STUDY ON MAGNETIC FIELD-INDUCED 0RIENTATI0N OF A CHIRAL SIDE-CHAIN LIQUID CRYSTAL POLYACRYLATE USING INFRARED DICHROISM

Magnetic field-induced orientation of a chiral side chain liquid crystalline polyacrylate(P-11) was studied by using IR dichroism. For the investigated P-11, it has been shown thatthe magnetic alignment takes place over the entire temperature range between its meltingpoint and clearing point and the orientation level is strongly temperature-dependent, thedevelopment with time of the magnetic orieatation follows an exponeotial-type relation,and the smectic phase state influences the thermal relaxation process in the absence of themagnetic field.     

A photometric detector driven by beta radiation

It was recently found that typical Chromatographic carrier gases such as argon or nitrogen could be used in a modified flame photometric detector for general or selective determination of eluted molecules. The detector was powered not by a flame but by a radioactively stimulated, mild discharge. The luminescence arose from the second positive system of nitrogen (in argon), and various emissions from aroyl-containing molecules (in nitrogen).This study describes experiments that take away not only the flame but also the discharge: The energy that produces the luminescence is derived solely from the beta decay of⁶³Ni. Because of this low power input, the sensitivity of the present beta-driven photometric detector (-PD) is limited to about 25 ppm of nitrogen (in argon), and to about 5 pg/s for benzaldehyde and other well-responding aroyl compounds (in nitrogen). In accordance with mechanisms postulated earlier, other types of molecules do not produce significant responses in the absence of an electrical field.Material taken from doctoral thesis     

Study on oxidation of polymers treated by high LET radiation

The oxidation of medical silicone rubber and segmented polyether urethane which were bombarded with 11.2 MeV Si⁺ or F⁺ at the dose of 5 × 10¹⁴ ions/cm² was studied. In XPS measurements, it was found that the oxygen concentration on the surface of the implanted polymeric membranes had been increasing in three months at least. ESR measurement showed that some free radicals existed in these membranes and their quantities decreased with time. Chemical analysis proved that peroxides were generated in the γ irradiated membranes. The reason for the increasing of oxygen concentration was that free radicals combined with oxygen in the air and produced peroxides on the membrane surface. Moreover, in order to demonstrate the radiation mechanism, low LET (γ rays) radiation of such polymeric membranes was carried out for comparison     

γ-射线辐照对尼龙6纤维结构的影响

<正> 过去的大多数研究表明,高能射线辐照会引起聚乙烯及聚丙烯等稀烃类聚合物分子链交联及降解,而且会导致结晶度下降。张利华等人最近的研究表明,对于尼龙1010塑料,仅当辐照剂量高到一定程度后,辐照才会破坏结晶。此外,Stowe等人曾经研究过近紫外线对尼龙66纤维结构的影响,结果表明,在空气气氛中的近紫外辐照主要导致尼龙66纤维降解,并使纤维结晶度提高。有关高能射线辐照对高度取向的合成纤维结构及性能的影响的研究尚不多见。本工作将讨论γ-射线对于尼龙6纤维结构的影响。     

The IINS, IR and DFT studies of hydrogen bonds in 6-Furfuryl and 6-Benzylaminopurines

FTIR and IINS spectra of 6-Furfurylaminopurine (6-FAP) and 6-Benzylaminopurine (6-BAP) taken at different temperatures have been analysed and compared with the spectra calculated by the ab initio DFT/B3LYP method and the semiempirical PM3 method in the isolated molecule approximation, for the tautomers N3-H, N7-H and N9-H, and dimers with hydrogen bonds. For 6-FAP the best agreement between the calculated and experimental (at 20 K) spectra has been found for the N9-H tautomer, whose structure was established by X-ray diffraction. For 6-BAP the analogous agreement for the N9-H tautomer structure has been poor and much better for the N7-H tautomer. The vibrational spectra calculated for dimers of the molecules studied involved in hydrogen bonds, permitted also an interpretation of the bands whose positions and FWHM in the FTIR spectra changed with temperature.     

固相氯化法合成氯化聚乙烯的红外光谱研究

本文研究在不同条件固相氯化聚乙烯(CPE)的红外光谱,探讨了一步和两步氯化合成的CPE的结构差别,着重讨论了两步氯化的CPE结构特点。从观察表征结晶结构和—(CH_2)_n—链段氯分布的特征频率变化表明,低温固相氯化主要发生在无定形区,并且在CPE中形成高氯化和低氯化链段(或未氯化)的嵌段结构。在两步固相氯化时,晶区受到较大程度的破坏,氯化作用已不局限在无定形区,其结晶结构的破坏主要同第二步氯化程度有关,即使CPE氯含量相同,若前后两步氯化程度不同,结构有很大差异。     

不同交联度的杜仲胶的红外光谱研究

研究了不同交联度的杜仲胶在室温及加热后红外光谱的变化规律．发现在室温下测定的样品红外光谱在低波数内对应链段变形振动的几个特征峰、加热后会消失或弥散，而交联度的改变对其影响不大，即使材料中结晶完全消失而变成高弹态．因此，推测这些特微峰的存在，应该和杜仲胶弹性网络中交联点间链段存在着明显的构象规整性有关．     

红外光谱法研究LB膜中的分子取向

The structure information of orientation and packing of molecular chains can be obtained from infrared transmission and reflection-absorbance (RA) spectra. In the present paper, on the basis of Umemura et al., their FORTRAN program of minicomputer was developed and can be run on 486 personal computer. By comparison of infrared transmission and RA intensities, surface enhancement factors and molecular orientation angle were calculated using the above program, and the influence of complex refractive index, angle of incidence, and thickness of LB film were discussed. These results are consistent with that of Umemura et al.     

同步辐射白光全反射XRF在痕量元素检测的初步应用研究

叙述了同步辐射白光全反射Ｘ射线荧光分析的实验装置，给出了几种标准物质ＴＸＲＦ实验的检出限，并对实验结果进行了讨论。     

Carboxylic acid functionalization of nylon 6 by radiation grafting and conversion to zinc salts: Effects on physical properties

 Functionalization of polymers by grafting monomeric species on to the backbone of molecular chains with the use of γ-radiation has been used extensively. In this work methacrylic acid was grafted onto a commercial grade of polycaproamide (Nylon 6) by preirradiating the polymer granules to 15 kGy at a rate of 1.0 kGy per hour and subsequently immersing these in a 10% aqueous solution of methacrylic acid in the presence of small quantities of FeSO₄ as homopolymerization inhibitor. The polymer was subsequently neutralized by mixing it with zinc acetylacetonate in a laboratory scale melt mixing device. The acid-grafting polymer modification resulted in an increase in glass transition temperature, while the addition of zinc acetylacetonate gave rise to two transitions: The lower transition corresponds to a miscible mixture of free polyamide and acid-grafted polymer, both plasticized with undecomposed zinc compound, while the upper transition corresponds to the zinc salt of the acid grafted polyamide. Through rheological measurements it was shown that both the acid-grafted polymer and the derived zinc salt have a branched structure, possibly containing also some crosslinked domains. Large improvements in solvent resistance were observed for both type of polymer modifications. Received: 13 December 1996 Accepted: 10 February 1997