& nbsp; & nbsp; Adhesives are widely used in the electronics industry, mainly for bonding, sealing, potting, coating, conformal coating, and SMT placement of electronic components. Adhesive not only needs to be used for mechanical fastening, but also needs to meet the requirements of thermal conductivity, insulation, impact resistance assembly, sealing, and substrate protection. If the adhesive fails, it is highly likely to cause the entire equipment to malfunction or even stop running, seriously affecting the normal use of users.
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  & nbsp; & nbsp; Adhesive, also known as adhesive or bonding agent, is abbreviated as glue. Adhesive refers to a substance that can firmly bond two identical or different materials together. The paste used in daily life is the simplest adhesive. With the development of modern science and technology, adhesives, as a new type of connecting material, are increasingly widely used in various fields of the national economy to bond connected components< br />


  & nbsp; & nbsp; Therefore, in the actual application process of adhesives, we will pay more attention to various physical properties of adhesives, such as appearance, density, viscosity, non-volatile matter content, pH value, curing time, aging, etc; So what are the main physical properties of adhesives? What are the testing methods for various physical properties of adhesives? Adhesive manufacturer Ruilangda will analyze for you< br />
What are the physical properties indicators of adhesives? Introduction to Testing Methods for Physical Properties of Adhesives

  & nbsp; & nbsp; 1. Adhesive appearance

Refers to color, condition, macroscopic uniformity, mechanical impurities, etc., which can intuitively evaluate the quality of adhesives< br />
  & nbsp; & nbsp; Testing method

  & nbsp; & nbsp; a. Pour the adhesive sample into a beaker, stir with a glass rod, and observe whether the adhesive solution is uniform and whether it contains other mechanical impurities or condensates< br />
  & nbsp; & nbsp; b. Tilt the adhesive into a vertical bottle and observe whether the adhesive flows evenly along the glass bottle wall from the top of the bottle< br />
  & nbsp; & nbsp; 2. Adhesive density

  & nbsp; & nbsp; Density is the mass per unit volume of a substance at a specific temperature, measured in grams per centimeter, which reflects the uniformity of adhesive mixing< br />
  & nbsp; & nbsp; Testing method

  & nbsp; & nbsp; a. Specific gravity method< br />
  & nbsp; & nbsp; b. Specific gravity method< br />
  & nbsp; & nbsp; c. Syringe method< br />
  & nbsp; & nbsp; What are the physical properties indicators of adhesives? Introduction to Testing Methods for Physical Properties of Adhesives

  & nbsp; & nbsp; 3. Adhesive viscosity

  & nbsp; & nbsp; Viscosity is a characteristic of adhesives that hinders their relative flow and is an important indicator for evaluating the quality of adhesives< br />
  & nbsp; & nbsp; Testing method

  & nbsp; & nbsp; a. Rotational viscometer method< br />
  & nbsp; & nbsp; b. Viscosity cup method.
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  & nbsp; & nbsp; 4. Adhesive non-volatile matter content

  & nbsp; & nbsp; Any adhesive containing solvents must have the non-volatile content of its components determined< br />
  & nbsp; & nbsp; Calculation formula for non-volatile matter content (X%):< br />
  & nbsp; & nbsp; X=（G1/G）*100%

  & nbsp; & nbsp; Note: G1— Mass of sample after drying (g) G‐ Quality of sample before drying

  & nbsp; & nbsp; 5. Adhesive pH value test

  & nbsp; & nbsp; The pH value can determine the acidity and alkalinity of the adhesive. The smaller the pH value, the stronger the acidity; The higher the pH, the stronger the alkalinity. If acidic substances are present, they can cause corrosion of metals, and caution must be taken when selecting< br />
  & nbsp; & nbsp; Testing method

  & nbsp; & nbsp; The simplest test method is to use pH test paper, but this method is only applicable to water-based or lotion adhesives, and is not accurate enough. The glass electrode acidimeter method is the most accurate for testing and is suitable for water-soluble, dry, or non-aqueous media, as well as adhesives that can dissolve, disperse, and suspend in water< br />
  & nbsp; & nbsp; 6. Adhesive shelf life

  & nbsp; & nbsp; The applicable period of adhesive is the time during which the formulated adhesive can maintain its usable performance. It is an important industrial indicator for chemical reaction adhesives and double liquid rubber adhesives< br />
  & nbsp; & nbsp; What are the physical properties indicators of adhesives? Introduction to Testing Methods for Physical Properties of Adhesives

  & nbsp; & nbsp; 7. Adhesive curing time

  & nbsp; & nbsp; The curing speed of adhesive is the main data for studying the curing conditions of adhesive, which can be used as a simple method to test the performance of adhesive products and identify whether the formula is correct< br />
  & nbsp; & nbsp; 8. Adhesive storage period

  & nbsp; & nbsp; The storage period of adhesive is the time during which the adhesive can maintain its operational performance and specified strength under certain conditions. By measuring the changes in viscosity and adhesive strength before and after storage, the storage period can be determined.
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  & nbsp; & nbsp; 9. Adhesive chemical resistance performance

  & nbsp; & nbsp; Chemical resistance is one of the durability indicators for adhesive useThe decrease in adhesive strength of a metal sample bonded with an adhesive after soaking it in a certain test liquid at a certain temperature for a specified time is used to measure the chemical resistance of the adhesive< br />
  & nbsp; & nbsp; 10. Adhesive aging

  & nbsp; & nbsp; During the use of experimental adhesives, the performance of the adhesive may decrease and be damaged due to various environmental factors and the effects of the medium, resulting in aging phenomena< br />
  & nbsp; & nbsp; Testing method

  & nbsp; & nbsp; a. Atmospheric aging test: Before the test, the exposure frame is installed at the designated location, and the samples are fixed on the exposure frame with stainless metal wire. The distance between the samples is not less than 10mm. The exposure time of the samples is generally at least one year, and they are measured once a month. The performance of each adhesive tested after aging is compared with that before aging< br />
  & nbsp; & nbsp; b. Atmospheric accelerated aging test: By using atmospheric accelerated aging test, the test cycle can be shortened and the test level can be improved. The test is conducted on a specially designed aging testing machine, which is an outdoor automatic exposure device that tracks the sun all day long< br />
  & nbsp; & nbsp; c. Damp heat aging test: The simultaneous effect of high temperature and high humidity is the main cause of adhesive aging, and the damp heat aging test is generally conducted in a temperature control box< br />
  & nbsp; & nbsp; d. Artificial simulated climate accelerated aging test: using artificially manufactured simulated aging light sources to replace sunlight for accelerated aging tests. Currently, the main test light sources are ultraviolet carbon arc lamps, sunlight carbon arc lamps, and xenon lamps< br />
  & nbsp; & nbsp; e. Salt spray corrosion test: This test is mainly conducted in various salt spray corrosion test chambers, where the adhesive, when in contact with seawater and steam, causes salt spray particles to settle on the adhesive and quickly absorb moisture to dissolve into a chloride aqueous solution, thereby penetrating into the adhesive layer and accelerating the electrochemical corrosion reaction, causing aging and corrosion of the bonded material.