Polyethylene/clay mechanical properties

The incorporation of unmodified and organically modified montmorillonite nanoclays (namely 15A and 30B) in chlorinated polyethylene (CPE) by the solution intercalation method and their influence on mechanical properties of the nanocomposites have been studied by Kar et al. [137]. The o-MMT-embedded nanocomposites show enhanced tensile strength and Young s modulus in comparison to the nanocomposites containing the unmodified nanoclay. They have shown from and XRD analyses that organically modified clay shows better dispersion in the CPE matrix. This has been further substantiated from FTIR analysis, which proves an interaction between the CPE matrix and the clay intercalates. 

As stated previously, styrene-diene triblock copolymers are the most important category of thermoplastic elastomers. Unlike most other TPEs, they can be blended with large quantities of additives without a drastic effect on properties. In almost all applications, the actual triblock copolymer content is less than 50%. Oils are used as a processing aid and do not result in a significant loss of properties if the polystyrene domains are not plasticized. For this reason, naphthalenic oils are preferred. The use of inert fillers such as clays or chalks reduces the cost of the final material. Unlike conventional rubbers, inert fillers do not have a substantial effect on the mechanical properties of TPEs. Thermoplastics such as polyethylene or polypropylene are also used to improve the solvent resistance and can increase the upper service temperature. Polystyrene homopolymer is used as a processing aid, which also increases the hard phase weight fraction and causes the material to stiffen. 

More recently, the same research group also reported that in hydro-calcite nanoparticle modified PE fibers [21] the incorporation of clay improved the thermal stability and induced heterogeneous nucleation of polyethylene crystals. Hydrocalcite exhibited good dispersion into the polymer matrix, and hence positively affected the mechanical properties in terms of both stiffness and strength. The toughness of the nanocomposite as spun fibers was also increased up to 30% with respect to neat polymer. 

Durmus, A., Woo, M., Kasgoz, A., and Macosko, C. W. 2008. Mechanical properties of linear low density polyethylene (LLDPE)/clay nanocomposites Estimation of aspect ratio and interfacial strength by composite models. Journal of Macromolecular Science, Part B Physics 47 608-619. 

HDPE/bamboo composites with different nanoclay and maleated polyethylene (MAPE) contents were fabricated by melt compounding. The compounding characteristics, clay dispersion, HOPE crystallization, and mechanical properties of the composites were studied. The X-ray diffraction (XRD) data showed that the clay was exfoliated only when 1% clay was added to pure HOPE wifliout MAPE. For HDPE/bamboo systems, MAPE was necessary to achieve clay exfoUatiOTi. For the HDPE/bamboo fiber composites, tensile strength, bending modulus, and strength were improved with the use of MAPE however, the use of the clay in the system led to reduced mechanical properties [27]. 

Rezanejad, S., Kokab, M. Shape memory and mechanical properties of cross-hnked polyethylene/clay nanocomposites. Eur. Polym. J. 43, 2856-2865 (2007)... 

Inorganic particulate fillers such as calcium carbonate and china clay can be compounded with PHB and extruded or moulded. The mechanical properties of the resultant products, however, provide no particular surprises, being stiffer but more brittle than the base polymer. Even so, calcium hydroxyapatite filled PHB is currently being evaluated as a potential bone substitute in maxillofacial surgery, for example, and in fracture fixation plates in much the same way as the recent development of apatite filled polyethylene. The main advantages of PHB over polyethylene (PE) in these applications are its biocompatibility and biodegradability, which will be discussed in more detail later. 

Ogata N, Jimenez G, Kawai H, Ogihara T (1997) Structure and thcmnal/mechanical properties of poly(l-lactide)-clay blend. J Polym Sci B Polym Phys 35 389—396 Okamoto M, Nam PH, Maiti P, Kotaka T, Hasegawa N, Usuki A (2001) A house of cards structure in polypropylene/clay nanocomposites under elongational flow. Nano Lett 6 295-298 Olley RH, Bassett DC, Hine PJ, Ward IM (1993) Morphology of compacted polyethylene fibres. J Mater Sci 28 1107-1112... 

Lee, Y. H., T. Kuboki, C. B. Park, M. Sain, and M. Kontopoulou. 2010. The effects of clay dispersion on the mechanical, physical and flame-retarding properties of wood fiber/ polyethylene/clay nanocomposites. JAppl Polym Sci 118 452-61. 

C. Zhao, H. Qin, F. Gong, M. Feng, S. Zhang, and M. Yang, Mechanical, thermal and flammabfiity properties of polyethylene/clay nanocomposites, Polym. Degrad. Stab. 87(1), 183-189 (January, 2005). 

Zhao, C., Qin, H., Gong, F., Feng, M., Zhang, S., Yang, M., Mechanical, thermal and flammability properties of polyethylene/clay nanocomposites . Polymer Degradation and Stability, 2005, 87, 183-189. 

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