Polyurethane foam synthesis

Polyurethane foam synthesis can be modified by additions of PEG in such a way that an open-cell, very flexible, highly elastic foam is produced, for example, for upholstery. 

Sucrose acrylate derivatives can be converted into polymers and hydrogels that can be used as flocculants, water adsorbents, bioimplantables, and dmg dehvery devices (42). Sucrose ethers have appHcations as surfactants and surface coatings, and as feedstocks for synthesis of polyurethane foams and... 

Uses Aerosol propellant refrigerant solvent blowing agent for polyurethane foams fire extinguishing chemical intermediate organic synthesis. 

Sucrose reacts with diisocyanates leading to polyurethanes, which are used as thermal insulating foams, notably in cars. Partially protected sucrose esters can be used for the synthesis of better-defined polymers (Scheme 46).265 A first step of hydroxypropylation is sometimes necessary to obtain sufficient miscibility with the diisocyanate derivative, as well as for tuning the physicochemical properties of the polyurethane foams.78,305,420... 

Step-Growth Polymerization Synthesis of Polyesters in the Melt Step-Growth Polymerization Synthesis of a Polyurethane Foam... 

Step-Growth Polymerization Synthesis of a Polyurethane Foam... 

Step-growth polymerization, 22, 24-25, 23, 84-86, 86,90-92,114-115, 261 compared with chain-growth polymerization, 88-89, 88-89 interfacial polymerization, 91-92 laboratory activities on synthesis of nylon, 228-230 synthesis of polyesters in the melt, 231-233 synthesis of polyurethane foam, 234-237 molar mass and, 86, 86 polycondensation of poly ethylene terephthalate), 90-91 polymers produced by, 86 types of monomers for, 90 Stereochemistry, 28, 37-39,41-42, 70 tacticity, 103-105 Stereoisomers, 41 Stereoregularity, 70 Stiffness, 142, 261 Strain, 142-143, 261 Strength... 

Step-Grouch Polymerization Synthesis of a Polyurethane Foam Studies of Solutions and Gels Polymer Precipitation Gels from Alginic Acid Salts Solid State Properties... 

If you have been highlighting a polymer a week, the first four experiments in Section A— Free Radical Polymerization, Synthesis of Nylon, Synthesis of Polyesters in the Melt, and Synthesis of a Polyurethane Foam —are excellent demonstrations to intersperse with the content as it is presented. If you want your students to actually perform the experiments, it might be best to wait until the end of a first-year chemistry course when the students have developed their laboratory techniques to the greatest extent. Another use for the four experiments would be to introduce a different one each quarter and discuss the polymer produced in the experiment. This is a good way to use the information on polymer chemistry if time does not permit the presentation of a Polymer of the Week. 

One of these four experiments can find a special use. Step-Growth Polymerization Synthesis of a Polyurethane Foam can be a special part of a study of stoichiometry. Although it does not deal with molar ratios, it does ask the students to calculate how much of each reactant is needed to produce an object of a desired volume. This reviews concepts such as unit conversions and volume. 

Not all copolymers which are produced by step-growth processes are random in nature. Block copolymers are also of major interest. An example of the synthesis of elastic polyurethane fibers was given in Section 1.5.4. Block and graft copolymers of polysiloxane-poly(alkylenc ethers) with segments like5-9 are used as surfactants in the production of polyurethane foams with uniform cell sizes. 

Methyl isocyanate (MIC) is used as an intermediate in organic synthesis, especially in the production of carbamate based pesticides. It is also used to produce polyurethane foams and plastics. Occasionally, it is present in cigarette smoke in very minute quantities. 

Use Ingredient of polyurethane foams, coatings, sealants, and elastomers intermediate in organic synthesis. 

Complexes of organotin with amidines have been found to be excellent catalysts for the preparation of polyurethane foams, which do not have the disadvantage of any amine odor and, in addition, delayed onset of the isocyanate-hydroxyl reaction An example of a mercapto-delayed organotin catalyst is 2,2,4,4-tetrakis(alkyl)- l,3,2,4-dithia-stannetane.55 Amine salts of amino acids, tertiary amino acids, and tertiary amino acid-nitrile compositions, have been found to be effective as delayed action catalysts for polyurethane synthesis. They are particularly effective when used in combination with an organometallic compound, such as an organotin. ... 

Phosgene is widely used as a chemical intermediate for the production of isocyanates used in polyurethane foams and in the synthesis of pharmaceuticals and pesticides [55]. Processes using phosgene require specialized cylinder storage, environmental enclosures, pipelines, fixtures under negative pressure... 

DMC catalysts are considered to be the ones that perform best at this time for PO polymerisation initiated by hydroxyl groups. Bayer developed the first continuous process, with a very high productivity, for the synthesis of polyether polyols with DMC catalysts (IMPACT Catalyst Technology). In a short and simple production cycle, a large variety of polyether diols of very low unsaturation for elastomers, sealants, coatings and low monol content polyether triols destined for flexible polyurethane foams are obtained. This is one of the best developments in the last few years in the field of polyether polyol synthesis [2],... 

The most important low molecular weight polyols used as starters for polyether polyols destined for rigid PU foams synthesis are glycerol, trimethylolpropane (TMP), triethanolamine, pentaerythritol, dipentaerythritol, a-methyl glucoside, xylitol, sorbitol and sucrose [1-27]. The main properties of these starter polyols, which are of interest for polyurethane chemistry, are presented in Table 13.1. 

As a general observation, the main reactions involved in the synthesis of polyether polyols for rigid polyurethane foams are ... 

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