diluents or adhesion promoters, on several substrates (steel, glass, polycarbonate) were evaluated, The influence of some general factors like volume shrinkage, substrate wetting, and relaxation of the internal stresses was taken into account. Specific interactions between the coatings and the substrates were introduced by using adhesion promoters (monomers containing free carboxylic and phosphorus acidic groups) on steel or coupling agents (alkoxysilane monomers) on glass. In the case of polycarbonate substrate, adhesion was obtained
through the presence of particular monomers able to interact with the substrate, thus suggesting a.diffusion-controlled adhesion mechanism.
The results obtained are discussed in the framework of the different mechanisms of adhesion involved
Cationic Oligomerization of 3-Methyl-1-Butene Catalyzed by BF3- Protonic Donor Complexes
No full textThe oligomerization of 3-methyl-1-butene was carried out in the presence, as catalysts, of BF3 complexes with different protonic donors (CH3OH, H2O, CH3CH2COOH, H3PO4) in a 1:1 molar composition. By working in n-hexane solution at temperatures between 0 and 70°C only unsaturated low MW oligomers (dimers to hexamers) were obtained. Each oligomer was a complex mixture of isomeric olefins as revealed by GLC and GLC-MS analysis. The presence of some fragmentation products containing one carbon atom more or less than the oligomer was pointed out. The results obtained show that the MW of the oligomers decreases by increasing the acidity of the protonic donor used as complexing agent of BF3. By increasing the temperature a decrease of the MW and an increase of the presence of fragmentation products was obtained
Some aspects of UV curable coatings on plastic substrates
No full textThe coatings of polycarbonate sheets with UV curable systems based on an epoxy acrylic res in the presence of different reactive diluent were investigated. A correlation was observed between the capacity to dissolve the polycarbonate and the adhesion on the plasic substrate. The adhesion is influenced by the diffusion of the monomer of the coating into the polycarbonate substrate. FTIR-ATR spectra support this meechanism. Analyses show the presence of glass transition typical of the two phases. In the case of good adhesion on the plastic substrate the presence of a transition layer between the two phases is indicated
Uv-curable coatings on plastic substrates: dynamic mechanical thermal analysis and Fourier transform infra-red analysis of the interfacial layer
No full textThe coating of a plastic substrate (polycarbonate sheets) with different uv-curable system was investigated. Systems based on an epoxy-acrylate resin (bisphenol-A-diglycidyl-ether-diacrylate) or on bisphenol-A-diethoxy-diacrylate were used in the presence of different reactive diluents. Pull-off experiments indicated that the presence of a reactive diluent able to dissolve or swell the polycarbonate matrix increased the adhesion properties; poor adhesion values were obtained by using reactive diluents which did not dissolve the polymer. When vinyl-pyrrolidone (VP) was used as a reactive diluent, Fourier transform infra-red analysis indicated that the VP diffused into the polycarbonate matrix. Dynamic mechanical thermal analyses performed on thin films of polycarbonate coated with these systems showed the presence of two glass transition regions attributable to the two polymeric phases. In the presence of diluent, the tan regions attributable to the two polymeric phases. In the presence of VP diluent, the tan delta peak of the coating phase was broader, thus suggesting the presence of a transition layer between the two phases
Oligomerizzazione cationica controllata di monomeri olefinici
No full textE' stato intrapreso lo studio della oligomerizzazione catalizzata da acidi di particolari monomeri olefinici e sono stati caratterizzati i prodotti ottenuti mediante gascromatografia, GPC, MS e spettrometria IR
Studio della fotopolimerizzazione di composti poliacrilici mediante tecniche calorimetriche e spettroscopia FTIR
No full textIn questo lavoro riporta la messa a punto di un'apparecchiatura di analisi DSC di spettroscopia IR per Io studio della fotopolimerizzazlone di composti UV reticolabili ed i primi risultati ottenuti nell'esame di alcuni composti diacrilici
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