Method reactive injection molding

Rapidly solidifying compositions used for reactive injection molding place some restrictions on measurement. In the time required to prepare the reaction mixture, place a sample in the measuring cell of an instrument, and achieve a steady state in the sample and the measuring system at a preset temperature, chemical conversion of the material may advance considerably, making viscosity measurements meaningless. The volume of lost information depends on the ratio of the transient time necessary to achieve a steady state in the sample and the characteristic time of the chemical reaction. The sensitivity of the reaction rate to temperature is also important. In order to avoid the necessity to maintain isothermal conditions for the measurements, a non-isothermal scanning method for viscosity measurements was proposed.156... 

The so-called RIM-process (reactive injection molding) is a current realization of the reactive molding process. The heart of the process is the shock mixing of the reactive ingredients, which is achieved by collision of two jets injected at a pressure of 10 - 20 MPa. The reactive mixture is injected into the mold in a laminar flow regime the pressure at this stage does not exceed 0.1- 0.4 MPa.259 The practical development of this method relies on automatic control systems and modem high quality equipment. 

This technology was first commercially applied to polyurethane blend [121] and patented as Rimplast (for Reactive Injection Molding), but many polymers have since been blended with polysiloxane thanks to this method polyethylene [122], polypropylene [122,123], polyamide [124-130], polyesters [128,131-133], poly(phenylene ether) [134], fluorocarbons [135] and many more. Many of them include reinforcing fillers such as fumed silica. The silicone base involved can moreover contain reactive groups such as the epoxy group [136,137]. A typical silicone base useful for these blends was de-... 

The latest trend in foamed composites is automotive structural parts produced by the SRIM (structural reaction-injection-molding) process. The SRIM process is a method of the reactive liquid injection molding (i.e., LIM). LIM includes RIM (reaction injection molding), RRIM (reinforced RIM) and RTM (resin transfer molding). IX M (Liquid Composite Molding) is a relatively new technical term which includes SRIM, RRIM and RTM (Resin Transfer Molding). 

Specifically, PVC blends with polyethylene, polypropylene, or polystyrene could offer significant potential. PVC offers rigidity combined with flammability resistance. In essence, PVC offers the promise to be the lowest cost method to flame retard these polymers. The processing temperatures for the polyolefins and polystyrene are within the critical range for PVC. In fact, addition of the polyolefins to PVC should enhance its ability to be extruded and injected molded. PVC has been utilized in blends with functional styrenics (ABS and styrene-maleic anhydride co-and terpolymers) as well as PMMA offering the key advantage of improved flame resistance. Reactive extrusion concepts applied to PVC blends with polyolefins and polystyrene appear to be a facile method for compatibilization should the proper chemical modifications be found. He et al. [1997] noted the use of solid-state chlorinated polyethylene as a compatibilizer for PVC/LLDPE blends with a significant improvement in mechanical properties. A recent treatise [Datta and Lohse,... 

BLENDING METHOD Mechanical blending COMPATIBILIZATION Chemical and reactive compatibilizer BLEND MANUFACTURE Injection molding or extrusion BLEND MORPHOLOGY... 

In bionanocomposites, the reinforcement content is very low, so they can be processed by the same methods used for the pure polymers. These methods are mainly limited by the fusibility of the polymer, nature of the reinforcements, and their thermal resistance (if melt processing methods are used). The most common methods are extrusion, injection molding, casting, and compression molding, with reactive extrusion a potential option [22, 59, 123, 130]. More information... 

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