• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.602-606
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• 2014

In this study, we observed changes in the physical properties of norbornene dialkyl ester applied to a PVC. The PVC specimens were prepared by blending PVC, norbornene dialkyl ester and stabilizers. Then, the hardness, tensile strength, elongation, tearing strength, transmittancy, haze and yellowness index of these specimens were measured, and were compared with DOP. The hardness of compounds except dicyclohexyl-5-norbornene-2,3-dicarboxylate (DCHN) were an equal to or higher than that of DOP. The tearing strength and tensile characteristic of DCHN could not be analyzed due to its high hardness. Tensile properties such as the tensile strength and elongation were improved for six compounds except diisononyl-5-norbornene-2,3-dicarboxylate (DINN). All compounds measured showed better tearing strength and transmittancy than those of DOP. Also all norbornene derivatives except DDN showed good haze indices. The yellowness index of DON and DPN showed similar values as DOP.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.72-76
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• 2013

In this study, the boric acid which is a by-product in the esterification process to obtain norbornene diester derivatives was recovered, and then its reusability for esterification of norbornene was investigated. Four types of trialkyl borate (tributyl borate, tripentyl borate, and triisopentyl borate, trihexyl borate) were synthesized through the esterification with boric acid and four types of alcohol. Then, diester derivatives were synthesized by esterification with the synthesized trialkyl borate and norbornene dicarboxylic acid. The conversion of norbornene dicarboxylic acid is 89.50~99.31%. The boric acid which is a by-product in the esterification were recovered with NaCl salt and used for synthesizing trialkyl borate. The recovery rate was 92.43~99.35 %. When the recovered trialkyl borate was used in esterification, there are little losses of the yield. Since boric acid which is a major by-product is able to be recovered, the process is expected to be a clean technology to prevent an environmental pollution by the emission of chemical compounds.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.259-264
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• 2016

In this study, we applied six different norbornene dialkyl esters as a plasticizer to an isoprene rubber (IR) and evaluated replaceability of DEHP which is an endocrine disruptor. IR test sheets were prepared by blending IR, norbornene dialkyl ester, vulcanizing agent, etc. and processing properties of the IR were evaluated by measuring Toque, scorch time, cure time and mooney viscosity. Mechanical properties of IR test sheet including hardness, tensile strength, 100% modulus and elongation were also measured and the physical properties of norbornene dialkyl ester applied as a plasticizer were compared to those using DEHN. Both the maximum and minimum toque for the norbornene dialkyl ester as a plasticizer were similar to those of using DEHP. In addition, the scorch and cure time of the former were slightly longer than those of the latter. The mooney viscosity for the case of DEHN was slightly lower than that of the latter. DEHN was also superior to DEHP in terms of processing. The hardness and thermal properties of all IR test sheets were measured to be similar to each other. The linear alkyl chain of norbornene compounds also exhibited good tensile characteristics.

• Polymer(Korea)
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• v.39 no.3
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• pp.487-492
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• 2015

The effects of chemical structure of alkyl groups of norbornene carboxylic alkyl esters(methyl, octyl, 4-chlorobenzyl) and endo/exo ratios of norbornene monomers on activity of palladium catalyst and polymerization behavior were investigated. Norbornene ester monomers were synthesized from the reaction of 5-norborene-2-carboxylic acid and various alcohols. Polymerization catalyst, di-${\mu}$-chloro-bis(-methoxybicyclo[2,2,1]-hept-2-ene)palladium(II) (DCBMP), was synthesized according to the literature procedure and silver hexafluoroantimonate ($AgSbF_6$) was used as a conjugate anion source. Gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) were the principal techniques for polymer characterization and $^1H$ NMR spectroscopy was used for chemical structures determination of monomers and polymers. For all of the norbonene alkyl esters GPC data showed that when the amounts of endo isomers exceeded those of exo isomers decreased molecular weight polymers were obtained probably due to the decreased catalyst activity. Polymerizations were conducted by varying the monomer/catalyst mole ratios (100:1, 200:1, 300:1). When 300:1 monomer/catalyst ratio was employed it was possible to synthesize high molecular weight ($M_n=27500g/mol$), film forming polymer from exo-norbornene carboxylic acid octyl ester.

• Applied Chemistry for Engineering
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• v.29 no.2
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• pp.225-228
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• 2018

Plasticizers added to thermoplastic polymers are known to shorten the life of products due to the elution to outside, and some of them are harmful to our environment and human body. Since the use of phthalate plasticizers suspected of being carcinogens has been gradually prohibited, there is a need for environmentally friendly plasticizers that can replace them. Most of the substances have a low compatibility with resin, high cost and lack of safety verification. Therefore, in this study, four kinds of norbornene dialkyl ester compounds possessing excellent physical properties, which are also reported as safe compounds from the toxicity evaluation, were added to PVC resin to evaluate the possibility of human exposure by leaching, and also the potential usage as plasticizer candidates alternative to commercial ones including DEHP, DINCH and DOTP. The test was carried out according to the American standard test method (ASTM). The results showed that di-2-ethylhexyl-5-norbornene-2,3-dicarboxylate (DEHN) in aqueous solvents and diisopentyl-5-norbornene-2,3-dicarboxylate (DIPN) compounds in oil solvents were superior or equivalent to DEHP. In addition, all four norbornene compounds showed lower values than 100 ppm, which is considered to have an influence on the environment, indicating that the polar norbornene structure affects the elution.

