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Esterification of starch based graft copolymers using reactive extrusion processing
장시훈,장소리,김진희,박노형 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0
Starch is a natural polymer with the advantages of environmentally friendly, biodegradable characteristics, relatively low cost and easy handling better than other carbohydrates etc. In this study, starch based graft copolymers with carboxylic acrylate monomer were prepared through reactive extrusion. The monomers were reacted with corn starch under various conditions in the reaction process with ammonium persulfate (APS) and potassium persulfate (KPS) as initiators, tetraethylene glycol diacrylrate (TEGDA) and N,N``-methylenebisacrylamide (MBA) as the crosslinking agents, ion exchanger as esterification agent. The various parameter of graft polymerization reaction were investigated with the amount of additives, reaction temperature and reaction time etc. The characteristics of starch based graft copolymer were verified using fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM).
장시훈,유영선,이윤석,김재능,박수일 한국포장학회 2008 한국포장학회지 Vol.14 No.2
There are increasing public concerns that the disposal of most synthetic carbon-based plastics is a great threat to the environment. These have led to intensive research and development of degradable plastics, such as biodegradable plastics, photodegradable plastics, and multi-degradable plastics. Although these degradable plastics may not completely replace common synthetic plastics, these minimize environmental impacts caused by non degradable plastics. Photodegradable plastics are synthetic polymers into which have been incorporated copolymers or light-sensitive additives to weaken the structural bonds in polymer chains when exposed to UV radiation. A better understanding of photodegradable plastics, which also play an important role in the degradation of multi-degradable plastics, will expand the usage of degradable plastics. The aim of present article is to review the formation, degradation mechanism and properties of photodegradable plastics.
장시훈,유영선,서종철,박수일 한국포장학회 2010 한국포장학회지 Vol.16 No.2
Starch was modified with epichlorohydrin(ECH) to improve the miscibility with LDPE and LLDPE. Native starch or epichlorohydrin treated starch was mixed with grycerol and LDPE/LLDPE resin using a kneader and extruded using a single screw extruder to make pallets. The pallets were compression-molded at 145 into composite boards to evaluate their color, oxygen permeation, mechanical and thermal properties, and degradability under UV irradiation. Sheets with epichlorohydrin treated starch generally showed higher L-value than that of native starch blend sheets. The hunter b-values in both native starch blends and epichlorohydrin treated starch blends increased with Increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. Tensile strength and percent elongation of sheets decreased with increasing starch contents. The degradability of blends under UV radiation increased with increasing starch contents in both blend types. The results represents that crosslinking of starch with epichlorohydrin may be a good method to improve miscibility of starch with petroleum-based materials.
2P-75 Synthesis and characterization of polyimide film with various dianhydrides
장시훈,서영석,박수일,박노형 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Polyimide (PI) are good engineering polymers that have been widely used in many industry fields due to their high performance characteristics such as mechanical properties, thermal stability, dimensional stability and low dielectric constant etc. In this study, three types of PI were synthesized from poly(amic acid) (PAA) solution as precursor. The PAA was prepared from the reaction of 4,4'-(1,3-phenylenedioxy) dianiline (TPE-R) with various dianhydrides. And we could obtain via the thermal imidization of PAA (30 min at 100°C → 30 min at 200°C → 1h at 350°C). The properties of PI films were compared with those of PI prepared from the reaction of TPE-R and the various dianhydrides (benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and 2,3,3',4'-biphenyl tetracarboxylic dianhydride (a-BPDA)). The PI films were characterized by mechanical properties, thermal stability and color.
A Study on the Twofold Restoration in the Epilogue of Job (42:7–17)
장시훈 한국기독교학회 2019 한국기독교신학논총 Vol.113 No.-
The purpose of this study is to reveal the multi-layered meaning of the twofold restoration in the epilogue of Job (42:7-17). As the first step, I suggest my translation and interpretation of 42:6, a task and a key that must precede a proper understanding of the meaning of the twofold restoration. Through this task, I argue that Job’s final word is not repentance, but rather a declaration of withdrawal of his hostile attitude toward God and a confession that he has been comforted by listening to God’s voice. Then, I look at the meaning of double restoration from both Job’s point of view and God’s point of view. By doing this, I will argue that the twofold restoration reveals that those who follow God ― including those who suffer from incomprehen- sible sufferings ― should live a life of relying on the grace of God beyond retributive justice and that those who hold on to God even in hard times will be given rewards. In addition, I argue that the twofold restoration implies not just material rewards, which result in disappointment as they are not given to every sufferer and believer, but ultimate hope and victory for those who hold onto God even in situations of hardship or suffering that cannot be understood.