Short answers, pulled from the story.
Chemists at Phillips Petroleum first demonstrated the polymerization of propylene in 1951. This initial discovery was a scientific curiosity before the true revolution arrived in March 1954 when Giulio Natta and Karl Rehn unlocked the secret of stereoselective polymerization.
The density of polypropylene ranges between 0.895 and 0.93 grams per cubic centimeter. This makes it the commodity plastic with the lowest density, allowing manufacturers to produce lighter parts that can be molded in greater numbers from a single mass of raw material.
The Food and Drug Administration issued multiple warnings and ordered 35 manufacturers to study the side effects of these devices in January 2012. This regulatory action followed a public health crisis regarding transvaginal mesh used to treat vaginal prolapse and urinary incontinence.
Less than 1 percent of the material generated globally was recycled as of 2015. The process of mechanical recycling degrades the carbon backbone more severely than in polyethylene because the methyl side group is highly susceptible to thermo-oxidative and photo-oxidative degradation.
The melting point of perfectly isotactic polypropylene reaches as high as 185 to 220 degrees Celsius, while commercial grades typically range from 160 to 170 degrees Celsius. The material remains brittle below 0 degrees Celsius.
A study published in September 2024 reported that polypropylene is the most common microplastic fiber found in the olfactory bulbs of the human brain. This finding compounds the environmental impact of the material despite its widespread use.