Examination techniques for physical features
Molecular Weight Determination
The firm interrelationship between molecular weights of plastic polymers and physical features, estimating the molecular weight of plastic substances is vital for the use of packaging. Normally, to ensure the power of packaging items, it is vital to remain assured that the quality of the whole packaging method is highly reliant on MW and its distribution. Fundamentally, there are two practical testing processes to find out the average MW and MW delivery of plastic substances. The two examinations are GPC (Gel Permeation Chromatography) and SEC (Size-Exclusion Chromatography). The mechanism of both these examinations is founded on steric isolation of the analytic molecules from the holes of the column packing material.
In the present consumer item business, color is one of the most basic/primary /fundamental determinants for communication with customers since it affects the initial impression, recognition, perception and parts of both quality and brand identity. For instance, most international brand products, trademarks, icons are meticulously linked to various special colors. Hence, exact and continuous color measurements are required in terms of controlling quality for the packaging system, which also covered labelling and printing. To find out the color of most packaged products, several types of spectroscopic tools, spectrometers, color data software, spectrophotometers and tools are utilized by scientists dealing with packaging.
Primarily, calorimeters can estimate the color of packaging films. For example, the light differences can be traced by different light reflectance of objects and films, total color difference (delta E*) along with color values (L*,a*, b*) is gathered.
Opacity is defined as the degree of pigmentation of packaging components found in black light. Opacity is helpful for packaging materials which are subtle to both ultraviolent light and visible light. The basic optical features of plastics which are examined are visible light absorption, gloss, refractive index, Ultraviolet rays, haze, yellowness index and color analysis along with transmission. These can be measured and analyzed by using a spectrophotometer.
The amount of light reflected by the surface of the material is called gloss. It is estimated at the angles of 85°, 20° and 40°. Haze is defined as the dispersion of light through a material which leads to a glaring sensation. The changes in color from pure white to yellow is estimated by the yellowness index.