• Textile Coloration and Finishing
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• v.7 no.4
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• pp.45-53
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• 1995

Natural rubber(NR)-polyacrylamide(PAAm) graft copolymers(GP)(toluene soluble GP : TSGP, water dispersible GP : WDGP) have been synthesized as coupling agents by pre-emulsification methods based on "inverse emulsion graft polymerization" technique. The polymerization was carried out at $65^{\circ}C$ using Azobisisobytyro nitrile(AIBN) as an initiator in the inverse emulsion system formed by inxing NR toluene solution with inverse emulsion of awueous AAm solution emulsified with $Tween^{\#}$ 80 in toluene. The mechanism of inverse emulsion graft copolymerization was studied on AAm conversion, % grafting, grafting efficiency, NR conversion, production ratio of TSGP and amount of GP(sum of TSGP and WDGP). The reaction has been confirmed through use of optical microscope to proceed via adsorption of emulsifier colloid particles onto the stretched NR molecule. From the analysis of the effects of various polymerization conditions on the grafting, it has also been found that the present rection system can easily yield high(over 90%) grafting efficiency and AAm conversion and relatively high(over 80%) NR conversion.onversion.

• Elastomers and Composites
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• v.58 no.3
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• pp.128-135
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• 2023

To improve the adhesive strength of natural rubber (NR) for a seismic isolation damper, citraconic acid-g-NR (CCA-g-NR) was synthesized via the melt grafting of citraconic acid (CCA) onto NR using an azobisisnomerobutyronitrile (AIBN) initiator. Subsequently, the influence of CCA and AIBN concentrations on the graft ratio G/R (%) and graft efficiency G/E (%) of the CCA-g-NR was investigated. The optimum CCA and AIBN concentrations required to achieve the desired G/R (3.49%) and G/E (49.8%) were found to be 7 phr and 0.13 phr, respectively. Additionally, we studied the influence of CCA-g-NR concentration on the mechanical properties (tensile strength, elongation at break, and modulus at 300%), adhesive strength, and cure characteristics of the rubber compound in the seismic isolation damper. As the concentration of CCA-g-NR increased, the elongation at break and adhesive strength of the compound increased, whereas its tensile strength and modulus at 300% decreased. Moreover, as the concentration increased, the maximum torque decreased and the scorch time was delayed to obtain an optimal vulcanization time.

• Nuclear Engineering and Technology
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• v.10 no.4
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• pp.195-201
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• 1978

The radiation-induced graft polymerization of methacrlic acid and methyl methacrylate onto a polyester fabric was investigated with ${\gamma}$-ray as the radiation source, and the rate of grafting was examined. When acrylic acid, methacrylic acid, and methyl methacrylate were grafted onto a polyester fabric, grafting efficiency was depened upon the dielectric constant of the solvent in the monomer mixture. The yield of the graft polymerization was related to the total dose, the concentration of the monomer, and the concentration of the swelling agent. The melting point and the glass transition temperature of MA and MMA grafted copolymers were analysed by means of DTA. Physical properties, such as the moisture regain, the antistatic property, and the wicking time were measured.

• Elastomers and Composites
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• v.24 no.4
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• pp.265-275
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• 1989

The graft copolymerizations of acrylonitrile (AN) and methyl methacrylate (MMA) onto chloroprene rubber (CR) were carried out with benzoyl peroxide(BPO) as an initiator. The effect of solvent, mole ratio of AN to MMA, reaction time and temperature, and initiator concentration on graft copolymerization were examined. It was observed that the grafting efficiency increased as increasing mole ratio of AN to MMA. the graft copolymer, acrylonitrile- CR-methyl methacrylate (ACM), was identified by infrared spectroscopy and morphology. Thermal stability of ACM was found to be improved when compared with those of CR.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.64.1-64.1
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• 2010

The morphology of mesoporous $TiO_2$ films plays an important role in the operation of a DSSC. For example, the energy conversion efficiency of DSSCs with well-organized mesoporous $TiO_2$ films is much higher than those with traditional films possessing a random morphology. In previous research, well-organized mesoporous $TiO_2$ films have mainly been synthesized using an amphiphilic block copolymer, e.g., a poly(ethylene oxide) (PEO)-based template. A graft copolymer is more attractive than a block copolymer due to its low cost and the ease with which it can be synthesized. In this work, we provide the first report on the successful synthesis of well-organized mesoporous $TiO_2$ films templated by an organized graft copolymer as a structure directing agent. Well-organized mesoporous $TiO_2$ films with excellent channel connectivities were developed via the sol gel processusing an organized PVC-g-POEM graft copolymer synthesized by one-pot ATRP. The careful adjustment of copolymer composition and solvent affinity using a THF/$H_2O$/HCl mixture was used to systematically vary the material structure. The influence of the material structure on solar cell performance was then investigated. A solid-state DSSC employing both the graft copolymer templated organized 700 nm-thick $TiO_2$ films and graft copolymer electrolytes exhibited a solar conversion efficiency of 2.2% at 100 $mW/cm^2$. This value was approximately two-fold higher than that attained from a DSSC employing a random mesoporous $TiO_2$ film. The solar cell performance was maximized at 4.6% when the film thickness was increased to $2.5{\mu}m$. We believe that this graft copolymer-directed approach introduces a new and simple route toward the synthesis of well-organized metal oxide films as an alternative to a conventional block copolymer-based template.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.392-399
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• 2019

