• 한국산업융합학회 논문집
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• 제24권2_1호
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• pp.79-89
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• 2021

Poly(lactic acid) (PLA) is considered as one of the most promising bio-based polymers due to its high strength, high modulus, good processability, transparency after processing, and commercial availability. This study aimed to investigate the mechanical, thermal, and migration properties of poly(lactic acid)/zeolite (10 phr) composites prepared with various biocompatible plasticizers, such as triethyl citrate(TEC), tributyl citrate(TBC), and poly(ethylene glycol)(PEG400), through differential scanning calorimetry(DSC), thermo-gravimetric analysis(TGA) and standard tensile testing. The incorporation of PEG400 significantly increased the elongation at break, and DSC results showed that the addition of plasticizers drastically decreased the T_g of PLA/zeolite composites and improved the melt flow and processability. Besides, it was found from TGA results that PLA/zeolites composites plasticized by TEC and TBC were more easily to be thermally degraded than the composites plasticized by PEG400.

• Computers and Concrete
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• 제17권6호
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• pp.815-829
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• 2016

This study has been carried out to investigate the effect of the surface properties of Portland cement, diatomite and zeolite on the performance of concrete composites. In this context, to describe the materials used in this study and determine the properties of them, chemical, physical, mineralogical, molecular, thermal, and zeta potential analysis have been applied. In the study, reference (Portland cement), 10%-20% diatomite, 10%-20% zeolite, 5+5%-10+10% diatomite and zeolite were substituted for Portland cement, a total of 7 different cements were obtained. Ultrasonic pulse velocity, capillary water absorption and compressive strength tests were performed on the hardened concrete specimens. Hardened concrete tests have been done on seven different types of concrete, for 28, 56 and 90 days. As a result of experiments it has been identified that both the zeolite and diatomite substitution has a positive effect on the performance of concrete.

• 한국포장학회지
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• 제24권3호
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• pp.149-157
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• 2018

Low density polyethylene (LDPE) has been researched in many industrial applications, and LDPE/zeolite 4A composites has been extensively studied for many applications such as microporous, breathable film and so on. LDPE/zeolite composite have a great potential for carbon dioxide adsorption film due to its high adsorption ability. In this study, LDPE/zeolite 4A composites with various contents were prepared by melt mixing process, and co-extrusion process was applied to develop a $CO_2$ adsorption conventional film and foamed film. The thermal, rheological, mechanical, physical and morphological properties of composite films has been characterized, and $CO_2$ adsorption of the composite films evaluated by thermogravimetric analysis (TGA) and the performance was found to be about 18 cc/g at 30.9 wt% of the zeolite content.

• 대한화학회지
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• 제47권5호
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• pp.472-478
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• 2003

본 연구에서는 표면처리된 제올라이트에 따른 제올라이트/DGEBA의 경화 동력학과 기계적 계면특성을 고찰하였다. 경화제는 4, 4''-diamino diphenyl methane(DDM)을 사용하였으며, 제올라이트는(PZ) 15와 35 wt% KOH (15-BZ 그리고 35-BZ)로 표면처리하여 XPS와 XRD로 분석하였다. 경화 동력학은 DSC로 분석하였으며, 시편의 기계적 계면특성은 임계응력 세기인자(critical stress intensity factor, $K_{IC}$)와 임계변형에너지 방출속도(critical strain energy release rate, GIC)를 통하여 알아보았다. XPS와 XRD의 결과로부터, KOH로 표면처리된 제올라이트는 나트륨 (Na)이 칼륨(K)으로 이온교환되었으며, 표면처리로 인한 Al-O의 결합세기의 약화로 $Si_{2p}/Al{2p}$의 값이 증가하였다. 동적 DSC와 기계적 계면특성 결과로부터, 제올라이트/DGEBA 중에서 15-BZ의 경화 활성화에너지($E_a$)는 감소하였으며, $K_{IC}$와 $G_{IC}$는 증가하였다. 이러한 결과들은 제올라이트의 표면처리에 의해 산성도가 증가하였으며, 이렇게 증가된 산성도가 제올라이트와 에폭시 사이의 경화반응에 영향을 준 것으로 관찰된다.

