Polyvinyl chloride mass polymerization

A carbon-halogen bond in the monomer, polymer or solvent is always a centre of transfer reactions. Transfer to monomer controls chain length in polyvinyl chloride so efficiently that the molecular mass of the products is independent of the amount of initiator over a rather wide concentration range [35], Also, vinylidene chloride lowers the polymerization degree of its own polymer by transfer [36]. 

Vinyl chloride plastics n. These are plastics based on reins prepared by the polymerization of vinyl chloride or co-polymerization of vinyl chloride with other unsaturated compounds, vinyl chloride being in greatest amount by mass. Wickson EJ (ed) (1993) Handbook of polyvinyl chloride formulating. John Wiley and Sons Inc., New York. 

Another close analogy is the precipitation mass polymerization system for polyvinyl chloride (PVC). In that case, the polymer does precipitate from the monomer, but it does not go through a self-adhering sticky stage. This allows... 

The densities of most polymer dispersions are close to 1 g cm as the corresponding polymers (with the exception of polyvinyl chloride and poly(vinylidene chloride)) have densities in the range 1.0 to 1.2 g cm [2]. Since the densities of the polymer particles almost match the density of the aqueous phase, sedimentation is usually only a problem in emulsion polymers if they contain very coarse particles. Density measurements have been used in the past to follow the course of emulsion polymerization reactions, because the density of the monomer is usually lower than that of the polymer (densitometry [1]). Densities can, for instance, be determined quite simply with a pycnometer (see ISO 2811). Very high precision density measurements ( 5 X 10 g cm" ) are possible with a vibrating-tube densimeter [3]. In this method, the change in the resonant frequency of the tube, which depends on its total mass, is measured when the dispersion is placed in it. It is essential that the sample is wholly free of gas bubbles. 

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