Reflections on the Teaching of Polymer Physics

Reflections on the teaching of "Polymer Physics" course Wang Xiangmei, Zhang Lihua (Department of Chemical Engineering, North China University of Technology, Taiyuan, Shanxi , 030) How should teachers engaged in teaching of "Polymer Physics" improve teaching quality in teaching content? Assessments and other aspects put forward some insights.

0: A difficult course to master. It has penetrated into various fields such as agriculture, forestry, industry and national defense as the basis of professional technology. For example, modern plastics, rubber, coatings, chemical fiber, and medicine are all based on Polymer Physics. Therefore, we should be familiar with and master the basic knowledge and experimental skills of Polymer Physics, and put forward higher requirements for students who are engaged in polymer science work in terms of knowledge, ability and quality.

With the continuous deepening of higher education reform and the implementation of the five-day work system, it has become an inevitable trend to reduce the number of teaching hours. In recent years, Polymer Physics has experienced several large-scale adjustments of school hours, reducing the number of hours of study. Almost half. How to improve the quality of teaching in a limited number of hours to meet the needs of the society for talents, analyze the teaching status and existing problems of the "Polymer Physics" teaching practice, and engage in the teaching of "Polymer Physics" How did the teachers improve the quality of teaching? Some ideas were put forward in terms of teaching content, experimental teaching, and assessment.

First, the current situation and existing problems in the teaching of "Polymer Physics" courses are comprehensive subjects including all physics contents of macromolecular compounds. It contains both the knowledge of synthetic chemistry necessary for polymer science and the high demands of mathematics and physics in the physical sciences. At present, within the teaching framework of China's higher education institutions, polymer science including macromolecule physics still belongs to the category of chemistry. Therefore, cultivating “polymer physics” talents with both a considerable chemical knowledge and a solid mathematical foundation is a problem for us to engage in the teaching of “polymer physics”.

To solve this problem, first of all, it is a challenge to the teaching staff of "Polymer Physics" how to adjust the knowledge structure. In addition, the relevant majors are required to work hard in the overall arrangement of the teaching plan according to the different teaching subjects.

2. Normative issues of commonly used terms in "polymer physics" textbooks With the publication of various "polymer physics" textbooks, uniform terminology in textbooks, especially some commonly used terms is necessary. Such as differentiation: polymers, polymers, macromolecules, macromolecules, amorphous and amorphous, linear polymer and linear polymer, processing and processing 1 Coder - Introduction: Wang Xiangmei (1968), female, Shanxi Ping Dingren 5 Lecturer Specialty "PiSiHouse." (Thoughts on "Polymer Physics" Teaching (Wang Xiangmei et al.) Forming, Polymer Aggregation and Polymer Aggregation, Deformation-Temperature and Temperature-Deformation Curves, Melt Index and Melt index and so on.

3. "Polymer Physics" and its corresponding course of some repeated textbooks suitable for different teaching subjects, teachers can only use different publishing materials published by the press. Therefore, how to coordinate their relationship, avoid duplication, and teach new content in a limited number of hours, will become the focus of teacher preparation.

2. Suggestions for Improving Teaching Quality 1. The teaching content should focus on the characteristics of the course of “Polymer Physics” and explain the characteristics of high polymers. Highlight the basic knowledge, basic theory, and basic skills (three bases) and pay attention to the theory and practice. In response to the basic principles of the latest achievements in polymer science and the need for professional training, in the teaching process, we must pay close attention to: the characteristics of the "polymer physics" course, speak through polymer characteristics.

Structure and properties, and through the study of molecular motion in polymers, reveal the intrinsic link between structure and properties and their basic laws, thus providing a theoretical basis for the synthesis, processing and testing of polymer materials.

The structure of the polymer is the material basis for the various properties of the polymer.

As the polymer is polymerized by thousands of structural units and has a large molecular weight, its structure is more complex than that of ordinary small molecules, and another structural layer polymer chain that is not available to small molecules generally appears. The remote structure gives the flexibility of the polymer chain. Quantitative changes lead to qualitative changes. The appearance of new structural levels must be accompanied by the appearance of new material properties, which are the high elasticity of polymers.

Polymers as a new type of material mainly use their various physical and mechanical properties, and the various molecular motions existing in the polymer are the bridges between the structure and properties.

The structure of the polymer is the material basis of the polymer's various properties. When an external force (external field) acts on this structure, the molecules that make up the structure will produce various motions. The performance is a macroscopic reflection of a certain molecular motion. This is the main line of the "Polymer Physics" course.

(2) Speaking about the characteristics of polymers in the course of “Polymer Physics”, the “Structure and Performance of Polymers” is essentially “Physical Chemistry” for high polymers. The extension of molecular science can sometimes also be called "macromolecular physical chemistry." Therefore, we must make clear the similarities and differences between polymer compounds and small-molecule compounds in course teaching. In particular, we must understand the characteristics of polymers. Only in this way can we truly understand the structure and performance of polymers. The essence.

Compared with small-molecule compounds, the most important feature of polymers is that they are 'large', which is formed by a large number (103,105) of structural units linked by chemical bonds, and each structural unit is equivalent to a small molecule compound. It is because of this “largeness” that quantitative changes lead to qualitative changes that cause the polymer to have essential differences with small-molecule compounds in terms of structure, molecular motion, and a series of physical properties, resulting in the unique structure and properties of polymers, such as: The flexibility of the chain, the unique entropy elasticity of the polymer, the unique WLF equation describing the movement of the segments, the possible large- and low-size orientations, the silver striations, the single-strand condensed state, the folded chains, and the extension chain Crystals, polydispersity of molecular weight, polymer solution characteristics, and elastic behavior of polymer melts, etc.

