淀粉的结晶性与非晶性研究进展

从淀粉结晶的类型、结晶度的测定、结晶的熔融及影响因素等方面着重介绍了淀粉结晶的研究和发展状况.与此同时,对淀粉的非晶性的研究现状、今后的发展进行了展望.     

消除水汽吸收峰干扰的红外光谱测量方法

红外光谱测量时,水汽吸收潜带常掩蔽重要的样品光谱信息.克服水汽干扰的方法有真空技术、干燥气体吹扫技术、样品穿梭技术、光谱差减技术和水汽补偿湿度滴定方法等.该文重点评述了新近发展的用于除去水汽噪音的湿度滴定法.不同于以往方法,该方法允许水汽带在光谱采集前期出现,并根据水汽吸收带的大小和正负方向,适时向光谱仪样品室通入干燥...     

Fused Isoindigo Ribbons with Absorption Bands Reaching Near‐Infrared

Through fusing isoindigo (IID) units at 6,7;6′,7′‐positions, a series of new near‐infrared (NIR) absorbing and stable ribbon‐like conjugated molecules, namely nIIDs in which n represents the number of IID units, have been synthesized. The optical band gaps of the molecules are lowered from 2.03 eV of 1IID to 1.12 eV of 6IID with the increase of the conjugation length. 3IID, 4IID, and 6IID have strong absorption in the NIR region and exhibit photothermal conversion efficiencies of greater than 50 % under laser irradiation at λ=808 nm.     

Ambiguity in Assignment of Near Infrared Vibrational Bands for Polymerisation Monitoring of Epoxy System

The curing process of epoxy affects the chemical structure of the final network so mechanical and physical properties of the polymeric matrix for a composite may be modified according to the polymerisation conditions. This paper describes the ambiguity in assignment of reference bands to follow the cure of poly-epoxy reactive systems using a laboratory-made system which allows the coupling of dielectric analysis and Fourier Transform Near Infrared Spectroscopy (FTNIR). The dielectric measurements were obtained using interdigitated electrode. In situ monitoring of extent of reaction was carried out from room temperature up to 160 °C using fibre-optic FTNIR spectroscopy. For the DGEBA/MCDEA system the epoxy band at 6060 cm⁻¹ was chosen in preference to the band at 4530 cm⁻¹ as representative of the epoxy function evolution during polymerisation because a small unknown peak probably due to the hardener appears in the 4530 cm⁻¹ region. The bands at 4620 and 4680 cm⁻¹ assigned to aromatic combination bands and widely used as reference bands are not unique for this formulation hence the band at 5980 cm⁻¹ is used as reference. The Principal Components Analysis (PCA) shows clearly also that the bands at 4620 and 4680 cm⁻¹ vary during the polymerisation. Surprisingly, the band at 4530 cm⁻¹ is equivalent to the one at 6060 cm⁻¹ to calculate the conversion rate. It is probably due to the fact that the hardener band near 4530 cm⁻¹ follows the same behaviour as the epoxy band at 4530 cm⁻¹.     

Infrared Spectra of Protonated Coronene and Its Neutral Counterpart in Solid Parahydrogen: Implications for Unidentified Interstellar Infrared Emission Bands

Large protonated polycyclic aromatic hydrocarbons (H⁺PAHs) are possible carriers of unidentified infrared (UIR) emission bands from interstellar objects, but the characterization of infrared (IR) spectra of large H⁺PAHs in the laboratory is challenging. IR absorption spectra of protonated coronene (1‐C₂₄H₁₃⁺) and mono‐hydrogenated coronene (1‐C₂₄H₁₃^.), which were produced upon electron bombardment of parahydrogen containing a small proportion of coronene (C₂₄H₁₂) during matrix deposition, were recorded. The spectra are of a much higher resolution than those obtained by IR multiphoton dissociation by Dopfer and co‐workers. The IR spectra of protonated pyrene and coronene collectively appear to have the required chromophores for features of the UIR bands, and the spectral shifts on an increase in the number of benzenoid rings point in the correct direction towards the positions of the UIR bands. Larger protonated peri‐condensed PAHs might thus be key species among the carriers of UIR bands.     

Crystallinity of bulk polyacetylene

The fine structure of bulk trans-polyacetylene (PA) was investigated by x-ray diffraction. The degree of crystallinity 0.81, determined by Ruland's method, was significantly higher than the value for linear polyethylene. The disorder parameter k was 5, which is much larger than the value for polyethylene. These results led us to propose that PA crystals are more disordered than PE crystals owing to the higher rigidity of PA chains. Small-angle x-ray diffraction indicated that the crystal morphology is of the extended-chain type rather than lamellar. All results obtained in this work showed that the fine structure of PA bulk is such as to facilitate electrical conduction of bulk PA.     

