Preparation of Polyester Polyurethane
Jul 28, 2023
Polypropylene glycol ester (PPG), TDI, 3,3-dichloro-4,4-diphenylmethanediamine (MOCA) and hydroxyl silicone oil were used to prepare polyester polyurethane and polyester polysiloxane block polyurethane elastomer by prepolymerization method. The results showed that the mechanical properties of the elastomer were slightly improved after introducing siloxane into the polymer main chain. The introduced polysiloxane chain segment is mainly distributed in the soft segment of the elastomer molecule, which makes the phase separation of the elastomer more obvious. The researchers studied the changes in structure and properties of segmented polyurethanes containing polyoxyethylene-polydimethylsiloxane-polyoxyethylene segments (PES) due to mechanical fatigue. Small-angle X-ray diffraction (SAXS) studies have found that when the mass fraction of 13% PES is added and the molecular weight of polytetrahydrofuran (PTMO) is 2000, the resulting polyurethane has good mechanical fatigue resistance due to the presence of PES that limits the crystallization of the PTMO soft segment.
Poly(siloxane-urethane) was synthesized by a two-step method. In the first step, IPDI was reacted with PT MO, and in the second step, BD was used as a chain extender. Studies have found that PDMS has higher reactivity than PTMO. The properties of the obtained membranes are very different depending on the time of adding PDMS. When the block polymer diol scraped by ABA formed by PDMS and polyoxyethylene reacts with TDI, two methods are used. One is a two-step method, that is, TDI and the block polymer are pre-polymerized in toluene solution, and then triisopropanolamine (TIPA) is used as a cross-linking agent for cross-linking reaction; the other is a one-step method, that is, TDI, block polymer, TIPA or hydroxycaproic acid glyceride are simultaneously added for reaction. The polymer obtained by the two-step method has a lower degree of crosslinking, but a higher diffusion coefficient and permeability to gases.
Alkanol shaft-capped aromatic hydrocarbon generation method.
Since the bracket is not directly connected to the atom but is connected through the alkylaryl group, the reactivity of the shaft group of the silanol ether is higher, and the performance of the obtained polyurethane is also different. Use two Functional group of methyl phenyl CPDMS), trifunctional polycaprolactone and multifunctional caprolactone and multifunctional heterooxygen catalyst synthesized under the action of catalyst diditin laurate can automatically short-circuit two atomic force microscopy tests It shows that when the PDMS content is 10%, the two-phase microstructure is clearly separated. The energy spectrum test shows that the surface is enriched with silicon elements, and it also suggests the influence of the formation of mixed co-solvents on the microstructure. The results show that at low fluctuations and high The cross-linking reaction in the bottom system is relatively stable. A series of PDMS-derived dispersions (PUD) were synthesized, in which PDMS was introduced into polyurethane chains through random dispersion and block arrangement, respectively, and the effects of the relative and relative molecular weight of PDMS species on the mechanical contact angle and properties of coatings were observed. With the increase of PDMS content, the contact angle of PDMS-PUD coating film also increases and the axial strength decreases. Scanning electron microscopy found that the PDMS in the block migrated to the surface of the material more easily. First of all, it is not directly connected to the silicon atom, but directly connected to the silicon atom in the form of an alkane structure. This method forms a -C-0 bond, and its impact resistance and stability are improved.
The researchers synthesized a new type of water-dispersed silicone-polyurethane copolymer with two-terminal hydroxybutyl polydimethylsiloxane as part of the soft segment, and analyzed and discussed the effect of the content of the siloxane segment on the hydrogen bonding and surface of the copolymer. performance impact. The study found that due to the embedding of butyl siloxane, it plays the role of diluting sulfonyl or tyroxy in the molecular chain, reducing the probability of forming hydrogen bonds in the molecule, and reducing the N—H content of hydrogen bonding. The mechanical properties of the material are improved compared with those without modification. Using 2,4-toluene diisooxyester, two-terminal hydroxybutyl polydimethylsiloxane (DHPDMS), polytetrahydrofuryl tyrodiol, and 1,4-butanediol as the main raw materials to synthesize a series of Silicone modified polyurethane (Si-PU). The contact angle, surface tension and temperature of modified polyurethane with different silicon content were studied on the performance of modified polyurethane. It was found that the higher the content of DHPDMS, the lower the temperature when the contact angle of Si-PU tended to be constant. With the increase of , the migration of silicon-containing segments to the surface is accelerated, resulting in a rapid increase of the contact angle.
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