A chemical catalyst to initiate the polymerization reaction. Catalysts are substances that we can add to make chemical reactions more likely to occur, and although they may change temporarily during the reaction process, they will eventually reappear in the original way; In other words, they don't change forever with the onset of repercussion. The Ziegler-Natta catalysts, developed jointly by German chemist Carl Ziegler and Italian chemist Giulio Natta, who won the Nobel Prize in Chemistry in 1963, are some of the most important catalysts for making polymers.

Since we need plastics to do a variety of things, we often have to add other ingredients to basic hydrocarbons to produce polymers with intact and correct chemical and physical properties. These additional raw materials include colorants (which help turn plastics into a wide variety of bright and happy colors), plasticizers (which make plastics more flexible, sticky and easy to shape), stabilizers (which stop us bonding in sunlight and hot plastics), and fillers (which are usually low-cost minerals, which means we need fewer expensive petroleum hydrocarbons, and so on). Make our last plastic products that we can consume and sell more cheaply).

Four plastic molding processes: injection molding, blow molding, extrusion, calendering.

Four common processes for making things out of plastic. Injection molding is the process of radiating hot plastic into a mold. Plastic particles (light blue) are passed through an auger (Archimedes screw), heated to make molten plastic, and then radiated through a needle (injection) into the mold. Blow molding is similar, but air (yellow arrow) is blown into the plastic after causing it to shrink and fill the mold. 3) Extrusion refers to the extrusion of plastic through a nozzle and a molding mold to make something similar to a pipe. 4) Roller rolling is used to make the plastic sheet flat, thin and smooth.