• Design & Manufacturing
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• v.15 no.2
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• pp.1-10
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• 2021

In this study, the current state of the plastics industry has been examined. The direction of development and innovation is reviewed and commented. The technical statuses of various sectors such as thermoplastic resin, composite material, mold engineering, and simulation have been scrutinized. In addition, the industrial status of each sector has been reviewed. Then, the challenges that the plastics manufacturing industry has to deal with have been discussed. Especially, the situation in Republic of Korea has been elaborated in detail. Based on the discussion, an open innovation strategy has been suggested. It has been argued in this work that the open innovation strategy will enables efficient funding and development by avoiding resource consuming rent seeking.

• Journal of Adhesion and Interface
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• v.9 no.2
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• pp.16-23
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• 2008

In this study, novel waste wool/polypropylene NFRPs (natural fiber reinforced polymer composites), which are constituted with waste wool discarded as industrial scrap during manufacturing processes of woven fabrics and general purpose thermoplastic polypropylene (PP), were fabricated by means of compressionmolding and their mechanical and thermal properties were characterized. The mechanical properties of PP resin were significantly improved by an introduction of waste wool to PP. In particular, as the loading of waste wool was 50 vol% in the NFRP, the flexural strength of the NFRP was increased about 20%, the flexural modulus about 143%, the tensile strength about 76%, and the tensile modulus about 90% in comparison with each of PP control. In addition, the maximum value of the heat deflection temperature (HDT) obtained with the NFRP was $138^{\circ}C$ at a 50 vol% loading of waste wool. This is $21^{\circ}C$ higher than the HDT of PP control. The result here suggests that waste wool be a potential candidate for a reinforcing material of thermoplastic matrix resins.

• Polymer(Korea)
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• v.35 no.1
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• pp.40-46
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• 2011

The synthesis of well-defined poly(styrene-b-isobutylene-b-styrene) (SIBS) triblock copolymers was accomplished by cationic sequential block copolymerization of isobutylene (IB) with styrene (St) using 1,4-di(2-chloro-2-propyl) benzene (DCC) /$TiCl_4$/2,6-di-tert-butylpyridine(DtBP) as an initiating system in methyl chloride ($CH_3Cl$)/methylcyclohexane(MeChx) (50/50 v/v) solvent mixture at $-80^{\circ}C$. The triblock copolymers exhibited excellent thermoplastic and elastomeric characteristics. Tensile strengths and Shore hardness increased with increasing polystyrene (PS) content, while elongation at break decreased. The blood-compatibility of SIBS was assessed by SEM observation of the platelet adhesion, blood clotting time and haemolysis ratio. The haemolysis ratios were below 5% which met the medical materials standard. The platelet adhesion test further indicated that SIBS block copolymers had a good blood compatibility.

• Textile Coloration and Finishing
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• v.35 no.1
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• pp.20-28
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• 2023

In this study, TPU resin for coating was prepared by varying the mixing ratio of antistatic TPU and recycled TPU to manufacture permanent antistatic materials. The coated yarn was prepared by coating on the nylon yarn, and then the thermal, rheological, mechanical properties and antistatic properties were analyzed. In addition, antistatic properties and durability were confirmed after manufacturing UD fabrics using coated yarns. The mixing ratio of antistatic TPU and recycled TPU was most appropriate at 4:6, and the antistatic property had a surface resistance of 2.20 × 10⁹ Ω and a static charge of 398 V. In the coating process, the coating speed was most appropriate at 0.21 m/s, and the surface resistance of the UD fabric manufactured with the coated yarn manufactured under this condition was 6.80 × 10⁹ Ω and the static charge was 484 V. The UD fabric had a surface resistance of 7.21 × 10⁹ Ω and a static charge of 517 V after washing 10 times, and it was confirmed that the permanent antistatic property was excellent.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.559-571
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• 2017

This study was conducted to determine the adhesive performances of plywoods affected by layering direction and the amounts of thermoplastic films. The face and back layers of veneer were hardwood species (Mixed light hardwood) and core layer veneer was radiata pine (Pinus radiata D. Don). Thermoplastic film used as adhesive were polypropylene (PP) film and polyethylene (PE) film. Thermal analysis and tensile strength were investigated on each films. As a result, the melting temperature of PP and PE films were $163.4^{\circ}C$ and $109.7^{\circ}C$, respectively, and the crystallization temperature were $98.9^{\circ}C$ and $93.6^{\circ}C$, respectively. Tensile strength and elongation of each films appeared higher on the width direction than length direction. Considering the characteristics of the thermoplastic films, the test for the amount of film used was carried out by layering film to the target thickness on veneer. The effecting of layering direction of film on plywood manufacturing was conducted by laminating in the length and width directions of the film according to the grain direction of veneer. Tensile-shear strength of plywood in wet condition was satisfied with the quality standard (0.7 MPa) of KS F 3101 when the film was used over 0.05 mm of PP film and over 0.10 mm of PE film. Tensile-shear strength of plywood after cyclic boiling exceeded the KS standard when PP film was used 0.20 mm thickness. Furthermore, higher bonding strength was observed on a plywood made with width direction of film according to grain direction of veneer than that of length direction of film. Based on microscopic analysis of the surface and bonding line of plywood, interlocking between veneers by penetration of a thermoplastic film into inner and cracks were observed.

