There is a tendency to utilize underground space for the less ornamental purposes of civilization; there is the Metropolitan Railway in London, for instance, there are new electric railways, there are subways, there are underground workrooms and restaurants, and they increase and multiply.
Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as clamshells), lids, bottles, trays, tumblers, and disposable cutlery.
Polypropylene is occasionally recycled. PP is strong and can. usually withstand higher temperatures. It is used to make lunch. boxes, margarine containers, yogurt pots, syrup bottles, prescription bottles. Plastic bottle caps are often made from PP. Polystyrene is commonly recycled, but is difficult to do. Items. such as disposable coffee cups, plastic food boxes, plastic cutlery. and packing foam are made from PS. Code 7 is used to designate miscellaneous types of plastic not. defined by the other six codes. Polycarbonate and Polylactide are. included in this category. These types of plastics are difficult to. recycle. Polycarbonate (PC) is used in baby bottles, compact discs, and medical storage containers.