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허현준,한동제,박인준,소원욱,강홍석,이상구,이수복,육신홍,손은호 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Vinylidene fluoride (VDF)-based fluoropolymers have been widely used in electrical application areas, including electric energy storage and harvesting, electromechanical sensors, electrostrictive actuators, etc, because it shows favorable dielectric, ferroelectric, piezoelectric properties. To use them into various applicable fields, VDF has been copolymerized with chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (TrFE). However, insufficient information about the effects of co-monomers on properties of copolymers make it difficult to utilize it. In order to improve this restrictive things, we investigated the change of crystalline properties according to inclusion of CTFE unit in PVDF film.
Green preparation of PVDF nanoparticles with controlled sizes
허현준,박인준,하종욱,이수복,이상구,소원욱,육신홍,이광원,손은호 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0
Poly(vinylidene fluoride) (PVDF) has been widely used in a variety of areas due to its excellent properties such as high melting temperature, high chemical resistance, mechanical and electrical properties. PVDF latex particles have been usually produced by emulsion polymerization using fluorinated surfactants, representatively, ammonium perfluorooctanoate (APFO). However, such surfactants with long fluorocarbon groups should be currently replaced with other surfactants as a result of global regulatory actions in the industrial field because of their bioaccumulative and persistent behavior in the environment. In this presentation, to avoid these limitations of the surfactants, we will suggest the green process for PVDF-production using non-fluorinated surfactants. The size of PVDF nanoparticles is also finely controlled to expand its applicability to various areas.
허현준,한동제,박인준,소원욱,강홍석,이상구,이수복,육신홍,손은호 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Vinylidene fluoride (VDF)-based homo- and copolymers have been widely used in a variety of areas due to their excellent and special. For the suitable properties to the intended application, VDF can be copolymerized with comonomers. In the case of poly(vinylidene fluorideco- chlorotrifluoroethylene) [P(VDF-co-CTFE)], its thermoplastic or elastomeric behavior, thermal and crystalline properties can be changed depending on the CTFE content. However, the lack of knowledge about the relation between those characteristics and mechanical properties of its film has made the applicable area narrow. In order to overcome this limitation, P(VDF-co-CTFE) copolymers with different molar ratio of CTFE have been synthesized and characterized. In this presentation, we will discuss the mechanical and crystalline properties of the copolymer films as a function of comonomer ratio.
허현준,한동제,박인준,소원욱,강홍석,이상구,이수복,육신홍,손은호 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0
Poly(vinylidene fluoride) (PVDF) has the excellent thermal, chemical, mechanical, and electrical properties. In this reason, PVDF has the second largest market share after poly(tetrafluoroethylene) (PTFE) in fluoropolymer areas. PVDF is commercially produced by emulsion polymerization of vinylidene fluoride (VDF) in the presence of a fluorinated surfactant, however, perfluorinated alkylated substances (PFASs) such as perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), and ammoniumperfluorooctanoate (APFO) were listed as persistent organic pollutants due to their persistent, bioaccumulative, and toxic nature. In this study, green emulsion polymerization of VDF was performed without any fluorinated surfactants. In order to characterize the properties of the prepared PVDF, SEM, DSC, TGA, NMR, GPC, DLS were used. In addition, produced pure PVDF latex dispersions were used as surface coating agents.
허현준(Hyun-Jun Heo),최주호(Jooho Choi) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In the automotive industry, rattle noise is one of the important issues, which occurs in the cockpit or other interior components when the parts in close proximity impact against each other under the excessive vibration. As more polymers are employed in these parts and the polymer is prone to degradation, the noise becomes more pronounced in the aged cars. Diverse efforts are being directed to solve these problems, one of which is to conduct FEA to simulate rattle occurrence. In this study, degradation of the material properties is investigated for the polymers of the automotive, which includes elastic modulus, Poisson ratio and CTE on the static side and storage and loss moduli on the dynamic side. Empirical models are established that describes the degradation behavior as a function of time as well as the temperature and humidity, by using some suitable models including Arrhenius and Layton models. In order to account for the scattered data, statistical techniques are employed which are the maximum likelihood and bootstrap methods, from which the model is obtained in the form of probability distributions. Once the models are established, they are used to predict the degradation under arbitrary cycles by applying the concept of cumulative degradation which is given by the integration of the degradation rate over time. Finally, the prediction is validated by applying arbitrary cycles to the coupon, measuring the property and comparing with the predicted values.