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The melting point of polypropylene occurs in a range, so the melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F).
Plastics are a wide range of synthetic or semi-synthetic ... high-temperature melt-processable ... and polypropylene (PP), the world's leading petrochemical-derived ...
Low molecular weight poly-alpha-olefins are useful as synthetic lubricants such as synthetic motor oils for vehicles and can be used over a wide temperature range. [ 8 ] [ 10 ] Even polyethylenes copolymerized with a small amount of alpha-olefins (such as 1-hexene , 1-octene , or longer) are more flexible than simple straight-chain high-density ...
The Gmelin rare earths handbook lists 1522 °C and 1550 °C as two melting points given in the literature, the most recent reference [Handbook on the chemistry and physics of rare earths, vol.12 (1989)] is given with 1529 °C. The World Book encyclopedia from 2002 lists 1529 °C. WEL: 1770 K: 1497 °C: 2727 °F CRC: 1529 °C: LNG: 1529 °C: 69 ...
Observed concentrations have been in the range of 0.1–4.8 parts per billion in rural air, 4–10.5 ppb in urban air, and 7–260 ppb in industrial air samples. [ 9 ] In the United States and some European countries a threshold limit value of 500 parts per million ( ppm ) was established for occupational (8-hour time-weighted average ) exposure.
Crystal growth is achieved by the further addition of folded polymer chain segments and only occurs for temperatures below the melting temperature T m and above the glass transition temperature T g. Higher temperatures destroy the molecular arrangement and below the glass transition temperature, the movement of molecular chains is frozen. [6]
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In polymers, such as plastics, thermal degradation refers to a type of polymer degradation where damaging chemical changes take place at elevated temperatures, without the simultaneous involvement of other compounds such as oxygen. [1] [2] Simply put, even in the absence of air, polymers will begin to degrade if heated high enough. It is ...