• Polymer(Korea)
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• v.35 no.6
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• pp.537-542
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• 2011

Fracture behaviors of polycarbonate (PC)/polyestrercarbonate (PEC) blends and their miscibility have been examined to find out the mechanism of ductilie-brittle transition of fracture behavior which would be a main governing factor on the thickness sensitivity of impact strength of PC. $T_g$ measurement showed that PEC with a carbonate content higher than 30 mol% was miscible with PC. In the notched Izod impact test of PC, ductile-brittle transition occurred in the range of 4 to 5 mm thickness. The impact strength of miscible PC/PEC5 blends ductile-fractured in the thin specimens decreased with increasing PEC5 content, which was in accordance with the decrease of elongation at break in tensile test. In the brittle fracture of the thick specimens, the impact strength was well correlated with the plastic zone size in the vicinity of the notch tip.

• Current Photovoltaic Research
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• v.7 no.3
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• pp.55-60
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• 2019

Polymer:nonfullerene solar cells with an inverted-type device structure were fabricated by employing the bulk heterojunction (BHJ) active layers, which are composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) and 3,9-bis(6-methyl-2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3-d']-s-indaceno[1,2-b:5,6-b']dithiophene (IT-M). The BHJ layers were formed on a pre-patterned indium-tin oxide (ITO)-coated glass substrate by spin-coating using the blend solutions of PBDB-T and IT-M. The solar cell performances were investigated with respect to the cell position on the ITO-glass substrates. In addition, the short-term shelf lifetime of solar cells was tested by storing the PBDB-T:IT-M solar cells in a glovebox filled with inert gas. The results showed that the performance of solar cells was relatively higher for the cells close to the center of substrates, which was maintained even after storage for 24 h. In particular, the PCE of PBDB-T:IT-M solar cells was marginally decreased after storage for 24 h owing to the slightly reduced fill factor, even though the open circuit voltage was unchanged after 24 h.

• Journal of Adhesion and Interface
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• v.23 no.4
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• pp.137-143
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• 2022

In this study, the polyurethane acrylates (PUA) resin with good adhesive and flexibility for adhesive for shoes and clothing were synthesized using that poly(tetramethylene adiphate glycol) (PTAd), poly(tetramethylene ether glycol) (PTMG) as polyester polyol and polyether polyol respectively, including 4,4'-methylene diphenyl diisocyanate (MDI), isophorone diisocyanate (IPDI), 1,4-butandiol (1,4-BD), 2-hydroxyethyl methacrylate (2-HEMA) and dibutyl amine (DBA). The effect of polyol blend in the polyurethane acrylate on thermal and mechanical properties, adhesion strength and flexural strength were studied. The glass transition temperature (T_g) of PUA was confirmed in range of -70~-40 ℃. In addition, the glass transition temperature (T_g), decomposition temperature (T_d), tensile strength adhesion strength and heat resistance were increased as increasing of PTAd amount while the elongation, water resistance and flexural properties were decreased. The synthesized polyurethane acrylate with 5:5 ratio of PTAd and PTMG indicated the highest adhesion strength and flexural properties.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.743-747
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• 1999

The component polymer was modified to enable the formation of intermolecular hydrogen bonding in the immiscibile polystyrene(PS)/polymethacrylate(PMA) blends. The mole percentages of hydroxystyrene of the poly(styrene-co-4-hydroxystyrene) copolymer(modified polystyrene, MPS) were controlled to 7%, 10% and 18%, respectively. MPS was used with PMA to study the variation of the miscibility in blends. PMA which had such different length of side chain as methyl, butyl, hexyl and ethylhexyl, respectively, was selected to study the effect of side chain length on the formation of intermolecular hydrogen bonding. As the hydroxyl content of MPS increased, the formation of intermolecular hydrogen bonding increased. The length of side chain of PMA had enormous effect on the miscibility of blend as confirmed from the result of cloud point measurement. As the length of side chain increased, the formation and the strength of intermolecular hydrogen bonding decreased severely due to the steric effect and the increased chain mobility.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.171-176
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• 2013

