Isotactic polypropylene/high density polyethylene blends

Jose S, Aprem A S, Francis B, Chandy M G, Werner P, Alstaedt V and Thomas S (2004) Phase morphology, crystallisation behaviour and mechanical properties of isotactic polypropylene/high density polyethylene blends, Eur Polym J 40 2105-2115. 

N.K. Madi, Thermal and mechanical properties of injection molded recycled high density polyethylene blends with virgin isotactic polypropylene. Mater. Des. 46, 435-441 (2013)... 

A TSC study of isotactic and atactic polypropylene, high density polyethylene, ethylene-propylene block copol)uners, ethylene-propylene rubbers and blends thereof [8] in the y and p relaxation range helped to identify the molecular origin of the relaxation peaks. Two 3 processes were observed in the copolymer samples, one (p,) around —5°C, the other one (Pj) at about -50°C. The former is attributed to the PP chains, while the latter is ascribed to microscopically random ethylene-propylene rubber segments. 

Blends of isobutylene polymers with thermoplastic resins are used for toughening these compounds. High density polyethylene and isotactic polypropylene are often modified with 5 to 30 wt % polyisobutylene. At higher elastomer concentration the blends of butyl-type polymers with polyolefins become more mbbery in nature, and these compositions are used as thermoplastic elastomers (98). In some cases, a halobutyl phase is cross-linked as it is dispersed in the polyolefin to produce a highly elastic compound that is processible in thermoplastic mol ding equipment (99) (see Elastomers, synthetic-thermoplastic). ... 

Doroudiani S, Park CB, Kortschot MT (1998) Processing and characterization of micro-cellular foamed high-density polyethylene/isotactic polypropylene blends. Polym Eng Sci 38 1205-1215... 

Figure 4 shows that the orientation of the two chains follow similar paths. The similarity suggests that the local environment is very much the same for both blend constituents. In contrast, a phase-separated binary mixture of polymer segments will exhibit a different orientation for each component. For example, high-density polyethylene and isotactic polypropylene form multiphase systems when blended together (16). When the incompatible blends are deformed, the component which constitutes the continuous phase always orients to a higher degree than... 

BLENDS OF POLYOLEFINS (HIGH DENSITY POLYETHYLENE AND ISOTACTIC POLYPROPYLENE) WITH A SEMIFLEXIBLE LIQUID CRYSTALLINE POLYMER... 

From a mechanical point of view, high density polyethylene (HDPE)/isotactic polypropylene (iPP) blend have generally been considered as very unsatisfactory materials In particular, they show very poor ultimate mechanical properties at room temperature in comparison with those of the blend constituents. This fact precludes their use for most commercial purposes. In previous papers we found that it is possible to improve the mechanical tensile performance of these blends by appropriately varying the testing conditions such as the temperature and the drawing rate. 

Zhang, C., Yi, X.S., YuL H., Asai, S., and Sumita, M. (1998) Selective localization and double percolation of short carbon fiber filled polymer blends high-density polyethylene/isotactic polypropylene. Mater. Lett., 36, 186. 

From B. Na, Y. Wang, Q. Zhang, Q. Fu, Shish and its relaxation dependence of re-crystallization of isotactic polypropylene from an oriented melt in the blends with high-density polyethylene. Polymer 45 (18) (2004) 6245-6260. 

Bartczak Z. Galeski A. PraceUa M. Spherulite nucleation in blends of isotactic polypropylene with high density polyethylene. Polymer. 1986,27,537-543. 

Thermoplastic NR (TPNR) is a physical modification of NR effected by blending with crystalline polyolefins such as high density polyethylene or isotactic polypropylene. Depending on the composition of the blends, TPNR can be used in many applications which require the use of a hard but flexible material, such as in flexible bumpers, sight shields and rubbing strips. 

Present work focuses on in-situ composites prepared by blending of high-density polyethylene with isotactic polypropylene using extrasion die with semihypetbohc-converging channel. Beside proper preparation of in-situ composites, interrelations between material composition, processing conditions and resulting stracture and properties of polyethylene-polypropylene blends are studied. 

High-density polyethylene LITEN TB 38 and isotactic polypropylene MOSTEN GB 003, both produced by Chemopetrol Litvinov, Czech Republic, were chosen as basic components of PP/PE blends. PP/PE blends were manufactured using counter-rotating twin-screw extruder at screw speed 35 rpm. The temperature of extruder ranged from 190 °C to 210 °C. The extraded blends with 20, 30 and 40 wt.% of PP were quenched and granulated. 

Similarly large anisotropies were later reported for highly emissive blends of alkoxy-substituted bis(phenylethynyl)benzene derivatives and polyolefins such as linear low-density polyethylene (LLDPE) and isotactic polypropylene (z-PP) [8,9]. The latter systems reach high levels of anisotropy at very low draw ratios, which is advantageous from a processing point of view. 

J. K. Keum, Y. Mao, F. Zuo, B.S. Hsiao, Flow-induced crystallization precursor stmcture in high molecular weight isotactic polypropylene (HMW-iPP)/low molecular weight linear low density polyethylene (LMW-LLDPE) binary blends. Polymer 54, 1425-1431 (2013)... 

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