Hydrophilic chain extender on the performance of the product

Hydrophilic chain extender on the performance of the product, the influence of dosage of DMPA on the effect on the stability of the dispersion. The study found that with the increase of content of hydrophilic group, dispersion particle size decreases, and the Zeta potential absolute value increases, both can improve the dispersion of storage, centrifugal and dilution stability.

This is because when the PU macromolecular hydrophilic group content of less than, the resistance to macromolecular reunion weak electric double layer, low Zeta potential, make the dispersion particle size is larger, milky white cloudy appearance; When the dosage of DMPA increasing, PU macromolecular hydrophilic group content increases, Zeta potential, the dispersion particle size decreases, and its storage, dilution, centrifugal stability enhancement.

The influence of the addition of DMPA way scattered system. With polyether type of polyurethane products as the goal, research the one-step and two-step add DMPA way affect dispersion system. The results showed that: two steps synthesis of emulsion appearance is better than one-step method, the emulsion particle size is small, but the mechanics properties of the one-step method is better than two footwork.

This is because the activity of DMPA and TDI from polyether polyols, using one-step loading, DMPA in preference to TDI reaction, formed a long hard segment and more intense sequence of hydrophilic group, makes the molecular chain containing hydrophilic group of hard segment between the electrostatic force and hydrogen bonding interaction between strengthening, leading to excessive dense hard segment, water molecules into the hard segment area; The ion concentration, on the other hand, to strengthen the hard and soft segment phase separation, makes the coating has good mechanical properties.

Polyether in two steps ahead of TDI formation of soft and hard segment block copolymer, joined after the hydrophilic ionic groups were long polyether molecular distribution of interval in the molecular chain, is superior to the rule of molecular chain distribution with a large number of hydrophilic group, and makes the molecular overall improved hydrophilicity, particle size is reduced, so the emulsion a one-step good appearance.

The influence of the mechanical properties of DMPA on the film. The study found that with the increase of DMPA content, the tensile strength of the coating and the shear strength increase, elongation at break decreased. This is because the PUA molecular block copolymer for the hard and soft segment, including carbamate keys (or with a small amount of urea key) constitute a hard segment, polyol composition of soft segment and hard and soft segment ratio directly determines its mechanical performance. Small molecules to the increase of the content of hydrophilic chain extender makes hard segment proportion in the molecular structure, molecular enhanced coulomb force and hydrogen bond, leading to the tensile strength and improve the mechanical strength, and elongation at break decreased.




Chinese name: Diethyl toluene diamine(DETDA)

Diethyltoluenediamine Uses:

The product is identical to Ethancure 100 and Lonza DETDA 80, DETDA is very effective polyurethane elastomer chain extender; also be used as polyurethane and epoxy resin curing agent, epoxy resin of an antioxidant, industrial oils and lubricants . In addition, also as intermediates in organic synthesis.Especially for the RIM (reaction injection molding), is important in the field of spray polyurea chain extender species. Also can be used for casting polyurethane elastomer (CPU) and a curing agent, epoxy curing agent, epoxy resin of antioxidants, lubricants and industrial oils other antioxidants.


The effects of DMPA on the phase transformation behavior. In contrast to other system turn, waterborne polyurethane prepolymer and water emulsification process will experience from the W/O to O/W transformation process. Study found that with the increase of DMPA content, system of phase transition point off, because the DMPA content increased, the hard segment ratio increase, with the improvement of system of ionization degree, increases the polarity of the differences between hard and soft segment, phase separation of system to improve, lattice density particles increase at the same time, more water is needed to make the solution completely assembled.

Although, increase the content of DMPA, can improve the look of the emulsion, improve the mechanical properties of the coating, etc., but the content of high make water resistance variation not only, and will lead to the phase transition point off, and keep the emulsifying process need more water, and solid content is reduced greatly.

Stripping interface PU side of ether and ester based carbon carbon content between PMMA and PU, and PMMA is closer, shows that PMMA has quite a few on the surface of the PU - EG, namely when at break of PU - EG - PMMA is not completely disconnected from the interface.

Polymer isocyanate was studied based on the steel surface bonding, found excellent adhesive effect comes from the interface formed the oxygen - cyanate ester bonds (similar to the carbamate). Found isocyanate based polymers on the surface of aluminum adhesive also follow this mechanism.

Reaction, therefore, we suspect that not fully isocyanate group functional groups migrate to the interface from the reaction mixture and reaction with hydroxyl groups on the surface of the PMMA. The PMMA and formed a strong chemical bonds between PU and makes bonding strength between them as well.

(1) as chain extender chain length increases, the H12MDI polyether elastic body of tensile strength, peel strength and shaw hardness decreased, elongation increased.

(2) chain extender of PTMEG/H12MDI system of optical transparency effect is not obvious. (3) contact Angle experiments prove that the PU/PMMA interface the ester exchange reaction.

Copyright: Zhang Jia Gang YaRui Chemical co.,Ltd 
 
Diethyl toluene diamine(DETDA)  http://www.yaruichem.com