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유화중합에 의한 전분-아크릴 그래프트 공중합에 관한 연구
황주호 ( Ju Ho Hwang ),류훈 ( Hoon Ryu ),조을룡 ( Ur Ryong Cho ) 한국고무학회 2008 엘라스토머 및 콤포지트 Vol.43 No.4
전분을 매트리스 고분자로 하여 아크릴 모노머인 2-ethylhexylacrylate와 methyl methacrylate, acrylic acid를 그래프트 중합하였다. 중합은 라디칼 유화중합에 의하여 전분의 함량을 증가시키면서 수행되었다. 효소인 α-amylase가 전분 대비 0.174% 투입되었을 때 가장 안정한 중합물이 얻어졌으며 전분의 함량이 증가함에 따라 중합물의 유리전이온도가 상승하였다. 전분함량의 증가에 따라 계내의 -OH기가 많아짐에 따라 중합물의 입자 크기와 점도가 증가하였다. Peel strength는 전분 함량이 증가할수록 -OH기 증가에 의해 중합물이 피착체 표면과의 친화력 상승이 일어나서 증가하였다. 반면 초기 점착력은 전분 함량이 증가할수록 유리전이온도의 증가에 따라 필름의 경도가 증가하면서 감소하였다. Starch as matrix polymer was used to do graft copolymerization with 2-ethylhexylacrylate, methyl methacrylate and acrylic acid. The polymerization was carried out by radical emulsion polymerization with increasing contents of starch. When 0.174% of α-amylase as enzyme for starch was added, it was found that it made the best stable emulsion. The glass transion temperature of the polymerized material was increased with starch contents. The particle size and viscosity of the emulsion increased with starch contents due to the increased hydroxy group. Peel strength also increased with contents of starch because the enhanced hydroxy group caused to increase affinity between substrate surface and polymer materials. However, the initial tackiness decreased with starch contents owing to film hardness by higher glass transion temperature.
란탄계열 원소를 활성체로 첨가한 LiPO3 유리 섬광체의 제작과 섬광특성
황주호 ( Hwang Ju Ho ),정석준 ( Jeong Seog Jun ),신상원 ( Sin Sang Won ),최석호 ( Choe Seog Ho ),수마로코프 ( S. Yu. Sumarokov ) 한국센서학회 2003 센서학회지 Vol.12 No.3
LiPO₃ glass scintillators were fabricated, and lanthanides(except Pm) oxides or chlorides were used as an activator. For the fabrication of LiPO₃ glasses, optimum heating conditions were obtained, and the photoluminescence of the glasses was measured by the monochromator. For the best transparency of the glass samples, optimum heating temperature and time are 950 ℃ and 90 min, respectively. It was found that Pr, Nd, Gd, Ho, Er, Tm, Yb and Lu do not work as activator, emission spectrums of samples with them were equal to those of samples without activators. In the case of samples with Europium, the peaks of emission spectrum of Eu^(2+) and Eu^(3+) were 420 ㎚ and 620 ㎚ respectively. And samples with Ce^(3+) were about 380 ㎚, and Tb^(3+) were about 550 ㎚. Glass scintillators with Bi^(3+), Eu^(2+), and Ce^(3+) were found to be more applicable to neutron detection. The result of neutron detection by Ra-Be sources showed that Ce^(3+) was found to be the best activator of LiPO₃