巧用Flash MX2004绘制化学实验装置图

结合实例介绍了用Flash MX 2004软件绘制常见化学实验仪器图的一般方法和技巧,以及利用已绘好了的单个化学仪器图组合为一套完整的实验装置流程图的步骤和方法。     

培养学生绘制化学实验仪器装置图的做法

化学实验仪器和装置图表示仪器的形象、装配、组合形式和实验的某些操作方法等。在学生作化学笔记,完成实验报告,根据实验习题的要求设计仪器装置时,都要画出实验装置图。通过绘图,有助于学生加深对化学基础知识的理解;掌握仪器装置的原理及其使用方法;同时,还有助于培养学生的实验操作能力.现在谈谈培养学生绘制实验仪器装置图的一些做法。     

利用化学实验图库绘制实验装置图

介绍了用Windows画图板绘制常见化学实验仪器图的技巧,建立化学实验装置图库的做法和要求,以及利用图库中的化学仪器组合图片绘制化学实验装置图的方法.     

化学实验仪器和装置图的画法

绘制化学实验仪器装置图是中师化学实验教学的一个重要内容,是中师生应该具备的基本技能之一。在中师教学中,板书和仪器装置图的绘制往往不被重视。笔者就如何绘制化学实验装置图这一问题谈点粗浅的看法。     

ChemWindow6.0在化学化工及教学中的应用

计算机在化学化工中的应用越来越广泛,ChemWindow 6 .0对化学专业的分子结构、反应机理、反应流程及实验仪器的装置图的绘制是不可多得的有利工具,改变了过去手工绘制的烦琐和不直观。ChemWindow 6 .0使化工专业的物料平衡图、物料流程图等及工艺流程图的绘制能够在极短时间内完成,并可以方便修正,彻底摆脱橡皮、铅笔等传统制图工具的约束,符合当今计算机辅助绘图的发展。同时培养大学生使用现代化手段来处理问题的能力及兴趣。     

用Windows的“画图”绘制实验装置图

化学教师利用计算机撰写论文或编拟习题、考卷,经常需要插入实验装置图,用Windows 98的“画图”程序进行装置图的绘制和编辑是一种易于掌握、方便、高效的方法。     

运用Word自带工具绘制化学图形的实践

从软件基本界面与基础图形绘制介绍着手,以流程图、曲线图、有机物结构简式和实验装置图等为例,介绍了利用微软公司Word 2013绘图工具绘制复杂化学矢量图形的创新方法和技巧,为化学图形制作提供了一种无需借助于其他软件的文档编辑途径。积累绘制的基本图形,创建图形模板库可以为后续的制图提供方便。     

培养学生绘制实验仪器装置图的能力

高考《考试说明》指出,绘制典型的实验仪器装置图(以下简称制图)的能力是实验能力的一个重要方面。结合本人多年教学实践,笔者就如何培养学生制图能力谈一点认识和做法。1　基本认识绘制规范、美观的实验仪器装置图是化学实验基本功之一。通过培养学生的制图能力,不仅能使学生这方面的能力得以提高,具备一项较好的化学实验基本功;而且,在教师的指导下,学生经过观察和绘图,还能激发学习兴趣,加深对仪器构造与用途的了解,巩固对装置组合原理与应用的认识,强化相关实验操作知识,促进观察能力和形象思维的发展,训练心眼手的配合,培养科学素质,提…     

加强实验教学 提高初中化学总复习的效果

一、实验在初中化学总复习中的地位初中化学课本共有演示实验79个：学生实验14个。其中训练基本操作实验9个,论证概念、理论的实验22个,元素化合物知识的实验60个,实验习题2个。通过上述实验培养学生的四种技能:1. 常用化学仪器的识别和使用： 2. 基本操作：3. 绘制常用仪器和实验装置图： 4. 记录实验现象和书写实验报告。     

谈谈化学实验技能的培养

化学实验技能属于动手技能 ,动手技能必须由学生亲自动手进行实验操作和实验练习才能形成 ,这是其他任何教学形式和教学方法所不能替代的。本文作者结合当前中学化学教学的实际 ,对中学化学实验中 5项技能 (①使用仪器和药品的技能 ,②实验基本操作的技能 ,③绘制仪器装置图的技能 ,④实验设计的技能 ,⑤实验记录和总结的技能 )的培养 ,提出了自己的看法。     

