• Title/Summary/Keyword: polyurethane

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Mechanical Behavior of Polymer Foam Reinforced with Silica Aerogel (실리카 에어로겔을 첨가한 폴리머 폼의 기계적 특성)

  • Ahn, Jae-Hyeok;Kim, Jeong-Hyeon;Kim, Jeong-Dae;Park, Sungkyun;Park, Kang Hyun;Lee, Jae-Myung
    • Journal of Ocean Engineering and Technology
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    • v.31 no.6
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    • pp.413-418
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    • 2017
  • In the present study, silica-aerogel-polyurethane foams were synthesized to improve the mechanical characteristics and insulation performance of the polyurethane foam applied to a liquefied natural gas carrier at a cryogenic temperature of $-163^{\circ}C$. A silica-aerogel-polyurethane foam bulk was prepared using a homogenizer by varying the weight ratio of the silica aerogel (0, 1, 3, and 5 wt%), while maintaining the contents of the polyol, isocyanate, and blowing agent constant. Compression tests were performed at room and cryogenic temperatures to compare the mechanical properties of the silica-aerogel polyurethane foams. The internal temperature of the universal testing machine was maintained through the cryogenic chamber. The thermal conductivity of the silica-aerogel-polyurethane foam was measured using a heat flow meter to confirm the insulation performance. In addition, the effect of the silica aerogels on the cells of the polyurethane foam was investigated using FE-SEM and FTIR. From the experimental results, the 1 wt% silica aerogel polyurethane foam showed outstanding mechanical and thermal performances.

Development of Eco-friendly Pavement Material using Polyurethane Binder (폴리우레탄 바인더를 활용한 친환경 도로포장용 혼합물 개발)

  • Choi, Ji Young;An, Young Jun;Park, Hee Mun;Kim, Tae Woo
    • International Journal of Highway Engineering
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    • v.15 no.2
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    • pp.113-119
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    • 2013
  • PURPOSES : The objectives of this study are to develop the eco-friendly pavement material using polyurethane binder and evaluate mechanical properties of the developed binder and concrete. METHODS : The bending beam test was conducted to select the sample candidates of polyurethane binder based on the bending strength. The characteristics of viscosity, curing time, and temperature change of sample binder was examined on different temperature conditions. The mechanical properties of polyurethane binder was estimated using the dynamic modulus testing. The indirect tensile strength test was conducted on polyurethane binder concrete with different gradation and binder content for evaluating the mechanical properties of concretes. RESULTS : Based on the beading beam test, four different binder samples were prepared for estimate the mechanical properties. The viscosity of polyurethane binder tends to increase with increase of liquid temperature and the hardening phenomenon begins 10 to 15 minutes at room temperature after mixing the resin and hardener. It is observed that the dynamic modulus of binder increases as loading frequency increases and change of modulus is found to be the highest in the PU-2I binder type. The PU-2I binder concretes shows the largest value of indirect tensile strength and indirect tensile energy. CONCLUSIONS : The use of polyurethane binder as pavement materials is capable of increasing the pavement performance and reducing the detrimental environmental effect during the highway construction.

THE INHIBITORY EFFECT OF CHLORHEXIDINE VARNISH AND POLYURETHANE SEALANT ON STREPTOCOCCUS MUTANS IN THE PRIMARY DENTITION (유치열에서 Chlorhexidine Varnish와 Polyurethane Sealant의 Streptococcus mutans억제 효과에 대한 연구)

