2,2-亚甲基-二(4,6-二正丁基苯酚)磷酸钠/凹凸棒土/二氧化硅复合成核剂改性聚丙烯的研究

通过喷雾干燥技术制备了一系列无机纳米粒子(凹凸棒土和/或二氧化硅)与有机磷酸盐类成核剂(NA11)复配的复合成核剂.研究了复合成核剂对聚丙烯力学性能与结晶行为的影响.采用透射电镜(TEM)、扫描电镜(SEM)、偏光显微镜(POM)、广角X射线衍射仪(WAXD)等对复合成核剂在聚丙烯中的分散和对结晶行为的影响进行了表征和分析,并且对复合成核剂改性聚丙烯的机理进行了探讨.结果表明,这种复合成核剂对聚丙烯力学性能的改善明显,聚丙烯的刚性迅速增加,其中三元成核剂对聚丙烯刚性的提高更显著,该成核剂在0.2%用量下对聚丙烯力学性能的改善效果,相当于同等添加量下纯NA11的改性效果.微观形态研究表明三元复合成核剂体系中,三组分形成了相互隔离的分散状态,使有机成核剂和无机纳米粒子可以在聚丙烯基体中实现良好分散.     

取向对聚左旋乳酸/聚右旋乳酸复合物纤维结晶性能的影响

通过熔融纺丝的方法制备了PLLA/PDLA复合物初生纤维,在60℃拉伸获得高取向的牵伸纤维.采用X-ray散射为主要表征手段,结合差示扫描量热(DSC)、扫描电子显微镜(SEM)以及傅里叶变换红外光谱(FTIR)等技术,系统研究了不同初始结构的PLLA/PDLA复合物纤维在不同温度下的结晶行为,重点阐明了取向对PLA复合物纤维结晶结构的影响.结果表明,取向促进复合物纤维中立构晶的形成;将纤维升温至200℃停留3 min后,再进行降温,降温过程中,高度取向的牵伸纤维只有立构晶形成,而初生纤维则在150℃左右出现α晶,表明纤维中取向的立构晶会抑制α晶的形成.综合实验结果发现,通过低温牵伸初生纤维,然后高温(α晶熔点以上)退火,可制备出高取向且具有高立构晶含量的PLLA/PDLA复合物纤维.     

高效液相色谱-四极杆串联线性离子阱质谱法测定水产品及饲料中的孔雀石绿、结晶紫及其代谢物

提出了高效液相色谱-四极杆串联线性离子阱质谱法测定水产及饲料中的孔雀石绿、结晶紫及其代谢物(隐色孔雀石绿、隐色结晶紫)的方法。样品经乙腈提取,Agilent XDB C18色谱柱分离,四极杆串联线性离子阱质谱进行检测。以氘代孔雀石绿、氘代隐色孔雀石绿、氘代结晶紫、氘代隐色结晶紫为内标物。4种化合物的线性范围均为0.05~5.0μg·L-1,检出限(3S/N)均为0.5μg·kg-1。以空白样品为基体做加标回收试验,计算得4种化合物的回收率在93.3%~120%之间,相对标准偏差(n=6)在1.4%~18%之间。另外,还采用数据相关采集模式结合增强离子扫描模式对4种化合物进行定性分析,可对试样中4种化合物在定量同时进行定性确证。     

拉曼光谱技术在聚合物研究中的应用进展

拉曼光谱可以提供分子的振动信息,对于聚合物分子链的构象和链间的相互作用非常敏感,能够提供聚合物固体、薄膜或溶液的物理化学特性信息,如聚合物的结构单元、空间构型、晶态结构、分子链的物理构象或分子链子链和侧基在界面间或在各向异性材料中的排列等链取向信息等。因此拉曼光谱作为一种原位无损检测技术,其衍生出的表面增强拉曼光谱技术(Surface-enhanced Raman Scattering,SERS)、变温拉曼光谱技术、共焦显微拉曼光谱技术(Confocal Raman Microscopy,CRM)、拉曼Mapping成像技术和共振拉曼散射技术(Resonance Raman scattering,RRS)等,广泛应用于物理、化学和生物医学等领域。本文从拉曼光谱的基本理论基础、拉曼光谱技术及其在聚合物研究中的最新应用进展等方面进行综述,以探索扩展拉曼光谱技术在高分子物理与化学领域中许多问题,如分子链的构象结构、分子链的结晶行为、分子链的扩散运动和共混体系相态结构变化等方面的应用。     

Partially crystallized Pd nanoparticles decorated TiO2 prepared by atmospheric-pressure cold plasma and its enhanced photocatalytic performance

TiO2 decorated with partially crystallized Pd nanoparticles （Pd/TiO2-P） was successfully prepared by atmospheric-pressure dielectric barrier discharge cold plasma. The XRD and XPS analyses proved that Pd ions were reduced to partially crystallized metallic Pd nanoparticles in Pd/TiO2-P. The XPS spectra also indicated that an enhanced metal-support interaction was formed due to the existence of partially crystallized Pd nanoparticles with lower coordination number in Pd/TiO2-P. Photocatalytic activity of Pd/TiO2-P was much higher than that of TiO2 samples decorated with well crystallized Pd nanoparticles.     