The internal rotation flexibility is large in molecular weight - uniquely high in elasticity, large in reversible deformation, low in modulus, proportional to temperature, and exothermic in adiabatic stretching, and is entropic elasticity. Significant 'viscoelasticity' is present at the same temperature and force time stickiness and elasticity. The unique temperature-dependent equations for segmental motion are difficult to be perfectly organized and can only form folded lamellae. Compared with small-molecule compounds, high mobility unit multiplicity, large-size orientation and small-size orientation are particularly important for molecular interactions. The polymer does not dissolve when the gas first swells, the polymer solution deviates greatly from the ideal solution, the viscosity is particularly large, the relative molecular mass is only statistically significant, there is a relative molecular mass distribution, and there are 50% plastically deformed polymers in the silver lines. The polymer melt has obvious elasticity, non-Newtonian behavior, extrusion swell, single-stranded, single-stranded, single-stranded single- and single-stranded amorphous polymers. Performance The Journal of North China Institute of Technology (Social Science Edition) is a comparatively young subject. Many basic issues need to be further clarified. This is a commonly encountered problem in teaching professional courses. On the one hand, teachers are required to have rich professional knowledge and to follow the development trend of the polymer discipline in a timely manner. On the other hand, it is required that the instructors have a clear understanding of the issues that can be controversial in this discipline. In lectures, students can be introduced to various opinions on disputes, guide students to accept different academic opinions and conduct free debate on different opinions. Teachers can also express their views on this issue and make classroom teaching full of life.

When introducing many of the theories of Polymer Physics, we must first grasp the basic points of the theory, clarify the theoretical assumptions, and make specific instructional derivation. For example, when deducing the WLF equation using the Dolrille formula for describing the viscosity of small molecules, the viscosity of an object is reduced from molecular motion to the measurement of the size of the molecular active space, which is a conceptual leap and must be clearly explained.

In recent years, the development of polymer science is quite fast. Many academic papers are published every year. Accumulating a lot of experimental data and unique insights are entirely possible and necessary to introduce relevant work at home and abroad when teaching.

Polymer physics experiments are an important part of Polymer Physics. It is not only to strengthen the theoretical knowledge it has learned, but more importantly, it can train students' methods and skills of scientific experiments through experiments; it can cultivate students' ability to operate, analyze problems and solve problems. Therefore, how to exert its maximum effect under the existing experimental conditions needs to be adopted: () Select the appropriate experimental form and experiment content. Use the existing experimental conditions to exert its effect as much as possible.

The specific performance is: increase the number of comprehensive experiments and reduce the number of confirmatory experiments, such as changing the experimental conditions, determining the relative molecular mass of the polymer by viscosity method, and determining the temperature-deformation curve of the polymer by a confirmatory experiment. Instead of comprehensive experiments, design experiments have been added, such as experiments on the rheological properties of polymers, and the types of experiments have to be diversified. There are experimental instruments that allow students to try their hand at the earliest possible time. Specially valuable experimental instruments are used by the teacher to perform demonstration experiments. Experimental instruments are not yet important experiments and are performed in the form of watching videos.

(2) Establish a reasonable set of experimental teaching assessment methods Establish a reasonable set of experimental teaching assessment methods, arrange the experimental assessment in various types of experiments, focus on examination of the basic operation of students and the effect of basic skills training, assessment of students' knowledge and The use of knowledge and ability to observe and analyze and judge experimental phenomena, the specific approach can be assessed from the following four aspects of the students' experimental results: experimental preview (20%). Students are required to carefully prepare preview reports before the experiment to understand and master the experimental principles, procedures, and precautions; experimental operations (50%). It is required that under the guidance of the teacher, the instrument can be used correctly, and the basic technique of experimental operation can be correctly grasped; the experiment report (20%). Students are required to finish the experiment and seriously process the experimental data, explain the experimental phenomena, and seriously answer the questions related to the experiment; the experimental style, health, and discipline (10%). Require quiet and dedicated experimentation during the experiment. Practice shows that this assessment method can effectively promote students to take every link of the experiment seriously, so that the students' experimental skills can be more effectively trained and improved. It is also conducive to training students with a scientific attitude of seriousness, rigorousness, and seeking truth from facts. At the same time, it is also helpful for teachers to evaluate student's experimental results in a comprehensive, objective and reasonable manner.

3. Establish a library of polymer physics test questions to achieve a standardized test In order to evaluate students' mastery of the "polymer physics" course, an examination is required. The traditional artificial proposition test method has many shortcomings. In order to be more objective and scientific, it is necessary to establish a "Polymer Physics" test item database to achieve standardized tests. However, there is no "H-type test database for macromolecular physics" yet. Through the efforts of the past three years, we have initially established the management system of the “Polymer Physics” test bank database. At the same time, some test questions have been collected. However, the number of test questions is still a certain distance from the test question bank requirements. In spite of this, we have enabled the test bank for students' assessments and make appropriate adjustments after questioning by the proposition teachers. Practice has proved that the annual reduction in the number of identical test papers is conducive to assessing students' mastery of the curriculum.