  • Yi, Soung-Hyuck;Jang, Ki-Jaeg;Kim, Chong-Chul
    • Journal of the korean academy of Pediatric Dentistry
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    • v.25 no.1
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    • pp.116-126
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    • 1998
  • Numerous chemical agents have been developed to reduce the activity of cariogenic bacteria. Of these, chlorhexidine is acknowledged as the most effective. Gel and mouthrinse have been the traditional method of its application in the mouth. It has been reported that chlorhexidine varnish has prolonged inhibitory effect on the number of streptococcus mutans in saliva and plaque. Recently, chlorhexidine varnish and polyurethane sealant have been developed to promote prolonged anticariogenic effect of chlorhexidine. Products containing 10% chlorhexidine varnish and polyurethane sealant have been developed to prevent caries by reducing the number of streptococcus mutans in the oral cavity. The purpose of this study is to investigate the inhibitory effect of chlorhexidine varnish and polyurethane sealant on streptococcus mutans in the primary dentition. Children with primary dentition containing no active carious lesion were divided into two groups. To the experimental group (n=11), chlorhexidine varnish and polyurethane sealant ($Chlorzoin^{(R)}$, Knowell Therapeutic Technologies, Inc. Canada.) was applied once a week for four weeks according to the manufacturer's instruction. Only oral prophylaxis was performed on the control group(n=7). Caries activity was measured after using $Cariescreen^{(R)}$SM (Knowell Therapeutic Technologies, Inc. Canada,) to incubate streptococcus mutans before and 5, 12, 24 weeks after initial varnish application. The following results were observed.; 1. There was statistically significant decrease in the number of streptococcus mutans in the experimental group for 5 weeks(P<0.01), 12 weeks(P<0.05) after the initial application. but, by 24 weeks significant difference had disappeared. 2. As the inhibitory effect of chlorhexidine varnish and polyurethane sealant application is not everlasting, reapplication at 12-24 weeks should be needed.

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The Effects of Kevlar Pulp on Polyurethane Foam for Cryogenic Temperature (극저온용 폴리우레탄 폼에 미치는 케블라 펄프의 영향)

  • Oh, Jong-Ho;Bae, Jin-Ho;Lee, Jae-Myung
    • Journal of the Society of Naval Architects of Korea
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    • v.55 no.6
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    • pp.514-520
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    • 2018
  • Polyurethane foam has excellent mechanical strength and insulation performance, and has been adopted as an insulation material for $-163^{\circ}C$ liquefied natural gas carrier. In this study, Kevlar Polyurethane Foams(K-PUF) were synthesized by adding Kevlar pulp with excellent mechanical strength for the purpose of improving the performance of existing polyurethane foam. Since polyurethane foam has mechanical performance depending on the proportions of Kevlar pulp added, the mechanical strength of the K-PUF with ratios of fiber0.2wt.%, 0.4wt.%, 0.6wt.%, 0.8wt.% and 1.0wt.%) was evaluated. The compression tests were performed on the 4 different temperatures($20^{\circ}C$, $-50^{\circ}C$, $-110^{\circ}C$ and $-163^{\circ}C$) in consideration of the environmental characteristics as a cryogenic insulation used in LNG carrier. Besides, the effects of the fiber addition on polyurethane foam with closed cell structure were evaluated in a phenomenological approach through SEM analysis. All the results were compared to Neat-polyurethane foam. As a results, 0.8wt.% K-PUF showed the improved mechanical strength, and the addition of Kevlar pulp in a certain ratio improves the mechanical performance by enhancing the compression resistance.

Electro-spinning of Polyurethane (Polyurethane의 전기방사)

  • 차동일;강영식;류영준;김학용;이덕래
    • Proceedings of the Korean Fiber Society Conference
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    • 2001.10a
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    • pp.348-350
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    • 2001
  • Polyurethane(PU)은 내마모성, 내약품성, 내용제성이 좋으며 내노화성과 산소에 대한 안정성이 뛰어난 고분자로서 spandex를 비롯하여 코팅, 고무, 도료, 플라스틱, 복합재료 등의 여러 분야에서 이용되어지며 PU를 전기방사 하여 얻은 부직포는 wound dressing, anti-bacteria mask, 인조 피혁, stent 등에 이용할 수 있을 것으로 기대된다. (중략)

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A Study on Foaming Characteristics of Polyurethane Reaction Injection Molding using Cup Foam Test (컵 발포시험을 이용한 폴리우레탄 반응사출성형의 발포 특성에 관한 연구)

  • Youn, J.W.;Kim, H.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2008.10a
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    • pp.106-109
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    • 2008
  • Polyurethane has been one of the most important materials for automobile elastic parts such as bumper, head rest, instrument panel and so on since it covers very wide range of mechanical characteristics with low production costs. The process variables such as formulation of ingredients and mold temperature, mixing speed, etc. can affect the quality of produced polyurethane foams so that process conditions should be determined appropriately. In this study, foaming behaviors of semi-rigid polyurethane were investigated by conducting cup foam tests with 2 major process variables such as environmental temperature and blowing agent content.

