Synthesis MDPUR

Based on the literature survey (see Section 6.2) and the anthor s preliminary experiments the following methods of synthesis of hybrid dispersions (after this point in the chapter they will be called modified DPUR (MDPUR)) were selected ... 

It was assumed that the method of MDPUR synthesis would have be the major factor that would determine particle morphology. In Figures 6.5-6.7, the methods (1) - (3) applied in this study are presented schematically. 

Hybrid dispersions obtained by polymerisation, i.e., according to methods la, lb and 2, will be designated as MDPUR-ASD and hybrid dispersions obtained by synthesis of PUR in ASD, i.e., according to method 3, will be designated as MDPUR. 

Analysis of the Process of MDPUR Synthesis Using Dispersion Particie Morphoiogy... 

When polymerisation is carried out after initial swelling of DPUR particles in monomers (Method lb), then formation of separate particles of acrylic/styrene polymer is also possible, but much less probable since the amoimt of monomer present in the system as monomer droplets is very low in this case (assmning that the amount of monomer used to swell DPUR particles was not higher than the maximmn amount resulting from the equilibrium swell curve (see Section 6.5.4)). It can be anticipated that in this method of MDPUR synthesis many more hybrid particles of much more uniform structure will be formed than when the monomers are continuously added to the reaction system (Method la), especially when a... 

In this case, the course of MDPUR synthesis seems to be much simpler than in Methods 1 and 2 because no polymerisation of monomers will proceed in the system. Before the process starts, only ASD particles are present in the system ... 

Characterisation of Starting Dispersions Used for Synthesis of MDPUR... 

Table 6.1 shows the properties of DPUR used for synthesis of MDPUR (MDPUR-ASD) together with the properties of prepolymer-ionomers used as intermediates in their preparation. 

Table 6.1 Properties of DPUR used as starting materials for MDPUR-ASD obtained according to methods la and lb (see Section 6.3.2) and of the prepolymer-ionomers (diluted with NMP or acetone) used in their preparation. Properties of prepolymer-ionomers diluted with monomers (designated as PPUR) used as intermediates in synthesis of MDPUR-ASD...

Properties of ASD used as starting materials in synthesis of MDPUR according to method 3 are presented in Table 6.4. 

Table 6.2 Properties of films from DPUR used as starting materials for synthesis of MDPUR-ASD according to methods la and lb. ...

Advances in Urethane Science and Technology 6.5.2 Synthesis of MDPUR and MDPUR-ASD... 

Hybrid polyurethane-urea-acrylic/styrene polymer dispersions were prepared according to methods la , lb , 2 and 3 described in Section 6.3.2. Dispersions designated as MDPUR-ASD were made by polymerisation of monomers in DPU according to the methods la, lb and 2 while dispersions designated as MDPUR were made by synthesis of DPUR in ASD according to method 3. In all syntheses the ratio of polyurethane-urea to acrylic/styrene polymer in the hybrid was 2 1. 

Table 6.8 Compositions of MDPUR prepared according to method 3 (synthesis of DPUR in ASD). Properties of starting prepolymer-ionomers are also included...

As can be seen from Table 6.18, the chemical structure of the polyurethane-urea part of the hybrid does not affect the properties of hybrid dispersions, obviously not counting the MFFT which is much higher if polyesterdiol has been used as a starting material for the prepolymer-ionomer synthesis (compare MDPUR-ASD 300 and MDPUR-ASD 24). 

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