Polyol ingredients

The use of rosin-derived alcohol, hydroabietyl alcohol, as a portion of the polyol ingredient yields a higher molecular weight modified alkyd, with improved solubility, better brushability, flow, hold-out, and greater hardness. 

The urethane forming ingredients in a polyurethane foam formulation are the isocyanate (1) and the polyol (2) as shown in equation 3. 

Fillers (qv) are occasionally used in flexible slab foams the two most commonly used are calcium carbonate (whiting) and barium sulfate (barytes). Their use level may range up to 150 parts per 100 parts of polyol. Various other ingredients may also be used to modify a flexible foam formulation. Cross-linkers, chain extenders, ignition modifiers, auxiHary blowing agents, etc, are all used to some extent depending on the final product characteristics desired. 

All d Ingredients Eor each of the three principal components of alkyd reskis, the polybasic acids, the polyols, and the monobasic acids, there is a large variety to be chosen from. The selection of each of these kigredients affects the properties of the reski and may affect the choice of manufacturkig processes. Thus, to both the reski manufacturers and the users, the selection of the proper kigredients is a significant decision. 

Some of the chemicals used in the production of polyurethanes, such as the highly reactive isocyanates and tertiary amine catalysts, must be handled with caution. The other polyurethane ingredients, polyols and surfactants, are relatively inert materials having low toxicity. 

Example 1. One-Shot Cast Elastomer. This is an example of a one-shot cast elastomer using a PMDI, two polyols, and a chain extender. It is a good formulation to begin with because it is simple and uses low-viscosity ingredients that can be blended and cast at room temperature. 

Polyester polyols, 25 464 468 Polyester resin(s), 11 302 coating resins, 7 104-106 cyclopentadiene and dicyclopentadiene applications, 8 230 flammability of, 20 115-116 properties in powder coating, 7 43t standard test methods for, 20 11 It unreinforced, 10 187t weathering of, 20 116 Polyester resin-based powder coatings, organic titanium compounds in, 25 125 Polyester resin composites, 26 762-763 Polyester resin formulations ingredients of, 20 96t unsaturated, 15 511-512 Polyesters, 10 185-189, 497 12 655-656. See also Thermoplastic polyesters Unsaturated polyesters acid resistance of, 20 7-8 antioxidant applications, 3 121 aromatic ionic, 23 722 based on 1,4-cyclohexanedimethanol, 12 674-675... 

Polyols and polyisocyanates are major ingredients for polyurethane (PU)-based composite propellants in addition to chain extenders and catalysts etc. A brief description on these materials is considered necessary in order to understand the chemistry of composite propellants in a better way. Polyols are the largest group of raw materials for PUs. The properties of PUs/PU products are largely determined by their chemical composition and molecular mass. They may be broadly classified [87] as ... 

The details are already available in the literature. However, some important aspects of popular polyols i.e. castor polyols and HTPB, diisocyanates/ polyisocyanates, other ingredients and preparative methods of PUs are given in this section. 

Fully cured polyurethanes present no health hazard they are chemically inert and insoluble in water and most organic solvents. Dust can be generated in fabrication, and inhalation of the dust should be avoided. Polyether-based polyurethanes are not degraded in the human body, and are therefore used in biomedical applications. Some of the chemicals used in the production of polyurethanes, such as the highly reactive isocyanates and tertiary amine catalysts, must be handled with caution. The other polyurethane ingredients, polyols and surfactants, are relatively inert materials having low toxicity. 

The starting point is to react two moles of the diisocyanate with one mole of the polyol (see Figure 2.25). The ratios of the two ingredients can be varied to change the overall properties. 

The reaction rates of the various ingredients must be understood to follow the probable course of the reaction. Certain polyols may have secondary hydroxyl groups that are very much slower in reaction than the primary hydroxyl groups. The preparation of a prepolymer will allow the secondary hydroxyls to fully react. The reaction of a 100-percent 2,4 TDI is much faster than the standard 80 20 TDI isomer blend. The reaction rate between the terminal NCO and chain extender can be adjusted to allow the prepolymer mix to fill the mold and allow entrapped air to escape before the material gels. 

The ingredients usually used in these products are polyols such as sorbitol, maltitol, lactitol, isomalt, erythritol and polydextrose ... 

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