• Elastomers and Composites
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• v.7 no.1
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• pp.12-20
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• 1972

• Polymer(Korea)
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• v.36 no.2
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• pp.137-144
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• 2012

The surface of polyethylene (PE) was modified through Ar atmospheric pressure plasma treatment and subsequent grafting of glycidyl methacrylate (GMA). Optimum plasma treatment conditions were determined through analyzing the surface free energies calculated from the contact angles between PE samples and three probe liquids, which were RF-power of 200 W, plasma treatment time of 600 sec, Ar flow rate of 5 LPM, and sample-holder moving speed of 20 mm/sec. To introduce the maximum amount of GMA on PE surface treated under the conditions, graft copolymerization conditions such as GMA concentration, temperature, and time were carefully controlled. Grafting degree (GD) was obtained through weight difference analysis of PE film before and after graft copolymerization. A maximum GD was achieved at the GMA concentration of 20 vol%, the temperature of $80^{\circ}C$, and the treatment time of 4 hr.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.316-320
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• 1976

Based on the results of graft copolymerization to proteins, an attempt is made to derive the rate equations to explain the mechanism of Ce(IV) ion-initiated graft copolymerizations. In this system the oxidative termination by Ce(IV) $[R{\cdot}+ Ce(IV) ${\rightarrow}$ R(inert) + Ce(III) + H^+]$ is considered characteristic particularly in higher concentration of Ce(IV) ion. The change in the mode of termination reactions with change in Ce(IV) ion concentration makes possible the presence of an optimum Ce(IV) ion concentration for maximum graft copolymerization yield. This effect is reflected in presently derived equations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2550-2558
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• 2013

Poly(o-hydroxyamides)(PHAs) copolymers having oligo(oxy ethylene) pendant in the main chain were synthesized by solution polycondensation reaction at low temperature. Copolymer precursors were studied by fourier transform infrared(FT-IR), differential scanning calorimeter(DSC), thermogravimetric analyzer(TGA), universal testing machine(UTM) and limited oxygen index(LOI). The inherent viscosities of the PHAs measured at $35^{\circ}C$ in DMAc or DMAc/LiCl solution were in the range of 0.74~1.42 dL/g. Solubility of the precursors with higher oligo(oxy ethylene) unit was increased, but the PBOs were nearly insoluble in a variety of solvents. The degradation temperature of the copolymer precursors was recorded in the ranges of $408{\sim}664^{\circ}C$ in nitrogen and char yields showed 13~59% values at $900^{\circ}C$. The mechanical properties and flame retardancy of copolymer precursors decreased with higher oligo(oxy ethylene) unit.

• Polymer(Korea)
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• v.24 no.1
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• pp.16-22
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• 2000

Poly(butylene terephthalate- co-oxybenzoate)(PBOT) containing mesogenic oxybenzoate units in the main chain was synthesized through ester exchange reaction by melt mixing of poly(butylene terephthalate)(PBT) and p-acetoxybenzoic acid (ABA). From the kinetics of the copolymerization reaction, the activation energies and the rate constants of homopolymerization and copolymerization, k$_{h}$ and k$_{c}$, could be determined. From the reaction conditions of different compositions, 4/6, 5/5, and 6/4 of PBT/ABA, at 250, 260, and 27$0^{\circ}C$, it was revealed that copolymerization between PBT and ABA proceeds on a pseudo-second order reaction if the ABA content and its conversion are low. In this case, the ratio of rate constants of homopolymerization to copolymerization was in the range from 1.08 to 3.17, indicating that the copolymer with more notable block character was obtained at the higher mole fraction of ABA and at higher temperature.e.e.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.11a
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• pp.297-300
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• 2002

고분자물질의 용도는 다양하다. 그러나, 열에 약한 것이 고분자물질의 가장 큰 단점으로서 이러한 열화현상은 피하거나 예방되어야 할 과제이다. 이런 과정을 제거하거나 지연시키는 작업 즉, 안정화가 필요하다. 따라서 공중합물질을 제조하는 과정은 안정화에 큰 영향을 미치고, 특히 유리전이온도나 기계적 강도를 높이기 위하여는 공중합에 의한 조성변화가 필요하다. 그 외에 형태학적 입자나 오염물질들도 안정화에 영향을 미치고, 고분자의 입체규칙도 역시 안정화에 영향을 미친다.(중략)

• Clean Technology
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• v.14 no.1
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• pp.29-34
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• 2008

Copolymerizations of propylene oxide (PO) and phthalic anhydride (PA) have been performed in the presence of double metal cyanide (DMC) catalyst as a means of incorporating ester groups in the polyol backbone. DMC catalyst was effective for the copolymerization and the reactivity ratios measured by modified Kelen-$T{\ddot{u}}d{\ddot{o}}s$ equation were $r_1(PA)\;=\;0$, and $r^2(PO)\;=\;0.248$. Four different Polyol samples containing 1.0, 2.1, 7.52, and 11.42 mol% of PA unit were utilized for the synthesis of thermoplastic polyurethanes of their hard segments of 19 wt%. As the incorporated amount of PA increases, the elongation of the resulting polyurethane decreases and the tensile strength and the tensile modulus increase. The modulation of the incorporated amount of PA into polyol backbone was proven to be a feasible way to tune the physical properties of polyurethanes.

• Polymer(Korea)
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• v.34 no.2
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• pp.154-158
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• 2010

We first synthesized N-phenylcyclotrisiloxazane ($D_3^{NPh}$) through a cyclization of $\alpha$,$\omega$- dichlorohexamethyltrisiloxane with aniline and prepared poly(dimethylsiloxane-co-N-phenylsiloxazane) copolymer (PDMS-NPSOX) by a ring opening copolymerization of them with hexamethylcyclotrisiloxane $D_3$. An acrylate monomer modified with PDMS-NPSOX was synthesized by using chloroethyl methacrylate and copolymerized with methylmethacrylate (MMA) and n-butylacrylate. The composition of the copolymer was chosen to control their glass transition temperature ($T_g$) to 25 $^{\circ}C$. By changing the comonomer from PDMS to PDMS-NPSOX, $T_g$ and adhesive strength of the copolymer were increased from 20 to 25 $^{\circ}C$ and from 1.76 to 2.23 N/cm, respectively.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.309-315
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• 1976

An efficient separation method and the utilization of sericin are searched. Sericin was extracted with hot water from cocoons under atmospheric pressure. The separated sericin was gel-filtrated with Sephadex G-75 and G-150 at room temperature and at $70^{\circ}C$. The results indicated that sericin is consisted of only one fraction in elution diagram. In the graft copolymerization of acrylonitrile to sericin ceric ammonium nitrate was chosen as an initiatior. A maximum yield was obtained at certain concentration of the initiator confirming our previous experiments. Viscosity measurement of alkali-hydrolyzed graft copolymers indicated that the polyacrylonitrile graft had the molecular weight in the range of 7,000.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.491-498
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• 1992

Graft polymerization of 2-hydroxyethyl methacrylate(HEMA) and styrene, from both their binary and unitary systems, onto polytetrafluoroethylene(PTFE) film was investigated by means of the simultaneous ${\gamma}-ray$ induced method. The effect of various parameters such as monomer concentration, dose rate, absorbed dose, HEMA/styrene feed ratios and the type of diluent on the extent of grafting in unitary and binary systems was studied. It was observed that when unitary HEMA was used for grafting, the grafting extent was very slight, whereas when comonomers were used, a good grafting yield could be obtained. Inclusion of sulfuric acid in the monomer solution resulted in enhanced grafting yields.