The Experts below are selected from a list of 2322 Experts worldwide ranked by ideXlab platform

Hyunjoong Kim - One of the best experts on this subject based on the ideXlab platform.

  • uv curing behavior and physical properties of waterborne uv curable polycarbonate based Polyurethane Dispersion
    Progress in Organic Coatings, 2011
    Co-Authors: Hyeondeuk Hwang, Hyunjoong Kim, Chohee Park, Jeik Moon, Tetsuo Masubuchi
    Abstract:

    Abstract Waterborne UV-curable Polyurethane Dispersions were synthesized from C5/C6 copolymers of polycarbonate diol(PCDL)s and different end-capping groups. The effects of the polyol molecular weight on the UV-curing behavior and physical properties were examined according to the molecular weight (800, 1000, 2000 g/mol) of PCDL. The UV-curing behavior was analyzed by Fourier transform infrared spectroscopy and photo-differential scanning calorimetry. The influence of the functionality of the end-capping group on the UV-curing behavior and physical properties were also investigated in a similar manner. 2-Hydroxyethylmethacrylate, 2-hydroxyethylacrylate and pentaerythritol tri-acrylate were used to impart mono-methacrylate, mono-acrylate and tri-acrylate functionality to the end-capping group, respectively. The pendulum hardness, curing rate and conversion increased with decreasing molecular weight of the PCDL. The pendulum hardness, curing rate and conversion of Dispersion with tri-acrylate functionality on end-capping groups were much higher than those of the other Dispersions with mono-methacrylate or mono-acrylate functionality.

  • uv curable low surface energy fluorinated polycarbonate based Polyurethane Dispersion
    Journal of Colloid and Interface Science, 2011
    Co-Authors: Hyeondeuk Hwang, Hyunjoong Kim
    Abstract:

    Abstract UV-curable low surface energy fluorinated polycarbonate-based Polyurethane Dispersions were synthesized by incorporating a hydroxy-terminated perfluoropolyether (PFPE) into the soft segment of Polyurethane. The effects of the PFPE content on the UV-curing behavior, physical, surface, thermal properties and refractive index were investigated. The UV-curing behavior was analyzed by photo-differential scanning calorimetry. The surface free energy of the UV-cured film, which is related to the water or oil repellency, was calculated from contact angle measurements using the Lewis acid–base three liquids method. The surface free energy decreased significantly with increasing fluorine concentration because PFPE in the soft segment was tailored to the surface and produced a UV-cured film with a hydrophobic fluorine enriched surface, as confirmed by X-ray photoelectron spectroscopy. With increasing the fluorine content, the refractive indices of UV-cured films decreased. However, the UV-curing rate and final conversion was decreased with increasing contents of PFPE, which resulted in the decrease of the glass transition temperature ( T g ), crosslink density, tensile strength and surface hardness.

Hyeondeuk Hwang - One of the best experts on this subject based on the ideXlab platform.

  • uv curing behavior and physical properties of waterborne uv curable polycarbonate based Polyurethane Dispersion
    Progress in Organic Coatings, 2011
    Co-Authors: Hyeondeuk Hwang, Hyunjoong Kim, Chohee Park, Jeik Moon, Tetsuo Masubuchi
    Abstract:

    Abstract Waterborne UV-curable Polyurethane Dispersions were synthesized from C5/C6 copolymers of polycarbonate diol(PCDL)s and different end-capping groups. The effects of the polyol molecular weight on the UV-curing behavior and physical properties were examined according to the molecular weight (800, 1000, 2000 g/mol) of PCDL. The UV-curing behavior was analyzed by Fourier transform infrared spectroscopy and photo-differential scanning calorimetry. The influence of the functionality of the end-capping group on the UV-curing behavior and physical properties were also investigated in a similar manner. 2-Hydroxyethylmethacrylate, 2-hydroxyethylacrylate and pentaerythritol tri-acrylate were used to impart mono-methacrylate, mono-acrylate and tri-acrylate functionality to the end-capping group, respectively. The pendulum hardness, curing rate and conversion increased with decreasing molecular weight of the PCDL. The pendulum hardness, curing rate and conversion of Dispersion with tri-acrylate functionality on end-capping groups were much higher than those of the other Dispersions with mono-methacrylate or mono-acrylate functionality.

  • uv curable low surface energy fluorinated polycarbonate based Polyurethane Dispersion
    Journal of Colloid and Interface Science, 2011
    Co-Authors: Hyeondeuk Hwang, Hyunjoong Kim
    Abstract:

    Abstract UV-curable low surface energy fluorinated polycarbonate-based Polyurethane Dispersions were synthesized by incorporating a hydroxy-terminated perfluoropolyether (PFPE) into the soft segment of Polyurethane. The effects of the PFPE content on the UV-curing behavior, physical, surface, thermal properties and refractive index were investigated. The UV-curing behavior was analyzed by photo-differential scanning calorimetry. The surface free energy of the UV-cured film, which is related to the water or oil repellency, was calculated from contact angle measurements using the Lewis acid–base three liquids method. The surface free energy decreased significantly with increasing fluorine concentration because PFPE in the soft segment was tailored to the surface and produced a UV-cured film with a hydrophobic fluorine enriched surface, as confirmed by X-ray photoelectron spectroscopy. With increasing the fluorine content, the refractive indices of UV-cured films decreased. However, the UV-curing rate and final conversion was decreased with increasing contents of PFPE, which resulted in the decrease of the glass transition temperature ( T g ), crosslink density, tensile strength and surface hardness.

Tetsuo Masubuchi - One of the best experts on this subject based on the ideXlab platform.

  • uv curing behavior and physical properties of waterborne uv curable polycarbonate based Polyurethane Dispersion
    Progress in Organic Coatings, 2011
    Co-Authors: Hyeondeuk Hwang, Hyunjoong Kim, Chohee Park, Jeik Moon, Tetsuo Masubuchi
    Abstract:

    Abstract Waterborne UV-curable Polyurethane Dispersions were synthesized from C5/C6 copolymers of polycarbonate diol(PCDL)s and different end-capping groups. The effects of the polyol molecular weight on the UV-curing behavior and physical properties were examined according to the molecular weight (800, 1000, 2000 g/mol) of PCDL. The UV-curing behavior was analyzed by Fourier transform infrared spectroscopy and photo-differential scanning calorimetry. The influence of the functionality of the end-capping group on the UV-curing behavior and physical properties were also investigated in a similar manner. 2-Hydroxyethylmethacrylate, 2-hydroxyethylacrylate and pentaerythritol tri-acrylate were used to impart mono-methacrylate, mono-acrylate and tri-acrylate functionality to the end-capping group, respectively. The pendulum hardness, curing rate and conversion increased with decreasing molecular weight of the PCDL. The pendulum hardness, curing rate and conversion of Dispersion with tri-acrylate functionality on end-capping groups were much higher than those of the other Dispersions with mono-methacrylate or mono-acrylate functionality.

Matjaž Krajnc - One of the best experts on this subject based on the ideXlab platform.

  • seeded semibatch emulsion copolymerization of methyl methacrylate and butyl acrylate using Polyurethane Dispersion effect of soft segment length on kinetics
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2004
    Co-Authors: Urska Sebenik, Matjaž Krajnc
    Abstract:

    Abstract Aqueous acrylic–Polyurethane (AC–PU) hybrid emulsions were prepared by semibatch emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) in the presence of two Polyurethane (PU) Dispersions. PU Dispersions were synthesized using isophorone diisocyanate (IPDI), 1000 or 2000 molecular weight poly(neopentyl)adipate, and dimethylol propionic acid (DMPA). The monomer mixture was added in the monomer emulsion feed. We studied the effect of PU chain rigidity on the rate of polymerization, the particle size and distribution, the number of particles, and the average number of radicals per particle. The rigidity was controlled by varying the molecular weight (Mn) of the polyol, which represents the soft chain segment. The monomer feed rate was varied in order to study its influence on the process. It was observed that PU particles, prepared with higher molecular weight polyol, swelled to a greater extent with acrylic (AC) component. In the pseudo steady state the polymerization rate acquired a constant value, comparable to the value of monomer addition rate. The total particle number in the reactor in the pseudo steady state was constant and similar to the number of PU particles in the initial charge. The obtained results suggested that the MMA/BA copolymerization in the presence of PU seeds showed intermediate behavior between Smith-Ewart cases I and II.

