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Material

Functional textiles refer to the textiles with special functions such as health care, anti protection and so on in addition to the basic functions of conventional decoration and warmth preservation, such as far infrared textiles, anti ultraviolet textiles, chitin fabrics, anti mite fabrics, magnetic therapy products, vitamin fabrics, antibacterial fabrics and so on.

Classification: comfort functional textiles, health care functional textiles, protective functional textiles and other functional textiles

Functional textiles can be obtained by means of functional fibers, functional finishing and compounding.

Functional fibers differential fiber high performance high sensibility special fiber

Differential fiber is usually refers to the original fiber composition on the basis of physical or chemical modification to improve the performance of the fiber.

Physical：     

1. Improve the polymerization and spinning conditions: such as temperature, time, medium, concentration, coagulation bath, which can change the polymerization degree and distribution, crystallinity and distribution, orientation degree, etc.

2. Changing the cross section: for example, using special spinneret hole shape to develop profiled fiber.

3. Surface physical modification: such as high energy ray（ γ Radiation β The surface of the fiber was etched, coated and electroplated by low temperature plasma.

4. Composite: the technology of spinning two or more kinds of polymers or the same kind of polymers with different properties into a fiber through a spinneret hole.

5. Mixing: that is to say, two kinds of polymers are mixed and spun into silk by using the miscibility and solubility of polymers.

Chemical:

The modification methods include copolymerization, grafting and crosslinking.

1. Copolymerization: two or more monomers are used for polymerization under certain conditions. For example, the copolymerization of acrylonitrile with vinyl chloride or vinylidene chloride can improve the flame retardancy of polyacrylonitrile, while the copolymerization of ethylene terephthalate with sodium m-phthalate or sodium p-Phthalate can improve the dyeing properties of polyester fiber.

2. Grafting: it is a chemical or physical method to make the macromolecular chain of the fiber be connected with the required groups. Grafting can be carried out in the polymer or on the surface of the formed fiber.

3. Cross linking: cross linking refers to the chemical linking of macromolecular chains of fibers. When the polymer is crosslinked, all single polymer chains form a large three-dimensional network structure. When the glass transition temperature is increased, the heat resistance, wrinkle resistance, crease retention, dimensional stability, elasticity and initial modulus of the fiber are improved, and the tensile strength and elongation of the fiber are also affected.

Composite fiber is a technology of spinning two or more kinds of polymers or the same polymer with different properties into a fiber through a spinneret hole. Through compounding, parallel type, skin core type, sea island type and other composite fibers can be obtained on the same section of the fiber.

Generally, the fibers with the size less than 0.3 denier (diameter less than 5 microns) are called superfine fibers.

At present, there is no common definition of high-performance fiber, which generally refers to the fiber with strength greater than 17.6cn/dtex and modulus greater than 440cn / dtex.

High sensitive fiber: refers to the ability of conducting electricity, transferring, storing, photoelectricity and biocompatibility when the fiber is subjected to external effects, which makes these effects change qualitatively or quantitatively. It includes electrical functional materials, magnetic functional materials, optical functional materials, superconducting materials, intelligent materials, hydrogen storage materials, biomedical materials, tissue engineering materials, nano drug carriers, functional membranes, functional ceramics and functional fibers.

Functional finishing of textiles

method:

Physical technology: plasma, laser

Chemical Technology: functional finishing agent, electroless plating, etc

Biotechnology: enzyme treatment

Nanotechnology:

Function arrangement:

Waterproof, water repellent and oil repellent finishing: a finishing agent is applied to the fabric to change the composition of the surface layer of the fiber. The surface of the fiber is covered by the finishing agent, and the surface performance is no longer the original performance of the fiber and cannot be wetted by water or oil. Such finishing is called water and oil repellent finishing.

Flame retardant finish: prevent fabric from burning. Or to slow down the burning speed of textiles, leaving the flame without burning.

Chemical antistatic method -- Antistatic Finishing Agent

Improve the moisture absorption of the fiber - hydrophilic antistatic agent, absorb moisture, reduce surface resistance, affected by air humidity.

