Plastic materials inventions by the 1940s revolutionized the fashion industry. Plastic materials replaced natural fabrics such as cotton, leather or linen. Products made using plastic were inexpensive, easy to handle and care for. For instance—you can't iron a piece made of plastic materials.
One of the most loved fashion products made of plastic materials was plastic footwear. They came in the form of colors or colorless. I think—plastic footwear was popular because they were lightweight, waterproof and easy to clean. Let's not neglect the cons of plastic footwear to leave feet hot and sweaty.
Another market hit for kids by the 1980s was vibrant plastic sandals, called jellies. They were often decorated with colors such as pink, green, red, yellow, black or blue. They also featured buckle fastening.
In today's world—plastic footwear like flip-flops and sandals have remained practical among women. They are especially suitable for home wear.
REFERENCES:
Cosgrave, Bronwyn. The Complete History of Costume and Fashion from Ancient Egypt to the Present Day. New York: Checkmark Books, 2000.