Nylons twin-screw extruders

However, some semiaromatic nylons can give problems as a result of the high melt viscosity. A process for producing polymers of hexamethylenediamine, adipic acid, terephthalic acid, and isophthalic acid has been developed, which involves vaporizing the salt mixture in a high temperature dash reactor followed by molecular weight increase in a twin-screw extruder with efficient moisture removal (17). 

Mineral-filled nylon 6/6 composites. Kaolin (Burgess) was treated with the appropriate silane in a Patterson Kelly 8-qt. twin shell blender with intensifier bar. Treatment levels were 1% active silane. The kaolin was compounded with nylon 6,6 (Vydyne 21x—Monsanto) in a Leistritz twin screw extruder. The compounds were tested in a dry as molded condition in accordance with ASTM D-638 (see Table 5). 

Plastics with a carbonyl group can be converted to monomers by hydrolysis or glycolysis. Condensation polymers such as polyesters and nylons can be depolymerized to form monomers. For Polyurethanes (PURs), what is obtained is not the initial monomer, but a reaction product of the monomer diamine, which can be converted to diisocyanate. For PURs. hydrolysis is attractive as they can be easily broken down to polyols and diamines. The only issue is to separate them later. Steam-assisted hydrolysis has been shown to yield 60 to 80 percent recovery of polyols from PUR foam products. A twin screw extruder can be used as a reactor for hydrolysis. Glycolysis of PURS, yields mixture of polyols that can be reused directly. 

The formation of compatibilizer frequently occurs by interfacial reaction of the modified polymers. An example is the use of maleic anhydride grafted to a polyolefin elastomer (EPM/EPM-g-MA) as the interfacial additive for reactive blending with a polyamide, nylon-6 (Van Duin et al., 2001), in a twin-screw extruder. It was found that the consumption of MA occurred rapidly and different blend morphologies were produced. However, it was found that the nylon-6 degraded during processing, due to the reaction of anhydride with the... 

Variations in the preparation of nanocomposites have now been investigated extensively. Liu et al. [202] proposed the preparation of nylon-6/clay nanocomposites by a melt-intercalation process. They reported that the crystal structure and crystallization behaviors of the nanocomposites were different from those of nylon-6. The properties of the nanocomposites were superior to nylon-6 in terms of the heat-distortion temperature, strength, and modulus without sacrificing their impact strength. This is attributed to the nanoscale effects and the strong interaction between the nylon-6 matrix and the clay interface. More recently, nanocomposites of nylon-10,10 and clay were prepared by melt intercalation using a twin-screw extruder [203]. The mechanical properties of the nanocomposites were better than those of the pure nylon-10,10. 

Giudici, R. Nascimento, C.A. O. Scherbakoff, N. Modeling of industrial nylon-6,6 polymerization process in a twin screw extruder reactor. I. Phenomenological and parameter adjusting, J. Appl Polym. Sci., 1998, 67, 1583-1587. 

Additional specimens were prepared by melting and kneading sodium-type montmorillonite (unorganized type) and nylon 6 using a twin screw extruder at 250 °C for the purpose of comparing them with the specimens prepared as described above. This method of preparing specimens is commonly used when compounding particulate fillers with polymers. The composite material prepared in this way was called NCC (Nylon 6-Clay Composite), and the NCC was compared with the NCH. 

Besides the polymerization method, a method of directly mixing nylon polymers and organophUic clay using a twin screw extruder was developed. Although clay mineral is not dispersed sufficiently using a single screw extruder (screw speed 40 rpm, barrel temperatme 240 °C), it can be weU-dispersed using a twin screw extruder (screw speed 180 rpm, barrel temperature 240 °C). Experimental results and mechanical characteristics have been re-... 

The process of organizing clay using ammonium ions has a considerable impact on the production cost. In order to omit this process, silicate layers of clay (sodium-type montmorUlonite) that are imiformly dispersed in water were turned into slurry form and mixed with a molten resin. The concept of this method is shown in Fig. 11. Clay slurry was injected using first a twin screw extruder and then a screw feeder, and water was removed imder reduced pressme. hi this process, a nanocomposite consisting of nylon and clay minerals uniformly dispersed in nylon was successfully fabricated. This method makes the simplification of the clay organization process possible. 

A nylon 66 clay nanocomposite was produced using the dry-compound method [26]. Co-intercalation organophihc clay was used as the clay base. Na-montmorillonite was first processed using hexadecyl trimethyl ammonium ions and epoxy resin. It was then kneaded using a twin screw extruder to make a clay nano composite. As the amount of clay that was added increased, the amount of y (gamma) phases increased. This is thought to be due to the strong interactions between the nylon 66 chains and the sinface of the clay layers. 

Nylon-6 and the functionalized terpolymer were first melt blended in a twin- screw extruder and then the extruded preblend was melt blended with the rubber modified copolymer using another twin- screw extruder (D). As shown in Table 5, the impact property of the nylon blend was affected by blending procedure as well as blend... 

In 1994, Monsanto patented a process to recycle aU the components of postconsumer nylon 6,6 carpet, without separation, into a filled thermoplastic product suitable for injection molding [62, 63]. It used a twin-screw extruder to accomplish high-intensity mixing of the thermoplastic from carpet samples. The recycled material contained 35-67 wt% nylon, 8-21 wt% polypropylene, 5-29 wt % SBR, and 10-40 wt % inorganic filler. In one study, no compatibilizer was used [62]. The carpet samples were fed directly into a twin-screw extruder operating at about 250-260°C and at a shear rate of 200-400 s The tensile... 

The montmorillonite-polymer nanocomposite that was evaluated by Fornes and Paul [5] was prepared by melt-blending nylon 6 (Capron B135WP) with an organomontmorillonite (montmorillonite exchan d with bis(hydroxyethyl)-(methyl)-rapeseed quaternary ammonium chloride at 95 meq/100 g of montmorillonite) with a Haake corotating twin-screw extruder. The montmorillonite content in the polymer was experimentally determined to be 0.65,1.31,1.91, and 3.3% by volume by weighing the ash that remained from combusting the polymer-montmorillonite nanocomposite in an oven at 900°C for 45 min. 

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