• Bulletin of the Korean Chemical Society
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• v.32 no.spc8
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• pp.3074-3080
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• 2011

We synthesized three novel poly(norbornene bisimide)s by ring opening metathesis polymerization (ROMP) and subsequent hydrogenation. Their thermal, mechanical and optical properties were investigated with TGA, DMA, UV-Vis spectrometer, and optical reflectometer. The new polymers showed high glass transition temperatures over $260^{\circ}C$ and good thermal stability with 5% wt-loss temperature higher than $390^{\circ}C$. When solvent casted, they yielded optically transparent and dimensionally stable films with a relatively low coefficient of thermal expansion of about 50 ppm $K^{-1}$. Therefore, the bisimide moieties substantially enhanced thermal and dimensional stabilities, as compared with normal ROMP-prepared polynorbornene films. Though the water uptake was increased to 0.6 wt-%, this water uptake is still considerably lower than that for polyethersulfones (1.4 wt-%) or polyimides (2.0 wt-%). Hence, the new poly(norbornene bisimide)s may become attractive candidates for flexible substrates of optoelectronic devices such as displays and photovoltaic solar cells.

• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.475-476
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• 2006

• Bulletin of the Korean Chemical Society
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• v.34 no.9
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• pp.2720-2724
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• 2013

Polynorbornenes prepared by vinyl addition pathway are known to have some desirable characteristics for wider application but they have some critical drawbacks such as brittleness, poor solubility and adhesion. In order to improve these drawbacks, extensive research for the successful homo- and copolymerization of polar functionalized norbornene with olefin has been carried out. Even though considerable advance has been achieved in the polymerization of polar functionalized monomers, successful catalytic systems for the homopolymerization of polar functionalized norbornene are rare. In this study, a novel successful catalytic system for the polymerization of polar functionalized norborene is proposed. This system employs Pd ${\beta}$-diketiminate/borate cocatalyst in water/organic mixed solvents and it is unique due to introduction of water as a component of solvents. Polymers obtained in this study show high Mw with narrow PDI. Effects of several reaction parameters to the polymer activity and properties are investigated and optimal catalytic system are proposed.

• Macromolecular Research
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• v.15 no.2
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• pp.185-190
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• 2007

Poly(norbornene dimethyl dicarboxylate)s, (PNDMD)s, were prepared by addition polymerization with palladium(II) catalyst from pure exo-monomers, and their structure and properties were compared with those of poly(norbornene dicarboxylic acid dialkyl ester)s, (PNDADA)s. Both polymer series exhibited good solubility in general organic solvents and excellent thermal stability up to $330^{\circ}C$. Wide-angle X-ray scattering (WAXS) study indicated the presence of nano-scale layer-like order in amorphous PNDADAs, while PNDMDs showed random amorphous structure. The glass transition temperatures and dielectric constants of solid polymers were found to decrease as the alkyl side-chain length increases for both polymer series. However, PNDMDs showed lower glass transition temperatures and higher dielectric constants, as compared with those of PNDADAs containing the same alkyl substituents. This difference, caused by the higher side-group mobility of PNDMDs, may be closely related to the nano-scale order in amorphous PNDADAs and its absence in PNDMDs.

• Polymer(Korea)
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• v.27 no.5
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• pp.429-435
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• 2003

Vinyl addition copolymerizations of norbornene (NB) and 5-vinyl-2-norbomene (VNB) were carried out using a cationic η$^3$-allyl palladium catalyst in the various mole ratio of comonomers. The copolymers could be obtained in good yield (65∼85%) with high weight-average molecular weights (M$_{w}$ > 760,000). Depending on increasing VNB contents, the molecular weight and yield of the copolymers decreased. FT-IR analysis confirmed that actual contents of VNB in polymer were proportional to the feeding content of VNB. From $^1$H-NMR spectroscopy, we found that both exo and endo VNB isomer were copolymerized with NB. Thermal stabilities of NB-VNB copolymers were independent on the VNB content and their initial decomposition temperatures were about 300 C. The NB-VNB copolymers were followed by epoxidation by using m-CPBA and hydroxylation by 9-BBN, respectively, and these post-polymers were characterized by FT-IR spectroscopy and $^1$H-NMR analysis..