Crystallinity of ethylene oxide oligomers

Nonaethylene glycol and pentadecaethylene glycol and their dimethyl ethers have been prepared and characterized, with respect to crystallinity by wide- and small-angle X-ray scattering, Raman scattering, i.r. spectroscopy and differential scanning calorimetry. Wide-angle X-ray scattering is similar to that from high molecular weight poly(ethylene oxide). The crystal habit is lamella. The lamellae are highly crystalline and the surface layers are ordered. Comparison with crystalline poly(ethylene oxide) prepared conventionally, and having a distribution of chain lengths, shows that such samples crystallize into lamellae with disordered surface layers.     

傅里叶变换近红外光谱法测定大麦中蛋白质、淀粉和赖氨酸含量

采用傅里叶变换近红外光谱法测定大麦中蛋白质、淀粉、赖氨酸的含量，并用光谱影响值法(leverage)对异常值进行判断和处理。蛋白质、淀粉和赖氨酸含量近红外光谱分析模型的测定系数R。分别为0．985、0．973和0．978；检验集的化学值与模型预测值的相关系数r分别为0．9853、0．9644和0．9172，分析模型的预测相对标准偏差RSD分别为4．0％、2．4％和5．4％，该结果可替代经典分析方法，满足农产品快速分析的需要。     

间规立构聚丙烯的结晶度研究

Ｎａｔａ等用Ｚｉｅｇｌｅｒ－Ｎａｔａ催化剂首次合成了间规度为～５０％间规聚丙烯，并对其进行了表征，指出其具有（ＴＴＧＧ）２螺旋构象，正交晶系，Ｃ２２２１空间群［１，２］．近年来用茂金属催化剂合成的间规立构聚丙烯（ｓＰＰ）的间规度可达９３％以上，高间规...     

聚合物材料结晶度（下）

4.2 Ruland方法使用式(2)计算结晶度时,Ruland考虑了热运动及晶格畸变的影响,从而使算得的结晶度值较合理。在不失计算结晶度W_(c,x)数值精度的情况下,在Ruland方法的实验中可以只取具有较大衍射峰强度的S范围,就可提高计算结晶度的数值准确性,克服了其它方法必须收集尽可能大范围S内的衍射强度数据的限制。Ruland方法测定结晶度的基本公式:     

Crystallinity of adsorbed EVA nanofilms: relevance to confinement and interfacial interactions

We used infrared spectroscopy to estimate the crystalline component concentration in thin films of ethylene‐co‐vinyl acetate (EVA) copolymers spin‐coated on gold and functionalized substrates. Bulk calibration methods are elaborated that allow the establishment of quantitative relationships between infrared response and the degree of crystallinity via simple equations. These equations are applied and transposed to the study of thin films in such a way as to avoid preferential orientation effects induced by adsorption. Therefore, for calibration we select groups that vibrate in the same direction and belong to the crystalline phase. Our results show a decrease of the crystalline amount in EVA9, 14, 24 and 28 thin films, as determined on the basis of infrared spectroscopy experiments. The low crystallinity degree calculated for EVA thin films is in good agreement with the reduced crystalline morphology observed by atomic force microscopy. Observed amorphization is considered to be induced by confinement (gold substrates) and interfacial interactions (functionalized substrates), which lead to a disordered chain conformation that makes crystallization less favourable. Copyright © 2003 John Wiley & Sons, Ltd.     

背景吸收强度可调控与扣除干扰组分影响的红外光谱测量方法

多组分混合物的红外光谱由于特征谱带的重叠或部分重叠而给谱峰的归属辨认带来极大的困难。本研究通过扫描两个背景样品(纯KBr压片(1)和KBr+C18TCNQ压片(2))实时合成一系列背景单光束谱。每个背景单光束谱既含有背景样品1的贡献也含有背景样品2的贡献。干扰组分C18TCNQ在系列背景谱中的吸收强度随扫描次数变化而改变。当待测混合物和背景样品中干扰组分的吸收强度相等时,就可以完全扣除干扰组分的影响。本测量方法用于硬脂酸与C18TCNQ混合物中扣除硬脂酸(或者C18TCNQ)的干扰,得到令人满意的结果。合成背景样品中干扰组分的含量在测量时成为与扫描次数有关的变量,为扣除干扰组分的影响提供了直接便利的红外光谱测量方法。     

