CAJ | 학술논문

采用分子动力学方法(MD),计算了双酚A型聚碳酸酯的应力应/变关系、能量/应变关系.研究中采用了COMPASS力场和NPT系综.应力-应变曲线的研究结果显示,应变εXX≤0.05为"弹性区域",在这一区域,应力-应变有很好的线性关系.在εXX=0.14处出现"屈服点",经过"屈服点",在0.15<εXX<1.0的区域出现应力脉动,应变εXX>1.0后发生了应变硬化.能量-应力关系的研究结果显示,在应力-应变呈线性关系的"弹性区域",体系的总势能及各势能分量随应变增大发生不规则的波动,在"屈服点"附近,Etot与Ebs的变化均产生突跃性的局部高点,而EVW在"屈服点"附近的变化刚好与前两者相反;当体系在经历"屈服区域"时,随着应变的增加,各能量项并不发生明显的变化;当体系处于"应变硬化"阶段时,Etot、Ebs和Ebe会随着应变的增大而继续增大.在整个拉伸过程中,Eto均没有发生明显的变化.对拉伸过程的分子链快照进行分析发现,材料在εXX≤0.16时发生均匀的形变,并维持初始的链结构,同时伴随了一些空穴的生成,在εXX>0.6时,可以清楚地看到密度变得不均匀.在εXX>1.0的应变硬化的初始阶段,新的网络结构生成了,长的直链与缠绕链形成的团簇相连.
채용분자동역학방법(MD),계산료쌍분A형취탄산지적응력응/변관계、능량/응변관계.연구중채용료COMPASS력장화NPT계종.응력-응변곡선적연구결과현시,응변εXX≤0.05위"탄성구역",재저일구역,응력-응변유흔호적선성관계.재εXX=0.14처출현"굴복점",경과"굴복점",재0.15<εXX<1.0적구역출현응력맥동,응변εXX>1.0후발생료응변경화.능량-응력관계적연구결과현시,재응력-응변정선성관계적"탄성구역",체계적총세능급각세능분량수응변증대발생불규칙적파동,재"굴복점"부근,Etot여Ebs적변화균산생돌약성적국부고점,이EVW재"굴복점"부근적변화강호여전량자상반;당체계재경력"굴복구역"시,수착응변적증가,각능량항병불발생명현적변화;당체계처우"응변경화"계단시,Etot、Ebs화Ebe회수착응변적증대이계속증대.재정개랍신과정중,Eto균몰유발생명현적변화.대랍신과정적분자련쾌조진행분석발현,재료재εXX≤0.16시발생균균적형변,병유지초시적련결구,동시반수료일사공혈적생성,재εXX>0.6시,가이청초지간도밀도변득불균균.재εXX>1.0적응변경화적초시계단,신적망락결구생성료,장적직련여전요련형성적단족상련.
Molecular dynamics simulation has been applied to study the behavior of a kind of polycarbenate (PC), bis-phenol-A-poly-carbonate, in this paper. The stress-strain curve and the energy-strain curve have been educed by using COMPASS force field and NPT ensemble. The stress-strain curve shows a linear elastic relationship up to the strain of 0.05, and the yield point was εxx=0.14, after the yield point, the curve becomes flat with little oscillation while the strain continues to increase until εxx=1.0, while after εxx=1.0 the strain hardening occurred. The energy-strain curve illustrates the change in the potential energy of the system. Etot and its compo-nents were ruleless at the elastic stage. An obvious phenomenon can be seen at the yield point, that is Etot and Ebs pass through a local climax and with sadden debase subsequently, while changes of EVW reverse to before-mentioned two energy items. All the energy items change slightly during the yield stage. Etot, Ebs and Ebe increasing with strain increased at the strain-hardening stage. The snapshots of molecular chains illustrated the material deforms homogeneously and maintains the initial chain structure until εzz= 0. 16, with few voids appeared. The homogeneity in the density becomes clearer when εxx= 0. 6. At he beginning of the strain hardening at εxx=1.0,a new network structure is generated where long straightened chains connect the clusters of entangled chains.