MDSC的原理与应用

调制DSC(MIDSC)在常规的线性升温的基础上,叠加了正弦升温曲线,以缓慢的基础升温速率提高了分辨率,同时以快速的瞬时升温速率提高了灵敏度,将可逆和不可逆效应区分开来,在检测微弱转变、多相转交、测定初始结晶度、热容、热导率等方面显示出不可比拟的优势。     

Study on the Mechanical Properties of Carbon Nanotube/Polyacrylonitrile Composite Fibers

The method of preparing the multi-walled carbon nanotubes (MWNTs)-polyacrylonitriIe (PAN) composite fibers is described and the effects of draw ratio on the mechanical properties of CNT/PAN fibers have also been discussed. The results show that the degrees of MWNTs dispersion in the polymer matrix have much effect on the mechanical properties.     

丙烯腈在1-丁基-3-甲基咪唑氯化物中的聚合及其表征

以离子液体1-丁基-3-甲基咪唑氯化物([bmim]Cl)为溶剂,研究了丙烯腈(AN)的自由基均聚和共聚反应,通过红外光谱(FT-IR)和核磁共振(NMR)分析了聚合产物的化学结构,研究了第二单体丙烯酸甲酯(MA)的含量对聚合反应速率及转化率的影响.结果表明:以离子液体为溶剂所得聚丙烯腈(PAN)的化学结构与在常规溶剂中的一致,聚合产物的组成比与投料比接近,分子量随着AN含量的增加而增大,反应转化率随着AN含量的增加先增大后减小,所得PAN的分子量分布窄(<1.7)、分子量高.差示扫描量热分析(DSC)结果表明:MA含量低于2%时有利于环化反应的控制.     

光散射法研究聚丙烯腈/1-乙基-3-甲基咪唑甲基磷酸酯盐的稀溶液特性

采用激光光散射法研究了聚丙烯腈(PAN)在1-乙基-3-甲基咪唑甲基磷酸酯盐[EMIM][(CH3O)HPO2]中的稀溶液性质.研究结果表明,[EMIM][(CH3O)HPO2]是PAN的良溶剂,PAN在[EMIM][(CH3O)HPO2]中是以单分子链形式存在的,呈无规线团构象;同时PAN分子链在[EMIM][(CH3O)HPO2]中的柔顺性比在常规溶剂如二甲基亚砜(DMSO)中要小很多.推测阴离子与PAN有很强的相互作用以及阳离子的空间位阻效应都能有效破坏PAN分子链间的偶极结构,这是导致PAN以单分子链形式溶解在[EMIM][(CH3O)HPO2]中的主要原因.     

Preparation of High Shrinkage Polypropylene

The common PP chips have been used to prepare high shrinkage PP fibers with shrinkage in boiling water higher than 50%. Meanwhile, the process conditions on fiber structure and properties have been discussed in detail. With the increase of drawing temperature, the shrinkage in boiling water of the fiber increases at first, and then decreases in the temperature range from 70℃to lOO℃. The better drawing temperature is from 75℃ to 85℃ according to the melt index of the PP material. The shrinkage in boiling water of PP fiber increases with the increase of pump delivery. The orientation factor and crystallinity increase with the increase of drawing temperature. With an increase in drawing temperature, unit-cell numbers and monomer unit numbers in every crystal nucleus tend to increase, but unit volume crystal nucleus tend to reduce.     

熔融沉积成型喷嘴内聚偏氟乙烯熔体温度场仿真与工艺参数研究

熔融沉积成型通过线材熔融沉积和冷却黏结的方式制备打印制件，但是线材在喷嘴内的温度会直接影响熔丝的黏结质量，从而影响打印制件的力学性能，而喷嘴内熔体温度对制件黏结质量的影响缺乏相应的理论研究。利用Fluent软件建立聚偏氟乙烯(PVDF)熔体在喷嘴内的温度场模型，研究打印参数对喷嘴内熔体温度场与打印制件黏结性能的影响，通过优化工艺参数为进一步提高打印制件的力学性能提供理论指导。结果表明：喷嘴温度升高时，喷嘴内的熔体温度升高，当喷嘴温度高于230℃时，PVDF线材可在喷嘴中充分熔融，喷嘴直径的改变对熔体温度的影响较小；提高喷嘴温度和减小喷嘴直径有利于熔丝黏结，喷嘴温度为250℃、喷嘴直径为0.4 mm时，打印制件的力学性能最佳。     

耐高温POSS基香料前体的制备及释香动力学研究

为研究耐高温香料前体在涤纶的芳香改性上的应用，以不同的香料醛分子和八(γ-氯氨丙基)多面体低聚倍半硅氧烷(OCAP-POSS)为原料，利用Schiff反应成功合成3种POSS基香料前体(M₁、M₂、M₃)。采用核磁共振氢谱、红外光谱及紫外-可见光谱表征香料前体的结构；用热失重法研究香料前体的热稳定性能；此外，探索香料前体在模拟人体酸性汗液、中性及碱性皂液环境中的释香动力学特征。结果表明：3种香料前体的热分解温度都超过285℃,即香料前体具有良好的热稳定性；香料前体的结构对其释放性能有显著影响，M₁在酸性汗液环境下达到平衡时的释放率为57.86%,M₃却只有33.32%,且缓释时间M₁(29 h)>M₂(16 h)>M₃(12 h);3种香料前体在皂液环境下均较为稳定，在酸性汗液中可实现缓慢释放，其释放规律满足一级反应动力学特征。     

简单连通图G(P,P)的块-割点划分

主要讨论简单连通图G(P，P)(P≥4)的块一割点划分。     

Computer Simulation of Unsymmetry of the Melt - spinning Hollow Fiber

Unsymmetrial cooling always exists in melt - spinning process with circle blowing or lateral blowing cooling, especially for hollow fiber. In melt spinning processes, due to this unsymmetrical cooling, the thermal conductivity is different in each direction. It is certain that in these regions the unsymmetrical structure is formed. In this paper, the computer simulation of unsymmetrical cooling in melt spinning system is researched. The results show that the maximum temperature difference is up to45℃. The point of the highest temperature is not in the center of fiber but near to lower thermal conductivity side. The throughput affects the formation along the spinning line and at lateral direction. The take - up velocity affects the axial formation but affects the lateral structure little.