경량 폴리머 콘크리트 복합체의 내열성능에 관한 연구

조영국 한국건축시공학회 2008 한국건축시공학회지 Vol.8 No.6

In recent years, the light-weight aggregate has widely been used to reduce the weight of construction structures, and to achieve the thermal insulation of building structures. The purpose of this study is to evaluate the heat resistance of polymer concrete composites with light-weight aggregate made by binders as resin and cement with polymer dispersion. The light-weight polymer concrete composites are prepared with various conditions such as binder content, filler content, void-filling ratio, light-weight aggregate content and polymer-cement ratio, and tested for heat resistant test, and measured the weight reducing ratio, strengths and exhaustion content of gas such as CO, NO and SO2. From the test results, the weight reducing ratio of light weight polymer concrete using UP binder after heat resistance test increase with an increase in the UP content irrespective of the filler content. The weight reducing ratio of polymer cement concrete is considerably smaller than that of UP concrete. In general, the strengths after heat resistance of polymer concrete composites are reduced about 40 to 65% compared with those before test. The exhausted quantity of CO, NO and SO2 gases in polymer concrete composites is less than EPS(Expanded poly styrene). From the this study, it is confirmed that the many types gases discharge according to binder type of polymer concrete composites, its amount is controlled by selection of the binder type and mix proportions. In recent years, the light-weight aggregate has widely been used to reduce the weight of construction structures, and to achieve the thermal insulation of building structures. The purpose of this study is to evaluate the heat resistance of polymer concrete composites with light-weight aggregate made by binders as resin and cement with polymer dispersion. The light-weight polymer concrete composites are prepared with various conditions such as binder content, filler content, void-filling ratio, light-weight aggregate content and polymer-cement ratio, and tested for heat resistant test, and measured the weight reducing ratio, strengths and exhaustion content of gas such as CO, NO and SO2. From the test results, the weight reducing ratio of light weight polymer concrete using UP binder after heat resistance test increase with an increase in the UP content irrespective of the filler content. The weight reducing ratio of polymer cement concrete is considerably smaller than that of UP concrete. In general, the strengths after heat resistance of polymer concrete composites are reduced about 40 to 65% compared with those before test. The exhausted quantity of CO, NO and SO2 gases in polymer concrete composites is less than EPS(Expanded poly styrene). From the this study, it is confirmed that the many types gases discharge according to binder type of polymer concrete composites, its amount is controlled by selection of the binder type and mix proportions.

Effects of Filler Characteristics and Processing Conditions on the Electrical, Morphological and Rheological Properties of PE and PP with Conductive Filler Composites

김윤희,김지문,김성현,김우년,김동현,이헌상 한국고분자학회 2009 Macromolecular Research Vol.17 No.2

The electrical, morphological and rheological properties of melt and dry mixed composites of polyethylene (PE)/graphite (Gr), polypropylene (PP)/Gr and PP/nickel-coated carbon fiber (NCCF) were investigated as a function of filler type, filler content and processing temperature. The electrical conductivities of dry mixed PP/NCCF composites were increased with decreasing processing temperature. For the melt mixed PP/NCCF composites, the electrical conductivities were higher than those of the melt mixed PE/Gr and PP/Gr composites, which was attributed to the effect of the higher NCCF aspect ratio in allowing the composites to form a more conductive network in the polymer matrix than the graphite does. From the results of morphological studies, the fillers in the dry mixed PP/NCCF composites were more randomly dispersed compared to those in the melt mixed PP/NCCF composites. The increased electrical conductivities of the dry mixed composites were attributed to the more random dispersion of NCCF compared to that of the melt mixed PP/NCCF composites. The complex viscosities of the PP/Gr composites were higher than those of the PP/NCCF composites, which was attributed to the larger diameter of the graphite particles than that of the NCCF. Furthermore, the fiber orientation in the ‘along the flow’ direction during melt mixing was attributed to the decreased complex viscosities of the melt mixed PP/NCCF composites compared those of the melt mixed PP/Gr composites.

