Brief introduction of PMMA material properties

PMMA a colorless transparent glassy substance with a specific gravity of 1.19 and a low surface hardness that is easily scratched by hard objects.

It is difficult to catch fire, but it can burn slowly. It can still keep burning after leaving the fire. When burning, it is easy to break and melt.

1.

Transparency: PMMA is an amorphous polymer whose internal molecules are arranged in such a way that they do not interfere with the speed of the incoming light as it passes through each part, so that the light travels at the same speed (that is, a uniform refractive index), and the light is not scattered in all directions to interfere with each other.

Therefore, PMMA has excellent optical properties, with a high light transmittance (90 ~ 92%, depending on the wavelength).

A sheet or bar with a very smooth surface can reflect all the light coming in from one end within a certain limit, and finally shoot out from the other end, just like water flowing through a pipe. (A certain degree of bending refers to the Angle between the bent position and the original position, which cannot exceed 42°;

When bending is curved, the arc radius must be greater than 3 times of rod diameter or sheet thickness.

But when a part of the surface is ground, light can escape from it to give off brightness.

This feature can be used to make edge light emitting devices, surgical medical devices, etc.

2.

Mechanical properties: PMMA is more than 10 times stronger than ordinary glass, but only moderately stronger than other plastics.

Its shortcomings are light brittle, easy to crack (or silver grain), low surface hardness, easy to scratch and lose luster;

The wear resistance is poor, the static friction coefficient between each other is 0.8, the dynamic friction coefficient of the steel is 0.45 ~ 0.50, so easy to scratch and grind.

3.

Electrical performance: THE electrical performance of PMMA is good, especially at low frequencies.

However, some of its electrical properties are unique: the tangent of the dielectric loss Angle decreases with increasing frequency.

Temperature and frequency have influence on the dielectric constant, while climate and humidity have little influence on the electrical properties.

But the electrical performance is worse than PE and PS.

4.

Thermal properties: PMMA heat resistance is not good enough, the use temperature is only 80℃.

The monomer can be copolymerized with ethylene glycol acrylate or propylene methacrylate to improve the heat resistance.

PMMA has a lower specific heat than most thermoplastics, allowing it to be thermoplasticized quickly.

In addition, it also has a certain cold resistance, at low temperature -50 ~ -60℃, the impact strength changes little.

5.

Chemical properties;

PMMA has a certain chemical resistance, but decreases with the increase of temperature.

Strong chemical resistance to gas, long-term contact with ozone, sulfur dioxide, no corrosion;

Chlorine can corrode its surface.

It can dissolve in ethyl acetate or butyl ester, glacial acetic acid, chloroform and benzene.

Can absorb a variety of alcohol organic compounds, volume expansion, surface rough hair, but insoluble in aliphatic compounds.

6.

Weather resistance: excellent weather resistance, little change in transparency and color in tropical climates.