Objective: to clean up

The fabric has the function of inhibiting the growth and reproduction of fungi. Prevent bacteria from growing on the fabric and producing odor.

Moisture absorption and perspiration textiles use the capillary phenomenon produced by the micro grooves on the fiber surface to make the sweat quickly migrate to the surface of the fabric through wicking, diffusion, transmission and other functions, and disperse to achieve the purpose of moisture transmission and quick drying. People also call this kind of fiber "respirable fiber".

1. The change of fiber section shape

Changing the shape of spinneret hole is a simple, direct and effective method to improve the water delivery property of fiber. The improvement of water delivery performance is mainly due to the generation of many grooves in the longitudinal direction of the profiled fiber, through which the fiber can absorb moisture and sweat. Dacron, a special-shaped and hollow polyester fiber invented by DuPont company, is one of these new synthetic fibers. A kind of high-function fabric made of this fiber is called Coolmax. Coolmax functional fabric has good moisture absorption, perspiration and air permeability, which makes clothes dry quickly, comfortable and easy to take care of.

2. Fabric structure design

The water absorbed by Cunninghamia lanceolata trees with a height of 20 meters can rise to the top of the tree, which is due to the ingenious use of capillary tube phenomenon. This kind of capillary diameter gradually becomes smaller from bottom to top, which solves the contradiction between core absorption height and transmission speed. Using this principle, 100% polyester multi-layer structure knitwear has been developed, with coarse fiber forming coarse mesh on the side near the skin, and fine fiber forming fine mesh on the outside, so that sweat can be released to the outside quickly. In addition, the selection of materials for different uses should be considered when designing fabrics. For example, in the design of double-layer casual wear fabric, the inner moisture absorption and quick drying fiber and the outer cotton are usually used, while the moisture absorption and quick drying fiber and the outer cotton have strong water storage capacity, which further speeds up its moisture absorption capacity. However, in professional sportswear and outdoor clothing, moisture absorption and quick drying fibers are often used in the inner and outer layers, because the water storage capacity of cotton will increase the burden of athletes when a lot of sweat is discharged.

3. Special dyeing and finishing methods

In order to make the fiber surface hydrophilic, the moisture absorption and perspiration fabric usually needs special dyeing and finishing process. During the development of Cooldry fiber products, Haitian Textile Co., Ltd. explored a set of special and effective dyeing and finishing methods through cooperation with domestic and foreign dye auxiliaries manufacturers. The requirements are as follows: 1) the contact angle between the fiber surface and water should be small after applying auxiliaries; 2) The auxiliary is not easy to fall off during washing; 3) Special soft finish. If the softener is water repellent, it can not achieve the effect of moisture absorption, and the hydrophilicity is too good to achieve the purpose of quick drying. It is necessary to control the water affinity of softener.

Anti bacterial textiles

Antibacterial textiles are textiles that can kill or inhibit bacteria, fungi, viruses and other microorganisms. The purpose of antibacterial textiles is not only to prevent textiles from being damaged by microorganisms, but also to prevent infectious diseases, ensure human health and wearing comfort, reduce the cross infection rate of public environment, and enable textiles to obtain new health care functions.

Uses: medical products, baby products, sanitary products, functional clothing, functional decorative materials, etc.

According to the structure of the antibacterial agent, it can be divided into: 1

Inorganic: TiO2, ZnO, zeolite, apatite and other porous materials, as well as silver, copper, zinc and other metals and their ionic compounds

Organic: organic acids, esters, alcohols, phenols

Biological: antibacterial agents extracted from plants and plants and produced by microbial fermentation, such as berberine, tetracycline and other macromolecular structural compounds, as well as plants such as garlic;

Processing methods of antibacterial textiles

The main processing methods of antibacterial textiles are spinning and finishing.

