Polymer high-shear mixing

Approach ii is applicable to all thermoplastic polymers and offers considerable practical advantage since reactively modified polymers can be readily produced by normal commercial high-shear mixing procedures at no additional cost. 

Quaternary ammonium and phosphonium halides were used as the phase transfer catalysts. For effective coupling, high-shear mixing and high concentrations of polymer and base were used. 

With high shear mixing equipment such as the Banbury or continuous mixer, the use of block polymers with a number average molecular weight (Mw) below 150,000 did not give the expected improvement in impact over polystyrene. This anomalous behavior occurred because the particle size of the discrete rubber phase averaged less than 0.2 pm compared with an average of 1 pm for blends with optimum impact obtained in the solution blends. 

In the second step, the urethane polymers were prepared from each of the four prepolymers by mixing with a stoichiometric amount of 1,4-butanediol (1,4-BDO). To a plastic cup was added 125 grams of prepolymer, 25 grams of 1,4-BDO, and 0.1 cc of UL-1, a dibutyl tin mereaptide from Witco Chemical Co. These room terrperature components were mixed for 10 seconds using a high shear mixing blade at 2400 rpm. The prepared polymers were allowed to cure at roan temperature for at least one week and then DSC s and TMA s were run. 

Some polymers contain reactive functionahty but are also themselves subject to mechano-chemical radical generation. When such polymers are blended under high-shear mixing with a second functionalized polymer, the architectures... 

In a separate vessel, combine the mineral spitits and the reactive amine polymer. Add to the above mixture with high shear mixing. 

This problem can be partially overcome by high-shear mixing of a number of polymers by some of the procedures discussed in the next section. High shear mixing of polymers leads to the breaking and reformation of chemical bonds in the polymer backbone and to the in situ formation of block copolymers that act as SPDs. 

Calcium carbonate can be mixed with 0.5 to 1% by weight of stearic acid and subjected to high shear mixing at high temperatures. The stearic acid is converted to calcium stearate in the process. The treatment improves the processability, reduces moisture absorption, and improves the mechanical and electrical properties of the filled polymer. 

Prepolymer ionomers with isocyanate end-groups and of sufficiently low molecular weight can be mixed with water in the presence of hydrophobic organic solvents, such as methylene chloride or toluene, or, in the case of sufficiently low viscosities, even without solvent. The prepolymers form emulsions, which in turn form polymer dispersion after chain extension by reaction of the isocyanate. Such a process requires powerful high-shear mixing equipment in the presence or absence of solvents. Solutions of ionomers in hydrophilic solvents form emulsions spontaneously in the presence of water. The formation of the emulsion must be... 

Starting from the dispersed droplets of water, further water is incorporated into the polymer matrix by high-shear mixing the matrix becomes restricted and finally disintegrates into spherical dispersed particles, each individually enclosed by a continuous aqueous phase. A typical dispersed particle consists of a hydrophobic interior of polyether or polyester segments and an outer hydrophilic layer of hydrated salt, methylolbiuret and urethane groups. 

Fig. 11.2 Simplified setup used for drop-in-, nozzle spraying-, and high-shear mixing-precipitation process. A Container for API/polymer solution. B Dosing pump API/polymer solution. C Reactor for MBP suspension. D Pump for circulation of antisolvent respective MBP suspension...

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