Crystalline polymers polypropylene and polyethylene display particle strengthening. Tampons are made of cotton, rayon, polyester, polyethylene, polypropylene, and fiber finishes. The company supplies polyolefin plastics (polyethylene and polypropylene). These two alkenes are precursors to polymers, including polyethylene, polystyrene, acrylates, polypropylene, etc. Polyethylene and polystyrene figures are made by injection moulding. The company is the largest licensor of polyethylene and polypropylene technologies. Antimony compounds are used as catalysts for polyethylene terephthalate (PET) production. Technology licence agreements have been signed for cracker, polyethylene and polypropylene units. Silica nano-particles are dispersed in a solution of polyethylene glycol. They can be diluted in solvents like pure ethanol and polyethylene glycol. Acetylene can be semihydrogenated to ethylene, providing a feedstock for a variety of polyethylene plastics. One application is as a stabilizer and catalyst for the production of polyethylene terephthalate. PPG has many properties in common with polyethylene glycol. Plastic #2, high-density polyethylene (HDPE) is a commonly recycled plastic. The membrane layer is often a thick flexible polyethylene sheeting called EPDM.