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Study on the Granting Demolding Ability through Polymerization on the Metal Mold Surface
강승인,권민호,김민경,백현종,성동기 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
Nowadays the demolding problem is having attention due to the increase of demand for smaller, more complex, products in various polymer processing fields. Traditionally, efforts have been made to reduce friction between mold and product to facilitate separation and this has been focused on reducing mold roughness in mechanical and physical ways. However, conventional methods such as CNC milling was limited and needs for various releasing agent treatment was increased. Unfortunately, because the effect of releasing agent is not permanent, stopping production lines to coat molds with agents is now significantly impact productivity. So, in this study, we conducted an experiment that gives permanent demolding ability to metal plates by growing different types of polymers to reduce surface energy. Later, by measuring lap shear stress using metal plates with polymer growth, it was intended to quantitatively measure and analyze the occurrence of release capability on metal plates.
Investigation of a New Liquid Composite Molding Process Based on Multiple Resin Drop Impregnation
강승인,성동기 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Carbon fiber reinforced plastic manufacturing systems have been upgraded from autoclave molding to liquid composite molding to keep overcoming some weaknesses like long cycle time and expensive equipment. In this work, we suggest a new liquid composite molding based on the multiple-resin drop impregnation system. The newly developed manufacturing process with an adaptable resin dosing system has the advantage of programming the dosing location and amount of the resin. The system improves the impregnation ability by dosing the exact amount of resin onto the expected unfilled zones. Several mechanical properties were measured to confirm the process feasibility, and the experimental results were considered to be equivalent to the properties of the products from the conventional vacuum assisted resin transfer molding. With these results, we believe the novel process can be a solution for the next-generation composite manufacturing industries after some more applicable studies will be done.
반응액상성형에서 ε-카프로락탐의 음이온 중합에 따른 점도 거동 평가
이재효,강승인,김상우,이진우,성동기 한국복합재료학회 2020 Composites research Vol.33 No.2
최근 내화학성, 내마모성 및 내충격성이 뛰어나면서 재활용이 가능한 열가소성 폴리아미드 기반 복합재료를 제조하는 기술을 개발하기 위한 연구가 활발하다. 특히, 열가소성 고분자는 높은 점도로 용융 상태에서의 가공이 힘들기 때문에 저점도 단량체 상태로 금형 내부로 주입하면서 동시에 중합을 시키는 반응액상성형 공정이큰 주목을 받고 있다. 그러나 단량체인 ε-카프로락탐은 중합속도가 매우 빠르고 외부 환경에 매우 민감하기 때문에 수지 함침과 중합 반응을 동시에 제어하면서 최적 공정조건을 확보하는 데 많은 어려움을 겪고 있는 실정이다. 따라서 본 연구에서는 ε-카프로락탐의 음이온 중합과정에서 주요한 공정 변수인 점도 변화 거동을 관찰하였고 ε- 카프로락탐의 빠른 중합, 낮은 점도, 수분 민감성에 따른 측정상의 문제 원인을 분석하여 개선책을 제시하였다. 개선된 점도 측정 방법에 대한 재현성과 신뢰성은 여러 상대습도에 대한 점도 측정 그리고 외부 환경(수분, 산소)과차단된 상황에서의 중합과 개선된 점도 측정 결과와의 비교를 바탕으로 검증하였으며, 이는 복합재료 반응액상성형 공정의 제어 인자로 활용함으로써 공정 최적화에 도움이 될 것으로 기대된다. Recently, fabrication process of thermoplastic polyamide-based composites with recyclability as well as impact, chemical, and abrasion resistance have been widely studied. In particular, thermoplastic reactive resin transfer molding (TRTM) in which monomer with low viscosity is injected and in-situ polymerized inside mold has received a great attention, because thermoplastic melts are hard to impregnate fiber preform due to their very high viscosity. However, it is difficult to optimize the processing conditions because of high reactivity and sensitivity to external environments of the used monomer, ε-caprolactam. In this study, viscosity as an important process parameter in TRTM was measured during in-situ anionic polymerization of ε-caprolactam and the solutions for problems caused by high polymerization rate and sensitivity to moisture and oxygen were suggested. Reliability of the improved measurement technique was verified by comparing the viscosity behavior at various environmental conditions including humidity and atmosphere, and it is expected to be helpful for optimization of TRTM process.
