Morphology, and Properties of Polyethylene Blends

Polyolefin Blends, Edited by Domasius Nwabunma and Thein Kyu Copyright 2008 John Wiley Sons, Inc. 

Monomer CH2=CH2 Symmetrical and compact for close packing, dispersive forces no other intermolecular interactions, polarity, or bulky steric groups 

Polymerization Ziegler-Natta, supported metal oxides such as PhiUps, Unipol and metallocene Stereospecific chain formation required weak interaction/complexation with any initiators/catalysts metal coordination complexes required 

Glass transition (Tg) -120 to -60 C An elastomer or viscous liquid at ambient 

Melting temperature (Tin) 137 C folded chain crystals strength properties derived from crystallinity low thermal resistance. Extended chain crystals can melt at about 145°C 

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Chapter 3 Miscibility, Morphology, and Properties of Polyethylene Blends 61... 

S. Mallick, B.B. Khatua, Morphology and properties of nylon6 and high density polyethylene blends in absence and presence of nanoclay. J. Appl. Polym. Sd. 121, 359-368 (2011)... 

M.A. Cowan, European Patent Application 095,299, 30 Nov 1983, to Intercpolyethylene blends, Ph.D. thesis. School of Molecular Sciences, Victoria University, Australia, 2004 A.L.N. Da Silva, M.C.G. Rocha, F.M.B. Coutinho, R.E.S. Bretas, C. Scuracchio, Rheological, mechanical, thermal, and morphological properties of polypropylene/ethyloie-octene copolymer blends. J. Appl. Polym. Sci. 75, 692-704 (2000)... 

S. MaUick, A.K. Dhibar, B.B. Khatua, Effect of nanoclay on the morphology and properties of poly(methyl methacrylate)/high-density polyethylene blends. Journal of Applied Polymer Science 116 (2) (2010) 1010-1020. 

Compatibility and various other properties such as morphology, crystalline behavior, structure, mechanical properties of natural rubber-polyethylene blends were investigated by Qin et al. [39]. Polyethylene-b-polyiso-prene acts as a successful compatibilizer here. Mechanical properties of the blends were improved upon the addition of the block copolymer (Table 12). The copolymer locates at the interface, and, thus, reduces the interfacial tension that is reflected in the mechanical properties. As the amount of graft copolymer increases, tensile strength and elongation at break increase and reach a leveling off. 

Akhtar has studied the morphology and physical properties of NR and high-density polyethylene blends prepared in Brabender plasticorder at 150°C at a rotor speed of 60 rpm [53]. Films were molded between two chromium plates at a pressure of 0.34 MPa. The films along with mold were... 

Sanchez-Solis, A. Estrada, M.R. Cruz, J. Manero, O. On the properties and processing of polyethylene terephthalate/styrene-butadiene rubber blend. Polym. Eng. Sci. 2000,40 (5), 1216-1225. Luzinov, I. Xi, K. Pagnoulle, C. Huynh-Ba, G. Jerome, R. Composition effect on the core-shell morphology and mechanical properties of ternary polystyrene/styrene butadiene rubber polyethylene blends. Polymer 1999, 40 (10), 2511-2520. 

Monika, P. Upadhyaya, N. Chand, Vi Kumar, Effect of poly lactic acid on morphological, mechanical, and optical properties of compatibilized polypropylene and high density polyethylene blend. Compos. Interfaces 21, 133-141 (2014)... 

The lower left qnadrant represents the simple blends. One type of TPE blend is the TPO, which is a simple polymer blend of a rigid thermoplastic polymer with a technologically compatible (not necessarily thermodynamically compatible) elastomeric polymer. Each of the polymeric components exists in its own phase (with its own Tg or The properties of the blend are partly predictable by the properties of the com nents however, the phase morphology is also extremely important. The hard phase must be continuous for the blend to be thermoplastic. Commercial TPO blends include those of EPDM rubber with PP or polyethylene (PE). Another type of simple polymer blend is that of poly(vinyl chloride) and nitrile rubber (NBR). This may have been the first useful rubber-plastic blend. 

To achieve good toughness, required for many applications, impact modifiers are added to PVC. Chlorinated polyethylenes, ethylene-vinyl acetate copolymers, styrene-methyl methacrylate grafted elastomers, vinyl rubbers, and polyacrylates are the most frequently used (316). These polymers are blended together with other additives. Blending conditions are extraordinary important for morphology control and consequently for final properties of the blends. 

Jayanarayanan K, Archana R, Dhivya R, Monikumar S, Abirami V, Thomas S and Joseph K (2010) Morphology and mechanical properties of normal blends and in situ microfibrillar composites from low density polyethylene and poly (ethylene terephthalate), Polym Plast Technol Eng 49 442-448. 

Table 1 lists polyethylene blend systems for which commercially available materials have been reported as providing a compatibilizing action. Note that the list of suppliers is indicative, and similar polymers may be available from alternative sources. In most cases the compatibilizing effect reported included establishment of a stable, fine morphology and achievement of improved impact or ultimate extensional properties compared to the un-compatibilized blend. The systems are discussed briefly below, where mention is also made of non-commercial systems described in the technical literature. Readers who wish to investigate further the systems described here are directed to Boimer and Hope (1993), which contains a comprehensive bibliography. 

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