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Due to the tertiary carbon atom, PP is chemically less resistant than PE (see Markovnikov rule). [11] Most commercial polypropylene is isotactic and has an intermediate level of crystallinity between that of low-density polyethylene (LDPE) and high-density polyethylene (HDPE). Isotactic & atactic polypropylene is soluble in p-xylene at
Their elastic modulus changes significantly only at high (melting) temperature. [4] It also depends on the degree of crystallinity: higher crystallinity results in a harder and more thermally stable, but also more brittle material, whereas the amorphous regions provide certain elasticity and impact resistance.
Poly(p-phenylene oxide) (PPO), poly(p-phenylene ether) (PPE), poly(oxy-2,6-dimethyl-1,4-phenylene), often referred to simply as polyphenylene oxide, is a high-temperature thermoplastic with the general formula (C 8 H 8 O) n. It is rarely used in its pure form due to difficulties in processing.
In liquid water at high temperatures, (e.g. that approaching the critical temperature), the solubility of ionic solutes tends to decrease due to the change of properties and structure of liquid water; the lower dielectric constant results in a less polar solvent and in a change of hydration energy affecting the ΔG of the dissolution reaction.
Temperature-responsive polymers or thermoresponsive polymers are polymers that exhibit drastic and discontinuous changes in their physical properties with temperature. [1] The term is commonly used when the property concerned is solubility in a given solvent , but it may also be used when other properties are affected.
Polypropylene glycol or polypropylene oxide is the polymer (or macromolecule) of propylene glycol. [1] Chemically it is a polyether , and, more generally speaking, it's a polyalkylene glycol (PAG) H S Code 3907.2000.
[1] [2] Simply put, even in the absence of air, polymers will begin to degrade if heated high enough. It is distinct from thermal-oxidation, which can usually take place at less elevated temperatures. [3] The onset of thermal degradation dictates the maximum temperature at which a polymer can be used.
For example, the system triethylamine-water has an LCST of 19 °C, so that these two substances are miscible in all proportions below 19 °C but not at higher temperatures. [1] [2] The nicotine-water system has an LCST of 61 °C, and also a UCST of 210 °C at pressures high enough for liquid water to exist at that temperature. The components ...