• Elastomers and Composites
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• v.45 no.1
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• pp.32-39
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• 2010

The mechanical properties of PTFE 100%, PTFT 90% + carbon black 10%, PTFE 85% + glass fiber 15%, PTFE 80% + glass fiber 15% + molybdenum disulfide ($MoS_2$) 5%, PTFE 75% + glass fiber 25%, and PTFE 75% + carbon black 18% + graphite 7% composites were investigated in this study. The differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to examine the heat of fusion(${\Delta}H_f$) and thermal stability of the composites. Also, the wear surface and wear volume of PTFE lip seal were examined using the durability test. Wear surface was observed using scanning electron microscope (SEM). It was found that the hardness, wear resistance and durability were enhanced by adding glass fiber and molybdenum disulfide into pure PTFE, but tensile strength and elongation were decreased. According to the experimental results, the composite (PTFE + 15% glass fiber + 5% molybdenum disulfide) showed the best properties for applying to oil-seal among six types of PTFE composites.

• Membrane Journal
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• v.5 no.2
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• pp.74-80
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• 1995

Asymmetric poly(vinyl alcohol) (PVA) membranes were prepared by varying the precipitation conditions of the phase inversion technique, and the influences of precipitation conditions on the water uptake of the membrane were investigate. The degree of water uptake of the membrane increased and reached a certain maximum value, as the precipitation time increased. However, it decreded after that. As the precipition temperauure became lower, the degree of water uptake increased more or less. The addition of a nonionic surfactant to the precipitaon solution was effective reducing the precipitation time by lowering the surface tension of the precipitation solution, but ig didn't change the maximum value of its own degree of water uptake. In addition, the relationship between the degree of water uptake and the separation characteristics and mechanical properies of the membrane were investigated. The selectivity factor of the membrane for pervaperation separation decreased, but the permeate flux increased, respectively, with increasing the degree of water uptake. The tensile strength and elongation of the membrane, respectively, increased to a maximum value with increasing the degree of water uptake, and then decreased abtuptly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1216-1221
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• 2014

Poly(ethylene-co-isosorbide terephthalate) (PEIT) is interest in polymer which has isosorbide monomer that is renewable resources such as corn. However, there is important drawback which is low mechnical properties as increasing isosorbide contents. In this study, polycarbonate used to make up for drawback of mechanical properties of PEIT. In addition, PEIT used to improve the tensile elongation of polycarbonate because PEIT has good sheet proccessability. The effect of polycarbonate on morphology, thermal and mechanical properties were investigated using FE-SEM, DMA, TGA, UTM, and notched izod impact strength tester. As a result of this study, PEIT/PC blends were in compatible system and polycarbonate can act as an improvement of thermal stability and mechanical properties in the blends.

• Polymer(Korea)
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• v.29 no.1
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• pp.81-86
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• 2005

In this study, waterborne polyurethanes were synthesized with poly(tetramethylene glycol) (PTMG), polycarprolactone PCL), dimethylol propionic acid (DMPA) and different molar ratio of chain extender. Particle size, polydispersity, thermal and mechanical properties of waterborne polyurethane were investigated. The particle size of waterborne polyurethane was in the range of 5∼200 nm and decreased with increasing the amounts of PCL and chain extender. Glass transition temperatures ($T_g$) were in the range of -70∼-45 ${\circ}C$ and increased with as PCL and chian extender (ED) contents increased. The $T_g$ of polyurethane prepared from the mixture showed similar trends as compared with those of in the same values of synthetic polyurethane using PTMG or PCL, respectively. Also, mechanical properties of mixed polyols (PTMG and PCL) were lower than those of PTMG and PCL, respectively.

• Elastomers and Composites
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• v.40 no.1
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• pp.12-21
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• 2005

In this work, magnesium carbonate and calcium hydroxide as metallic crosslinking agent were added to chlorosulfonated polyethylene rubber (CSM) emulsion to enhance the mechanical properties of emulsion film such as tensile strength, elongation at break, and tear strength and crosslinking density, thermal features, and surface energy were also investigated. Crosslinking density of the CSM emulsion film with increasing the amount of magnesium carbonate and calcium hydroxide increased, leading to the enhancement of water resistance. It was shown that compared with calcium hydroxide, magnesium carbonate had a little higher crosslinking density and $T_g$ value. The surface energy and mechanical characteristics of the CSM emulsion film, however, showed somewhat different behaviors. The highest surface energy, tensile strength, and tear strength were observed when 0.75% for magnesium carbonate and 1.0% for calcium hydroxide were added respectively. Therefore, it can be concluded that as metallic crosslinking agent to improve water resistance and mechanical properties of the CSM emulsion, magnesium carbonate is more preferable to calcium hydroxide.