The need of volatile organic compound (VOC) free coating material has been increased to solve environmental problems such as the global warming. Nowadays, about 70~80% of coating materials used in the worldwide are a liquid type. Therefore, the development of non-solvent coating material that can minimize VOCs emissions is necessary to solve the global warming problem. In this study, acrylic monomers were added to develop non-solvent paints in order to improve disadvantages of the poor adhesion of a conventional phenolic resin caused by acidification. As a result, the blend resins of 2.818 Mpa phenol- formaldehyde resin/poly methyl methacrylate (PE/PMMA) has the best properties and performances for the adhesives.

• Korea-Australia Rheology Journal
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• v.11 no.3
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• pp.255-263
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• 1999

Blends of two thermotropic liquid crystalline polymers, HX2000 and Vectra A950, were prepared by melt blending. Effects of transesterification on these blends are investigated by comparing properties of the blends with and without the addition of an inhibitor, in terms of blend miscibility and rheology. Both the uninhibited and inhibited blends are found to be largely immiscible with very limited miscibility in HX2000-rich phase. No strong evidence indicates the occurrence of transesterification in the blends in the solid state. Dynamic rheological behaviour, such as shear storage modulus (G') and shear loss modulus (G") as a function of frequency, of the blends are interpreted by a three-zone model. HX2000 shows terminal-zone and plateau-zone behaviour, whilst Vectra A950 shows plateau-zone and transition-zone behaviour. The un- inhibited blends show plateau-zone behaviour up to 50% Vectra A950 content and the inhibited blends show plateau-zone behaviour up to 60% Vectra A950 content. Compositional dependence of the complex viscosities of the uninhibited and inhibited blends displayed positive deviations from additivity, which is a characteristic feature for the immiscible thermoplastic blends. When under steady shear, both the uninhibited and inhibited blends show shear thinning behaviour and their viscosities decrease monotonically with the addition of Vectra A950. Compositional dependence of the steady shear viscosities of the two sets of blends displayed negative deviations from additivity and the uninhibited blends were more viscous than the inhibited blends for the full composition range. Although limited agreement with the Cox-Merz rule is found for the inhibited blends, these two sets of blends, in general, do not follow the rule due to their liquid crystalline order and two-phase morphology. Despite being immiscible blends, transesterification, such as polymerization, in the blends might occur during the rheological characterization, supported by the facts that uninhibited blends show HX2000-dominant behaviour at lower Vectra A950 content and are more viscous than the inhibited blends. The addition of transesterification inhibitor in such blends is advised if only physical mixing is desired.ired.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.511-516
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• 2009

Photodegradation characteristics of polyolefin composites were studied. Thermogravimetric analysis results suggest that the polyolefin blends used in this study have different amounts of talc. The mechanical behaviors of polyolefin blends, which experienced UV-irradiation in accordance with SAE J1960, are investigated using tensile and Izod impact tests. These results show that as the UV-exposure time increases, a significant drop in the elongation at break and impact strength at a low temperature are observed. This may be explained by the decreases in elastic energy derived from the scission of polymer molecular chains and the low density of entanglement after UV- photodegradation. Scanning electron microscopy observations indicate that no crack and surface damage are observed, while the additional talc particles are exposed, on the UV-exposed surfaces. The exposure of talc particles may be responsible for the discoloration of UV-exposed polyolefin blend surface. Observation using Fourier transform infrared spectroscopy (FT-IR) confirms the presence of photodegradation on the surface of UV-exposed polyolefin blend.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1141-1146
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• 1999