1. Spinning method

(1) Blending process

In the process of CO spinning, antibacterial agents, dispersants and other additives are mixed with fiber matrix resin to produce antibacterial fibers by melt spinning. This method mainly aims at some fibers without reactive side groups, such as polyester, polypropylene, etc; Antibacterial agents not only exist on the surface of the fiber, but also disperse evenly in the fiber, so the antibacterial effect is more durable. The antibacterial fabric made by this method is mainly used for medical and health care, clothing and industrial decoration.

(2) Composite spinning

The composite spinning method is to use the fibers containing antibacterial components and other fibers or fibers without antibacterial components to make parallel, core sheath, mosaic, hollow and multi heart antibacterial fibers.

2. After finishing

The finishing method is to use the solution or resin containing antibacterial agent to impregnate, pad or coat the fabric. When the fabric is evaporated by high temperature baking or other methods, a layer of insoluble or slightly soluble antibacterial agent will precipitate on the fabric, so that the fabric can obtain antibacterial properties. Generally, it can be processed in the final stage of dyeing and finishing, or after the finished product is made. Two kinds of antibacterial textiles, dissolution type and non dissolution type, can be produced.

Dissolution antibacterial textiles are textiles that can diffuse from the inside to the surface of the fiber to form an antibacterial ring, thus killing the bacteria in the ring. This kind of textiles is not good in water washing, and is suitable for disposable textiles or textiles with less washing times, such as bandages for hospital bandages, disposable surgical clothes, disposable tablecloths and towels, etc.

The non dissolving antibacterial textiles are generally obtained by chemical reaction with antibacterial groups on the surface of the fibers. These antibacterial agents can form covalent or ionic bonds with the fibers. The antibacterial agents can not diffuse when acting, but the bacteria in contact with the fibers can be killed, and the antibacterial effect is more durable. It can be used for bedding, underwear, towel and other textiles.

Definition: textile material that can provide one or more protective properties

Physical Protection

Chemical Protection

Biological Protection

Textile materials for protection are often different due to different protection purposes and principles, from natural fibers, synthetic fibers to new fibers, such as impact resistant para aromatic polyamide and high strength and high modulus polyethylene fiber products, oil repellent fluorinated compounds, radiation resistant polyimide fiber, etc.

Anti electromagnetic radiation textiles

There is an electric field around any charged body, and the periodic electric field will produce periodic magnetic field, that is, there is electromagnetic wave and electromagnetic radiation. Excessive electromagnetic radiation not only causes various disturbances to military, national defense or other industrial fields, but also damages the health of organisms and human beings. In order to prevent the harm of electromagnetic radiation, the development and use of textile products with anti electromagnetic radiation function is one of the most simple and effective means.

The realization of anti electromagnetic radiation textiles

The development of anti electromagnetic radiation textile products simulates the working principle of conventional electromagnetic shielding materials, that is, the principle of metal isolation is used to control the induction and radiation propagation of electromagnetic interference from one area to another, and this isolation is realized by the reflection or absorption of electromagnetic shielding materials to the incident electromagnetic radiation. There are mainly three ways: (1) to achieve the purpose of anti electromagnetic radiation by blending or interweaving metal or conductive fiber with other fibers. At present, most of the anti electromagnetic radiation textile products are prepared in this way, and its mechanism is mainly reflection, which has a certain anti electromagnetic radiation effect（ 2) The coating agent containing conductive materials (some metals and their salts, carbon black, etc.) was used to coat the fabric. This kind of anti electromagnetic radiation textile material has certain efficacy and is easy to process, but the wearability of the fabric is poor（ 3) By coating the fabric, such as metal sputtering, vacuum metal coating, electroplating or electroless plating, a conductive film is formed on the surface of the fabric, which has good anti electromagnetic radiation function, but poor durability.

Anti UV textiles

Introduction to ultraviolet

Ultraviolet light accounts for about 6% of the solar spectrum. The International Commission on illumination (CIE) divides ultraviolet light (200-400 nm) into near ultraviolet, far ultraviolet and ultra short ultraviolet according to wavelength.