홍원표,강승인 한국지반공학회 2000 한국지반공학회논문집 Vol.16 No.4
성토지지말뚝 상부의 성토지반내에서 발생되는 지반아칭효과에 의하여 성토하중이 말뚝에 전달되는 효과를 조사하면서 제안된 이론해석의 신뢰성을 확인하기 위하여 일련의 모형실험을 수행하였다. 본 모형실험에서 말뚝은 성토 아래에 일렬로 수열의 줄말뚝으로 설치하였으며, 말뚝캡보는 성토의 길이방향에 직각방향으로 말뚝두부에 설치하였다. 성토재의 하중전달에 가장 큰 영향을 미치는 요인으로는 말뚝캡보사이의 간격과 성토고를 들 수 있다. 이전의 이론적인 연구에 의해 제안된 지반아치의 반경보다 약 33%정도 큰 최소소요성토고보다 높게 성토를 실시할 경우 지반아치는 완벽하게 발생될 뿐만 아니라, 실험치와 이론치는 잘 일치함을 모형실험결과 확인할 수 있다. 모형말뚝캡보에 작용하는 성토하중의 분담률은 말뚝캡보사이의 간격이 증가함에 따라 감소하는 반면, 성토고가 높아짐에 따라 증가하였다. 따라서, 설계시 말뚝의 성토하중지지효과를 극대화시키기 위해서는 성토고를 충분히 높게한 상태에서 말뚝캡보의 간격비를 감소시켜야 한다. 여기서 말뚝캡보의 간격비를 감소시키려면 말뚝캡보사이의 간격을 감소시키거나 말뚝캡보의 폭을 증가시켜야 한다. A series of model tests were performed both to investigate the load transfer by soil acrching in fills above embankment pils and to verify of the theoretical analysis. In the model tests, the piles were installed in a row below the embankment and the cap beams were placed on the pile heads perpendicular to the longitudinal axias of the embankment. The space between pile cap beams and the embankment height was focused as the major factors affecting the load transfer in embankment fill. When the embankment fill was higher than the minimum required height, which was about 33% higher than the radius of the soil arch proposed by theoretical discussion in the previous study, not only the soil arching could be developed completely but also the experimental results showed good agreement with theoretical predictions. The portion of the embankment load carried by model pile cap beams decreased with increment of the space between pile cap beams, while it increased with increment of the embankment height. Therefore, to maximize the effect of embankment load transfer by piles on design, the interval ratio of pile cap beams should be decreased under considerably high embankments by reducing the space between cap beams and/or enlarging the width of pile cap beams.
Fabrication Process of CFRP with Anisotropic Conductivity
김민경,강승인,성동기 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
The research of electrically conductive CFRP is being conducted in various ways and the importance of these studies is increasing today due to the increased usage of lightweight polymer with adaptive conductivity to various industries. A typical method to give electrical conductivity to CFRP is the hybrid composite production that impregnates nanomaterials dispersed resin such as CNT and graphene into the fiber reinforcement. But the biggest problem is inhomogeneous dispersion of nanoparticle and high viscosity of resin. In this study, CFRP was fabricated through a newly programmed high-speed process with a multi-drop method granting anisotropic conductivity. The use of surfactants implemented dispersion stability and minimized the conductivity loss. Also optimizing two nanomaterial content ratios maximized its anisotropic property. Various characterizations were conducted to prove that anisotropic electrical conductive CFRP was well produced and validity of the developed process.