Nanocomposites melt blending

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. 

Su, S., Jiang, D. D., and Wilkie, C. A. Novel polymerically-modified clays permit the preparation of intercalated and exfoliated nanocomposites of styrene and its copolymers by melt blending, Polym. Degrad. Stab. (2004), 83, 333-346. 

In the work of Wilkie et al.,55,56 oligomers of styrene, vinylbenzyl chloride, and diphenyl vinyl-benzylphosphate and diphenyl vinylphenylphosphate (DPVPP) have been prepared and reacted with an amine and then ion-exchanged onto clay. The resulting modified DPVPP clays have been melted blended with polystyrene and the flammability was evaluated. XRD and TEM observations proved the existence of intercalated nanocomposite structures. Cone calorimeter tests have shown a substantial reduction in the PHRR of about 70% in comparison with pure PS. According to the authors, this reduction was higher than the maximum reduction usually obtained with PS nanocomposites. Other vinylphosphate modified clay nanocomposites were also elaborated. The reduction in PHRR was greater with higher phosphorus content than for DPVPP. Consequently, the reduction in PHRR seemed attributed to both the presence of the clay and to the presence of phosphorus. 

Journal of Vinyl and Additive Technology 8, No.2, June 2002, p.139-50 MELT BLENDING PREPARATION OF PVC-SODIUM CLAY NANOCOMPOSITES... 

The results are reported of an in depth study of the structure, thermal properties, dynamic mechanical properties, flammability and smoke properties of melt blended PVC-sodium montmorillonite nanocomposites. Investigative properties employed included X-ray diffraction, TEM, TGA, DMA and cone calorimetry. The effects of clay loading, DOP concentration, annealing, blending time and molec.wt. on the formation of the composites are discussed and fire properties of PVC-organically modified clay and PVC-sodium clay nanocomposites are presented and discussed. 15 refs. USA... 

Intercalated and partially exfoliated PVC-clay nanocomposites were produced by melt blending in the presence and absence of DOP and characterised by X-ray diffraction and transmission electron microscopy. The effects of various factors, including volume fraction of clay, plasticiser content, melt compounding time and annealing, on nanocomposite structure and the thermal and mechanical properties of the nanocomposites were also examined. It was found that the best mechanical properties were achieved at 2% clay loading and 5 to 10% DOP loading. 18 refs. 

For nanocomposites produced via melt blending, formation of mixed type composite occurs already at 5 wt% of layered silicate in polyethyleneterephthalate. X-ray diffraction analysis patterns are shown on Figure3. 

Some physieal-mechanieal properties of nanocomposites produced by in situ method, and also produeed via melt blending polyethyleneterephthalate with organomodified montmorillonite (nalchikit-M), educed from bentonite clay of Gerpegezh field (Russia, KBR) and from eommercial clay bentonite-128. 

Poly(ethylene)/ZCHS nanocomposites were prepared via melt blending using established methods (7). Poly(ethylene) nanocomposites were prepared by mixing x g of the additive with (100- x g) of pristine poly(ethylene) to achieve x % mass fractions. Melt blending was then performed on a Brabender mixer for 10 minutes at a temperature of about 130°C and speed of 60 rpm. The prepared nanocomposites are identified as PE/ZCHS-5 and PE/ZCHS-10 for 5% and 10% loadings respectively. A reference sample of pure poly(ethylene) was prepared by following the same procedure in the absence of additive. 

An HDS additive, zinc/copper hydroxy stearate, was melt-blended with low density poly(ethylene). X-ray diffraction analysis of the composite materials was similar to that found with copper hydroxy dodecyl sulfate combined with poly(vinyl ester), where nanocomposite formation was observed, but additional work is necessary for full characterization of the dispersion. The (nano) composites were found to have better thermal stability via TGA and improvement in PHRR in cone calorimetry. However, smoke production was observed to increase. The 5% loading had better overall performance than 10% in terms of thermal stability and most fire properties. 

PLA nanocomposite samples used in this study were prepared with PLA (Teramac , Unitika) and organically modified clay (S-BEN W , Hojun). The samples were put into a Labo-plastomill consisting of a 30C150 kneader and an RlOO mixer (Toyo Seiki Seisaku-sho, Ltd., Tokyo) to melt-blend at 190 °C and 50 rpm for about 10 minutes. Pellets thus obtained were pressed into 0.2 mm thick sheet sandwiched between two thick Teflon films by a hot press at 190 °C. 

Mederic, R, Razaflnimaro, T., and Aubry, T., Influence of melt-blending conditions on structural, rheological, and interfacial properties of polyamide-12 layered silicate nanocomposites,... 

Pluta et al. investigated PLA/MMT nanocomposites by studying the dispersions of modified and unmodified MMT prepared by melt blending. XRD showed that the good affinity between the organo-modified clay and the PLA was sufficient to form an intercalated structure in the nanocomposite. TGA showed that... 

Pluta, M., Galeski, A., Alexandre, M., Paul, M. A., and Dubois, P. (2002). Polylactide/montmorillonite nanocomposites and microcomposites prepared by melt blending Structure and some physical properties. J A lPoI rrhSd., 86,1497-1506. 

Botana et al. [50] have prepared polymer nanocomposites, based on a bacterial biodegradable thermoplastic polyester, PHB and two commercial montmorillonites [MMT], unmodified and modified by melt-blending technique at 165°C. PHB/Na and PHB/ C30B were characterized by differential scanning calorimetry [DSC], polarized optical microscopy [POM], X-ray diffraction [XRD], transmission electron microscopy [TEM], mechanical properties, and burning behavior. Intercalation/exfoliation observed by TEM and XRD was more pronounced for PHB30B than PHB/Na,... 

Three main types of structures, which are shown in Fig. 5.3, can be obtained when a clay is dispersed in a polymer matrix (1) phase-separated structure, where the polymer chains did not intercalate the clay layers, leading to a structure similar to those of a conventional composite, (2) intercalated structure, where the polymer chains are intercalated between clay layers, forming a well ordered multilayer structure, which has superior properties to those of a conventional composite, and (3) structure exfoliated, where the clay is completely and uniformly dispersed in a polymeric matrix, maximizing the interactions polymer-clay and leading to significant improvements in physical and mechanical properties [2, 50-52]. Production of nanocomposites based on polymer/clay can be done basically in three ways (a) in situ polymerization, (b) prepared in solution and (c) preparation of the melt or melt blending [53]. 

Paul et al. [54] developed the plasticized PLA nancomposites by melt blending of PLA with 20 wt% of poly(ethyleneglycol) 1000 (PEG 1000) and different amounts of MMT to investigate the thermal and morphological properties of the plasticized PLA nanocomposites. X-ray diffraction (XRD) has pointed out that all the studied MMT led to intercalated nanostructures, even the unmodified MMT had produced an intercalated structure. The researchers stressed that the particular... 

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