Near ultraviolet A (UVA: 320-400nm) for short, has less energy and can penetrate glass, some clothing and human skin, accounting for 95% - 98% of the total amount of ultraviolet. Appropriate amount of irradiation can promote the absorption of vitamin D, but excessive irradiation will damage the dermis and subcutaneous tissue, promote skin blackening, and cause skin aging. Segment a is involved in light sensitivity and immunosuppression, and also in the formation of dermatoma.

Ultraviolet B (UVB: 280-320nm), which accounts for 2% - 5% of the total ultraviolet, has high energy. It is responsible for sunburn, gene mutations and tumors.

Ultra short ultraviolet C (UVC: 200-280nm) has the largest energy, but it is almost completely absorbed by the ozone layer and will not cause harm to human beings. Therefore, the protection of ultraviolet is mainly to shield the excessive radiation from ultraviolet A and B.

UV resistant fiber

The so-called anti ultraviolet fiber refers to the fiber which has strong absorption and reflection properties to ultraviolet. Its preparation and processing principle is usually to add the material which can shield ultraviolet to the fiber, mix and treat it, so as to improve the absorption and reflection ability of the fiber and its fabric to ultraviolet.

There are two kinds of substances that can shield ultraviolet rays

(1) ultraviolet shielding agent: a substance that can reflect ultraviolet light.

Usually, some metal oxide powders, such as: Al2O3, MgO, ZnO, TiO2, SO2, CaCO3, carbon black, metal, kaolin and so on, are used to make these materials into nanometer ultrafine powders.

(2) ultraviolet absorber: a substance that has strong selective absorption of ultraviolet rays and can carry out energy conversion to reduce its transmission.

Salicylic acid esters, metal ion chelates, benzophenones and benzotriazoles are commonly used.

Production method of anti ultraviolet fiber

blended spinning

This is the main processing method to produce anti ultraviolet fiber.

Advantages: the ultraviolet shielding agent or ultraviolet absorber can be evenly distributed on the corresponding fiber, and the anti ultraviolet function of the fiber is stable and durable.

There are two kinds of blending methods

(1) direct blend spinning: for chemical fiber varieties, UV shielding agent can be added in two ways, either in polymerization or in spinning melt.

(2) masterbatch and Chip Co blended spinning: the UV shielding agent or absorbent, dispersant, heat stabilizer and other additives are mixed with the carrier, and the anti UV masterbatch is made by melting extrusion, pelleting, drying and other processes. The masterbatch is added to the chip according to a certain amount, and the anti UV fiber is made by mixing, spinning, drawing and other processes. The advantages of this method are high flexibility and high addition (up to 10%).

Anti ultraviolet processing of fabrics -- finishing technology

The common process methods are: high temperature and high pressure exhaustion method, some insoluble or insoluble in water ultraviolet absorbents, can use high temperature and high pressure dyeing method similar to polyester; In normal pressure exhaustion method, some water-soluble finishing agents only need to be treated in water solution under normal pressure when they are used to treat wool, silk, cotton and nylon textiles, which is similar to water-soluble dye dyeing; The disadvantage of this method is that it will affect the style, handle, water absorption and air permeability of the fabric after finishing; Coating method, the disadvantage of this method is that it will affect the washing fastness and handle. It is generally used in decorative and industrial textiles; The printing method is suitable for fabrics with low requirement of UV shielding agent.

Microencapsulation technology

Microcapsule technology has been widely used in the field of industry. It is a special packaging form. The material in the capsule can be solid particles, liquid or bubble. When the ultraviolet absorbent is injected into the capsule, the capsule is adsorbed on the clothing, and the outer layer of the capsule is broken due to friction in the process of taking, so as to achieve the effect of slow release of the ultraviolet finishing agent and resist the ultraviolet radiation for a long time.

Sol gel technology

Sol-gel technology refers to the process that metal alkoxy compounds are used as precursors to decompose sols under mild conditions to synthesize sol, which is converted into reticulated oxide gel by solvent evaporation or heating treatment. Using silica or other metal oxide nano sol to process fabric, a porous structure of oxide xerogel film can be formed on the surface of the fabric, and the original nano sol particles form a three-dimensional network structure. Nano sol is easy to be chemically or physically modified, which can greatly improve the wearability of the fabric, make it multifunctional, and has excellent UV resistance.

