Braune Nalgene™ HDPE-Weithalsflaschen in Laborqualität

At the molecular level, polypropylene copolymer consists of a pattern of co-polymerized ethylene and propylene monomer “units” and so in some ways could be considered a “mixture” of polyethylene and polypropylene. It was created in order to combine some of the ideal properties of each; i.e., the high-temperature warping resistance of polypropylene and the low-temperature brittleness resistance of polyethylene. The polymer industry's standard nomenclature for this material is polypropylene copolymer. In common parlance, however, “polypropylene” can often refer to copolymer (PPCO) as well as “pure” polypropylene (homopolymer, PP or PPHO) consisting entirely of propylene monomers. Many of the product molds we use for PPCO items were set up to stamp a “PP” material specification on the base, which can be misleading. Our specification sheets and compliance certificates, however, always accurately identify the material in question.

In order to function as a leakproof system without a liner (one of the key advantages of our laboratory and packaging products), the surfaces of the container and closure that meet and push together when tightened must be dissimilar materials with different hardnesses. Even our polypropylene copolymer (PPCO) bottles with polypropylene homopolymer (PP) bottles are different enough to function properly. On some larger carboy products, this difference cannot be sufficiently maintained so a pliable thermoplastic elastomer (TPE) gasket is added for proper leakproof seal function.