Nanocomposites melt-extruded

In addition to the recast samples, as-received, melt extruded films of the nylon 6 and nylon 6/layered silicate nanocomposite (7.5wt%) were exposed to the oxygen plasma. The nylon 6 nanocomposite develops of a colorful, interferometric surface reflection upon exposure (not shown). The optical interference effects suggest highly uniform alteration of the surface composition on the order of 200-500 nm. 

Processing conditions also strongly influence the flame-retardant behavior. For example, in the case of PS-based nanocomposites, extrusion above 180°C imder partially oxidative conditions yields an intercalated nanocomposite but with no flammability improvement, whereas the melt-extruded system at 170°C imder nitrogen or vacuum exhibits flame-retardant efficiency (41). The way thermal degradation of the organic modifier alters the flammability reduction mechanism has yet to be imderstood. 

For melt-compounded nanocomposites, the screw rotation speed of an extruder has a large influence on the dispersion of carbon nanotubes in the polymer matrix. Chen et al employed an ultrahigh-shear extruder to mix pristine MWNTs with PVDF pellets at a screw speed of 1000 rpm (1470 [62]. For the purpose of comparison, the MWNT/PVDF... 

Radhakrishnan V K, Davis E W and Davis V A (2010) Influence of initial mixing methods on melt-extruded single-walled carbon nanotube-polypropylene nanocomposites, Polym Eng Sci 50 1831-1842. 

Hiroi et al. [15] prepared PLA/organically modified layered titanate (OHTO) nanocomposites by a melt extrusion method. For nanocomposite preparation, the OHTO (dried at 120°C for 8h) and PLA were first dry mixed by shaking them in a bag. The mixture was then melt extruded using a twin-screw extruder (KZW15-30TGN, Technovel Corp.) operated at 195°C (screw speed = 300 rpm, feed rate = 22 g/ min) to yield nanocomposite strands. XRD patterns and TEM observations showed the formation of intercalated structures. 

Intercalated PET montmorillonite clay nanocomposites were compounded via melt-blending in a corotating mini twin-screw extruder. Nanocomposites compounded with l,2-dimethyl-3-N-hexadecyl imidazolium treated montmorillonite showed higher levels of dispersion and delamination than those with a typical quaternary aimnonium salt (39). 

Dean K, Yu L, Wu DY (2007) Preparation and characterization of melt-extruded thramoplastic starch/clay nanocomposites. Compos Sci Technol 67(3-4) 413-421 Dean KM, Do MD, Petinakis E, Yu L (2008) Key interactions in biodegradable thermoplastic starch/poly(vinyl alcohol)/montmorillonite micro- and nanocomposites. Compos Sci Technol 68(6) 1453-1462... 

C5 ras VP, Manfredi LB, Ton-That M-T, Vazquez A (2008) Physical and mechanical properties of thermoplastic starch/montmorillonite nanocomposite films. Carbohydr Polym 73 55-63 de Morals Teixeira E, Correa A, Manzoli A, de Lima Leite F, de Oliveira C, Mattoso L (2010) Cellulose nanofibers from white and naturally colored cotton fibers. Cellulose 17 595-606 de Moura MR, Aouada FA, Avena-Bustillos RJ, McHugh TH, Krochta JM, Mattoso LHC (2009) Improved barrier and mechanical properties of novel hydrox5q)ropyl methylcellulose edible films with chitosan/tripolyphosphate nanoparticles. J Food Eng 92 448—453 Dean K, Yu L, Wu DY (2007) Preparation and characterization of melt-extruded thermoplastic starch/clay nanocomposites. Compos Sci Technol 67 413 21 Duanmu J, Gamstedt EK, Rosling A (2007) Hygromechanical properties of composites of crosslinked allylglycidyl-ether modified starch reinforced by wood fibres. Compos Sci Technol 67 3090-3097... 

The materials were dried before mixing for a minimum of 6 h at 80 °C. Five grams of mixtures of R-BAPS and nanoparticles were extruded to obtain blend concentrations of 2, 6, 10, and 15 wt% nanoparticles in the PI. The melt-compounding was carried out at a barrel temperature of 340 °C and a screw speed of 100 rpm for a period of 20 min. Extruded nanocomposite pellets were injection molded into standard specimens using a DACA Instruments Microinjector. The test specimens had length 20 mm, width 5 mm, and thickness 1 mm. These specimens were prepared using a barrel temperature of 380 °C, a mold temperature of 90 °C, and an injection pressure of 100 bar. 

UDS cross section of an extruded nanocomposite perpendicular to the melt flow direction, TEM ... 

Dean, K., Yu, L., and Wu, Y. D. Preparation and characterization of melt-extruded thermoplastic starch/clay nanocomposites. Composite Science and Technology 67,413-421 (2007). 

Similar observations were noted when FKM/o-MMT clay nanocomposites were prepared by melt blending and the as-prepared nanocomposites showed both intercalated as well as exfoliated structure [103]. The apparent shear viscosity of the FKM/o-MMT nanocomposites was lower than that of the pristine polymer at all shear rates and temperatures. The nanocomposites exhibited reduced equilibrium die swell with a smooth extrudate appearance. A comparison of the flow properties of the nanocomposites with the conventional composites revealed that the nanocomposites exhibited improved processability. 

HDPE-CaC03 nanocomposites were prepared by mixing (melting) the individual components in a twin-screw extruder. Mixing was performed at a temperature of 210-220 °C with a screw speed of 15-25 rpm over 5 min. Test samples were obtained using a casting under pressure method on casting machine at 200°C and a pressure of 8 MPa. 

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. 

Muksing, N., Nithitanakul, M., Grady, B. P., Magaraphan, R. (2008). Melt rheology and extrudate swell of organobentonite-filled polypropylene nanocomposites. Polym. Test, 17, 470-479... 

A modified melt blending method has been developed for preparing exfoliated nanocomposites of poly(m-xylylene adipamide) with sodium montmoril-lonite [100]. There, an aqueous solution of sodium montmorillonite was blended with the polymer in a twin-screw extruder. This kind of mixing ensures that the silica nanoparticles are exfoliated in the polymer matrix through fixing the nanoparticles within the polymer matrix just as they are in water. Oxygen permeation data show enhanced the barrier properties of the nanocomposites. 

CaCOj-polylactide nanocomposites can also be prepared via melt compounding technique using twin screw extruder [64]. The temperature of the mixing zone varied from 150°C at entry to 190° at exit at a mixing speed of 150 rpm. These samples were then injection molded to the desired shape. 

Cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) are thermoplastic materials produced through esterification of cellulose and are used for many packaging applications. Different raw materials such as cotton, recycled paper, wood cellulose, and sugarcane are used in the production of cellulose ester biopolymers in powder form. Such cellulose ester powders in the presence of different plasticizers and additives are extruded to produce various grades of commercial cellulose plastics. Recently, Misra et al. successfully used melt intercalation technique for the fabrication of cellulose nanocomposites and studied the effect of C30B on its performance characteristics [44]. From the study, the... 

---