Mechanical Properties of UV Cured Mixture of Linear and Hyperbranched Urethane Acrylates

Ispitivane su smeše uretan akrilata na bazi linearnog poliestra i dva uretan akrilata, sa istim stepenom akrilovanja, na bazi alifatskih hiperrazgranatih poliestara (HRP). Linearni poliestar sintetisan je od neopentil glikola i adipinske kiseline. HRP treće generacije dobijen je od 2,2- bis(hidroksimetil)propionske kiseline i di-trimetilol propana. Modifikacija 60 % završnih OH grupa HRP-a izvedena je masnim kiselinama sojinog ulja ili izononskom kiselinom. Linearni uretan akrilat (LUA) i hiperrazgranati uretan akrilat (HUA) na bazi HRP modifikovanog masnim kiselinama sojinog ulja i HUA na bazi HRP modifikovanog izononskom kiselinom dobijeni su reakcijom određenog poliestra i izocijanatnog adukta, prethodno dobijenog reakcijom ekvimolarnih količina izoforon diizocijanata i 2-hidroksietil akrilata. Procena mešljivosti smeša LUA i HUA izvršena je na osnovu viskozimetrijskih merenja koristeći metodu koju je ustanovio Chee. Ovako pripremljenim smešama dodato je 20 mas. % heksandioldiakrilata i 4 mas. % fotoinicijatora, Irgacure 184, i umrežene su pod dejstvom UV zračenja. Umreženi uzorci ispitivani su u ogledima dinamičkog uvijanja i jednoosnog istezanja. Mehanička svojstva umreženih uzoraka zavise od mešljivosti komponenata smeše i od njenog sastava.The mixtures of urethane acrylate resin based on linear polyester and two urethane acrylates, with the same degree of acrylation, prepared from partially modified aliphatic hyperbranched polyesters (HBP), were examined. Linear polyester was obtained from neopentil glycol and adipic acid. HBP of the third generation was synthesized from 2,2-bis(hydroxymethyl)propionic acid and ditrimethylol propane. The modification of 60 % OH end-groups of HBP was carried out with soybean fatty acids or isononanoic acid. Linear urethane acrylate (LUA) and hyperbranched urethane acrylate (HUA) based on the HBP modified with soy been faty acid and HUA based on the HBP modified with isononanoic acid were obtained by reaction of appropriate polyester and NCO adduct, previously obtained by reaction of equimolar amount of isophorone diisocyanate and 2-hydroxyethyl acrylate. The miscibility of the prepared mixtures of LUA and HUAs was estimated according to viscosity measurements using the approach developed by Chee. UV curable formulation was obtained by adding hexanediol diacrylate (20 wt. %) and photoinitiator, Irgacure 184, (4 wt. %) to the prepared LUA and HUA mixtures. The UV cured samples were examined by dynamic torsion and uniaxial tension. It was obtained that mechanical properties of the UV cured samples depend on miscibility of mixture’s constituents and on its composition

Synthesis of new hyperbranched urethane-acrylates and their evaluation in UV-curable coatings

Three series of hyperbranched urethane-acrylates (HB-UA), based on aliphatic hyperbranched polyesters and polyethyleneglycol acrylate, were prepared and evaluated for use in UV-curable coatings. UV-curing kinetics were monitored by FT-IR spectroscopy. The thermal and mechanical properties of UV-cured HB-UA were investigated by means of differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) and correlated to the mechanical properties of coatings (hardness and flexibility). These new HB-UA's are very reactive and did not show oxygen inhibition. Obtained coatings have good mechanical properties and solvent resistance

Solution properties of hyperbranched polymers

Cilj ovog rada je proučavanje interakcija hiperrazgranatih polimera sa rastvaračem i ispitivana su njihova svojstva u rastvoru

The behavior of polyester-based hyperbranched polymers in dilute solution

Due to its molecular structure and large number of end groups, hyperbranched polymers and dendrimers have numerous specific properties that differ significantly to those of linear polymers of similar chemical composition. Consequently, in the past ten years, there has been an increasing number of publications in the literature devoted to the study of the influence of the molecular structure of these polymers on their properties in both the solid state and in solution [1,2,3]. The influence of the molar mass, i.e. the generation of hyperbranched polymers, HBP, of the polyester type on the values of the limiting viscosity number, cm3/g, and hydrodynamic radius, Rh, nm, of these macromolecules in various solvents at 25ºC, was studied. The obtained values of the limiting viscosity number, LVN, in various solvents were used to determine the solubility parameter of the investigated hyperbranched polymers, (J/m3)0.5

