In comparison with PE, Polypropylene is the harder variant among plastics. It is a structured crystalline plastic that is very difficult to extrude. Only a few profiles can be extruded from polypropylene. In comparison to HDPE, PP is stiffer and has a harder surface. However, the mechanical qualities combined with its heat and chemical resistance make it a valuable plastic.
nowadays polypropylene is mixed with rubber. A particular procedure with the raw-material induces a vulcanization process; this causes the plastic to remain a thermoplastic. These thermoplastic rubber sorts are treated individually.
PP profiles are commonly found in:
when PP plastic is co-polymeric with other plastics like ethylene, the higher impact resistance can be achieved at lower temperatures. The maximum tolerable temperature rests at approximately 110⁰ C (230⁰ F). the hard and stiff, not impact resistant variant is called a Homo-polymer, the impact-resistant variant is called a co-polymer. PP plastic comprises a stretched chain-structure which allows it to be pulled while fibers and bands develop with high tensile strength. We all know the ropes and straps from PP plastic that are used to tie-up boxes and crates. Other than this, PP plastic is often used for appliances, garden furniture, the automobile, and the electronic industry. Polypropylene is scentless and does not affect the taste of foodstuffs. PP plastic is hypoallergenic, the reason why it is often used in the food industry and medicine. Due to the a-polar qualities of polypropylene, glues do not bond with the surface. However, hot-air and mirror welding are good alternatives to bond PP plastic.
Polypropylene can be colored effortlessly into beautiful, brilliant colors with a high gloss surface shine. The used compound of PP plastic and the lightfastness of the pigment determines whether or not the PP is weatherproof. Printing on and painting of the PP is difficult.
None of the polyolefins are self-extinguishing, the same goes for Polypropylene, this plastic burns with a blue flame without emitting toxic gasses. Adding special additives can render the material fire retardant or even self-extinguishing.
Pure polypropylene is very tough to paint; however, mixed with a mineral filler or EPDM, it is possible to paint polypropylene. To affix the paint on this a-polar plastic, the surface must be oxidized by burning or by corona discharge on the surface. The corona discharge releases a high electric current onto the surface, which alters the surface tension. This method is commonly practiced in the packaging industry. In most cases, a primer must be applied before painting.
Polypropylene is easy to weld with conventional welding processes and equipment. The welding method should, however, be based on heat source welding methods, like hot air or mirror welding. The material's sparse polarity makes it difficult to weld with high-frequency and ultra-sonic techniques.
Polypropylene is amply resistant to chemicals and other toxins and watery solutions. At high temperatures, the chemical resistance deteriorates quickly.
Polypropylene bonds very well with other thermoplastics. Especially the co-, tri-, and quad extrusions. Next to bonding with pure polypropylene, like in a different color, the material also bonds well with PP and thermoplastic rubbers (SBS, SEBS, TPO, and TPV)