Preparation and Tactile Performance of Soluble Eggshell Membrane (S-ESM) Embedded Waterborne Polyurethane (WPU) Composite

주수현,Tridib Kumar Sinha,문준호,오정석 한국고무학회 2023 엘라스토머 및 콤포지트 Vol.58 No.3

Herein, we propose a facile water-processible method to develop an eggshell membrane (ESM)-embedded waterborne polyurethane (WPU)-based bio-degradable and bio-compatible coating material that exhibits attractive tactile properties. Virgin ESM is not dispersible in water. Hence, to develop the ESM-based WPU composite, soluble ESM (SESM) was first extracted by de-crosslinking the ESM. The extracted S-ESM at different concentrations (0, 0.5, 1.0, 1.5 wt %) was mixed with WPU. Compared to virgin WPU, the viscosity of S-ESM/WPU dispersion and the in-plane coefficient of friction (COF) of the composite film surfaces decreased with an increase in the S-ESM content. In addition, an increase in the S-ESM content improved the tribo-positive characteristics of the film. Different good touch-feeling biomaterials, such as fur, feather, and human skin exhibit tribo-positivity. Thus, the enhanced tribo-positive characteristics of the S-ESM/WPU and the decrease in their COF owing to an increase in the S-ESM content imply the enhancement of its touch-feeling performance. The S-ESM embedded WPU composites have potential applications as coating materials in various fields, including automobile interiors and artificial leather.

STUDY ON SEATING COMFORT OF POLYURETHANE MULTILAYER SEAT CUSHIONS

문준호,Tridib Kumar Sinha,곽성복,하진욱,오정석 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5

Instead of a monolayer, multi-layered cushion can be promising to develop more comfortable automotive seat if the layer materials are properly selected. In this study, we have examined the seating comfort of different types of multilayer seat cushions. Polyurethane foams (PUFs) of three different hardness, memory foam, and technogel were used in different combination to prepare four types of multilayer seat cushions. The short-term seating comfort of the seat cushions has been investigated in terms of hardness, initial hardness factor (IHF), modulus irregularity factor (MIF), sag factor (SF), and hysteresis loss as derived from the indentation force deflection (IFD) curves. Long-term comfort has been compared to the respective stress relaxation behavior of the seat cushions. It has been observed that both the short and long-term conditions of comfort are not only influenced by the characteristics of the upper layer, but also by the bottom layer (i.e., supporting material). The present work will help the seat designer to consider the material characteristics for fabricating a good automotive seat on the basis of the desired features needed to provide traveling passengers with proper short- and long term comfort.

UV curable silicone rubber and its composite for futuristic flexible electronics

Xiaojie Zhang,Tridib Kumar Sinha,안영준,김진국 한국고분자학회 2017 한국고분자학회 학술대회 연구논문 초록집 Vol.42 No.2

Solution Based Epoxidation Towards Facilitating the Production of Epoxidized Isoprene Rubbers

( Xiaojie Zhang ),( Tridib Kumar Sinha ),( Jeong Seok Oh ),( Jin Kuk Kim ) 한국고무학회 2020 엘라스토머 및 콤포지트 Vol.55 No.3

Considering the immense applicability of isoprene rubbers, such as natural rubber (NR) and synthetic polyisoprene rubber (IR), attempts are being made to introduce more functionality within the rubber structure, e.g. epoxidation, to widen their technological viability. Epoxidation introduces polar epoxy bonds into the rubber molecular chain, resulting in enhanced intermolecular interactions among the rubber chains, increasing the oil resistance and air impermeability. Although there have been many reports on the epoxidation of NR in its latex form, there has been no such report using its solid form (or gum), which limits the epoxidation in terms of portability. Furthermore, the gum form has longer lifetime, while the latex form has limited lifetime for its efficient use. In this study, the epoxidation of natural rubber and polyisoprene rubber (using meta-chloroperoxybenzoic acid (mCPBA) as the epoxidizing agent) by dissolving their gum in hexane (i.e., the solution method) have been studied and compared. The effects of the amount of mCPBA, reaction time, and reaction temperature were investigated. The present process is easy and facilitates the epoxidation of rubbers in their solid form; therefore, it can be used for industrial upscaling of epoxidized rubber production.

