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Branch point in a polymer Glycogen, a branched polysaccharide In polymer chemistry , branching is the regular or irregular attachment of side chains to a polymer 's backbone chain . It occurs by the replacement of a substituent (e.g. a hydrogen atom ) on a monomer subunit by another covalently-bonded chain of that polymer; or, in the case of a ...
Branching also affects chain entanglement, the ability of chains to slide past one another, in turn affecting the bulk physical properties. Long chain branches may increase polymer strength, toughness, and the glass transition temperature (T g) due to an increase in the number of entanglements per chain. A random and short chain length between ...
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
Increase in concentration which can occur via solvent evaporation, induces interaction between molecular chains and a possible crystallization as in the crystallization from the melt. [12] Crystallization from solution may result in the highest degree of polymer crystallinity.
Star-shaped polymers were first reported by John Schaefgen and Paul Flory in 1948 while studying multichain polymers; they synthesized star-shaped polyamides. [9] The next major publication regarding star-shaped polymers was in 1962 by Maurice Morton et al. [10] Their research presented the first study demonstrating a method to create well-defined star-shaped polymers; this route was through ...
Linear polyethyleneimine is soluble in hot water, at low pH, in methanol, ethanol, or chloroform. It is insoluble in cold water, benzene, ethyl ether, and acetone. Linear polyethylenimine has a melting point of around 67 °C. [3] Both linear and branched polyethylneimine can be stored at room temperature.
The subglacial discharge caused a 15.7 per cent jump in sea-level rise from 0.74 inches (19mm) to 0.86 inches (22mm) by 2300, the researchers found.
This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which increases the substance's temperature to the melting point. At the melting point, the ordering of ions or molecules in the solid breaks down to a less ordered state, and the solid melts to become a liquid.