A highly transparent interfacial layer (HTIL) to enhance the performance of dye-sensitized solar cells (DSSCs) was prepared via a polymer-assisted (PA) approach. Poly(vinyl chloride)-graft-poly(oxyethylene methacrylate) (PVC-g-POEM) was synthesized via atom-transfer radical polymerization (ATRP) and was used as a sacrificial template. The PVC-g-POEM graft copolymer induced partial coordination of a hydrophilic titanium isopropoxide (TTIP) sol-gel solution with the POEM domain, resulting in microphase separation, and in turn, the generation of mesopores upon calcination. These phenomena were confirmed using Fourier-transform infrared (FT-IR) spectroscopy, UV-visible light transmittance spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The DSSCs incorporating HTIL60/20 (consisting of a top layer with a pore size of 60 nm and a bottom layer with a pore size of 20 nm) exhibited the best overall conversion efficiency (6.36%) among the tested samples, which was 25.9% higher than that of a conventional blocking layer (BL). DSSC was further characterized using the Nyquist plot and incident-photon to electron conversion efficiency (IPCE) spectra.

• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.561-568
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• 2019

Objectives: The most commonly detected heavy metals in rocks and soils, including Pb, Cd, Cu, Fe, Mn and As, are representative pollutants discharged from abandoned mines and have been listed as potential sources of contamination in drinking water. This study focused on increasing the removal efficiency of heavy metals from drinking water resources by surface modification of natural adsorbents to reduce potential health risks. Methods: Iron oxide coating and graft polymerization with zeolites and talc was conducted for bipolar surface modification to increase the combining capacity of heavy metals for their removal from water. The removal efficiency of heavy metals was measured before and after the surface modification. Results: The removal efficiency of Pb, Cu, and Cd by surface modified zeolite showed 100, 92, and 61.5%, respectively, increases compared to 64, 64, and 38% for non-modified zeolite. This implies that bipolar surface modified natural adsorbents have a good potential use in heavy metal removal. The more interesting finding is the removal increase for As, which has both cation and anion characteristics showing 27% removal efficiency where as non-modified zeolite showed only 2% removal. Conclusions: Zeolite is one of the most widely used adsorptive materials in water treatment processes and bipolar surface modification of zeolite increases its applicability in the removal of heavy metals, especially As.

• Elastomers and Composites
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• v.28 no.3
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• pp.191-197
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• 1993

The graft copolymerization of methyl methacrylate(MMA) onto natural rubber latex(NRL) initiated by t-butyl hydroperoxide(t-BHPO) was investigated in aquous medium. The grafting percentage, grafting efficiency and total conversion were observed in various reaction conditions such as monomer, initiator and emulsifier concentration, reaction temperature, reaction time and agitation speed. The optimum conditions for the graft copolymerization onto natural rubber latex were as follows ; At given monomer concentration of $3{\times}10^{-2}mole/l$, the maximum grafting percentage was appeared in the case of grading in initiator concentration of $4{\times}10^{-2}mo1e/l$ and emulsifier concentration of 0.2wt.% at $40^{\circ}C$ for 5hrs.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.83-91
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• 2011

Mesoporous titanium dioxide ($TiO_2$) thin films were prepared using poly(vinyl chloride)-graft-poly(N-vinyl pyrrolidone) (PVC-g-PVP) as a templating agent via sol-gel process. Grafting of PVC chains from PVC backbone was done by atom transfer radical polymerization (ATRP) technique. The successful grafting of PVP to synthesize PVC-g-PVP was checked by fourier-transform infrared spectroscopy (FT-IR) and gel permeation chromatography (GPC). The carbonyl group interaction of PVC-g-PVP graft copolymer with $TiO_2$ was confirmed by FT-IR. The porous morphologies of the $TiO_2$ films genereated after calcination at $450^{\circ}C$ was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mesoporous $TiO_2$ films with 580 nm in thickness were used as a photoelectrode for solid state dye sensitized solar cell (DSSC) and showed an energy conversion efficiency of 1.05% at 100 $mW/cm^2$.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.251-255
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• 2012

Pulp is typically used for paper industry to manufacturing various types of papers. However simply chemical modification makes enable the pulp to a wide range of application in various industrial fields. To bring the polymerization the gamma ray irradiated on the mixture of kenaf and PEGMA in various dose ranges from 20 to 60 kGy. As a results, the graft degree of 20.0% was obtained from 475 g of gamma ray irradiated pulp and PEGMA. After the polymerization, the chemical structure and morphology of the surfaces were examined by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscope. Chemical structure of grafted pulp has significantly growth in carbonyl content with increasing the radiation dose. Also surface morphology was distinctly changed with decreased the degree of roughness and increasing the diameter. These results were explained gamma ray irradiation improve performance of graft polymerization efficiency.