Polyethylene is often classified based on density. Density is the mass per unit volume. As each polymer changes from a molten solid to a solid, a number of chains may be arranged in much more regular order. This happens to molecules that have long, repetitive parts. Crystallization does not occur in parts with irregular patterns, such as the top of a branch or the end of a chain, and these areas are called amorphous. Some polymers, such as polystyrene, are completely amorphous due to inhibition of the integrated molecular structure to crystallize. Low-density polyethylene is synthesized to form a polymer with many branches. These branches may include short chains (less than 6 carbon atoms in length) or long chains (approximately the length of the main chain). The branching points along the chain act as breaking points of the system order and prevent crystallization. Lower levels of crystallinity lead to lower densities. LDPE generally has a density of 0.91-0.93. LDPE processing is relatively easy. Because compared to other types of polyethylene, it melts at a relatively low temperature (240-220 and 115-105) and does not require much energy. LDPE blown films have an average high viscosity, but the presence of a wide range of branching in the chains leads to an increase in the processing range and high melt resistance in the bubble. This results in a stable bubble that can work with a low-altitude solidification line. LDPE thermal stitching is very easy. Distinctive features of LDPE blowing film are toughness and flexibility. Toughness is the result of strength and tensile strength, especially when processed with a high-altitude, transversely oriented (TD) machine. Flexibility is the result of a low degree of crystallinity. LDPE films have a certain softness compared to HDPE films. In general, LDPE is not as strong as HDPE.
