Low-Density Polyethylene (LDPE) Balls
Low-density polyethylene (LDPE) is a thermoplastic derived from the monomer ethylene and defined by a density range of 0.910-0.940 g/cm³. It is nonreactive at room temperatures, except by strong oxidizing agents, and some solvents that can cause swelling. LDPE can continuously withstand temperatures of 80ºC and, for short periods, 95ºC. Made in translucent or opaque variations, it is quite flexible and sturdy but still breakable.
Since LDPE has more branching than HDPE, its intermolecular force is weaker, tensile strength is lower, and its resilience is higher, and because its molecules are less tightly packed and less crystalline, its density is also lower when compared to HDPE.