• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.533-538
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• 2003

It has been shown that ion implantation produces remarkable improvements in surface-sensitive physical and chemical properties as well as other mechanical properties, in polymers. In this study, ion implantation was performed onto polymer, PC(polycarbonate), in order to investigate surface hydrophilic property through contact angle measurement using distilled water. PC was irradiated with N, Ar, Xe ions at the irradiation energy of $20\;{\sim}\;50keV$ and the dose range of $5{\times}10^{15},\;1{\times}10^{16},\;7{\times}10^{16}\;ions/cm^2$. The contact angle of water has been reduced with increasing fluence and ion mass but increased with increasing implanted energy. The changes of chemical and structural property are discussed in view of infrared spectroscopy and FT-IR, XPS, which shows increasing C-O bonding and C-C bonding. The root mean square of surface roughness examined by means of AFM changed smoothly from 0.387nm to 0.207nm and the change of wettability was discussed with respect to elastic and inelastic collisions obtained as results of TRIM simulation. It was found that wettability of the modified PC surface was affected on change of functional group and nuclear stopping or linear energy transfer(LET, energy deposited per unit track length per ion) that causes chain scission by displacing atom from polymer chains, but was not greatly dependant on surface morphology.

• Macromolecular Research
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• v.15 no.6
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• pp.520-526
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• 2007

The effects of poly($({\varepsilon}$-caprolactone) (PCL) on poly(acrylonitrile-butadiene-styrene) (ABS) and polycarbonate (PC) blends were studied. Blends of ABS/PC (70/30, wt%) with PCL as a compatibilizer were prepared by a twin screw extruder. From the glass transition temperature $(T_g)$ results of the ABS/PC blends with PCL, the $T_g$(PC) of the ABS/PC (70/30) blends decreased with increasing PCL content. From the results of the morphology of the ABS/PC (70/30) blends with PCL, the phase separation between the ABS and PC phases became less significant after adding PCL in the ABS/PC blends. In addition, the morphological studies of the ABS/PC blends etched by NaOH indicated that the shape of the droplet was changed from regular round to irregular round by adding PCL in the ABS/PC blends. These results for the mechanical properties of the ABS/PC blends with PCL indicated that the tensile, flexural and impact strengths of the ABS/PC (70/30) blends peaked at a PCL content of 0.5 phr. From the results for the rheological properties of the ABS/PC (70/30) blends with PCL content, the storage modulus, loss modulus and complex viscosity increased at PCL content up to 5 phr. From the above results of the $T_g$, mechanical properties, morphology and complex viscosity of the ABS/PC blends with PCL, it was concluded that the compatibility was increased with PCL addition in the ABS/PC (70/30, wt%) blends and that the optimum concentration of PCL as a compatibilizer is 0.5 phr.

• Polymer(Korea)
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• v.24 no.3
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• pp.314-325
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• 2000

Thermal degradation of thermoplasitc polyurethane modified polycarbonate has been investigated by means of DSC, GPC and FT-IR techniques. The polyurethanes used in this study are TPU-35 and TPU-53 containing 35.5 and 53.4 wt% of hard segments, respectively. The more content of hard segment, the higher the glass transition temperature (T$_{g}$) of TPU was observed. On the other hand, the T$_{g}$ of the TPU modified PC decreased with the content of TPU and the annealing temperature regardless of the hard segment contents. The latter behavior nay arise from the thermal degradation of TPU upon annealing process: the observed thermal degradation temperatures were at 240 and 25$0^{\circ}C$ for the PC/TPU-35 and PC/TPU-53, respectively. The molecular weight, molecular weight distribution and viscosity agree well with the DSC measurement, which implicates a thermal degradation of TPU. In addition, thermal stability of the TPU modified PC linearly decreased with an incorporation of TPU. Transesterification or any interaction was not observed using FT-IR: the evidence was no frequency shift or any variance betwere the carbonyl stretching and NH group. For the specimens prepared below the degradation temperature, the enhancement of the thickness dependent impact strength of the PC/TPU blend was observed, and the morphology of the two blends was compared.d.

• Composites Research
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• v.29 no.5
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• pp.269-275
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• 2016

Multiscale hybrid composites, which consist of polymeric resins, microscale fibers and nanoscale reinforcements, have drawn significant attention in the field of advanced, high-performance materials. Despite their advantages, multiscale hybrid composites show challenges associated with nanomaterial dispersion, viscosity, interfacial bonding and load transfer, and orientation control. In this paper, carbon nanotube(CNT)/carbon fiber(CF)/polycarbonate(PC) multiscale hybrid composite were fabricated by a solution process to overcome the difficulties associated with controlling the melt viscosity of thermoplastic resins. The dependence of CNT loading was studied by varying the method to add CNTs, i.e., impregnation of CF with CNT/PC/solvent solution and impregnation of CNT-coated CF with PC/solvent solution. In addition, hybrid composites were fabricated through surfactant-aided CNT dispersion followed by vacuum filtration. The morphologies of the surfaces of hybrid composites, as analyzed by scanning electron microscopy, revealed the quality of PC impregnation depends on the processing method. Dynamic mechanical analysis was performed to evaluate their mechanical performance. It was analyzed that if the position of the value of tan ${\delta}$ is closer to the ideal line, the adhesion between polymer and carbon fiber is stronger. The effect of mechanical interlocking has a great influence on the dynamic mechanical properties of the composites with CNT-coated CF, which indicates that coating CF with CNTs is a suitable method to fabricate CNT/CF/PC hybrid composites.