• Elastomers and Composites
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• v.38 no.1
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• pp.72-80
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• 2003

Phosphoric ester compound was employed as thermal resistant and flame retardant for chlorinated polyethylene(CPE) rubber material which is used to prepare automotive oil cooler hose. Cure characteristics, physical properties, thermal resistance, and flame retardation of CPE rubber compounds were investigated. CPE rubber which has excellent properties such as cold resistance and chemical corrosion resistance, and is inexpensive in price than existing ethyleneacrylate rubber(EAR) was used to prepare a rubber compound useful for hose. A non-halogen flame retarding agent N,N'-bis- (diphenylphosphoro) diaminohexane(BDPDH), which is condensed phosphoric ester, was synthesized and it was mixed to CPE rubber material with the range of $0{\sim}30 phr$. From the test results, rheological properties, heat resistance, and flame retardance of CPE rubber compounds were found out to be much increased. The optimum content of BDPDH to rubber which gives maximum effect on thermal resistance and flame retardation, within the range of tolerable specification for rubber materials, was determined to be 20 phr.

• Polymer(Korea)
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• v.38 no.1
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• pp.9-15
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• 2014

Polyamide4 (PA4)-polyurethane (PU)-PA4 triblock copolymers were synthesized by isocynated (NCO)-terminated PU prepared from 4,4'-diphenyl methane diisocyante (MDI) and polytetramethylene glycol (PTMG) as an initiator and potassium pyrrolidonate (P-py) as a catalyst for anionic ring opening polymerization of 2-pyrrolidone. Subsequently copolymer was controlled to contain different or same molecular weight of PA4 hard block with same or different molecular weight of PU soft block in order to investigate the effects of those differences on various properties of triblock copolymers as a thermoplastic elastomer. As the results shown in typical properties of block copolymeric elastomers, the mechanical strength and melting point ($T_m$) of the copolymers increased with an increase in molecular weight of PA4 block while the elongation at break increased with an increase in that of PU block.

• Journal of Adhesion and Interface
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• v.22 no.1
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• pp.8-15
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• 2021

In this study, a polyol was prepared using Jeffamine D-400 as a propylene glycol-based diamine to impart flexibility to the urethane-modified epoxy, and a urethane-modified epoxy was synthesized using the polyol. Urethane-modified epoxy synthesized with existing Bisphenol A diglycidyl ether (BADGE) epoxy, a curing agent, and a curing accelerator are mixed to prepare an epoxy adhesive, and shear strength is measured by measuring adhesion strength. As a result, shear strength and shear elongation tended to increase. These results are due to the high crosslinking density. It is believed that it can be applied to structural adhesives that are restricted in use.

• Journal of Adhesion and Interface
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• v.20 no.1
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• pp.15-22
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• 2019

In this study, polybutadiene based di-functional urethane acrylate oligomer (PB-UAO) were synthesized from polybutadiene diol and isophorone diisocyanate. And then, pressure sensitive adhesive films were prepared by mixing with synthesized oligomer, tri-functional acrylate monomer (Tris(2-acryloyloxyethyl) isocyanurate (TAOEIC) or Trimethylolpropane triacrylate (TMPTA) or Pentaerythritol triacrylate (PETA)), mono-functional acrylate monomer (Stearyl acrylate) and UV initiators. Effects of types and contents of trifunctional acrylate monomers on peel strength, tensile strength, elongation, thermal stability and water absorption property were studied. As the contents of tri-functional acrylate monomer increased, and as the molecular weight of tri-functional acrylate monomer decreased, peel strength, elongation and water absorption showed a tendency to decrease whereas tensile strength and thermal stability showed a tendency to increase.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.2
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• pp.135-142
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• 2009

This experiment was conducted to determine the usability of biodegradable plastic in the mulching cultivation of sweetpotato. For this, we investigated the physical characteristics, biodegradability, leaching, yield, workability, etc. of biodegradable films. Compared with general mulching materials, biodegradable Poly butyleneadipate-co-butylene succinate (PBSA) and PLC+starch showed $2{\sim}27$% higher tensile strength, but $2{\sim}22$% lower elongation and $2{\sim}6$% lower tear strength. In the leaching test on the biodegradable films, heavy metals were detected very little or not at all. As to difference in ground temperature according to mulching material, the temperature was high in order of PLC+starch > PBSA > Low Density Polyethylene (LDPE) > Control during the period from late June to mid July, but in order of LDPE > PLC+starch > PBSA > None during the period from late July to late September. In the mulching cultivation of sweet potato, biodegradable films PBSA (EA, EB, EC) and PLC+starch (DD, DE, DF) began to degrade after 60 days from the cut planting of sweet potato, and over 95% degraded after 120 days. The quantity of roots was 3,070 kg/10a for PBSA, 3,093 kg/10a for PLC-starch, and 2,946 kg/l10a for LDPE, showing no significant difference according to mulching material. Considering the physical characteristics, biodegradability, environment, convenience in harvesting work, yield, etc. of the films in the mulching cultivation of sweet potato, biodegradable films are expected to be very useful.