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Study on Flow and Stirring Characteristics of Polyurethane resin in a mixer (교반기내의 폴리우레탄 레진의 혼합 특성에 관한 연구)

  • Heo, Seong-Gyu;Park, In-Hyeung;Ha, Kyong-Ho;Suh, Yong-Kweon
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3045-3049
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    • 2007
  • This paper presents a numerical study to enhance the mixing of polyurethane resin in a container. In general, the properties of polyurethane resin vary with the production environment, such as temperature. However in this study we assumed that the dynamic viscosity of the polyurethane is kept constant at 15 [Pa s]. We computed the flow solution and visualized the mixing pattern for different shapes of mixers by using commercial code, ANSYS CFX. In order to quantify mixing, we employed the concept of mixing index by volume integration.

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Study on the Underwater Acoustic Properties of Polyurethane Elastomer

  • Shin, Hyun Dai;Ahn, Byung Hyun
    • Elastomers and Composites
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    • v.52 no.4
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    • pp.326-331
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    • 2017
  • Two kinds of polyurethane elastomers were prepared and their acoustical properties underwater investigated. Their dynamic mechanical properties were measured using a dynamic mechanical analyzer. The sound speed and echo reduction in the 1-50 kHz frequency range were calculated from the data obtained using the analyzer. The sound speed, transmission and attenuation cofficient in 300-800 kHz were measured in a water-filled tank. Impedance tube experiments were performed to determine the reflective coefficient and echo reduction in the 3-8 kHz range. The polyurethane elastomer containing a hollow glass sphere showed a lower reflective coefficient and a higher echo reduction than the polyurethane elastomer without a filler.

Recent Development in Polyurethanes for Automotives

  • Moon, Junho;Kwak, Sung Bok;Lee, Jae Yong;Oh, Jeong Seok
    • Elastomers and Composites
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    • v.52 no.4
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    • pp.249-256
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    • 2017
  • The history of polyurethane is relatively shorter compared to that of the other polymers, though its importance has grown rapidly. Due to its unique properties, polyurethanes are widely applied in various fields. In particular, the automotive industry is one of the important application fields. To date, polyols and isocyanates used in the polyurethane industry are generally of petrochemical origin. Recently, owing to the oil crisis, legislation, and growing awareness towards environmental preservation, the demand for more sustainable and eco-friendly raw materials has increased. In this paper, the latest research and development trends in polyurethane applications were reviewed, with a focus on the automobile industry in areas such as seat comfort, noise reduction, light weight, biomass-based polyurethane, and recycling.

Studies on the Preparation of Polyurethane Diagnostic Membranes for Blood Glucose Measurements (5) : Effects of Temperature and Humidity on the Measurements of Glucose Concentration (혈당측정을 위한 폴리우레탄 진단막의 제조에 관한 연구(5) : 온도와 습도가 글루코우즈의 농도 측정에 미치는 영향)

  • Kwon, Suk-Ky;Park, In-Hee;Yoon, Do-Young
    • Membrane Journal
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    • v.17 no.1
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    • pp.31-36
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    • 2007
  • Polyurethane diagnostic membranes were prepared to measure blood glucose level of diabetics. Final absorbances at 680 nm through activated polyurethane membranes were measured at various concentration of glucose in plasma or blood. The effects of storage temperatures on the measurements of glucose concentration were studied after storage of 3 days, 1 week, 3 weeks, and 5 weeks at various temperatures. The stabilities of polyurethane diagnostic membranes were examined at RH 80%.