Polyurethane Reinforcing agents

At room temperature, a number of raw polyurethane polymers are liquid, simplifying the production of many large and intricately shaped molded products. When cured, these elastomeric parts are hard enough to be machined on standard metalworking equipment. Cured urethane does not require fillers or reinforcing agents. 

Details of vegetable oil-based polymers conventional composites have been discussed in an earlier chapter. In this chapter, nanocomposites of vegetable oil-based polymers are discussed. Certain questions arise as to how much difference there is between these composites. The questions are significant when the same reinforcing agent is used in both cases. As an example, a vegetable oil-based polyurethane with alkali-treated chopped jute fibres in a conventional composite and cellulose nanofibres (obtained from jute fibres) in a vegetable oil-based polymer nanocomposite are discussed. The... 

The polyurethanes and polyureas may be formulated to be flexible or rigid, solid or foamed. Fillers and/or reinforcing agents (for example, glass fibers or flake) may be added to one or both components (in which case the process is sometimes known as RRIM—reinforced RIM). A major application of RIM is to produce energy-absorbing front and rear ends and body panels for automobiles. Cycle times of two minutes or less are feasible for such large parts. 

The two components are kept in temperature-controlled tanks, with pumped re-circulation when injection is not taking place. For the polyurethane system, one tank contains an isocyanate (usually MDI) and the other a mixture of polyol, chain extenders, catalyst and mould release (and possibly blowing agent or reinforcing additives). An amine catalyst accelerates the initiation of the polymerisation, while an organotin catalyst... 

In painted SMC in particular (as weh as in RIM or RRIM - reinforced reaction injection molding - of polyurethane), mold release agents (zinc or calcium stearates) are used that exudate at the molding surface during curing/crosslinking and make for efficient demolding. 

Chem. Descrip. y-Glycidoxypropyltrimethoxysilane CAS 2530-83-8 EINECS/ELINCS 219-784-2 Uses Adhesion promoter in water-borne acrylic sealants, urethane and epoxy coatings coupling agent in polysulfide and polyurethane caulks and sealants, min.-filled or glass-reinforced thermosets and thermoplastics, and in glass roving size-binders Properties Colorless transparent liq. m.w. 236.4 dens. 1.065-1.075 vise. 

Chem. Descrip. y-Methacryloxypropyltrimethoxysilane CAS 2530-85-0 EINECS/ELINCS 219-785-8 Uses Adhesion promoter for adhesives and coatings coupling agent for glass-reinforced and min.-filled thermosetting resins blend additive in resin systems (polyester, acrylic), and filled or reinforced thermoplastic polymers (polyolefins, polyurethanes)... 

Mold release agents are used in a variety of applications, including fiber-reinforced plastics, castings, polyurethane foams and elastomers, injection-molded thermoplastics, vacuum-formed sheets, and extruded profiles. Because each application has its own plastic, mold material, cycle time, temperature, and final product use, there is no universal... 

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