• Macromolecular Research
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• 제11권6호
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• pp.476-480
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• 2003

The rate of hydrolysis of Langmuir monolayer films of biodegradable polylactide (PLA) derivates was investigated at the air/water interface. The present study investigated such parameters as surface pressure, pH, and time. The hydrolysis of polyester monolayers depended strongly on the subphase pH, the concentration of active ions. Under the conditions studied here, polymer monolayers showed faster rates of hydrolysis when they were exposed to a basic subphase rather than they did when exposed to acidic or neutral subphases. By increasing the concentration of the degradation medium, the hydrolytic rate of dl-PLA monolayers was accelerated (accelerating effect). In addition, the basic hydrolysis of modified PLA with small amounts of hydrophilic (benzyloxycarbonyl) methyl morpholine-2,5-dione or glycolide was much faster than that of the PLA homopolymer.

• Proceedings of the Korean Fiber Society Conference
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.183-184
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• 2003

Poly(lactic acid) (PLA) is a highly versatile, biodegradable, aliphatic polyester derived from 100% renewable resources, such as corn and sugar beets. Because of the degradation mechanism, PLA is ideally suited for many applications in the environment where recovery of the product is not practical, such as agricultural mulch films and bags. Composting of post consumer PLA items is also a viable solution for many PLA products. (omitted)

• Journal of Adhesion and Interface
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• 제5권1호
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• pp.29-35
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• 2004

We have prepared polyster/nanQhybridized polyimide films in the range of 1~9 wt% of organophilic synthetic layered silicate (STN). Firstly, poly(amic acid)/STN nanocomposite solutions were prepared via solution blending method in DMAc or THF/MeOH solution, and then cast on the polyester film followed by imidization reaction, thermal and chemical method repestively. XRD and TEM experiment showed that the STN was fully exfoliated through the polyimide matrix. Surface morphologies of nanohybridized polyimide films were characterized by AFM and thermal, mechanical properties were also confirmed by TGA, DMA and UTM each. And also, the water vapor permeabilities highly depended on the content of STN. The sample from chemical imidization route and THF/MeOH solvent system showed better water vapor barrier properties than thermal one and DMAc system.

• Polymer(Korea)
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• 제25권6호
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• pp.803-810
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• 2001

A nonlinear optical hyperbranched polyester (PE-Azo/Hyper) was synthesized from 4-[N,N-bis(hydroxyethyl)amino-4'-formyl] azobenzene and cyanoacetic acid by a Knoevenagel polycondensation using 4-(dimethylamino) pyridine as a base. The resulting polymer was soluble in polar aprotic solvents such as N,N-dimethylformamide and 1-methyl-2-pyrrolidinone and could be processed into optical quality films by spin coating. The molecular weight was determined to be $M_w$=61,800 ($M_W/M_n{=1.86}$) by gel permeation chromatography using polystyrene as a standard. No melting point was detected by differential scanning Calorimeter, indicating that this polymer presents an amorphous state. It shows a glass transition temperature of $121^{\circ}C$. The second-order nonlinear optical coefficient $d_{33}$ of the poled polymer determined by the second harmonic generation at 1064 nm was 25.4 pm/V.

• Applied Chemistry for Engineering
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• 제19권5호
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• pp.547-553
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• 2008

To achieve the ideal performances of paint film, resins and hardeners have to be chosen and designed in a proper way depending on the exposure circumstance of substrate and the requested physical properties. Six different kinds of clear paints were made in this experiment using alkyd polyol, polyester polyol, polyester modified acrylic polyol and another 3 acrylic polyol resins whose $T_g$ and OH value were partially modified. Then the tests for chemical, physical, and mechanical properties were measured after forming the paint films using aliphatic and aromatic polyisocyanate. The viscosity and elasticity of paint film were then measured in terms of gel point and $tan{\delta}$ using Rheometer and DMA. Through this viscoelastic characteristic test of polyurethane resin, we were able to choose the adequate resins and hardeners which are the most important in the top and primer painting system of urethane paint and, as a result of observing the physical, mechanical, and chemical properties of paint film by urethane, we have finally reached the conclusion that we could apply the proper polyol to top and primer paint for developing the polyurethane paint system.

