• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.405-413
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• 2005

본 연구에서는 3톤/일의 플라스틱 투입량을 기준으로 혼합폐플라스틱으로부터 대체연료유를 생산할 수 있는 소용량 중심의 폐플라스틱 유화설비를 설계 제작하였으며 장기간에 걸친 시운전을 통하여 유화설비의 운전성 평가에 대한 실증연구를 수행하였다. 대상 폐플라스틱으로는 플라스틱 재활용 업체에서 분리 선별된 폴리에틸렌과 폴리프로필렌 그리고 이들을 혼합한 폐플라스틱을 각각 적용하였으며 $400\sim420^{\circ}C$의 분해 운전온도에서 폐플라스틱의 종류에 따른 시운전 평가를 하였다. 본 실증연구로부터 폴리에틸렌의 경우에 있어서는 79%의 재생유 회수율을 그리고 폴리프로필렌의 경우에 있어서는 80%의 재생유 회수율을 각각 얻을 수 있었으며 플라스틱 종류별 안정적인 운전조건을 확보할 수 있었다. 또한 폐플라스틱 투입량에 대한 설계용량과 운전용량과의 비교로부터 약 40$\sim$50%의 설계오차가 발생한 것으로 평가되었으며 이는 유화설비의 설계를 위하여 사용된 혼합폐플라스틱의 부정확한 물성 값에 기인한 것으로 판단된다. 따라서 본 연구로부터 얻은 시운전결과를 바탕으로 설계인자들을 확립하는 과정이 반드시 필요할 것으로 판단된다.

• Resources Recycling
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• v.12 no.4
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• pp.44-50
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• 2003

Separation of mixed plastics is not a simple task due to similarities of specific gravity and limitations of sizes, etc. In this study, a new technique was developed to separate plastics selectively by a thermal adhesion method using the different softening or melting temperatures of various types of plastics. Tests were conducted to investigate softening or melting temperatures and adhesion probabilities of plastics with change in temperature. Tests also were conducted to analyze the operating variables, including contact times, size and color pigment. It was founded that LDPE, HDPE and PVC, PET, etc among mixed plastics could be separated selectively according to the change of temperature.

• Journal of Energy Engineering
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• v.14 no.2 s.42
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• pp.159-166
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• 2005

In Korea, although the generation of waste plastic has been increasing, the rate of recycling is considerably low and moreover, there is no suitable method for the treatment of waste plastics. However, pyrolysis, which is appropriate for the treatment of highly polymerized compounds, such as plastics, has recently gained much interest. In this study, a property of the products from the pyrolysis of mixed waste plastics, with a possible practical use for the recycling oil produced, were assessed. First of all, in order to investigate the pyrolysis characteristic of waste plastics, TGA (Thermogravimetric analysis) and DCS (Differential Scanning Calorimetry) were performed on a number of different plastics, including PP, LDPE, HDPE, PET and PS, as well as others. According to the result, it appeared that PP was the most efficiently pyrolyzed by changing the temperature, followed by LDPE, HDPE, PET, PS and the other plastics, in that order. From the results, the optimum conditions f3r pyrolysis were set up, and the different waste plastics pyrolyzed. The recycling oil produced from the flammable gases generated during the pyrolysis was com-pared with fuel oil by an analysis using the petroleum quality inspection method on KS(Korea industrial Standard). The results of the analysis showed the recycling oil was of a similar standard to fuel oil, with the exception of the ignition point, with a quality somewhere between that of paraffin oil and diesel fuel. With respect to these results, the quality of the recycling oil produced by the pyrolysis of waste plastics was suf-ficient for use as fuel oil.

• Resources Recycling
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• v.14 no.3
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• pp.55-62
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• 2005

Mechanical properties of shell powder containing mixed recycled plastics were investigated depending on the shell content and surface modification. First, shell powder and LDPE were compounded using the twin screw extruder to manufacture 40 wt% master batch(M/B), and the M/B was blended with LDPE to produce bulk specimens with 10, 20, 30 and 40 wt% shell content. To improve the compatibility of shell powder with mixed recycled plastics matrix, surface of shell powder was chemically modified with cations or cationic surfactant. Surface modified shell was also used to prepare bulk specimens with the same shell content. Mechanical property analysis showed obvious improvement for the surface modified shell containing bulk specimens compared to unmodified ones. These results can lead to the development of new applications for the mixed recycled plastics.

