The significance of Shanghai Baosheng Water Activity Measurement Device:

Microbial growth: Water activity is closely related to the growth of microorganisms such as bacteria, mold, yeast, etc. Most microorganisms require a certain level of water activity to grow. For example, bacteria typically grow in environments with aw>0.91, while fungi grow in environments with aw>0.7.

Chemical reactions: Water activity also affects the rate of chemical reactions, especially those related to water. Low water activity helps to delay these reactions, thereby improving the stability of the substance.

Food preservation: In food science, water activity is a key factor affecting the shelf life and safety of food. Lower water activity helps to reduce microbial growth and delay the spoilage process of food.

Taste and texture: Water activity is also related to the texture and taste of food. For example, foods with low water activity are usually drier, while foods with high water activity may be wetter.

Common applications of Shanghai Baosheng water activity measurement device:

Food industry: Control the water activity of products such as dried fruits, meat, bread, etc. to extend their shelf life.

Pharmaceutical industry: Ensure drug stability and avoid drug degradation.

Chemical Industry: Controlling Chemical Reaction Rates to Improve Product Stability

When the conductive foam liner is compressed, the relationship between the dynamic change of resistance and the compression percentage is a complex process. The following is the analysis on the compression percentage of conductive foam liner and the mechanism of resistance dynamic detection curve:

1. Basic structure and characteristics of conductive foam liner

Conductive foam is usually composed of foam matrix with conductive particles (such as carbon black, metal powder, etc.). It exhibits a larger porosity and lower resistance when not compressed, but when compressed, the porosity decreases, and the deformation of the material and changes in the conductive path can cause changes in resistance.

2. Relationship between compression percentage and resistance change

·Initial state: when the conductive foam is not compressed, the porosity of the foam is high, the current flow path is relatively long, and the resistance is high.

·Compression process: with the compression of foam, the porosity gradually decreases, the contact between conductive particles in the foam structure increases, and the path of current flow becomes shorter, leading to the reduction of resistance.

·After compression to a certain percentage: when the foam is compressed greatly, the pores almost disappear, the structure of foam may collapse or become compact, and the resistance changes gradually tend to be stable. At this point, the change in resistance usually tends to stabilize, or there may be a sharp increase in resistance due to irreversible damage to the material.

3. Mechanism of resistance dynamic change curve

The resistance change of conductive foam liner during compression is usually shown in the following stages:

·Stage 1: Low Compression Ratio Stage (Initial Stage):

·At this stage, the resistance gradually decreases with increasing compression. With the gradual compression of the foam structure, the contact area between the conductive particles increases, and the path of the current becomes shorter, leading to the reduction of resistance. The resistance change at this stage is relatively gentle.

·Stage 2: Medium Compression Ratio Stage:

·When entering the medium compression stage, the pores of foam begin to reduce significantly, the geometry of foam and the arrangement of conductive particles may change, and the change of resistance is more obvious, and the speed of resistance reduction may become faster.

·Stage 3: High Compression Ratio Stage (Compression Limit Stage):

·When the compression ratio approaches the limit, the pores of foam basically disappear, and the change of resistance tends to be stable. At this stage, if plastic deformation or damage occurs to the foam, the resistance may suddenly increase, which is shown by a sharp rise in resistance.

·Stage 4: Irreversible deformation stage (if any):

If the foam undergoes permanent deformation under high compression (such as material fracture, conductive particle shedding, etc.), the resistance will rise sharply. This phenomenon usually occurs after the compression reaches a certain limit.

4. Factors affecting resistance changes

·Distribution of conductive particles: the change of resistance of conductive foam is affected by the distribution uniformity of conductive particles. If the conductive particles are evenly distributed in the foam, the resistance change will be smooth.

·Elasticity and plasticity of materials: the difference of elasticity and plasticity of different conductive foam will affect the change of resistance. In the softer foam, the resistance changes greatly during compression, while in the harder foam, the resistance change may be small.

·Compression rate: The speed of compression can also affect the dynamic changes in resistance, and rapid compression may lead to a larger range of local stress concentration, resulting in a sharp change in resistance.

5. Experimental testing of resistance and compression percentage

In experiments, the dynamic changes in resistance during compression are usually detected through the following steps:

·Use the pressure sensor to record the compression percentage of foam.

·Use four probe method or resistance strain gauge to monitor the resistance change of foam liner in real time.

·Compare the compression percentage with the resistance value to obtain the resistance compression percentage curve.

6. Summary

There is a complex relationship between the dynamic change of resistance of conductive foam gasket and the compression percentage. During the initial compression process, the resistance usually decreases because the foam structure is more compact and the contact between conductive particles increases. But as the compression continues, the resistance change will gradually stabilize and may experience a sharp change due to irreversible deformation or material damage after reaching a certain compression percentage.