Drawing behavior and characteristics of laser‐drawn polypropylene fibers

Drawing behavior, flow drawing, and neck drawing, was studied for isotacticpolypropylene fibers in CO₂ laser drawing system, and the fiber structure and the mechanical properties of drawn fibers were analyzed. For a certain laser power, flow drawing of polypropylene (PP) was possible up to draw ratio (DR) 19.5. Though the drawing stress was very low, the flow‐drawn PP fiber exhibited oriented crystal structure and improved mechanical properties. On the other hand, neck‐drawing was accomplished from DR 4 to 12, with significant increase in drawing stress that enhanced the development of fiber structure and mechanical properties. Unlike PET, the drawing stress depends not only on the DR, but on irradiated laser power also. The 10–12 times neck‐drawn fibers were highly fibrillated. The fibers having tensile strength 910 MPa, initial modulus 11 GPa, and dynamic modulus 14 GPa were obtained by single‐step laser drawing system. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 398–408, 2006     

Poly(ethylene terephthalate) Nanofibers Made by Sea–Island‐Type Conjugated Melt Spinning and Laser‐Heated Flow Drawing

Nylon‐6/poly(ethylene terephthalate) (PET) ultra‐multi‐island sea–island conjugated melt‐spun fibers are flow‐drawn at a draw ratio of 174 with heating by CO₂ laser irradiation. Continuous PET nanofibers that have a diameter of 39 nm could be obtained from the flow‐drawn fiber with further drawing and removal of the sea component. In addition, the drawn fiber has a strength of 0.54 GPa. This result shows that a PET nanofiber having a strength almost equal to that of a conventional PET fiber can be obtained by the combination of conjugate‐melt‐spinning and laser‐heated flow‐drawing.

     

Rheo-optical Raman study of microscopic deformation in high-density polyethylene under hot drawing

In situ observation of the microscopic structural changes in high-density polyethylene during hot drawing was performed by incorporating a temperature-controlled tensile machine into a Raman spectroscopy apparatus. It was found that the load sharing and molecular orientation during elongation drastically changed at 50°C. The microscopic stress of the crystalline chains decreased with increasing temperature and diminished around 50°C. Moreover, the orientation of the crystalline chains was greatly promoted above 50°C. These microscopic structural changes were caused by the thermal activation of the molecular motion within lamellar crystalline chains owing to the onset of relaxation of the crystalline phase.     

Strain‐rate dependence of the microstructure and mechanical properties for hot‐air‐drawn nylon 6 fibers

A hot‐air (HA) drawing method was applied to nylon 6 fibers to improve their mechanical properties and to study the effect of the strain rate in the HA drawing on their mechanical properties and microstructure. The HA drawing was carried out by the HA, controlled at a constant temperature, being blown against an original nylon 6 fiber connected to a weight. As the HA blew against the fiber at a flow rate of 90 liter/min, the fiber elongated instantaneously at strain rates ranging from 9.1 to 17.4 s⁻¹. The strain rate in the HA drawing increased with increasing drawing temperature and applied tension. When the HA drawing was carried out at a drawing temperature of 240 °C under an applied tension of 34.6 MPa, the strain rate was at its highest value, 17.4 s⁻¹. The draw ratio, birefringence, crystallite orientation factor, and mechanical properties increased as the strain rate increased. The fiber drawn at the highest strain rate had a birefringence of 0.063, a degree of crystallinity of 47%, and a dynamic storage modulus of 20 GPa at 25 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1137–1145, 2000     

Changes in superstructure and mechanical properties of poly(ethylene‐2,6‐naphthalate) fibers with critical necking tension

Poly(ethylene‐2,6‐naphthalate) fibers were zone‐drawn under a critical necking tension (σ_c) defined as the minimum tension needed to generate a necking at a given drawing temperature (T_d). In the zone drawing under σ_c, the neck was observed from 110 to 160 °C. The superstructure in a neck zone induced at each T_d was studied. The σ_c value decreased exponentially with increasing T_d and dropped to a low level at a higher T_d. The draw ratio increased rapidly with T_d increasing above 90 °C, but the birefringence and degree of crystallinity decreased gradually. To study the molecular orientation in the neck zone, we measured a dichroic ratio (A_‖/A_?) of a C? O band at 1256 cm^?1 along a drawing direction in the neck zone with a Fourier transform infrared microscope. A_‖/A_? at T_d = 110 °C increased rapidly in the narrow neck zone, and that at T_d = 140 °C increased in the edge of the wide neck zone. Wide‐angle X‐ray diffraction patterns of the fibers obtained at T_d = 130 °C and lower showed three reflections due to an α form, but those at T_d = 140 and 150 °C had reflections due to the α form and a β form. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1629–1637, 2001     

Recent developments in oriented polymers for biomedical and engineering applications

A review is presented of recent research at Leeds University which has been directed at devising novel methods for the production of oriented polymer structures. First, the new hot compaction process for oriented fibre and tapes is described, together with its applications to polyethylene and polypropylene where there are a number of practical developments. Secondly, there is the use of hydrostatic extrusion to make load bearing oriented products from hydroxyapatite filled polyethylenes. The production routes include the application of high pressure annealing prior to hydrostatic extrusion and the preparation of high modulus polyethylene fibre/hydroxyapatite billets as the starting point. Finally, recent progress on die-drawing as a means to producing oriented monofilaments and biaxially oriented tubes is described, where the applications include polymer ropes, pipes for gas and water distribution and transparent cans for packaging.     

