The thermoplastic stands up quite well to steam-sterilization and autoclaving, managing to resist physical damage and environmental stress-cracking when exposed to high corrosion chemicals in tests. This result is something one can easily expect due to the ability of the material to be fatigue resistant, have high tensile strength, and unbelievable elongation abilities. Such high material characteristics ensures an almost infinite flex life for polypropylene oriented moldings in integrated hinges, making it quite responsive to injection speed and pressure. The plastic also sets in a shorter time when placed in the mold, which ensures a higher production rate for molders. Polyprolene has proven to be excellent when considering is chemical resistant abilities, abrasion strength, dimensional stability, and high surface gloss. Such unique qualities makes the polymer versatile and suitable for superior strength, grease resistance, and moisture barring in film and fibers.
While pre-drying is not necessarily required when molding Injection Molding Polypropylene is molded in standard screw making equipment as these can be done without alteration in normal conditions, filled resins may sometimes require pre-drying. The manufacturing process however, isnt as simple as it sounds. The molder needs to take note of additional considerations such as the cylinder temperature and injection pressure. These two of the most closely related variables that take the forefront of the molding parameters will be discussed in the succeeding paragraphs.
The most advisable temperature range for cylinders are between 400- 570°F. Normally the temperature should be 25-50°F above the normal temperature when molding polypropylene. However it should not be molded above 570°F so the normal range for molding would be kept anywhere between 400-525°F. The cylinder temperature is best kept with the hopper or feed section lower than the nozzle at 30-50°F.