High-density polyethylene mechanical properties

Even with the same monomer, the properties of a polymer can vary significantly depending on how it is prepared. Free-radical polymerization of ethylene gives low-density polyethylene coordination polymerization gives high-density polyethylene. The properties are different because the structures are different, and the difference in the structures comes from the mechanisms by which the polymerizations take place. Free-radical polymerization of ethylene gives a branched polymer, coordination polymerization gives a linear one. 

Ziegler-Natta polymerization leads to linear unbranched polyethylene, the so-called high density polyethylene (HDPE), which is denser, tougher and more crystalline. By copolymerization with other alkenes it is possible to obtain linear low density polyethylene (LEDPE) with better mechanical properties than LDPE. Blends of LLDPE and LDPE are used to combine the good final mechanical properties of LLDPE and the strength of LDPE in the molten state. 

EFFECT OF MOLECULAR WEIGHT ON MECHANICAL AND MORPHOLOGICAL PROPERTIES OF HIGH DENSITY POLYETHYLENE FOAMS... 

Butene is used in the plastics industry to make both homopolymers and copolymers. Polybutylene (1-polybutene), polymerized from 1-butene, is a plastic with high tensile strength and other mechanical properties that makes it a tough, strong plastic. High-density polyethylenes and linear low-density polyethylenes are produced through co-polymerization by incorporating butene as a comonomer with ethene. Similarly, butene is used with propene to produce different types of polypropylenes. 

We focus here on the polystyrene/high-density polyethylene (HDPE) system. We have studied this system in greater detail than any other and describe here the phase behavior of this system, the blend synthesis, and some mechanical properties of the composites. 

Wenzhoug Tang, Michael H. Santare, Suresh G. Advani. Melt processing and mechanical property characterization of multi-walled carbon nanotube/ high density polyethylene (MWNT/HDPE) composite films. Carbon 2003 41 2779-2785. 

For high density polyethylene the MWD represents one of the basic parameters which, together with average molecular weight, density, short and long chain branching content, determines the physical, mechanical and rheological properties of the polymer and therefore its end uses (Table 1). 

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. 

Despite its origin form the nature, PLA s good stiffness and strength has enabled it to compete with other existing chemically based commodity plastics. