• The Journal of Korean Academy of Prosthodontics
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• v.36 no.3
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• pp.453-467
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• 1998

This study helps to clarify conflicting reports by comparing the physical properties and accuracy of complete denture processed by the pack and press technique, continuous- pressure injection technique(SR-Ivocap system) and Mark press technique. The 6 different specimens have been evaluated using the SEM, Impact test, DSC (Differential Scanning Calorimetry) and DMTA (Dynamic Mechanical Thermal Analysis). Each sample was made of SR-Ivocap resin and QC-20 resin by different processing methods. The results were as follows ; 1. As the result of the observation on the fracture surface of resin by use of SEM, sample SR-Ivocap resin cured by continuous pressure injection method showed the most homogeneous structure. This is why molecules in SR-Ivocap resin have no orientation. 2. As the result of the Impact test in order to measure the deformity, fracture energy and impact resistance of resin, the samples with QC-20 acrylic resin and SR-Ivocap resin cured by continuous pressure injection method were exellent. 3. In consequence of measuring ${\alpha}$-glass transition temperature by use of DSC on the basis of temperature change, the glass transition temperatures of sample QC-20 resin cured by pack and press method and sample SR-Ivocap resin cured by continuous pressure injection method were very similar. Thus volumetric stability could not be evaluated only by glass transition temperature. 4. In comparing volumetric stability data by DMTA, the glass transition temperature(Tg) showed $137.88^{\circ}C$ at sample QC-20 resin cured by pack and press method and $139.78^{\circ}C$ at sample SR-Ivocap resin cured by continuous pressure injection method. Therefore sample SR-Ivocap resin cured by continuous pressure injection method seems to be superior to sample QC-20 resin cured by pack and press method in the dimensional stability at high temperature. 5. In comparing storage modulus data by DMTA, the storage modulus of sample SR-Ivocap resin cured by continuous pressure injection method was higher than that of sample QC-20 resin cured by pack and press method. So. sample SR-Ivocap resin cured by continuous pressure injection method seems to be superior to sample QC-20 resin cured by pack and press method in impact strength.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.59-65
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• 1998

Morphology and thermal properties of polyurethane synthesized from 4,4'-diphenylmethane diisocyanate (MDI), polyester polyol, and 1,4-butane diol are investigated using fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and dynamic mechanical thermal analysis (DMTA). From the FT-IR study, it is found that the stretching peaks of hydrogen bonded N-H and C=O are shifted to the low frequencies with the increase of hard segment content of the polyurethanes. The shift of the stretching peaks of hydrogen bonded N-H and C=O indicates that the degree of hydrogen bonding is increased. From the DSC study, it appears that the glass transition temperature ($T_g$) of the polyurethanes is increased with the increase of the hard segment content. Also, it is found that the polyurethanes investigated in this study have the homogeneous network structure due to the high functionality of the MDI. From the DMTA study, transition of the soft segment was not found. Therefore it is concluded that the polyurethanes investigated in this study have the one-phase morphology which is consistent with the DSC results.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1212-1215
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• 2004

Diffraction modes of holographic grating were fabricated with polyurethane acrylates(PUA). Two types of silica (AEROSIL 200 and AEROSIL R812) were added to reduce the shrinkage of polymer matrix. It was founded that shrinkage of PUA composite film was reduced with the addition of silica. HPDLC based PUA/silica composite also showed high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.520-523
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• 2003

We used three types of reactive diluents with different chemical structures, N-vinyl-pyrrollidone(NVP), ethyl hexyl acrylate(EHA) and hydroxyehtyl methacrylate(HEMA). It was founded that N-vinylpyrrollidone(NVP) and ethyl hexyl acrylate(EHA) based PUA with low molecular weight polypropylene glycol(PPG) at low oligomer content give high diffraction efficiency. The morphology of the resultant gratings was analyzed by using scanning electron microscopy(SEM) and Tg of the polymer matrix by dynamic mechanical thermal analysis(DMTA).

• Proceedings of the Korean Fiber Society Conference
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• 1996.04a
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• pp.64-68
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• 1996

PP-EVOH(poly(vinyl alchol-co-ethylene)) blends were prepared by the mixing of polypropylene and poly(vinyl alcohol-co-ethylene) containing 38mol% of ethylene units (EVOH38) at melt state above PP melting temperature. The materials were characterized by using dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and contact angle measurement to detemine the glass transition, meltin, decomposition temperatures, and wettability respectively. From the results, PP-EVOH(poly(vinyl alcohol-co-ethylene)) blends exgibits partial miscibility.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.148-153
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• 1999

In situ composites containing a thermotropic liquid crystalline polymer were prepared by polycondensation of 1,4-bis(p-hydroxy-benzoyloxy)butane with 2-bromoterephthaloyl chloride in a poly(methyl methacrylate) solution. Morphology and mechanical, thermal properties of the composites were examined by differential scanning calorimeter(DSC), dynamic mechanical thermal analyser(DMTA), optical microscope and scanning electron microscope(SEM). The TLCP domains showed nematic phase. The glass transition temperature($T_g$) and mechanical properties of the PMMA in the composites increased with increasing the content of TLCP. The TLCP domains were finely dispersed in the PMMA matrix. The 20 wt % TLCP/PMMA composite prepared by in situ polymerization showed more improved mechanical property with finely well dispersed morphology compared with that prepared by solution blending of the same composition.