Application of anti ultraviolet textiles

Anti UV textiles are mainly used in summer clothing. It can also be used for sunshade hat and stockings with anti ultraviolet function.

The tools needed for outdoor operation, such as field work clothes, fishery work clothes, agricultural work clothes, also need to have the function of anti ultraviolet.

Other fabrics such as curtain cloth, advertising cloth and tarpaulin have higher requirements for anti ultraviolet.

Foreign biochemical protective clothing is generally divided into two categories: one is the isolation type protective clothing, which is usually made of rubber and plastic outside, and the inside is made of textile, which is air tight and moisture tight. In the case of nuclear, biochemical and other related incidents, this kind of clothing is used for special professionals such as decontamination teams and weapon destruction personnel (chemical soldiers). The other is the breathable protective clothing, which is relative to the isolated protective clothing. The outer fabric can block the small droplets and vapor of the poison, so that it can not pass through the protective clothing, but the air and water vapor can pass through, which improves the wearing comfort. This kind of protective clothing can be divided into three categories

This kind of protective clothing can be divided into three categories: physical absorption type, which uses solvent to absorb poison. When the protective clothing absorbs the poison and loses the ability of anti poison, it can be recovered after ventilation or hot air disinfection, so as to continue to use. The disadvantage is that there is desorption phenomenon and the anti-virus time is short. Chemical absorption type is soaked in chemicals (mainly chloramine), which can protect mustard gas, steam and small droplets. The protective surface is narrow, and chloramine is easy to lose chemical activity in the air, stimulate skin and corrode clothing. The physical adsorption type is composed of multilayer structure. The outer layer of the chemical protective clothing of the US Army is nylon, cotton or blended fabric, which has the functions of protecting harmful gases, liquids and flame retardancy. The carbon particles have strict uniform size and chemical protection functions. The outer layer also uses activated carbon fiber, which has higher adsorption capacity and faster adsorption or desorption speed, good formability, easy to make clothing, and after impregnation treatment, it can also load catalyst, chemical treatment agent and bactericide.

Hollow fiber membrane is an important branch in the field of separation membrane, in which the hollow fiber wall has selective permeability, which can make some components of gas and liquid mixture pass through the hollow fiber wall from the inner cavity to the outside or from the outside to the inner cavity, and at the same time, it can intercept other components.

With the development of membrane technology, hollow fiber membrane is not only used as separation membrane to separate gas and liquid mixture, but also used as catalytic reactor, enzyme membrane bioreactor, membrane fermentor, membrane tissue culture device, membrane evaporator and so on in the field of catalytic reaction and biological reaction. Hollow fiber membrane has been in the experimental or research stage in membrane sensor, controlled release, membrane electrode and so on.

Properties and requirements of medical textiles

Biocompatibility

Biocompatibility refers to the adaptability between the material implanted in the organism and the body. For organisms, implanted materials are foreign bodies regardless of their structures and properties. Out of instinct self-protection, there is generally exclusion. The severity of this rejection determines the biocompatibility of the material. Therefore, to improve the biocompatibility of polymer materials with human body is a subject that materials and medical scientists must face.

Biocompatibility can be divided into tissue compatibility and blood compatibility. Histocompatibility refers to the mutual adaptability between materials and human tissues, such as bones, teeth, internal organs, muscles, tendons, skin, etc., while blood compatibility refers to whether the contact between materials and blood will cause adverse reactions such as coagulation and hemolysis.

Nanotechnology: the technology of researching and processing materials on the nanometer scale is called nanotechnology.