• Polymer(Korea)
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• v.35 no.4
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• pp.356-362
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• 2011

The branched polycarbonates (B-PCs) with two different branching agents were synthesized from melt polymerization. The contents of branching agent were in the range of 0.001~0.005 mol%. The chemical structure of the synthesized PC was determined by FTIR, $^1H$ NMR, and $^{13}C$ NMR, spectroscopy. The molecular weight, glass transition and degradation temperatures were determined by GPC, DSC, and TGA. The molecular weight of the phloro type B-PC had a lower value than the other one, and the glass transition temperature increased with molecular weight. Compared with linear PC, the rheological properties of the B-PC indicated an increase of complex viscosity in the low frequency region and shear thinning tendency. Power law index(n) representing shear thinning was calculated by linear regression and the values were in the range of 0.483~0.996. The rheological properties of the B-PCs were measured by a dynamic rheometer.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.168-175
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• 2020

Purpose: The purpose is to test and evaluate the physical properties of commonly used temporary restoration materials and newly emerged materials. Materials and Methods: Four groups of polymer materials were evaluated: Polymethyl methacrylate (PMMA) 2 groups, Polyetheretherketone (PEEK), Polycarbonate. Four physical properties were tested: surface hardness, bending strength, abrasion resistance during wear, wear behavior. The 3-axis bending strength and Vickers hardness test were measured using a universal testing machines respectively. The microstructure was observed with a scanning electron microscope and weight comparison was evaluated after 100,000 chewing tests using a chewing simulator. Kruskal wallis test was performed to evaluate statistical significance. Results: The four groups showed the highest flexural strength and Vickers hardness of PEEK, followed by PC, PMMA-H, PMMA-T. Microstructure observation also showed the least surface roughness in the PEEK group, followed by PC, PMMA-H, PMMA-T. Conclusion: PC is considered to have sufficient mechanical properties that can be applied to the manufacture of temporary teeth. However, further studies, such as biocompatibility, are considered to be necessary for practical clinical applications.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.98-103
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• 2010

The effect of plasma treatment on surface characteristics of polycarbonate (PC) films was investigated using low pressure plasma and atmospheric pressure plasma with oxygen and argon. Untreated PC has a contact angle of $82.31^{\circ}$ with de-ionized water which reduced to $9.17^{\circ}$ as the lowest value after being treated with a low pressure plasma treatment with oxygen. Increase of delivered powers such as RF and AC with a high frequency and gas flow rates was not effective to reduce contact angles dramatically but gave the trend of reducing gradually. The surface of PC treated with plasma shows a low contact angle but the contact angle increases rapidly according to the exposure time in air ambient. Oxygen plasma was more effective to generate the polar functional group regardless of the type of plasma. Conclusively, a low plasma treatment with oxygen is more recommendable when the hydrophilic surface of PC is required.

• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.355-358
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• 2010

Inductively coupled low temperature plasmas with oxygen, argon, mixture of oxygen and argon, and nitrogen have been used to modify polycarbonate(PC) films at the various process conditions. All plasma treatments generally had a tendency to increase the surface roughness of PC regardless of process conditions. The treatment of oxygen plasma showed the highest value in the surface roughness and mostly enhanced the generation of oxygen containing polar groups as much as 43% in comparison of untreated PC. The contact angle of untreated PC decreased from $82.31^{\circ}$ to the lowest value of $9.17^{\circ}$ after oxygen plasma treatment. The increase of RF delivered power had an effect on the rapid reduction of contact angle, but gas flow rates did not effect to reduce contact angles so much.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.875-879
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• 2008

A method for the depolymerization of polycarbonate waste by glycolysis using ethylene glycol without catalyst was explored in order to get the monomer bisphenol A (BPA). The effect of operation variables such as reaction time, reaction temperature, EG/PC weight ratio and the kinetic of glycolysis were studied. It was found that the polymerization reaction has two different activation energies depending on the reaction temperature. A drop in activation energy with temperature indicates that the reaction mechanism has shifted from one of a succession of elementary steps to another in the series. The maximum yield of BPA of 95.6% was achieved at reaction temperature $220^{\circ}C$ for 85min with EG/PC weight ratio 4.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.247-255
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• 1998

The morphological changes during melt compounding of ternary blends containing various combinations of acrylonitrile-butadiene-styrene(ABS), methyl methacrylate-butadiene-ethyl acrylate(MBE), styrene-acrylonitrile(SAM) copolymers, and poly(methyl methacrylate)(PMMA) as dispersed components in a fixed matrix of polycarbonate(PC) have been investigated. Depending on the composition of the blend, MBE particles and PMMA phase appear to locate at the PC-SAN interface under the influence of interfacial tensions and motion induced coalescence. The interfacial viscosity is found to be a critical factor that affects the amount of coalescence.