• Textile Coloration and Finishing
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• 제32권3호
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• pp.176-183
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• 2020

In order to study wearable air cushion materials capable of responding to massive impact in high-altitude fall situation, high tenacity woven fabrics were bonded by heat only depending on various type of thermoplastic films and then mechanical properties were measured. Tensile strength, elongation, and 100% modulus measurement results for 4 types of films show that TPU-2 has higher impact resistance and easier expansion than PET-1. After thermal bonding, the combination with the highest tensile strength was a material with a TPU-2 film for nylon and a PET-2 film for PET, so there was a difference by type of fabric. The tear strength of the bonded materials were increased compared to the fabric alone, which shows that durability against damage such as tearing can be obtained through film adhesion. All of the peel strengths exceeded the values required by automobile airbags by about 5 times, and the TPU-2 bonded fabric showed the highest value. The air permeability was 0 L/dm2 /min. For both the film and the bonded material, which means tightness between the fabric and the film through thermal bonding. It is expected to be applied as a wearable air cushion material by achieving a level of mechanical properties similar to or superior to that of automobile airbags through the method of bonding film and fabric by thermal bonding.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제67권3호
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• pp.448-453
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• 2018

PV module protective film plays an important role in protecting the solar cell from external environment by anti-hydrolysis polyester, UV resistance and mechanical properties. The backsheet was manufactured by using Roll-to-Roll dry laminating process. The backsheet structure is composed of 3 layers, which are PE, PET, and Fluorine polymer films. In this study, we have experimented the variation of thermal conductivities depending on MgO inputs 10% to 25% in order to confirm the dependence of the module efficiencies. High thermal conductive backsheet can increase the module output power efficiency because the heat is dissipated by spreading out the internal heat. Long-term environment weatherability tests were conducted for confirming 25 year reliability in the field such as PCT, UV, and power efficiency degradations. As the evaluation result, high thermal conductivity can be effective for increase of power efficiency of solar panel by using thermal conductive MgO masterbatch.

• Polymer(Korea)
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• 제27권3호
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• pp.169-175
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• 2003

Pyrophosphoric lactone modified polyester (PATT) containing two phosphorous functional groups in one unit structure was synthesized to prepare a non-toxic reactive flame-retardant coatings. Then the PATT was cured at room temperature with isocyanate, toluene diisocyanate-isocyanurate , to get a two-component polyurethane flame-retardant coatings (PIPUC). Comparing physical properties of the films of PIPUC with those of film of non-flame-retardant coatings, there was no deterioration observed in physical properties by the introduction of a flame-retarding component into the resin. We found that the char lengths measured by 45$^{\circ}$ Meckel burner method were 3.1∼4.4 cm and LOI values recorded 27∼30%. These results indicate that the coating prepared in this study is a good flame-retardant. The surface structure of coatings investigated with SEM does not show any defects and phase separation.

• Journal of the Korean Applied Science and Technology
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• 제17권3호
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• pp.203-211
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• 2000

Pyrophosphoric lactone modified polyester(PATT) that contains two phosphorous functional groups in one unit base resin structure was synthesized to prepare a non-toxic reactive flame retardant coatings. Then the PATT was cured at room temperature with isocyanate, Desmodur IL, to get a two-component polyurethane flame retardant coatings(PIPUC). Comparing the physical properties of the films of PIPUC with the film of non-flame retardant coatings, there was no degradation observed in physical properties by the introduction of a flame-retarding component into the resin. We found that the char lengths measured by $45^{\circ}$Meckel burner method were $3.1{\sim}4.4cm$ and LOI values recorded $27{\sim}30%$. These results indicate that the coatings prepared in this study is good flame retardant one. The surface structure of coatings investigated with SEM does not show any defects and phase separation.

• Macromolecular Research
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• 제15권6호
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• pp.506-512
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• 2007

2,3-Di-(2'-hydroxyethoxy)-4'-nitrostilbene (3) was prepared and condensed with terephthaloyl chloride, adipoyl chloride, and sebacoyl chloride to yield novel Y-type polyesters (4-6) containing the NLO-chromophores 2,3-dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4-6 were soluble in common organic solvents such as acetone and N,N-dimethylformamide. Polymers 4-5 showed thermal stability up to $300^{\circ}C$ in thermogravimetric analysis with glass transition temperatures $(T_g)$, obtained from differential scanning calorimetry, in the range $81-95^{\circ}C$. The second harmonic generation (SHG) coefficients $(d_{33})$ of the poled polymer films at the 1064 nm fundamental wavelength were around $3.68{\times}10^{-9}$ esu. The dipole alignment exhibited high thermal stability up to $T_g$, and there was no SHG decay below $T_g$ due to the partial main-chain character of the polymer structure.