• Resources Recycling
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• v.16 no.5
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• pp.71-76
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• 2007

The mixed plastic waste generated from households after hand-picking and/or mechanical sorting processes amounts to 1,750,000 ton in 2006, and most of these waste are finally end up with landfill and/or incineration due to the lacks of separation technologies and economical reasons. The mixed plastic wastes can not be used as raw materials for chemical and/or thermal recycling processes because of their high content of PVC(upto 4.0 wt.%). In the present research, gravity separation system has been developed to remove PVC from the mixed plastic waste and to recover the PO-type plastics. This system mainly consists of air classification, magnetic separation, one-step crushing, feeding system at fixed rate and wet-type gravity separation system. The gravity system based on centrifugal separation has been developed at capacity of 0.5 ton/h and it consists of mixing, precleaning, separation, dewatering, recovery system and wastewater treatment system, etc. The main objective of this process is to achieve high separation efficiency of polyolefins with less than 0.3 wt.% PVC content and less than 10% moisture content in the final products. In addition, a crushing unit of with 8 rotor system is also developed to improve the crushing efficiency of soft-type plastics. The system with a capacity of 1.0 ton/h is developed and operational results are presented.

• Resources Recycling
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• v.13 no.1
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• pp.39-46
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• 2004

Triboelectrostatic separation process is a technology that different particles charged after contact and rubbing different materials are separated in a high electric field. This technology has an advantage in that it can be used for separating non-conducting materials such as plastics unlike other electrostatic separation processes. There are two objectives in this study. One is to develop an effective continuous tribo-electrostatic separation process. The other is to apply the developed device for the separation of mixed plastics. Results show that almost all tested plastics reaches over 95% in yield and grade after separation.

• Resources Recycling
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• v.17 no.3
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• pp.21-28
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• 2008

Using the post-consumer waste and edge scrap mixed PET with small amount PP air filter elements of automobiles. It was studied that these mixed waste plastics of the various types of the PET were practicable for the material recycling. Various waste PET/PP plastics were collected, crushed, dried in vacuum, and extruded to recycled PET/PP chips. These chips were mixed with three kinds compatibilizers, EVA, MBS, and recycled PVB of the ratio of $3{\sim}10wt.%$ for the purpose of the compatibility for the post-consumer waste and edge scrap. We investigated mechanical and thermal properties of PET/PP mixtures which were compound with the weight ratio of compatibilizers. Compatibilizer, MBS application was showed the most excellent mechanical properties in the range of the $3{\sim}5wt.%$ EVA application was displayed good impact strength and thermal property in the range of $3{\sim}5wt.%$ Last, recycled PVB application was showed poor mechanical properties in the whole range ratio of the PVB.

• Polymer(Korea)
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• v.27 no.6
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• pp.562-568
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• 2003

Environmental problems due to waste tire and waste plastics let us develop practical and economically feasible products. For this purpose, the characteristics of waste tire/plastic composites including various additives were examined using internal mixer. Experimental results indicated that the tensile strength and the flexural strength of waste tire/plastic composites decreased with the waste tire content. When 20 wt% of PP was added to the waste tire (60 wt%)/HDPE composites, the tensile strength was 1.5 times higher than the composite without PP, It was also found that the strain at break of composites increased by 2.5 times with 10 wt% addition of ethylene vinyl acetate and styrene ethylene butylenes styrene respectively. When 10 wt% of glass fiber was added to waste tire (60 wt%)/ HDPE composites, the tensile strength was 63% higher than the composite without glass fiber.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2001.05a
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• pp.348-351
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• 2001

• Elastomers and Composites
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• v.38 no.1
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• pp.19-26
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• 2003

Mechanical properties of the commingled waste plastics filled with waste newspaper were studied. To improve adhesion at the interface, abietic acid was used. Tensile strength increased with fiber concentration. However the abietic acid did not have any influence on the strength. Tensile strain and impact strength as well decreased with increasing fiber level in the composite, but the abietic acid at low level of concentration with low level of fiber dramatically improved both properties. The reason seemed to be attributed to double-chemical nature of abietic acid.