• Fire Science and Engineering
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• v.34 no.3
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• pp.1-7
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• 2020

Due to the complexity and large size of buildings, plastic resin is widely used as a building material. Accordingly, the occurrence of fires caused by plastics is increasing. Due to the nature of plastic resin fires, the amount of damage to properties and human life caused by combustion products such as smoke are large, and these damages are related to smoke production and smoke generation. Therefore, this study reviews smoke measurement methods and laws on domestic buildings and fire services. Experiments were conducted based on three smoke-related test standards (ISO 5660-1, ISO 12136, ASTM E 662). The experiment results indicate a total smoke production and generation by PP, PVC, and PMMA of 43.27, 32.83, and 12.33 ㎡, and 27.855, 9.599, and 6.975 g, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.233-239
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• 2022

The injection molding process is a process in which thermoplastic resin is heated and made into a fluid state, injected under pressure into the cavity of a mold, and then cooled in the mold to produce a product identical to the shape of the cavity of the mold. It is a process that enables mass production and complex shapes, and various factors such as resin temperature, mold temperature, injection speed, and pressure affect product quality. In the data collected at the manufacturing site, there is a lot of data related to good products, but there is little data related to defective products, resulting in serious data imbalance. In order to efficiently solve this data imbalance, undersampling, oversampling, and composite sampling are usally applied. In this study, oversampling techniques such as random oversampling (ROS), minority class oversampling (SMOTE), ADASYN(Adaptive Synthetic Sampling), etc., which amplify data of the minority class by the majority class, and complex sampling using both undersampling and oversampling, are applied. For composite sampling, SMOTE+ENN and SMOTE+Tomek were used. Artificial neural network techniques is used to predict product quality. Especially, MLP and RNN are applied as artificial neural network techniques, and optimization of various parameters for MLP and RNN is required. In this study, we proposed an SA technique that optimizes the choice of the sampling method, the ratio of minority classes for sampling method, the batch size and the number of hidden layer units for parameters of MLP and RNN. The existing sampling methods and the proposed SA method were compared using accuracy, precision, recall, and F1 Score to prove the superiority of the proposed method.

• Composites Research
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• v.31 no.4
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• pp.122-127
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• 2018

Sandwich composites of carbon fiber reinforced plastic(CFRP) and polymer foam will be used to automobile and aerospace industry according to increasing importance of light weight. In this study, mechanical and heat resistance properties of sandwich composites were compared with type of polymer foam (polyethylene terephthalate(PET), polyvinylchloride(PVC), epoxy and polyurethane). All types of polymer foams were degraded to 30, 60, 120, 180 minutes in $180^{\circ}C$. After heat degradation, the polymer foams were observed using optical microscope and compressive test was performed using universal testing machine(UTM). Epoxy foam had the highest compressive property to 2.6 MPa and after thermal degradation, the mechanical property and structure of foam were less changed than others. Epoxy foam had better mechanical properties than other polymer foams under high temperature. Because the epoxy foam was post cured under high temperature. As the results, Epoxy foam was optimal materials to apply to structures that thermal energy was loaded constantly.

• Polymer(Korea)
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• v.24 no.5
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• pp.701-712
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• 2000

The continuous fiber reinforced composites of GF/PA were fabricated using a pultrusion resin impregnation apparatus and cut into pellets of 6 mm length. GF/PA pellets were then melt-mixed with PP resin to prepare new types of ternary composites, GF/PA/PP. Mechanical and rheological properties of such composites revealed to be better than conventional ternary composites due to the longer average glass fibers. Measurements also showed that the mechanical properties of the composites prepared by direct injection molding were higher than those of the composites prepared by injection molding followed by extrusion. To improve adhesions of fiber surfaces and polymer matrix, PP-MAH (maleic anhydride) has been introduced in the GF/PA/PP composites as a compatibilizer. It was found that PP-MAH did indeed improve surface adhesion between fibers and polymer matrix and that, as a result, various mechanical properties were markedly enhanced. Visualization of the phase structure in the samples was done by means of SEM. The surfaces of glass fibers in GF/PA/PP composites revealed that the fibers remained to be encapsulated by PA resin. However, pre-encapsulation did not persist in GF/PA/PP/PP-MAH composites due to the improvement of surface adhesion between fibers and polymer matrix, although resin sticking to the fiber was observed.

• Journal of Adhesion and Interface
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• v.16 no.1
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• pp.29-34
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• 2015

Hydrocarbon resins, which are defined as low molecular weight, amorphous, and thermoplastic polymers, are widely used as tackifier for various types of adhesives, as processing aids in rubber compounds, and as modifiers for plastics polymers such as isotactic polypropylene. Typically, hydrocarbon resins are non-polar, and thus highly compatible with non-polar rubbers and polymer. However, they are poorly compatible with polar system, such as acrylic copolymer, polyurethanes, and polyamides. Moreover, recently the raw materials of hydrocarbon resin from naphtha cracking had been decreased because of light feed cracking such as gas cracking. To overcome this problem, in this study, novel hydrocarbon resins were designed to have a highly polar chemical structure which material is sustainable. And, it was successfully synthesized by Diels-Alder reaction of dicyclopentadiene monomer and sorbic acid from blueberry as renewable resources. Acrylic resins were formulated with various tackifiers solution including sorbic acid grafted hydrogenated dicyclopentadiene hydrocarbon resins in acrylic adhesive and rolling ball tack, loop tack, $180^{\circ}$ peel adhesion strength, and shear adhesion strength were measured. The properties depend on the softening point and polar content of tackifiers.