Zero dimensional materials -- Atomic Clusters

One dimensional material fiber structure

Two dimensional material -- layered structure

Three dimensional materials -- grains with one dimensional scale limited to nanometer scale

Basic principle of electrospinning

Electrospinning is polymer jet electrospinning, which is different from traditional methods. Firstly, the polymer solution or melt is charged with tens of thousands to tens of thousands of volts of high voltage static electricity, and the charged polymer droplet is accelerated at the top of Taylor cone of capillary under the action of electric field force. When the electric field force is large enough, the polymer droplet overcomes the surface tension and forms a jet stream. In the process of spraying, the solvent evaporates or solidifies, and finally falls on the receiving device to form a nonwoven like fiber felt. In the process of electrospinning, the droplet usually has a certain static voltage and is in an electric field. Therefore, when the jet moves from the end of the capillary to the receiving device, there will be acceleration phenomenon, which leads to the jet stretching in the electric field.

Nanocomposite fiber is a kind of composite fiber whose dispersed phase size is less than 100nm and polymer is continuous phase. The composition of dispersed phase can be inorganic compound or organic compound. Inorganic compound usually refers to ceramics, metals and so on.

Common preparation methods of nanocomposite fibers

1. Nano particles are dispersed in polymer. The polymer can be solution or melt, or can be obtained by blending nano particles with polymer powder directly. Before blending, dispersant, coupling agent, surface functional modifier or ultrasonic assisted dispersion are used

2. nanoparticles can also be dispersed in monomers, followed by bulk polymerization, emulsion polymerization, oxidative polymerization and condensation.

3. Interlayer insertion method: this method is to insert polymer into layered inorganic compounds such as silicates

Clay, phosphate, graphite, metal oxide, disulfide, etc. The lamellar spacing is generally nanometer, which can accommodate monomer and polymer molecules. It not only makes a single polymer chain embedded in the interlayer to form "embedded nanocomposites", but also makes the lamellar layers of lamellar fillers peel off, so as to uniformly disperse in the polymer as a single sheet to form "exfoliated nanocomposite fibers".

4. sol-gel method is to use compounds containing high chemical active components as precursors, to mix these raw materials evenly in liquid phase, to carry out hydrolysis and condensation reaction, and to form a stable transparent sol system in the solution. The sol-gel slowly polymerized through the aged colloidal particles to form a three-dimensional space network structure gel, and the gel network is filled with solvent with no fluidity. Form gel. The gel has been prepared by drying and sintering to produce molecular or even nanostructured materials.

The high vacuum (about 10-6 atmospheres) in the sample chamber and the tube of ordinary SEM can only test the dry solid samples which are conductive and heat-conductive. Low vacuum scanning electron microscopy (LVSEM) can directly examine non-conductive and thermal conductive samples without treatment, but only backscattered electron images can be obtained in low vacuum. In addition to all the functions of the above two kinds of electron microscopy, the environmental scanning electron microscopy (ESEM) also has the following main features: 1. The air pressure in the sample chamber can be greater than the saturated vapor pressure of water at room temperature; 2. The secondary electron imaging can be performed in the environmental state; 3. The dynamic process of phase change (in the range of - 20 ℃ ~ + 20 ℃) such as dissolution, solidification and crystallization of the sample can be observed Environmental scanning electron microscopy (ESEM) can be used to observe the morphology and qualitative and quantitative analysis of elements (C-U) of various solid and liquid samples, and to observe the phase transformation process of some solutions. For biological samples, water samples and oil samples, there is no need for dehydration or conducting treatment, and the secondary electronic image can be observed and the element composition can be analyzed directly in the natural state.

Atomic force microscope (AFM) is a kind of analytical instrument which can be used to study the surface structure of solid materials including insulators. It studies the surface structure and properties of materials by detecting the very weak interatomic force between the sample surface and a micro force sensor. When one end of a pair of microcantilever which is extremely sensitive to weak force is fixed and the tip of the other end is close to the sample, it will interact with it, and the force will make the microcantilever deform or change its motion state. When scanning the sample, the force distribution information can be obtained by using the sensor to detect these changes, so as to obtain the surface structure information with nanometer resolution.