Blends of thermoplastic starch and some thermoplastic polymers

Thermoplastic starch (TPS) was blended in a twin screw mixer with 5 and 10 mass % of poly(ethylene-co-acrylic acid) (EAA), poly(ethylene-co-vinyl acetate) (EVA) or cellulose acetate (CA) in order to improve the TPS properties. The influence of such low amounts of thermoplastic polymer (TPP) on the processability, mechanical properties and water resistance of TPS was investigated. The specimens for mechanical properties determinaiton were conditioned at 45, 67 acid 85% relative humidity (RH) before measurements. Processability, characterized by viscosity vs. shear rate dependence, was determined by capillary rheometry. The obtained results showed that the TPS blends behaved as pseudoplastic polymers and that even 10 mass% of EAA or EVA significantly decreased the TPS viscosity, whereas addition of the same amount of CA had no influence on the TPS viscosity. Tensile measurements showed that the RH had a much larger influence on the tensile properties than the addition of the investigated TPP. Tensile strength and tensile modulus values for TPS and its blends, after conditioning at 45% RH were an order of magnitude larger than the values for the corresponding samples kept at 85% RH, whereas elongation at break values were nearly ten times smaller. Dynamic mechanical analysis of the TPS and its blends was performed using a mechanical spectrometer. The specimens were subjected to dynamic torsion at a constant frequency in the temperature range from 30 to 170 degrees C. The glass transition temperature, determined from the temperature dependence of tan delta, was influenced much more by relative humidity than by the type of TPP used. The swelling of the TPS and the investigated blends was determined gravimetrically. It was found that the TPS/EAA blends had the largest water resistance

Photoreactive hyperbranched urethane acrylates modified with a branched saturated fatty acid

Urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP) were synthesized. HBP of the second and the third pseudo-generation were synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of 60% of the OH end-groups was carried out with isononanoic acid. Urethane acrylates with different degrees of acrylation were obtained by reaction of partially modified HBP and different amounts of acrylate-isocyanate adduct (NCO), which had been previously obtained by reaction of equimolar amounts of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by FT-IR, H-1 and C-13 NMR spectroscopy and GPC. The rheological properties of uncured samples and the mechanical and thermal properties of UV cured urethane acrylates diluted with 20 wt.% hexanediol diacrylate were examined. The modification of the OH end-groups with isononanoic acid caused a rapid decrease in the viscosity of the HBPs. The examined properties of the urethane acrylates mainly depended on the degree of acrylation

UV-curable hyperbranched urethane acrylate oligomers containing soybean fatty acids

Urethane acrylate resins based on partially modified aliphatic hyperbranched polyesters (HBP) have been synthesized. HBP of the second and the third generation were synthesized from 2,2-bis(hydroxymethyl)propionic acid and di-trimethylol propane. The modification of certain amount of OH end-groups was carried out with soybean fatty acids. The urethane acrylates with different degrees of acrylation have been obtained by reaction of partially modified HBP and different amounts of NCO adduct which had been previously obtained by reaction of equimolar amounts of isophorone diisocyanate and 2-hydroxyethyl acrylate. The synthesized samples were characterized by FT-IR,H-1 and C-13 NMR and GPC. The theological properties of uncured samples and mechanical and thermal properties of UV cured urethane acrylates diluted with 20 wt.% hexanediol diacrylate were examined. The modification of OH end-groups with soybean fatty acids causes a rapid decrease in viscosity of HBP. The examined properties of urethane acrylates depend on the degree of acrylation. After irradiating, the additional cross-linking, which is caused by reaction of double bonds from unsaturated fatty acids, has also important effect on the properties of cured samples

Preparation of thermoplastic starch

Native starch and WX-starch, i.e., native starch enriched with amylopectin, were mixed with plasticizers and thermomechanically treated in a twin screw mixer in order to obtain thermoplastic starch. Ethylene glycol, propane tricl (glycerine) or poly(ethylene glycol) with a molar mass less than 1000 g/mol were used as plasticizers. Transformation to thermoplastic starch was only successful when glycerine or ethylene glycol were used as the plasticizers, the temperature of the thermomechanical treatment being dependent on the plasticizer and starch used. Rheological properties of the obtained thermoplastic starch were determined using a mechanical spectrometer. As a result of these measurements, the complex viscosity (η*), shear moćulus of stored (G') and of lost energy (G'') were obtained as a function of frequency at constant temperature. The measurements were performed at three temperatures: 140, 170 and 210°C. The results obtained showed that the thermoplastic starch behaved like a typical thermoplastic polymer

Dynamical mechanical analysis of photocrosslinked hyperbranched urethane acrylates

A series of acrylate functionalized samples based on hyperbranched hydroxy-terminated polyesters with different molecular weights and different degrees of acrylation were synthesized. The obtained urethane acrylates were slightly yellow viscose liquids. Their composition characterized by FTIR and H-1-NMR spectroscopy and their molecular weights were measured by GPC. All the synthesized samples were diluted with 25 wt.% 1.4-butanediol dimethacrylate (BDDM). The rheological properties of the uncured samples and the dynamic mechanical properties of the UV cured samples were examined. All the samples exhibit Newtonian behavior, which indicates the absence of physical entanglements in these polymers. The viscosity increases with increasing number of acrylic groups per molecule. The glass transition temperature of the UV cured samples increases with increasing the number of acrylic groups per molecule. The value of the storage modulus in the rubber-elastic plateau and the cross-link density increase with increasing number of acrylic groups per molecule. The formed networks are inhomogeneous and the residual unsaturation is the highest in the samples with the largest number of acrylic groups per molecule