• Nuclear Engineering and Technology
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• 제54권6호
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• pp.1991-2003
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• 2022

The problem of water contamination by long-living cesium and strontium radionuclides is an urgent environmental issue. The development of facile and efficient technologies based on nanostructured adsorbents is a perspective for selective radionuclides removal. In this regard, current work aimed to obtain the nanostructured magnetic zeolite composites with high adsorption performance to cesium and strontium ions. The optimal conditions of hydrothermal synthesis were established based on XRD, SEM-EDX, N₂ adsorption-desorption, VSM, and batch adsorption experiment data. The role of chemical composition, textural characteristics, and surface morphology was demonstrated. The monolayer ionexchange mechanism was proposed based on adsorption isotherm modeling. The highest Langmuir adsorption capacity of 229.6 and 105.1 mg/g towards cesium and strontium ions was reached for composite obtained at 90 ℃ hydrothermal treatment. It was shown that magnetic characteristics of zeolite composites allowing to separate spent adsorbents by a magnet from aqueous solutions.

• 폴리머
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• 제33권3호
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• pp.243-247
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• 2009

셀룰로오스 디아세테이트(CDA)에 가소제로서 트리아세틴(TA)과 에폭시화된 콩기름(ESO)을 첨가하여 고속믹서에서 일차적으로 CDA를 가소화한 후, 여기에 천연 zeolite를 충전제로서 첨가하여 용융압출로 CDA/zeolite 복합체를 제조하였다. DMA 측정을 통하여 가소화한 CDA의 $T_g$는 $106^{\circ}C$이며 여기에 zeolite를 50% 첨가한 복합체의 경우는 $125^{\circ}C$의 $T_g$를 확인하였다. Zeolite의 함량이 10에서 50%까지 증가함에 따라 탄성률은 1.7 GPa에서 3.6 GPa로 2배 이상 증가하였으며, 인장강도는 62 MPa에서 조금 증가하다가 51 MPa로 감소하였고 파단신율도 10%로 증가하다가 3.2%로 감소하였다. 복합체의 SEM 이미지로부터 CDA와 zeolite의 상용성을 확인하였다. Zeolite의 함량이 증가할수록 더 효과적으로 zeolite가 초산기를 흡수하였다.

• Macromolecular Research
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• 제11권5호
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• pp.357-367
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• 2003

The linear low density polyethylene (LLDPE)/zeolite composite using novel inorganic filler, zeolite, is prepared by a conventional compounding procedure using a twin-screw extruder. The observed scanning electron microscopic (SEM) morphology shows a good dispersion and adhesion of zeolite in the LLDPE matrix. The mechanical properties in terms of the Young's modulus, the yield stress, the impact strength, and the elongation at break were enhanced with a successive increment of zeolite content up to 40 wt%. The X-ray diffraction measurement is of supportive for the improved mechanical properties and the complex melt viscosity is as well. Upon applying a certain level of strain on the composites, the dewetting, the air hole formation and its growth are characterized. The dewetting originates around the filler particles at low strain and induces elliptical micropores upon further stretching. The microporosity such as the aspect ratio, the number and the total area of the air holes is also characterized. Thus, the composites loaded 40 % zeolite and 300 % elongation may be applicable for breathable microporous films with improved modulus, impact and yield stress, elongation at break, microporosity and air hole properties.

• 한국재료학회지
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• 제16권11호
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• pp.692-697
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• 2006

Deodorization of natural zeolites have been improved not only for polar but also for non-polar pollutants by sucessive ion exchanges of H and Ag ions starting from Korean natural zeolite with high adsorption capacity. The modified zeolites with $TiO_2$ coating on the surface revealed high deodorization and photocatalytic decomposition effects. Further modification was made with $10{\sim}20nm$ silica nano particles coating on the surface, the resulting composite particles of $SiO_2/TiO_2/modified$ natural zeolite revealed not only comparable deodorization but also better durability and resisatnce to color change compared to the $TiO_2$/modified natural zeolite without much compensation of photocatalytic decomposition effect, when the composite particles were exposed to the polypropylene non-woven fiber coated with organic binder. It is expected for the composite particle prepared here to be used as indoor building materials for indoor air quality control.

• Macromolecular Research
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• 제12권5호
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• pp.443-450
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• 2004

We have studied the effects that inorganic zeolite powder have on structurally different copolymer [poly(propylene-co-ethylene)] and terpolymer [poly(propylene-co-ethylene-co-l-butene)] systems and the possibility of preparing suitable porous composite films. The impact strength and yield stress of the composites did not improve upon any further loading of zeolite, but the modulus increased gradually with respect to the filler loading. The experimental modulus of each of the two systems was compared with theoretical models. We performed a morphological study of the filler mixing efficiency and image analysis. The number-, weight-, and z-average air hole diameters were compared with respect to the draw ratio as well as the zeolite loading. The experimental results suggest that these two matrices can provide a new choice for preparing future multiphase polymeric porous films by stretching them unidirectionally. In particular, we suggest that a 40 wt% zeolite loading at a draw ratio of 4 is useful for porous film applications.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 추계학술발표회
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• pp.16-16
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• 1997