EDS (energy dispersive spectrometer) is a device connected with scanning electron microscope or transmission electron microscope. In the scanning electron microscope (SEM) or transmission electron microscope (TEM), the atomic core of the sample is ionized by the incident electron beam to produce characteristic X-rays for measurement to determine the chemical composition of the substance. Analysis scope: qualitative and quantitative analysis of element 4-100.

Features: 1. It can quickly and quantitatively analyze all the elements of be-u in the micro area of various samples in a few minutes. 2. The requirements for the geometric position of the sample and detector are low: the requirements for W.D. are not very strict; The results of X-ray scanning and surface distribution can be obtained at low magnification. 3. The probe current required for energy spectrum is small: the sample that is easy to be damaged after electron beam irradiation, such as biological sample, fast ion conductor sample, glass and so on, is less damaged. The detection limit is generally 0.1% - 0.5%. The quantitative phase error of main elements with medium atomic number without overlapping peaks is about 2%.

The basic principle of X-ray photoelectron spectroscopy

When X-ray of certain energy irradiates the sample surface and interacts with the material to be measured, the electrons in the atoms of the material to be measured can separate from the atoms and become free electrons.

The process can be expressed as follows:

hn=Ek+Eb+Er

Where HN is the energy of X-ray; EK: energy of photoelectron; EB: binding energy of electron; Er: recoil energy of the atom.

Work function of instrument material Φ It is a fixed value, about 4ev, and the incident X-ray energy is known. Thus, if the kinetic energy EK of the electron is measured, the binding energy of the electron in the solid sample can be obtained. The orbital electron binding energy of various atoms and molecules is certain. Therefore, by measuring the photon energy of the sample, we can understand the composition of the elements in the sample. The chemical environment of elements is different, the binding energy will be slightly different. The tiny difference of binding energy caused by different chemical environment is called chemical shift. The state of elements can be determined by the size of chemical shift. For example, when an element loses electrons and becomes an ion, its binding energy will increase. If the electron becomes a negative ion, its binding energy will decrease. Therefore, the chemical shift value can be used to analyze the valence and existing form of elements.

XRD working principle

X-ray is the optical radiation produced by the transition of electrons in the atomic inner layer under the bombardment of high-speed moving electrons. There are mainly two kinds of X-ray: continuous X-ray and characteristic X-ray. Crystals can be used as X-ray gratings. The coherent scattering of a large number of atoms or ions / molecules will interfere with the light, which will affect the enhancement or weakening of the intensity of the scattered X-ray. Due to the superposition of a large number of scattered waves of atoms, the beams with the maximum intensity produced by mutual interference are called X-ray diffraction.

If the diffraction condition is satisfied, the Bragg formula: 2dsin can be used θ=λ

Use X-ray of known wavelength to measure θ This is used for X-ray structural analysis; The other is to use the crystal of known d to measure θ Then the wavelength of characteristic X-ray can be calculated, and the elements contained in the sample can be found out from the existing data.

XRD is X-ray diffraction, X-ray diffraction, through the X-ray diffraction of the material, analyze the diffraction pattern, analyze the composition of the material.

XRD application range

XRD can be used for qualitative and quantitative analysis. That is, it can analyze the phase composition and content in the alloy, determine the lattice parameters, determine the structural direction and content, determine the internal stress and crystal size of the material, etc.

Generally, it is mainly used to analyze the phase composition and content in the alloy.

At the junction of solid, liquid and gas, the angle between the solid-liquid interface and the gas-liquid interface is called contact angle θ express.

The measuring methods of contact angle can be divided into three categories: ① angle measuring method, which is to observe the shape of droplet or bubble on the solid surface, make tangent line at the intersection of solid, liquid and gas, and directly measure the angle with a protractor; ② The length measurement method calculates the contact angle by measuring the height and width of the droplet on the solid surface, such as the maximum height method of the droplet and the hanging piece method; ③ The weight method, using the principle of the hanging piece method to measure the surface tension of liquid, can measure the contact angle of liquid to solid (hanging piece).