• Polymer(Korea)
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• v.31 no.4
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• pp.289-296
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• 2007

The material factors influencing the sound absorption of the polyurethane foam were investigated with FT-IR, small-angle X-ray scattering (SAXS), and dynamic mechanical thermal analyzer (DMTA). The measurements were performed using the samples which had a similar cell structure but different absorption coefficients. It was found that the ability of the sound absorption of the polyurethane foams was closely related to the damping behavior over the transition range. In order to confirm the use of the low monol polyol (LMP) in high-performance applications, the polyurethanes based on LMP and polypropylene oxide polyol (PPG) were prepared by the solution polymerization method. The microstructure and the physical properties of these polyurethanes were compared. The PPG-based polyurethane showed a higher level of the phase-separated structure because the considerable amount of monol presented in PPG made a contribution to the increased chain mobility. However the short chains formed due to the monol species deteriorated the damping property. As a result, the LMP-based polyurethane showed the superior damping behavior as compared with the PPG-based one.

• Journal of Adhesion and Interface
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• v.13 no.4
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• pp.156-162
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• 2012

Polyurethane (PU)/organoclay nanocomposites were prepared by mixing UV curable urethane acrylate oligomer with organoclay, and a subsequent curing by UV irradiation. As organoclays, commercially available Cloisite 20A (C20A) and acrylsilane modified C20A were used. XRD and TEM analyses revealed that the UV cured PU/clay nanocomposites formed intercalated nanocomposites, and acrylsilane modified C20A are dispersed more finely than unmodified C20A in PU matrix. DMTA, pencil hardness and adhesion test onto PET substrate showed that the clay nanolayers induced an increase in the properties, and the enhancement in the properties was more pronounced in the PU/acrylsilane modified C20A nanocomposites than in the PU/unmodified C20A nanocomposites. It was also observed that the PU/surface modified clay nanocomposites showed remarkably lower shrinkage upon UV curing than the unfilled PU. The nanocomposites showed excellent optical transparency but lower gloss as compared to unfilled PU.

• Textile Coloration and Finishing
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• v.13 no.3
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• pp.188-196
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• 2001

1, 1-diamino-3, 3, 5, 5-tetrachlorocyclotriphosphazene, 1, 1-diami-no3, 3, 5, 5-tetra-(p-bromophenoxy)cyclotriphosphazene, and 1, 1-diamino-3, 3, 5, 5-tetra-(p-chlorophenoxy) cyclotri-phosphazene(ACPP) was prepared from hexachlorocyclotriphosphazene and used for the curing agent of bisphenol A type epoxy resin and phenol novolak. The resistance to chemicals and water of the cured epoxy resins were examined by DMTA and compared with those of the epoxy rosins cured with phosphazene derivatives and 4, 4'-diaminodiphenylmethane. The effect of the curing agent on resistance to chemicals and water of the cured epoxy resins were investigated. The epoxy resins cured with 1, 1-diamino-3, 3, 5, 5-tetrachlorocyclotriphosphazene and 1, 1- diamino-3, 3, 5, 5-tetra- (p-bromophenoxy)cyclotriphosphazene showed superior resistance to chemicals and water to those of 1, 1-diamino-3, 3, 5, 5-tetra- (p-chlorophenoxy)cyclotriphosphazene and 4, 4'-diaminodiphenylmethane. It is an effective curing agent for epoxy resins to enhance the resistance to chemicals, water and tome proofing.

• Korea-Australia Rheology Journal
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• v.19 no.4
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• pp.227-232
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• 2007

The use of various shearing apparatuses to study the phase behavior of poly(styrene-b-isoprene) diblock copolymer micelles is described. A DMTA rheometer was modified so that one can apply oscillatory shear and obtain the scattering pattern along the shear gradient direction. A cone and plate shear cell was designed to access scattering along the shear vorticity direction, and both oscillatory and steady shear can be applied. The most popular way to employ steady shear on relatively low viscosity fluids is to use a Couette cell, because a high shear rate can be readily achieved without disturbing the sample by overflow. In this work, oscillatory shear was used to obtain a single crystal-like scattering pattern, and thereby to examine the mechanism of the thermotropic transition between face-centered cubic (fcc) and body-centered cubic (bcc) lattices. By applying the steady shear, the response of the fcc lattices to various shear rates is discussed.