Selective and Tunable Near‐Infrared and Visible Light Transmittance of MoO3−x Nanocomposites with Different Crystallinity

In this Communication, we report MoO_3−x nanocomposites in which the near‐infrared and visible light transmittance can be selectively modulated through the crystallinity. The MoO_3−x nanocomposites were fabricated by a hydrothermal method, and their optical properties were characterized by UV‐Vis spectrometer. The obtained results proved the possibility to tune the nanocomposite's optical properties in the UV/Visible spectral region: crystalline MoO₃ mainly regulates the near‐infrared range (800–2600 nm), and amorphous MoO_3−x mainly changes the visible range from 350 nm to 800 nm and MoO_3−x , with semi‐crystalline structures mainly modulating around 800–1000 nm. These kinds of optical modulations could be attributed to small polar absorption, free electron absorption and plasmon absorption according to different crystallinity. Our work may create new possibilities for future applications such as photochromism, photocatalysis, and electrochromism.     

甲壳胺的结晶度和结晶形态

首次制得非晶甲壳胺样品,并给出了根据X射线衍射图精确计算甲壳胺结晶度的公式,计算得知甲壳胺的结晶度随脱酰度的增加(74%～85%)而增加,发现甲壳胺的结晶结构和结晶形态与制样条件有关。     

Crystallinity and stability of covalent organic frameworks

Covalent organic frameworks(COFs) are a class of organic porous polymers with high crystallinity, and their structures can be precisely tailored via topology design. Owing to the characteristics of permanent pores, periodic structures and rich building blocks, COFs have triggered tremendous attention in the past fifteen years and are extensively investigated in various fields.Crystallinity and stability are two crucial features for practical applications. In general, these two features are contradictory for COFs formed via dynamic covalent chemistry(DCC). High thermodynamic reversibility is usually required to attain exceptional crystallinity of COFs, often resulting in limited stability. The first two reported COFs are based on the boroxine and boronate ester linkages, which are unstable in water and even in humid conditions. Therefore, many researchers doubt the stability of COFs for real applications. Actually, in these years, various novel linkages have been developed for the construction of COFs,and numerous newly synthesized COFs are robust towards strong acid/base and even some of them can resist the attack of strong oxidizing and reducing agents. In this review, we focus on the linkage chemistry of the COFs in terms of crystallinity and stability, further extending it to the investigation in the mechanisms of the crystal growth and the overall regulation of the contradiction between stability and crystallinity. The strategies for improving the crystallinity, including selecting building units,introducing non-covalent interactions and slowing nucleation and growth rate, are described in the third section, while the methodologies for increasing the stability from the viewpoints of chemical modification and non-covalent interactions are summarized in the fourth section. Finally, the challenges and perspectives are presented.     

4—苯甲酰氧基苯甲酸液晶性的研究

关于个苯甲酸氧基苯甲酸（BBA）的合成虽已有报道［‘j，但其双分子缔合物具有液晶性则属本文作者首次发现．一般认为在有机分子结构中引人不对称性及柔性基团对其液晶性的形成十分重要“‘．在不具备这两个条件时，当分子的长径比达到一定值（约l／d＞4）时也可能出现液晶性，但实例不多，且一般t。。很高．如聚合度为5的聚苯t。。一388”C［’j，而且难溶．这给此类液晶化合物的研究带来很大不便．BBA以双分子缔合物（BBA）。形式存在，结构对称，亦无柔性基团，但却具有液晶性，其t。。为230C．BBA与个乙酸氧基苯甲酸形成的低共熔…     

Evaluation of the Alpo-11 Crystallinity by Thermogravimetry

The evaluation of the crystallinity of several samples of ALPO-11 was performed by X-ray diffraction and thermogravimetry. Through XRD, the degrees of crystallinity of the samples were determined by the measurement of the area of the peaks at 2γ ranging from 20.7 to 24.1 degrees. The sample that presented the largest area was considered as 100% crystalline and the areas of the other samples were normalized in relation to this. From TG, the degree of crystallinity was determined considering the mass loss in the temperature range from 453 to 653 K that is related to remotion of di-isopropylamine molecules used during the synthesis procedure. The quantity of diisopropylamine on the material is proportional to the degree of crystallinity. This revised version was published online in July 2006 with corrections to the Cover Date.