  • the structure and properties of acrylic Polyurethane hybrid emulsions and comparison with physical blends
    Journal of Applied Polymer Science, 2000
    Co-Authors: Dolores Kukanja, Janvit Golob, A Zupancicvalant, Matjaž Krajnc
    Abstract:

    Aqueous acrylic-Polyurethane hybrid emulsions were prepared by semi- batch emulsion polymerization of a mixture of acrylic monomers (butyl acrylate, methyl methacrylate, and acrylic acid) in the presence of Polyurethane Dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and Polyurethane Dispersion. The weight ratio between acrylic and Polyurethane components varied to obtain differ- ent emulsion properties, microphase structure, and mechanical film properties of hy- brid emulsions and physical blends. Particle size and molecular mass measurements, scanning electron microscopy, glass transition temperature, and rheological measure- ments performed characterization of the latex system. The mechanical properties were investigated by measuring tensile strength and Koenig hardness of dried films. The experimental results indicate better acrylic-Polyurethane compatibility in hybrid emul- sions than in physical blends, resulting in improved chemical and mechanical proper- ties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 67- 80, 2000

Mona A. Kulkarni - One of the best experts on this subject based on the ideXlab platform.

  • Effect of dicarboxylic acids on the performance properties of Polyurethane Dispersions
    Journal of Applied Polymer Science, 2010
    Co-Authors: Vilas D. Athawale, Mona A. Kulkarni
    Abstract:

    A series of low molecular weight linear polyester polyols were synthesized by using various diacids, neopentyl glycol, as a diol, and a trimethylol propane, as a branching monomer. Polyurethane Dispersions were prepared primarily from isophorone diisocyanate, polyester polyol, and dimethylol propionic acid, as potential ionic center for water dispersibility, and were subsequently chain extended with ethylene diamine. The effect of polyester polyols based on variable diacids, on the physico-chemical and thermal properties of Polyurethane Dispersions were evaluated by hardness, flexibility, impact resistance, solvent resistance, thermogravimetric analysis, and differential scanning calorimetry. Particle size was evaluated by particle size analyzer. It was observed that the number of alkylene groups present in the polyester polyol soft segment in addition to its molecular weight had a pronounced effect on the particle size, physico-chemical, and thermal properties. With a proper selection of the soft segment, it is possible to fine-tune properties of aqueous Polyurethane Dispersion coatings with respect to the final application. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

  • preparation and properties of urethane acrylate composite by emulsion polymerization technique
    Progress in Organic Coatings, 2009
    Co-Authors: V D Athawale, Mona A. Kulkarni
    Abstract:

    Abstract Aqueous Polyurethane–acrylic hybrid emulsions were prepared by semibatch emulsion polymerization of a mixture of acrylic monomers (styrene, butyl acrylate and acrylic acid) in the presence of Polyurethane Dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and Polyurethane Dispersion. The weight ratio between acrylic and Polyurethane components was varied to obtain enhanced performance properties and microphase structure of hybrid latexes. The synthesized emulsion hybrids and physical blends were characterized by fourier transform infrared spectroscopy, thermogravimetric analysis. The experimental results indicate better acrylic–Polyurethane compatibility in hybrid emulsions than in physical blends, resulting in improved chemical and mechanical properties. The blend ratio 50:50% (w/w) exhibited synergistic effects between the two polymers and revealed remarkable improvement in various coating properties over other blend ratios and the individual resin components.

  • Synthesis and evaluation of acrylate modified Polyurethane Dispersion by semibatch emulsion polymerization technique
    2009
    Co-Authors: Vilas D. Athawale, Mona A. Kulkarni
    Abstract:

    Polyurethane Dispersions (PUDs) have been an active area of research since the early 1940s because of legislative restrictions on the use of organic solvents in conventional solvent-based products. However, PUDs are not a direct plug-in for the solvent-based Polyurethanes. One of the drawbacks of PUDs is their relatively higher cost To compensate for the higher cost and to improve the property/performance, the PUDs are blended with other low cost acrylic emulsions. Aqueous Polyurethane- acrylic hybrid emulsion was prepared by emulsion polymerization of a mixture of acrylic monomers (butyl acrylate, styrene, and acrylic acid) in the presence of Polyurethane Dispersion and characterized by using infrared spectroscopy, particle size analyzer, scanning electron microscopy. The thermal and mechanical properties were examined by thermogravimetric analyzer, differential scanning calorimetry and hardness testers. It was found that the thermal resistance chemical resistance, hardness, glass transition temperature can be noticeably increased by acrylate incorporation in PU matrix. The morphology of hybrid Dispersion was well defined and properly controlled by latex composition and compatibility of both phases.