Comfort property of polyurethanes on multilayer seat cushions

Junho Moon,Tridib Kumar Sinha,Jeong Seok Oh 한국자동차공학회 2019 한국자동차공학회 학술대회 및 전시회 Vol.2019 No.11

Temperature dependent amphoteric behavior of Bis[3-(triethoxysilyl)propyl]tetrasulfide towards recycling of waste rubber: A triboelectric investigation

Zhang, Xiaojie,Sinha, Tridib Kumar,Lee, Jinho,Ahn, Youngjoon,Kim, Jin Kuk ELSEVIER 2019 JOURNAL OF CLEANER PRODUCTION Vol.213 No.-

<P><B>Abstract</B></P> <P>Here, we have examine the efficacy of bis[3-(triethoxysilyl)propyl]tetrasulfide (Si69) for physic-chemical recycling of waste rubber tyre (WRT) at two different operating temperatures (i.e., 170 °C and 190 °C). The reclaimed rubbers (RR) have been used to fabricate devices similar to the single electrode triboelectric nanogenerator (SETNG) to realize its future applicability. Sol content, crosslink density, Moony viscosity, and rheology of the RR samples have been investigated to understand the effect of operating temperatures on the reclamation (alias regeneration) process. Although very low content of Si69 (i.e., 1g) reclaims the WRT at both the temperatures, with increasing the concentration (i.e., ≥ 3g), it shows coupling behavior (i.e., re-vulcanization) at 190 °C and reclaiming behavior (i.e., de-vulcanization) at 170 °C. Hot-pressing at 170 °C and 190 °C reproduced the similar observations. SETNG made of RR at 170 °C produced more output voltage than that of the 190 °C, and exhibits distinct tactile sensation towards different objects viz., human finger, latex rubber glove, cotton glove and PTFE sheet. The tactile sensing capability is further visualized by exploiting the principal component analysis (PCA). This work represents a low-cost, low-temperature, time-resolved way for regeneration of eco-hazard waste rubber and its future applicability towards development of tactile sensing materials, energy harvester, etc. Also, the response of TNG can be utilized to know the degree of regeneration.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Si69 showed temperature-dependent amphoteric behavior in waste rubber regeneration. </LI> <LI> De-/re-vulcanized reclaimed rubber (RR) were obtained at 170 °C/190 °C. </LI> <LI> Triboelectric nanogenerator (TNG) made of RR (at 170 °C) showed better response. </LI> <LI> The responses were used to predict the regeneration (i.e., de-/re-vulcanization). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preparation and characterization of silicone based 3D printing materials

Xiaojie Zhang,Tridib Kumar Sinha,오정석,김진국 한국고분자학회 2019 한국고분자학회 학술대회 연구논문 초록집 Vol.44 No.1

Effect of Surface Modifying Agents Towards Enhancing Performance of Waste Gypsum Based PBAT Composite

( Tae Woong Kong ),( In Tae Kim ),( Tridib Kumar Sinha ),( Junho Moon ),( Dong Ho Kim ),( Inseon Kim ),( Kwangyong Na ),( Min-woo Kim ),( Hye-lin Kim ),( Taegyeong Hyeong ),( Jeong Seok Oh ) 한국고무학회 2020 엘라스토머 및 콤포지트 Vol.55 No.4

Stearic acid (SA), polyethylene glycol (PEG), and malic acid (MA) have been used to modify the surface of waste gypsum to develop corresponding poly (butylene adipate-co-terephthalate) (PBAT) composites. According to the mechanical properties, MA-treated gypsum (MA-gypsum) showed the best performance, whereas SA-gypsum showed the worst performance. In contrast to SA and PEG (having -COOH and -OH as polar functional groups, respectively), the presence of both -OH and -COOH in MA is responsible for the superior surface treatment of gypsum and its better dispersion in the polymer matrix (as revealed by FE-SEM analyses). The presence of long aliphatic chain in SA is supposed to inhibit the dispersion of SA-gypsum. Further, the performance of MA-gypsum/PBAT was enhanced by adding polylactic acid (PLA). The maximum optimized contents of MA-gypsum and PLA are 20 and 7.5 wt% for developing a high-performance PBAT composite.

