Rigour (BrE) or rigor (AmE) (see spelling differences) describes a condition of stiffness or strictness. Rigour frequently refers to a process of adhering absolutely to certain constraints, or the practice of maintaining strict consistency with certain predefined parameters.
PLA stands for polylactic acid and is a resin made from corn starch. PLA is used to make clear compostable containers and PLA lining is used in cups and containers as an impermeable liner. PLA is biodegradable, and fully compostable. It uses 65 percent less energy to produce than conventional oil-based plastics and generates 68 percent fewer greenhouse gasses and contains no toxins.
Bisphenol A, or BPA, is a chemical compound used to make polycarbonate plastics, epoxy resins, and other materials. Virtually everyone in the U.S. comes across BPA every day. Among other things, BPA is used to make: 1  shatterproof polycarbonate hard plastic bottles and containers.