Solid content, polymer polyols

The polymer polyols of low solid content are obtained by dilution of high solid content polyether polyols with ungrafted polyether polyol (the same polyol used for radical polymerisation). At the same solid content, the polymer polyols obtained by dilution of high solid content polymer polyols with ungrafted polyethers, always have a lower viscosity than the polymer polyols obtained by direct synthesis. Thus, a polymer polyol having 20% copoly (ACN - styrene) obtained by direct synthesis, has a higher viscosity... 

Normally a 70/30 to 50/50 blend of a 4500-6500 EO-capped polyether triol with a polymer polyol is used, together with an 80 20 blend of TDI (80/20 isomer ratio) and polymeric MDI. Recently, higher-solids-content graft polyols, e.g., 30-50% solid polyols, have become available in the market. 

It is possible to obtain a bimodal distribution of final particles median diameter (distribution with two maxima), by seeded radical polymerisation. For example, if a polymer polyol having particle diameter of 0.3-0.6 pm is added to the poly ether before the radical polymerisation, after the normal polymerisation of the vinylic monomers, polymer polyols with a bimodal distribution of particles are obtained. As a general rule, a bimodal distribution leads to lower viscosities than an unimodal distribution of particle diameters, at the same solid content [32]. This is a method to obtain high, solid polymer... 

MPa-s at 25 °C) than a polymer polyol having the same solid content, but obtained by the dilution of a polymer polyol with 40% solid content (viscosity after dilution around 1800-2100 MPa-s). 

The hydroxyl number of a polymer polyol is lower than the hydroxyl number of the initial polyether polyol used for grafting. The hydroxyl number decrease is a function of the polymer polyol solid content (generally the solid part has no hydroxyl groups). For the estimated hydroxyl number calculation at a known solid content, equation 6.17 is used ... 

Usually the viscosity of PHD polymer polyols is higher than the viscosity of graft polyether polyols, at the same solids content. For example a graft polyether polyol, with a 20% solid fraction (copoly[ACN - styrene]), has a viscosity of 2000-3000 MPa-s at 25 °C, but a PHD polyol, with the same solids concentration has a viscosity of 3000-3500 MPa-s at 25 °C [10, 67-69]. This high viscosity is direct evidence of the intensive interaction, by secondary forces, between the polyurea filler and the continuous liquid polyether phase. 

As is the case for all polymer polyols, the main problem is to obtain high solid contents at lower viscosities. Two general phenomena linked to the viscosity of PIPA polyols are observed ... 

Uses Polyol for urethane elastomers and adhesives, fabric coatings, foams, gears, hot-melt adhesives, industrial coatings, inj.-molded parts, resins, sealants, shoe soles, tubing food pkg. adhesives, polymers Regulatory FDA 21CFR 175.105,177.1390 compliant Properties Solid m.w. 1250 sp.gr. 1.071 (20 C) vise. 280 cSt (55 C) m.p. 40-50 C acid no. 0.25 hyd. no. 90 0.03% max. water content TONE Polyol 0240 [Dow]... 

Talja RA, Helen H, Roos YH, Jouppila K (2007) Effect of various polyols and polyol contents on physical and mechanical properties of potato starch-based films. Caibohydr Polym 67 288-297 Tam KH, Djurisic AB, Chan CMN, Xi YY, Tse CW, Leung YH, Chan WK, Leung FCC (2008) Antibacterial activity of ZnO nanorods prepared by a hydrothermal method. Thin Solid Films 516 6167-6174... 

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