rigorous (Adjective). Manifesting, exercising, or favoring rigour; allowing no abatement or mitigation; scrupulously accurate; exact; strict; severe; relentless; as, a rigorous officer of justice; a rigorous execution of law; a rigorous definition or demonstration. rigorous (Adjective). Severe; intense; inclement; as, a rigorous winter.
Polylactic acid or polylactide (PLA, Poly) is a biodegradable thermoplastic aliphatic polyester derived from renewable resources, such as corn starch (in the United States and Canada), tapioca roots, chips or starch (mostly in Asia), or sugarcane (in the rest of the world).eing able to degrade into innocuous lactic acid, PLA is used as medical implants in the form of anchors, screws, plates, pins, rods, and as a mesh. Depending on the exact type used, it breaks down inside the body within 6 months to 2 years.
Plywood. Plywood is also an engineered wood product that is made by pressing and binding sheets of wood veneer together into one solid piece. Plywood comes not only in different thicknesses, but also in different grades, so you can choose the right one for your project. MDF is basically glorified particle board. 2  Just like particle board, MDF will soak up water and other liquids like a sponge and swell unless itâs very well sealed on all sides and edges with primer, paint, or another sealing product.