Comparison of ultrasonic-treated rice husk carbon with the conventional carbon black towards improved mechanical properties of their EPDM composites

Kim In Tae,Lee Kwang Ho,SINHA TRIDIB KUMAR,Oh Jeong Seok 한국탄소학회 2021 Carbon Letters Vol.31 No.5

Because of depletion of fossil fuel from the earth curst and increase of environmental concerns, in search of an efcient alternative to the traditional carbon black (CB), a biochar known as rice husk carbon (RHC) has been examined here as a fller material to develop the EPDM composite. In this regard, the ball milled RHC was further treated with ultrasonic wave and used with or without its surface treatment by the silane coupling agent [i.e., 3-mercaptopropyl triethoxysilane (3-MPTMS)]. Among the RHC, ultrasonic treated RHC (UHC) and silane treated UHC (USHC), the EPDM composite of USHC showed nearly similar tensile strength to that of the CB (e.g., CB: 33.88 kgf/cm2 , USHC: 31.38 kgf/cm2 at 20 wt% fller loading) with an enhanced elongation at break (e.g., CB: 206%, USHC: 342% at 20 wt% fller loading) and surprisingly much less compression set value (CB: 40.87%, USHC: 18.95% even after 40 wt% of fller loading). Compared to RHC, the UHC also showed its better performance next to the USHC. In addition to presence of both the carbon and silica in RHC and additional silica within the fexible aliphatic chain in USHC, the disintegration of RHC by ultrasonic treatment towards its narrow particle distribution, smaller particle size, and increased surface area is considered very much efective to develop the corresponding high performance EPDM composites. Thus, the use of waste material, i.e., rice husk through the ultrasonication of RHC followed by its surface treatment can be used as a potential fller material to prepare the environment friendly and cost efective high performing composites to be used in diferent efcient end products, and motivated further for industrial upscaling.

Comparing Waste Gypsum with CaCO₃ as Filler Towards Developing Low-cost PBAT C omposites

Tae Woong Kong(공태웅),In Tae Kim(김인태),Junho Moon(문준호),Tridib Kumar Sinha,Dong Ho Kim(김동호),Inseon Kim(김인선),Kwangyong Na(나광용),Kyum Woo Choi(최겸우),Jeong Seok Oh(오정석) 한국고분자학회 2021 폴리머 Vol.45 No.1

폐석고(CaSO₄) 및 탄산칼슘(CaCO₃)을 이용하여 poly(butylene adipate-co-terephthalate)(PBAT) 복합체를 용융혼합으로 제조한 뒤 비교하였다. 석고와 탄산칼슘은 Ca<SUP>2+</SUP> 양이온을 동일하게 포함하지만 다른 크기의 음이온 즉, 각각 SO₄<SUP>2-</SUP>, CO₃<SUP>2-</SUP>을 함유하고 있다. Fajans’ rule에 따르면 CaCO₃는 이온성이 더 큰 반면, CaSO₄는 편극성이 더 크다. 석고는 탄산칼슘에 비해 편극성이 크기 때문에 filler-matrix간 정전기적 상호작용에 의해 PBAT 내에 분산이 더 잘 되었다. 석고/PBAT 복합체는 충전제-고분자 함량 20:80의 비율에서 탄산칼슘/PBAT 복합체 대비 낮은 인장강도와 높은 연신율 값을 나타냈다. Polylactic acid(PLA)를 첨가함에 따라 석고/PLA/PBAT 복합체는 인장강도와 연신율이 향상했지만 탄산칼슘/PLA/PBAT 복합체의 경우에는 PLA의 첨가에 따른 효과가 관찰되지 않았다. 이는 탄산칼슘에 의한 PLA의 depolymerization에 기인하는 것으로 사료된다. 이러한 복합체의 기계적 거동은 열적, 형태학적, 결정학적 분석을 통해 잘 설명되었다. Melt-mixed composites of poly(butylene adipate-co-terephthalate) (PBAT) with the waste gypsum and calcium carbonate were prepared and their properties were compared. Calcium carbonate and gypsum contain the same cation (Ca<SUP>2+</SUP>) but different anions i.e., smaller CO₃<SUP>2-</SUP> and larger SO₄<SUP>2-</SUP> respectively. According to the Fajans’ rule, CaCO₃ is more ionic whereas gypsum is more polarizable. Because of the abundant polarizability, gypsum was well dispersed in the PBAT matrix through the filler-matrix electrostatic interaction. The gypsum/PBAT showed lower tensile strength but higher elongation at break at a filler to matrix ratio of 20: 80 than those of CaCO₃/PBAT. Further, the addition of polylactic acid (PLA) enhanced both the tensile strength and elongation at break of the gypsum/PLA/PBAT while no such effective changes were observed for CaCO₃/PLA/PBAT maybe due to the possibility of depolymerization of polymers in the presence CaCO₃. Thermal, morphological, and crystallography studies well corroborate with the mechanical behavior of the composites.