Optical and shape memory properties of semicrystalline poly(cyclooctene) upon cold‐drawing

Semicrystalline thermoplastic poly(cyclooctene) (PCO) shows significant improvement in transparency when cold‐drawn at room temperature, unlike other semicrystalline polymers whose fibrillated chains cause crazing upon cold‐drawing, making the polymers opaque to visible light. Upon heating, transparent cold‐drawn PCO recovers its original opacity as well as its undeformed shape. In situ wide‐ and small‐angle X‐ray diffraction and polarized Fourier transform infrared analyses show that molecular density differences between the PCO crystalline and amorphous phases were reduced due to strain‐induced crystallization and that fibrillated chains and voids, an indication of craze, were not observed due to chain entanglements concentrated in trans double‐bond regions. These two factors explain the unique optical properties of PCO. Finally, it is demonstrated that crosslinked PCO enhanced optical and shape memory recovery without deterioration of the transparency of the polymer. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1595–1607     

Effects of drawing on creep parameters of polyoxymethylene-drawn fibers

The effects of drawing on creep parameters (modulus, viscosity, and retardation time) of polyoxymethylenedrawn fibers were examined on the basis of a series-parallel, four-element, mechanical model. These parameters increased with the draw ratio. The change in the modulus was the same between the series and parallel components. This was true also for the viscosity, although the change in the viscosity was much greater than that in the modulus. This means that the series and parallel components are deformed in the same mode by drawing. The parallel viscosity increased with elapsed loading times according to an experimental power function; this was also derived from the usual rate equation for viscosity change in the amorphous component. In contrast, the series viscosity remained unchanged over the short creep range due to an extremely larger value than that of the parallel. © 1995 John Wiley & Sons, Inc.     

Tensile drawing,morphology, and mechanical properties of poly(butylene terephthalate)

The concept of the drawing of a molecular network has been employed to derive a total network draw ratio from the combination of the two deformations occurring in the production of poly(butylene terephthalate), PBT, fibers by the consecutive processes of melt spinning and cold drawing. The mechanical properties of PBT can then be more readily explained in terms of increases in this total network draw ratio. However, the preorientation and crystallization that occurs in the melt-spinning process can occur at different strain rates and temperatures, depending on the wind up speed employed, on the extensional viscosity of the polymer, and on the variation of the extensional viscosity with temperature. Therefore, for polymers such as poly(butylene terephthalate), which can exist in two crystalline forms, the morphology of the final drawn fiber might be expected to depend on the first melt-spinning stage of the process as well as on the total network draw ratio. In this work, density, birefringence, mechanical measurements, and WAXD measurements, which have been made on the melt-spun fibers and on the drawn fibers, are described. Small differences in some of the drawn yarn mechanical properties at the same overall network draw ratio are related to the crystallinity and in particular to differences in the proportion of the α and β phases present in the drawn yarn. These in turn are related to differences in the temperature and stress during melt spinning and drawing. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2465–2481, 1997     

Microstructure and mechanical properties of hot‐air drawn poly(ethylene terephthalate) fibers

Hot‐air drawing method has been applied to poly(ethylene terephthalate) (PET) fibers in order to investigate the effect of strain rate on their microstructure and mechanical properties and produce high‐performance PET fibers. The hot‐air drawing was carried out by blowing hot air controlled at a constant temperature against an as‐spun PET fiber connected to a weight. As the hot air blew against the fibers weighted variously at a flow rate of about 90 ℓ/min, the fibers elongated instantaneously at a strain rate in the range of 2.3–18.7 s⁻¹. The strain rate in the hot‐air drawing increased with increasing drawing temperature and applied tension. When the hot‐air drawing was carried out at a drawing temperature of 220°C under an applied tension of 27.6 MPa, the strain rate was the highest value of 18.7 s⁻¹. A draw ratio, birefringence, crystallite orientation factor, and mechanical properties increased as the strain rate increased. The fiber drawn at the highest stain rate had a birefringence of 0.231, degree of crystallinity of 44%, tensile modulus of 18 GPa, and dynamic storage modulus of 19 GPa at 25°C. The mechanical properties of fiber obtained had almost the same values as those of the zone‐annealed PET fiber reported previously. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1703–1713, 1999