尼龙66/蒙脱土复合材料结晶行为的研究

在密炼机中采用熔融共混法制备蒙脱土重量分数为 2 5 %、4 5 %的尼龙 6 6 /蒙脱土复合材料 .通过DSC法对非等温结晶行为及在 2 2 8～ 2 4 0℃范围内的等温结晶行为进行研究 ,并与纯尼龙 6 6进行比较 .从其等温和非等温结晶行为的研究表明 ,蒙脱土起成核剂的作用 ,它的填入使尼龙 6 6结晶速率提高 ,但填料与基体间的相互作用使其链段运动困难 ,结晶活化能提高 ;在研究的填料含量变化范围内 ,结晶行为变化不大 ,并且找到该复合材料在 2 2 8～ 2 34℃范围结晶对温度的不敏感区 ;对非等温结晶过程分析 ,刘结平 莫志深方程是适用的 ,而Ozawa方程则是不适用的 .     

Elastic behavior of non-Gaussian polymethylene chains

In this paper, elastic behaviors of non-Gaussian polymethylene (PM) chains with chain length N=100 are investigated by rotational isomeric state model. Here the tetrahedral lattice of PM chain and the non-local interaction of Sutherland potential are adopted. In the metropolis movement of PM chain, a four-bond movement model is used. The average energy and average Helmholtz free energy with various elongation ratios λ are calculated by Monte Carlo simulation method. The average energy increases with elongation ratio λ and the average Helmholtz free energy decreases with elongation ratio λ. The elastic force f and the energy contribution to elastic force f_u can be obtained from f=∂〈A〉/∂r and f=∂〈U〉/∂r. We find that the elastic force f increases with elongation ratio λ and the energy contribution f_u decreases with elongation ratio λ, and f_u is less than zero. The ratio f_u/f is close to −0.21 for λ?1.25, and −0.04 to −0.35 for λ>1.25 at T=364 K. In our calculation, the rubber elasticity may be discussed in terms of the chemical structure of polymer chains.     

Synthesis and characterization of thermoresponsive isopropylacrylamide-acrylamide hydrogels

In this study, hydrogels of poly(N-isopropylacrylamide-co-acrylamide) having a thermoresponsive character were prepared by a redox polymerization method. NIPAM-co-AAm hydrogels with different thermoresponsive properties were obtained by changing the initial NIPAM/AAm mole ratio and crosslinker concentration.Equilibrium-swelling ratio, dynamic swelling ratio and dynamic deswelling ratio were evaluated for all hydrogel systems. The fast shrinking was observed with all gels. The time required for equilibrium shrinking increased with the increase of acrylamide content in the gel.     

Development of new solid-phase microextraction fibers by sol-gel technology for the determination of organophosphorus pesticide multiresidues in food

Allyloxy bisbenzo 16-crown-5 trimethoxysilane was first used as precursor to prepare the sol-gel-derived bisbenzo crown ether/hydroxyl-terminated silicone oil (OH-TSO) SPME coating. The coating procedure involving sol solution composition and conditioning process was presented. Compared with commercial SPME stationary phases, the new coatings showed higher extraction efficiency and therefore could provide higher sensitivity for organphosphorous pesticides (OPs). Limits of detection (LODs) were in the range of 0.003-1.0 ng/g for these OPs in food samples (honey, juice, orange and pakchoi). The optimal extraction conditions of the new coatings to OPs in these samples were investigated by adjusting extraction time, salt addition, extraction temperature, and dilution ratios of samples with distilled water by using SPME coupled with gas chromatography (GC)-flame photometric detection (FPD). The method was applied to determine the concentrations of OPs in real samples.     

A simple direct enzyme immunoassay of antibodies based on the differences in diffusion rates in a gel of a synthetic antigen and of its complex with antibodies

A simple direct enzyme immunoassay for semiquantitative detec tion of antibodies is suggested. It is based on the difference in diffusion rates in a gel for a synthetic low-mol-wt antigen and of its complexes with antibodies to be detected. Sensitivity and specificity of the devel oped assay are equal to an ELISA method. The assay has been tested with antibodies against HIV protein gp41 in rabbit serum. Possible applications and limitations of the method are discussed.     

碳氟链与碳氢链表面活性剂在固液界面上的吸附

全氟辛酸及其钠盐和十二烷基硫酸钠在R972上的吸附等温线均为S型或LS型，指示固液界面吸附过程中有表面疏水缔合物生成．碳氟表面活性剂的饱和吸附量显著高于碳氢表面活性剂的饱和吸附量．加电解质于液相使各体系吸附量上升．对于碳氟表面活性剂，甚至引起吸附等温线类型变化．例如，不加电解质时全氟辛酸在R972上的吸附等温线为S型，而加入HCl（c＝0．05mol·dm－3）使吸附等混线变成LS型．全氟辛酸比全氟辛酸钠在R972上的吸附更强．几种表面活性剂在R972上的吸附均随温度升高而减少。应用两阶段吸附模型及通用吸附等温线公式可以很好地解释所得实验结果．     

Background-free,fast protein staining in sodium dodecyl sulfate polyacrylamide gel using counterion dyes,zincon and ethyl violet

A background-free, fast protein staining method in polyacrylamide gel electrophoresis using an acidic dye, zincon (ZC) and a basic dye, ethyl violet (EV) is described. It is based on the counterion dye staining technique that employs two oppositely charged dyes to form an ion-pair complex in staining solution. The selective binding of free dye molecules to proteins in acidic solution produces bluish violet-colored bands. It is a rapid and end-point staining procedure, involving only fixing and staining steps that are completed in 1-1.5 h. The detection limit of this method is 8-15 ng of protein that is comparable to the sensitivity of the colloidal Coomassie Brilliant Blue G (CBBG) stain. Due to its sensitivity and speed, this stain may be more practical than any other dye-based stains for routine laboratory purposes.     

PABA疏水缔合水溶性共聚物溶液的合成与性能研究

本文根据高分子的分子设计原理，合成了带苯基的疏水单体N－苯基对正丁基丙烯酰胺（BBAM）。采用自由基胶束共聚的方法制备了水溶性丙烯胺／N－苯基对正丁基丙烯酰胺（BBAM）疏水缔合型共聚物（PABA）。研究了共聚物溶液的性能及影响因素。结果表明，随共聚物溶液浓度的增加，在临界缔合浓度以上，分子间缔合大量形成，水溶液表现粘度迅速增加，表现出明显的疏水缔合行为，与HPAM相比有优异的抗盐性。     

Inorganic—Organic Hybrid 18—Molybdodiphosphate Nanoparticles Bullk—modified Carbon Paste Electrode and Its Electrocatalysis

A kind of inorganic‐organic hybrid 18‐molybdodiphosphate nanoparticles ([(C₄H₉)₄N]₆P₂Mo₁₈Q₆₂·4H₂O) was firstly used as a bulk‐modifier to fabricate a three‐dimensional chemically modified carbon paste electrode (CPE) by direct mixing. The electrochemical behavior of the solid nanoparticles dispersed in the CPE in acidic aqueous solution was characterized by cyclic and square‐wave voltammetry. The hybrid 18‐molybdodiphosphate nanoparticles bulk‐modified CPE (MNP‐CPE) displayed a high electrocatalytic activity towards the reduction of nitrite, bromate and hydrogen peroxide. The remarkable advantages of the MNP‐CPE over the traditional polyoxometalates‐modified electrodes are their excellent reproducibility of surface‐renewal and high stability owing to the insolubility of the hybrid 18‐molybdodiphosphate nanoparticles.