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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.
Xiaojie Zhang,Jianhua Xiao,김진국,오정석,이진호 한국고분자학회 2023 폴리머 Vol.47 No.6
The functionalization of polylactic acid (PLA) is examined by grafting cardanol onto its main backbone chain through a dynamic reaction to improve compatibility between PLA and thermoplastic polyurethane (TPU). Cardanol-grafted PLA (PLAC)/TPU blend-based filaments for fused deposition modeling are tested using melt extrusion. Effects of PLAC grafting ratio on the rheological properties and thermal transformation of the PLAC/TPU blends and the mechanical properties of three-dimensional-printed parts are investigated. A decrease in the glass transition temperature and crystallinity from differential scanning calorimetry are observed with increasing cardanol concentration, implying improved miscibility between PLAC and TPU and as a result, PLAC/TPU blends exhibit improved toughness.
Xiaojie Zhang 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3
Prestressed Concrete Cylinder Pipe (PCCP) is a composite pipe structure commonly subjected to earth pressure, internal pressure, and ground loads. To confirm the bearing capacity of PCCP by using the in-direct design method, one of the most important experiments is the Three-Edge Bearing (TEB) test. A rational theoretical analysis method and Finite Element Analysis (FEA) are developed in this study because the TEB test is costly and difficult to conduct. The proposed theoretical analysis method and Finite Element (FE) method can be used to calculate the internal force, the displacement, the cracking load, and the bearing capacity of PCCP under the TEB load. In addition, a parametric study is carried out by using the validated theoretical analysis and FEA method. It is found that the concrete strength, the prestressing level, and the radius-to-thickness ratio of the steel cylinder affects the bearing capacity of PCCP under the TEB load. Furthermore, the proposed theoretical analysis method can be used to calculate the bearing capacity of other kinds of rigid pipes under the three-edge bearing load.
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>
ON C-STIELTJES INTEGRAL OF BANACH-VALUED FUNCTIONS
Xiaojie Zhang,Dafang Zhao,Guokju Ye 한국수학교육학회 2007 純粹 및 應用數學 Vol.14 No.2
In this paper, we define the C-Stieltjes integral of the functions mapping an interval [a,b] into a Banach space X with respect to g on [a,b], and the C-Stieltjes representable operators for the vector-valued functions which are the generalizations of the Henstock-Stieltjes representable operators. Some properties of the C-Stieltjes operators and the convergence theorems of the C-Stieltjes integral are given.
장소걸 ( Zhang Xiaojie ),안영준 ( Youngjoon Ahn ),김진국 ( Jin Kuk Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2018 No.-
Tire rubber recycling or reclaiming is the process of recycling vehicles' tires that are no longer suitable for use on vehicles due to wear or irreparable damages. The waste rubber have been disposed of by incineration, pyrolysis, landfill or reclaimation. Here, we recycle ground waste rubber powder by compression molding method. The influence of compression temperature, pressure and time on tensile properties are examined. Also, we use the ground rubber powder as a filler filled in reclaimed rubber composites. The effect of powder content on Mooney viscosity, cure characteristics and tensile properties of composites are investigated.