Being a person nestled in the dark and humid recesses of industry, I find myself boggling at certain things out in the bright and sunny world. Truly, it boggles my mind how little appreciation people have for polyolefin resins. That is to say, polyethylene, polypropylene and all the myriad copolymers and formulations found thereto. Ok, let’s throw PVC and polystyrene in the mix as well.
Why do I boggle at this? What makes my head spin in puzzlement? I’m so glad someone asked. Polyolefin films look innocent enough to be ignored. In their uncompounded state they are clear and colorless or they may be white. Polyolefin films and extruded components are ubiquitous in packaging and thus are not normally an object of desire. They serve the object of desire. They occupy a lesser state interest in nearly all contexts. They are made inexpensively enough to be torn asunder from the desired object and tossed wantonly to the side for later clean up.
But if the uneducated user of polyolefins only knew the extent to which modern science and engineering had been carefully applied to the lowly stretch wrap or the roll of 1 mil PE film. If they only knew the scientists and engineers who carefully devised the ethylene crackers to produce high purity ethylene, or if they knew the highly educated people who devise the polymerization process, they might have heard an account of the long march to produce water white films with properties matched to the end use.
Puncture resistance, elongation, fish-eyes, haze, modulus, crystallinity, glass transition temperatures, melt points, low volatiles, melt viscosity and strength- all attributes carefully tended to so that the film appears invisible to the consumer. High gloss, low haze films to make the product look even better. Low volatiles and residues for food contact use. Polyolefins engineered for specific densities for the global market.
All of the attributes above to attend to with a continuous polymerization loop that spews 50,000 to 80,000 lbs per hour of pellets into silos and rail cars. Pellets that will eventually go to converters who will blow films and extrude widgets all day long. All so the consumer product can arrive at its destination wrapped unscuffed and free of dust.
Polyolefin materials are incredibly useful and amazing in their own right. We should have more appreciation for these materials and how they serve our needs.