Silorane 복합레진의 중합수축의 동력학

권영철,이인복 大韓齒科保存學會 2010 Restorative Dentistry & Endodontics Vol.35 No.1

복합레진이 개발된 이후 많은 물성의 향상이 이루어졌으나 복합레진의 중합수축은 아직 해결되지 않은 주요 단점으로 남아있다. 중합수축이 적은 복합레진을 만들기 위한 많은 노력이 이루어졌고, 최근에 기존의 methacrylate 기질이 아닌 silorane 기질의 복합레진이 개발되었다. 본 연구에서는 silorane 기질의 복합레진과 methacrylate 기질의 복합레진의 중합수축거동을 측정하고 비교하고자 하였다. 온도변화에 민감하지 않으며 실시간으로 복합레진의 체적 중합수축을 측정할 수 있는 계측장치를 제작하여 사용하였다. 5종의 methacrylate 기질의 수복용 복합레진(Beautifil, Z100, Z250, Z350, Gradia X)과 silorane 기질 복합레진 (P90)의 중합수축을 10분 동안 측정하여, 중합수축량, 최대 중합수축률 그리고 최대수축시간을 비교하였다. 복합레진의 중합수축은 제품별로 많은 차이를 보였다. Silorane 기질의 P90복합레진의 중합수축이 1.48%로 가장 낮았고 Beautifil 복합레진의 중합수축이 2.80%로 가장 높았다. Methacrylate 계열의 복합레진 사이에도 중합수축량에 제품별로 유의한 차이를 보였다(p<0.05). 최대 중합수축률은 P90이 0.13%/s로 가장 낮았고 Z100이 0.34%/s로 가장 높았다. 최대 수축시간은 methacrylate기질의 복합레진(2.4-3.1초)에 비해, silorane 기질의 P90 복합레진이 6.7초로 두 배 이상 길었다. 최대중합수축률은 중합수축과 최대수축시간의 역수를 곱한 값과 강한 양의 상관관계를 보였다(R = 0.95). Dental composites have improved significantly in physical properties over the past few decades. However, polymerization shrinkage and stress is still the major drawback of composites, limiting its use to selected cases. Much effort has been made to make low shrinking composites to overcome this issue and silorane-based composites have recently been introduced into the market. The aim of this study was to measure the volumetric polymerization shrinkage kinetics of a silorane-based composite and compare it with conventional methacrylate-based composites in order to evaluate its effectiveness in reducing polymerization shrinkage. Five commercial methacrylate-based (Beautifil, Z100, Z250, Z350 and Gradia X) and a silorane-based (P90) composites were investigated. The volumetric change of the composites during light polymerization was detected continuously as buoyancy change in distilled water by means of Archemedes' principle, using a newly made volume shrinkage measurement instrument. The null hypothesis was that there were no differences in polymerization shrinkage, peak polymerization shrinkage rate and peak shrinkage time between the silorane-based composite and methacrylate-based composites. The results were as follows: 1. The shrinkage of silorane-based (P90) composites was the lowest (1.48%), and that of Beautifil composite was the highest (2.80%). There were also significant differences between brands among the methacrylate-based composites. 2. Peak polymerization shrinkage rate was the lowest in P90 (0.13%/s) and the highest in Z100 (0.34%/s). 3. The time to reach peak shrinkage rate of the silorane-based composite (P90) was longer (6.7 s) than those of the methacrylate-based composites (2.4-3.1 s). 4. Peak shrinkage rate showed a strong positive correlation with the product of polymerization shrinkage and the inverse of peak shrinkage time (R = 0.95).

Hexadecyltrimethylammonium Bromide-Modified Sericite Mica-Based Polyimide Composites: A Comparison Between In situ Polymerization and Solution Intercalation Processes

Qi Zhang,Duxin Li,Dengwang Lai,Baoli Ou 한국고분자학회 2015 Macromolecular Research Vol.23 No.9

In order to increase the spacing between clay layers and study the effects of processing on the morphology and properties of PI/organoclay composites, polyimide (PI) composites containing multi-step procedure-modified sericite mica were prepared via in situ polymerization and solution intercalation. The structure-property relationships of the composites were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS). The results of XRD patterns revealed d002-spacing of clay was expanded from 0.99 to 2.77 nm. TEM photographs indicated majority of the organoclay exhibited an exfoliated morphology in composites prepared by in situ polymerization. TGA summarized the composites prepared by solution intercalation and in situ polymerization had a 9 and 29 oC increment in T5 compared with pristine PI respectively. XPS indicated the interaction of organoclay and polymer matrix in composites prepared by in situ polymerization was stronger than other types of composites. The glass transition temperature (Tg) and storage modulus of the composites prepared via in situ polymerization was much higher. Especially the Tg of this composites revealed a 33 oC increase compared with pure PI.

폴리머-탄소나노튜브 복합체 에어로졸 입자의 생성 및 이를 이용한 하이브리드 복합체 박막 제조

김휘동,안지영,김수형 한국입자에어로졸학회 2010 Particle and Aerosol Research Vol.6 No.2

In this paper, we describe a new method to form polymer thin films, in which carbon nanotubes (CNTs) are homogeneously distributed so that they can strengthen the mechanical property of resulting polymer film. To do so, we first homogeneously mixed CNTs with polymer in a DMF solvent. With the assistance of ultrasonic nebulizer, the polymer/CNT solution was then aerosolized into micro-sized droplets and finally turned into solidified polymer/CNT composite particles by gas-phase drying process. As the results of SEM and TEM analysis, CNTs were found to be homogeneously immobilized in the polymer matrix particles due to rapid drying process in the gas phase. For comparison purpose,(i) the polymer/CNTs composite particles prepared by aerosol processing method and (ii) polymer/CNTs sheets prepared by simple solution-evaporation method were employed to form polymer/CNTs composite thin films using a hot press. As the result, the aerosol processing of composite particles was found to be a much more effective method to form homogeneously distributed-CNTs in the polymer matrix thin film.