磁性石墨烯对结晶紫的吸附性能研究

本文研究了磁性石墨烯对结晶紫的吸附特性,考察了pH、吸附剂用量、结晶紫浓度以及温度等对吸附平衡的影响。磁性石墨烯吸附结晶紫符合准二级动力学模型。不同温度下磁性石墨烯对结晶紫的吸附等温线满足Langmuir方程(R20.99)、Freundlich方程(R20.97)以及D-R模型(R20.96)。吸附热力学计算结果表明该吸附过程的△G0,并且随着温度升高△G越来越小,表明该吸附反应是自发进行的吸热反应。     

Effect of Molecular Weight on the Properties of Poly（butylene succinate）

Poly（butylene succinate） （PBS） with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by IH-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties （crystallinity as well as crystal morphology）. Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.     

Influence of different inorganic salts on crystallization-driven morphological transformation of PCL-b-PEO micelles in aqueous solutions

Different inorganic salts, including NaSCN, NaCl, MgCl2 and Na2SO4, were added into the aqueous solution containing poly(ε-caprolactone)-b-poly(ethylene oxide)(PCL-b-PEO) semicrystalline micelles. The effects of inorganic salt on the micellar size and morphology were investigated with TEM and DLS. It is found that addition of NaSCN leads to increase of the micellar size, but the micelles remain to be spherical. By contrast, the other three inorganic salts can induce sphere-to-cylinder or sphere-to-lamella transformations of the PCL-b-PEO semicrystalline micelles. The alteration rate of the micellar size with the time after addition of the inorganic salts decreases in the following order: Na2SO4 NaCl ≈ MgCl2 NaSCN. These results were interpreted in terms of the "salting-out" ability of the cations and anions. The anions SO42- and Cl- have a stronger "salting-out" ability, driving the morphological transformations of the micelles and leading to a rapid change in micellar size. By contrast, SCN- has a weaker salting-out" ability. The cations Na+ and Mg2+ may associate with the PEO blocks, leading to a "salting-out" effect as well. However, the "salting-out" ability of cations is weaker than that of SO42- and Cl- anions, and the "salting-out" abilities of Na+ and Mg2+ are similar.     

How polydispersity of network polymers influences strain-induced crystal nucleation in a rubber

Network polymers in a rubber or a gel often contain non-uniform chain lengths. By means of dynamic Monte Carlo simulations of polymer mixtures with various compositions of two chain lengths, we investigated how the factor of polydispersity influences their strain-induced crystal nucleation. Under a high temperature and a high strain rate, the stretching of both polymers revealed that crystal nucleation is mainly accelerated by the presence of short-chain polymers; nevertheless, both polymers join together in the nucleation process. Further analysis proved that crystal nucleation is initiated from those highly stretched short segments, which are rich on the short-chain polymers.     

快速扫描量热法研究聚对苯二甲酸-1,4-环己烷二甲醇酯的结晶和熔融行为

采用快速扫描量热法(FSC)结合传统的差示扫描量热仪(DSC)考察了聚对苯二甲酸-1,4-环己烷二甲醇酯(PCT)聚酯在接近玻璃化转变(T_g)和熔融温度(T_m)范围(100~270 ℃)的结晶和熔融行为。 较大过冷度时PCT聚酯结晶较快,FSC有效地抑制降温过程结晶的发生,而较低过冷度下传统DSC可以避免样品降解对实验结果的影响,二者的结合能很好地对PCT聚酯结晶动力学进行测量,实验结果表明在175 ℃时结晶速率最快。 并且利用Flash DSC对等温结晶温度下形成的片晶熔点进行加热速率的相关测量,在熔融动力学建模的基础上进行校准,以确定零加热速率下片晶的熔点。 Hoffman-Weeks方程中T_m与结晶温度(T_c)的线性关系与T_c=T_m的交点给出了PCT晶体的平衡熔融温度$T_m^o$为315 ℃。