Melt blend of PA6/PP-g-MA system containing SEBS-g-MA as a compatible impact modifier was prepared to investigate the change of mechanical properties and morphologies. The tensile strength slightly decreased, but the elongation at break increased with increasing content of SEBS-g-MA in the blend. Also the notched izod impact strength increased with increasing the content of PP-g-MA and SEBS-g-MA. It is attributed to improved compatibilization and interfacial adhesion by reaction of the amide of PA6 with maleic anhydride of SEBS-g-MA and PP-g-MA. The result of dynamic mechanical analysis(DMA) showed a typical behavior of the compatibilization in the polymer blends. Finally, in the phase structure observed by the use of SEM, we confirmed improvement of the compatibilization and interfacial adhesion with increasing the content of SEBS-g-MA and PP-g-MA.

• Bulletin of the Korean Chemical Society
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• v.2 no.4
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• pp.142-147
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• 1981

A blend polymeric system composed of poly(methyl methacrylate) (PMMA or PM) and polystyrene (PS) dissolved in chloroform was rheologically studied. The viscosities ${\eta}_{bl}$ of the blend system with various blending ratios ${\chi}$ changing from zero (pure PS solution) to unity (pure PMMA solution) were measured at $25{\circ}C$ as a function of shear rates ${\dot{s}}$ by using a Couette type viscometer. ${\eta}_{bl}$ at a given ${\dot{s}}$ decreased exponentially with ${\chi}$ reaching asymptotic constant value of ${\eta}_{bl}$ ; ${\eta}_{bl}$ at a given ${\chi}$ is greater at a smaller ${\dot{s}}$. These results are explained by using Ree-Erying's theory of viscosity, ${\eta}_{bl}=(x_1{\beta}_1/{\alpha}_1)_{b}_1＋ (x_2{\beta}_2/{\alpha}_2)_{bl}[sinh^{-1}{\beta}_2(bl) {\dot{s}}]/{\beta}_2(bl){\dot{s}}$. The Gibbs activation energy ${\Delta}G_i^\neq$(i = 2 for non-Newtonian units) entering into the intrinsic relaxation time ${\beta}$ is represented by a linear combination ${\Delta}G_i^\neq(bl) ={\chi}{\Delta}G_i^{\neq}_{iPM}+(1-{\chi}){\Delta}G_i^{\neq}_{iPS}$;the intrinsic shear modulus$[[\alpha}_i]^{-1}$ is also represented by $[{\alpha}_i(bl)]^{-1}={\chi}[{\alpha}_{iPM}]^{-1}+(1-{\chi})[{\alpha}_{iPS}]^{-1}$ and the fraction of area on a shear surface occupied by the ith flow units $x_i(bl)$ is similarly represented, i.e., $x_i(bl) = {\chi}x_{iPM}+(1-{\chi})x_{iPS}$. By using these ideas the Ree-Eyring equation was rewritten which explained the experimental results satisfactorily.

• Polymer(Korea)
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• v.28 no.1
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• pp.77-85
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• 2004

It has been widely used ultra high molecular weight polyethylene (UHMWPE) for the biomaterials due to its excellent mechanical properties and biocompatibility. In the case of blend of UHMPE with another polymeric biomaterials, however, UHMWPE might have low blend compatibility due to surface inertness. In this study, in order to improve the mechanical properties of poly(methyl methacrylate) (PMMA) bone cement by means of the impregnation of UHMWPE powder, we developed the novel surface modification method by the mixture of methyl methacrylate (MMA) and xylene. We investigated the variation of composition of MMA/xylene. It was confirmed by the analysis of Fourier transform infrared-attenuated total reflectance, scanning electron microscope, universal transverse mercator, and digital thermometer. The maximum mechanical strength of surface modified UHMWPE powder impregnated PMMA bone cement compound was observed the ratio of 1 : 1 (v/v％) MMA/xylene. Also its curing temperature decreased from 103 $^{\circ}C$ to 58 ∼ 73 $^{\circ}C$ The mechanism of surface modification of UHMWPE powder by the mixture of MMA/xylene has been proposed.