Review Paper : A Review on the Flammability and Flame Retardant Properties of Natural Fibers and Polymer Matrix Based Composites

( M. N. Prabhakar ),( Atta Ur Rehaman Shah ),( Jung-il Song ) 한국복합재료학회 2015 Composites research Vol.28 No.2

Natural fibers reinforced polymer composites are being used in several low strength applications. More research is going on to improve their mechanical and interface properties for structural applications. However, these composites have serious issues regarding flammability, which are not being focused broadly. A limited amount of literature has been published on the flame retardant techniques and flammability factor of natural fibers based polymer matrix composites. Therefore, it is needed to address the flammability properties of natural fibers based polymer composites to expand their application area. This paper summarizes some of the recent literature published on the subject of flammability and flame retardant methods applied to natural fibers reinforced polymer matrix composites. Different factors affecting the flammability, flame retardant solutions, mechanisms and characterization techniques have been discussed in detail.

Effects of Filler Characteristics and Processing Conditions on the Electrical, Morphological and Rheological Properties of PE and PP with Conductive Filler Composites

Kim, Youn-Hee,Kim, Dong-Hyun,Kim, Ji-Mun,Kim, Sung-Hyun,Kim, Woo-Nyon,Lee, Heon-Sang The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.2

The electrical, morphological and rheological properties of melt and dry mixed composites of poly ethylene (PE)/graphite (Gr), polypropylene (PP)/Gr and PP/nickel-coated carbon fiber (NCCF) were investigated as a function of filler type, filler content and processing temperature. The electrical conductivities of dry mixed PP/NCCF composites were increased with decreasing processing temperature. For the melt mixed PP/NCCF composites, the electrical conductivities were higher than those of the melt mixed PE/Gr and PP/Gr composites, which was attributed to the effect of the higher NCCF aspect ratio in allowing the composites to form a more conductive network in the polymer matrix than the graphite does. From the results of morphological studies, the fillers in the dry mixed PP/NCCF composites were more randomly dispersed compared to those in the melt mixed PP/NCCF composites. The increased electrical conductivities of the dry mixed composites were attributed to the more random dispersion of NCCF compared to that of the melt mixed PP/NCCF composites. The complex viscosities of the PP/Gr composites were higher than those of the PP/NCCF composites, which was attributed to the larger diameter of the graphite particles than that of the NCCF. Furthermore, the fiber orientation in the 'along the flow' direction during melt mixing was attributed to the decreased complex viscosities of the melt mixed PP/NCCF composites compared those of the melt mixed PP/Gr composites.

폴리머 디스퍼전과 시멘트로 만든 균열보수용 폴리머 시멘트 복합체의 기초적 성질

조영국 한국구조물진단유지관리공학회 2023 한국구조물진단유지관리공학회 논문집 Vol.27 No.5

본 연구는 RC 구조물의 균열보수를 위한 보수재로서 폴리머 디스퍼전과 시멘트만으로 구성된 폴리머 시멘트 복합체 (polymer cement Composites ; PCCs)를 제작하여 실험적으로 기초물성을 파악하고자 하였다. 연구를 위한 시험배합은 EVA 및 SAE 폴리머 디스퍼전을기반으로 보수재의 충전성을 고려하여 폴리머 시멘트비를 4가지(20, 60, 80 및 100%)로 변환시키면서 물시멘트비를 정해 PCCs의 점도를 결정하였다. 또한 PCCs의 강성을 개선시키기 위하여 P/C 80%와 100%에 실리카퓸을 혼입한 시험편도 제작하였다. PCCs의 균열보수용으로서의점도, 유동성, 충전성, 인장강도, 신장률 및 탄성계수 등 기초적 물성을 실험하였다. 연구결과, 폴리머의 종류에 따라 P/C는 점도와 유동성에 큰영향을 미쳤으며 RC 구조물의 균열보수용으로서 충전성을 고려한 적절한 점도를 맞춘 배합설계를 위해 상당한 가수가 필요하였다. 본 연구에서 설계한 모든 배합은 충전성이 우수하였으며, PCCs의 인장강도와 신장률은 시멘트 혼입 폴리머계 방수재에 대한 KS 규정을 만족하였다. 또한 실리카퓸을 혼입함으로써 PCCs의 인장강도와 탄성계수가 개선되었으며, 폴리머 종류에 따라서는 SAE를 사용한 경우가 EVA를 사용한 경우에 비해 RC 구조물 균열 보수재로서 우수한 기초적인 물성을 나타냈다. 본 연구결과를 종합하면, RC 구조물의 균열보수용으로 SAE를 사용한 P/C 80% 또는 100%와 실리카퓸 30%까지 혼입한 배합을 적절한 배합으로 제안할 수 있었다. The aim of this study was to produce polymer cement composites (PCCs) composed of polymer dispersion and cement as crack repair materials for RC structures, and to investigate their fundamental properties. The test mixtures for the study were based on EVA and SAE polymer dispersions, and the water-cement ratio was determined while varying the polymer-cement ratio(P/C) in four different levels (20%, 60%, 80%, and 100%) to achieve the desired viscosity of PCCs considering their fillability as crack repair materials. Additionally, silica fume was incorporated into P/C 80% and 100% specimens to enhance their stiffness. The basic properties of PCCs as crack repair materials, such as viscosity, flowability, fillability, tensile strength, elongation, and modulus of elasticity, were examined. The results showed that P/C depending on the type of polymer significantly affected the viscosity and flowability, and appropriate w/c ratios were needed to achieve the desired viscosity for the mixture design with consideration of fillability as crack repair materials for RC structures. All designed mixtures in this study exhibited excellent fillability. The tensile strength and elongation of PCCs satisfied the KS regulation for cement- polymer modified waterproofing coatings. The incorporation of silica fume improved the tensile strength and modulus of elasticity of PCCs. Depending on the type of polymer, mixtures using SAE showed better fundamental properties as crack repair materials for RC structures compared to those using EVA. In conclusion, SAE-based P/C 80% or 100% with the addition of up to 30% silica fume can be recommended as suitable mixtures for crack repair of RC structures.

