• Polymer(Korea)
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• v.38 no.4
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• pp.535-543
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• 2014

This work, which was about the synthesis of naphthalimidopropyl acrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect (Q), polar effect (e) and fluorescence of naphthalene. Azobisisobutyronitronitryl (AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide (DMF) of solvent for the copolymerization of NIPA. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from Fineman-Ross (F-R), Kelen-$T{\ddot{u}}d{\ddot{o}}s$(K-T) methods. NIPA was found to be more copolymerized than GMA. $r_1{\cdot}r_2$ product was lower than 1, copolymerization was maked random-alternating type. The fluorescence spectrum of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm. Fluorescence life time of NIPA monomer showed fluorescence cover with UV 355 nm at room temperature, and life time showed $5.1449{\times}10^{-7}s$.

• Journal of the Korean Chemical Society
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• v.15 no.5
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• pp.281-284
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• 1971

Copolymerization of glycidyl methacrylate(GMA) with methyl acrylate(MA) and the reaction of the copoly mer with primary amines were investigated. The monomer reactivity ratios were determined by Mayo-Lewis intersecting method. $r_1=0.22{\pm}0.03(GMA),\;r_2=0.50{\pm}0.07(MA)$. GMA and MA copolymerized to afford the polymer having good alternate arrangements of the units of the monomers.

• Polymer(Korea)
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• v.27 no.4
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• pp.364-369
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• 2003

The copolymerizations of 2-fluorohexylethyl acrylate (FA) with 2-(o-(1'-methylpropylidenamino)carboxyl amino)ethyl methacrylate(MEM) with different molar ratios of the two monomers were carried out in methyl ethyl ketone using ${\alpha}$,${\alpha}$'-azobisisobutyronitrile as an initiator to synthesize water repellent polyacrylate derivatives with protected isocyanate groups. The contents of FA and MEM in the copolymers were analyzed by NMR. The monomer reactivity ratios of MEM (1) and FA (2) were determined by Kelen-Tudos plot as follows : r$\_$1/＝1.59 and r$\_$2/＝0.50. The number-average molecular weights of the copolymers were in the range of 39400 to 72400 and the polydispersity indexes were about 1.5. The protected isocyanate groups in the copolymers were converted into isocyanate groups above 150$^{\circ}C$. The contact angle of the copolymer with 65 ㏖% of FA fur water was about 95$^{\circ}$.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1915-1919
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• 2008

Second-order rate constants ($k_N$) have been measured spectrophotometrically for reactions of 3,4-dinitrophenyl benzoates (5b) with a series of alicyclic secondary amines in 80 mol % $H_2O$/20 mol % DMSO at 25.0 ${\pm}$ 0.1 ${^{\circ}C}$. The kinetic data have been compared with the data reported previously for the corresponding reactions of 2,4- dinitrophenyl benzoates (5a) to investigate the effect of changing the nucleofuge from 2,4-dinitrophenoxide to 3,4-dinitrophenoxide on reactivity and mechanism. The kinetic results show that aminolyses of 5a and 5b proceed through the same mechanism, i.e., a zwitterionic tetrahedral intermediate ($T^{\pm}$) with a change in the rate-determining step (RDS). Substrate 5a is more reactive than 5b when breakdown of $T^{\pm}$ is the RDS but less reactive when formation of $T^{\pm}$ is the RDS. Dissection of kN values into the microscopic rate constants (e.g., $k_1$ and $k_2/k_{-1 }$ ratio) has revealed that 5a results in larger $k_2/k_{-1}$ ratios but smaller k1 values than 5b for all the amines studied. Since 2,4-dinitrophenoxide is less basic and a better nucleofuge than 3,4-dinitrophenoxide, the larger $k_2/k_{-1}$ ratios determined for the reactions of 5a than for those of 5b are as expected. The steric hindrance exerted by the ortho-nitro group on 5a contributes to the smaller k1 values found for the reactions of 5a than for those of 5b.

• Polymer(Korea)
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• v.37 no.1
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• pp.74-79
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• 2013

Polyvinylidene fluoride (PVDF) and its copolymer with hexafluoropropylene (HFP) were successfully prepared from free radical solution polymerizations using diisopropyl peroxidicarbonate (DIPPDC) in the presence of 1,1,2-trichlorotrifluoroethane (R-113). The reactivity ratios of VDF and HFP were estimated as$r_{VDF}=2.06{\pm}0.03$ and $r_{HFP}{\approx}0$. This result indicates that HFP cannot undergo self propagation. The weight-average molecular weight and molecular weight distribution of copolymers were found to decrease with increasing HFP content. The melting temperature of copolymers linearly decreased with the increase of HFP content because of the introduction of HFP. Moreover, no melting peak was observed for the copolymers with high HFP content. The glass transition temperature of copolymers gradually increased with the increase of HFP content due to the restricted flexibility of the polymer chains.

