Dr Laks says â[e]ven were the regression line to have a slope of zero, if the SD of the duct diameter increases as a function of time, then the upper limit of normal value would increase with age.â There is no indication that the variance increases with age.
PET, which stands for polyethylene terephthalate, is a form of polyester (just like the clothing fabric). It is extruded or molded into plastic bottles and containers for packaging foods and beverages, personal care products, and many other consumer products.ET is a polymer of ethylene glycol and terephthalic acid. Pellets of PET resin are heated to a molten liquid, which can be easily extruded or molded into almost any shape. PET was first synthesized in the U.S. during the mid-1940s by DuPont chemists searching for polymers that could be used to make new textile fibers.
The soda bottle so common today is made of Polyethylene Terephthalate (PET) , a strong yet lightweight plastic. PET is used to make many products, such as polyester fabric, cable wraps, films, transformer insulation, generator parts, and packaging.ext, the dimethyl terephthalat, is combined with an excess of ethylene glycol at 305 degrees Fahrenheit (150 degrees Celsius) to yield another substance, bis 2-hydroxyethyl terephthalate and methanol. The final step of polymerization involves the condensation polymerization of the bis 2-hydroxyethyl terephthalate.