Engineering magnetic type radio-absorbers based on composites with a dual-phase polymer matrix

Marek Gořalík,Marek Jurča,Constantin Bubulinca,Vladimír A. Babayan,Jarmila Vilčáková,Natalia E. Kazantseva,Petr Sáha 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.4

This work is focused on the optimization of electromagnetic and mechanical properties of magnetic polymer composites forEMI applications as radio absorbers (RAs). Polymer composites with a dual-phase polymer matrix, vinyl-terminated polydimethylsiloxane(PDMS) in epoxy (ER), were investigated for fabricating highlyfilled manganese zinc ferrite (MnZn) andcarbonyl iron (CI) composites with respect to radio-absorption and mechanical properties. The dielectric and magnetic propertiesof the composites were determined by the type, concentration as well as the polymer matrix composition. Increase ofthe filler and the PDMS concentration leads to an increase in magnetic losses due to a decrease in the demagnetizing field. Theelectromagnetic properties of the composites were evaluated in the RF band using the impedance method (1 MHz–3 GHz). Based on the complex permittivity (ε*) and the complex permeability (μ*), the reflection loss RL (dB) of single-layer metalbackedRAs were calculated. The RAs with a MnZn ferrite demonstrated a larger bandwidth to thickness ratio in comparisonwith the CI-based RAs due to a proper ratio between ε* and μ* which leads to the better impedance matching conditions. According to the mechanical analyses (DMA, Charpy impact strength) the significant increase of stiffness up to 125% andthe impact strength up to 150% was achieved due to the optimal composition of the polymer matrix and the filler.

Correction to: Engineering Magnetic Type Radio‑Absorbers Based on Composites with a Dual‑Phase Polymer Matrix

Gořalík Marek,Jurča Marek,Bubulinca Constantin,Babayan Vladimír A.,Vilčáková Jarmila,Kazantseva Natalia E.,Sáha Petr 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.5

This work is focused on the optimization of electromagnetic and mechanical properties of magnetic polymer composites for EMI applications as radio absorbers (RAs). Polymer composites with a dual-phase polymer matrix, vinyl-terminated polydimethylsiloxane (PDMS) in epoxy (ER), were investigated for fabricating highlyfilled manganese zinc ferrite (MnZn) and carbonyl iron (CI) composites with respect to radio-absorption and mechanical properties. The dielectric and magnetic properties of the composites were determined by the type, concentration as well as the polymer matrix composition. Increase of the filler and the PDMS concentration leads to an increase in magnetic losses due to a decrease in the demagnetizing field. The electromagnetic properties of the composites were evaluated in the RF band using the impedance method (1 MHz–3 GHz). Based on the complex permittivity (ε*) and the complex permeability (μ*), the reflection loss RL (dB) of single-layer metal-backed RAs were calculated. The RAs with a MnZn ferrite demonstrated a larger bandwidth to thickness ratio in comparison with the CI-based RAs due to a proper ratio between ε* and μ* which leads to the better impedance matching conditions. According to the mechanical analyses (DMA, Charpy impact strength) the significant increase of stiffness up to 125% and the impact strength up to 150% was achieved due to the optimal composition of the polymer matrix and the filler.