• International Journal of Concrete Structures and Materials
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• v.8 no.4
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• pp.315-326
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• 2014

This study evaluates the dosages of Class F fly ash, lithium nitrate and their combinations to suppress the excessive expansion caused by alkali-silica reactivity (ASR). In order to serve the proposed objective, the mortar bar specimens were prepared from (1) four dosages of Class F fly ash, such as 15, 20, 25 and 30 % as a partial replacement of Portland cement, (2) up to six dosages of lithium nitrate, such as lithium-to-alkali molar ratios of 0.59, 0.74, 0.89, 1.04, 1.19 and 1.33, and (3) the combination of lithium salt (lithium-to-alkali molar ratio of 0.74) and two dosages of Class F fly ash (15 and 20 % as a partial replacement of Portland cement). Percent contribution to ASR-induced expansion due to the fly ash or lithium content, test duration and their interaction was also evaluated. The results showed that the ASR-induced expansion decreased with an increase in the admixtures in the mortar bar. However, the specimens made with the both Class F fly ash and lithium salt produced more effective mitigation approach when compared to those prepared with fly ash or lithium salt alone. The ASR-induced expansions of fly ash or lithium bearing mortar bars by the proposed models generated a good correlation with those obtained by the experimental procedures.

• Journal of Biomedical Engineering Research
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• v.8 no.1
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• pp.29-40
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• 1987

2-Hydroxyethyl methacrylate(HEMA) was copolymerized with allyltrimethylsilane- (ATMS) and allylt.imethoxysilane(ATMOS) at 70。C in N, N'dimethylformamide- (DMV) using $\alpha$ , $\alpha$'-azobisisobutyronitrile(AIBN). The compositions of unreacted monomers were determined by gas chromatographic analysis. The monomer reactivity ratios were determined by Fireman-Ross, Helen-Tiidus and intersection methods. The average values are as follows : $$r_1(HEMA) : 6.62 $\pm$ 0.07, r_2(ATMS) : 0.07 $\pm$ 0.01 for HEMA-ATMS system.$$ $$r_l(HEMA) : 4.09 $\pm$ 0.14, r_2(ATMOS) : 0.06 $\pm$ 0.01 for HEMA-ATMOS toys tem.$$ The lower rl(HEMA) In the HEMA-ATMOS system as compared to HEMA ATMS system may be contributed to higher relative reactivity of ATMOS toward the poly(HEMA) radical. The compositions of synthesized copolymers were determined from silicon con tents estimated gravimetrically. The thermal stabilities of the copolymers were investigated by thermogravimetry(TG). The enthalpic changes associated with the endothermic transition were evaluated by differential scanning calorimetry(DSC). The swelling properties of the copolymers in water were also investigated.

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.220-224
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• 2007

Second-order rate constants (kN) have been determined spectrophotometrically for reactions of 2,4-dintrophenyl 2-furoate (2) with a series of alicyclic secondary amines in 80 mol % H2O/20 mol % dimethyl sulfoxide (DMSO) at 25.0 oC. The furoate 2 is more reactive than 2,4-dintrophenyl benzoate (1) toward all the amines studied. The higher acidity of 2-furoic acid (pKa = 3.16) compared with benzoic acid (pKa = 4.20) has been suggested to be responsible for the reactivity order, at least in part. The Brønsted-type plots for the reactions of 1 and 2 are curved downwardly, indicating that the aminolyses of both 1 and 2 proceed through a zwitterionic tetrahedral intermediate (T±) with a change in the rate-determining step on changing the amine basicity. Dissection of the kN values into their microscopic rate constants has revealed that the pKao and k2/k-1 ratios for the reactions of 1 and 2 are identical, indicating that the nature of the nonleaving group (i.e., benzoyl and 2-furoyl) does not affect the reaction mechanism. The k1 values have been found to be larger for the reactions of 2 than for those of 1, which is fully responsible for the fact that the former is more reactive than the latter.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.2
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• pp.220-229
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• 2016

A numerical study on lifted flame structure in impinging jet geometry with syngas composition ratio was investigated. The numerical calculations including chemical kinetic analysis were conducted using SPIN application of the CHEMKIN Package with Davis-Mechanism. The flame temperature and velocity profiles were calculated at the steady state for one-dimensional stagnation flow geometry. Syngas mixture compositions were adjusted such as $H_2:CO=10:90(10P)$, 20 : 80 (20P), 30 : 70 (30P), 40 : 60 (40P), 50 : 50 (50P). As composition ratios are changed from 10P to 50P, the axial velocity and flame temperature increase because the contents of hydrogen that have faster burning velocity increase. This phenomenon is due to increase in good reactive radicals such as H, OH radical. As a result of active reactivity, the burning velocity is more faster and this is confirmed by numerical methods. Consequently, combustion reaction zone was moved to burner nozzle.

• Advances in environmental research
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• v.3 no.2
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• pp.107-116
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• 2014

This study aimed to synthesize dispersed and reactive nanoscale zero-valent iron (nZVI) with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), nontoxic and biodegradable stabilizer. The nZVI used for the experiments was prepared by reduction of ferric solution in the presence of PVP/VA with specific weight ratios to iron contents. Colloidal stability was investigated based on the rate of sedimentation, hydrodynamic radius and zeta potential measurement. The characteristic time, which demonstrated dispersivity of particles resisting aggregation, increased from 21.2 min (bare nZVI) to 97.8 min with increasing amount of PVP/VA (the ratios of 2). For the most stable nZVI coated by PVP/VA, its reactivity was examined by nitrate reduction in a closed batch system. The pseudo-first-order kinetic rate constants for the nitrate reduction by the nanoparticles with PVP/VA ratios of 0 and 2 were 0.1633 and $0.1395min^{-1}$ respectively. A nitrogen mass balance, established by quantitative analysis of aqueous nitrogen species, showed that the addition of PVP/VA to nZVI can change the reduction capacity of the nanoparticles.