Download e-book for kindle: Chemistry and technology of polyols for polyurethanes by Mihail Ionescu
By Mihail Ionescu
Polyurethanes are some of the most dynamic teams of polymers, they locate use in approximately each point of contemporary existence, in functions corresponding to furnishings, bedding, seating and tool panels for autos, shoe soles, thermoinsulation, carpet backings, packaging, adhesives, sealants, binders and as coatings.
In 2004 10.6 million a whole lot polyurethanes have been produced, in 2014 the realm construction was once just about 20 million lots. within the final decade (2005-2015) very important, around the world advancements within the region of polyols for polyurethanes have been conducted, in particular for polyols from renewable assets, defined intimately during this moment version of the book.
The major uncooked fabrics used for the creation of PU are polyols and isocyanates. the 1st of those is the topic of this quantity handbook.
Volume 1 is devoted to polyols for elastic PU (flexible foams, elastomers and so on).
Volume 2 is devoted to polyols for inflexible PU (rigid foams, wooden alternative, packaging, flotation fabrics and so on).
The booklet considers the uncooked fabrics used to construct the PU polymeric structure. It covers the chemistry and expertise of oligo-polyol fabrication, the features of many of the oligo-polyol households and the consequences of the oligo-polyol constitution at the houses of the ensuing PU. It offers the main points of oligo-polyol synthesis, and explains the chemical and physico-chemical subtleties of oligo-polyol fabrication.
This booklet hyperlinks information and data about the chemistry and know-how of oligo-polyols for PU, offering a finished evaluation of:
- Basic PU chemistry
- Key oligo-polyol characteristics
- Synthesis of the most oligo-polyol households, together with: polyether polyols, crammed polyether polyols, polyester polyols, polybutadiene polyols, acrylic polyols, polysiloxane polyols, aminic polyols
- Polyols from renewable resources
- Flame retardant polyols
- Chemical restoration of polyols
- Relationships among polyol constitution and PU properties
This ebook may be of curiosity to all experts operating with polyols for the manufacture of PU and to all researchers that will wish to understand extra approximately polyol chemistry.
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Extra info for Chemistry and technology of polyols for polyurethanes
1 MPa. The last traces of unreacted PO are removed in two steps: first by nitrogen bubbling and finally by vacuum distillation. The degassing step of approximately 1–2 h is considered to be sufficient for the efficient removal of unreacted monomer traces. The removal of catalyst is not so important for rigid polyether polyols as for polyether polyols for flexible foams. 5). Practically, the polyether polyols obtained are neutral, but the content of remnant ions (K+ and Na+) is much higher than for flexible polyols.
If the same mixture is propoxylated in the presence of KOH as catalyst, a large quantity of sucrose remains unreacted and is aggregated into big particles. As an immediate consequence, the resulting sucrose polyol has a lower viscosity and lower OH# than the expected values. The polyoxyethylene chains have a much stronger solvating effect on solid polyols, such as sucrose, than the polyoxypropylne chains. It was observed that if EO is used in the first part of the alkoxylation (10–15% from the total monomers needed), the solid sucrose is totally consumed.
This change of the tertiary amine structure used as catalyst, during PO anionic polymerisation initiated by hydroxyl groups, explains the presence of two total different reaction rates of the PO consumption. 13). 4. The point of the sudden change in the PO consumption rate is the moment of total transformation of the initial amine in a trialkanolamine of lower catalytic activity. Because of the low PO polymerisation rate in the second part of the reaction, at normal polymerisation temperatures of 110–120 °C, it is practically impossible to obtain, in the presence of tertiary amines as catalysts, polyether polyols with a OH# lower than 400 mg KOH/g.
Chemistry and technology of polyols for polyurethanes by Mihail Ionescu