Melt Index
The melt index indicates how many grams of polyethylene can be extruded from a 2.08 mm die at a temperature of 190 ° C and at a pressure of 0.3 MPa (3 kgf/cm 2 ) within ten minutes. Approved by the International Organization for Standardization ISO (R292-1963 Method a) and used to indicate the melt viscosity of polymer materials.
This method requires higher cost equipment and generally does not measure the melt index by the film supplier. However, complete information on the melt index, density, friction, strength properties and optical properties of various polyethylene materials can be obtained from raw material suppliers. Get it there.
(2) Coefficient of friction
The amount obtained by measuring the frictional resistance between the two surfaces of the same film is the coefficient of friction. The practice is: use a sliding body that can adjust its own weight to fit the sliding surface area, pull it over the surface of the film, and use Strain gauge to determine the sliding friction. Turn the instrument to zero position, the sliding body and the film should be freely hanging, the maximum value of sliding friction is one.
(3) Glossiness
Gloss is a measure of the smoothness of the surface of a film. A film sample is attached to the black glass piece of a standard test device with a strip of glue, and the film is irradiated with light at an angle of 45 or 60 degrees in the same plane. The reflected light is then measured. The intensity, and the intensity is compared with the intensity of the light reflected from the uncoated glass sheet to obtain the gloss value.
(4) Photo-haze
Film haze is generally expressed by the light scattering ability of the film. The test method specifies that the sample thickness is 0.038 mm and the sample is fixed so that the light passes through the film. The haze is more than 2.5 degrees from the incident beam direction. The ratio of the intensity of transmitted light to the total transmitted light intensity. The haze is a measure of the turbid appearance of the film.
(5) Permeability
Permeability is a measure of the ability of a gas to permeate through a film under certain climatic conditions. The simplest description of the test method is to dissolve the gas or vapor on one side of the film and the opposite side of the film through the concentration gradient. Evaporation. After a short period of time, the equilibrium is reached. As long as the pressure difference between the two sides of the film remains the same, the gas passes through the film at a constant rate. Permeability is the thickness, time and pressure by volume. Poor representation.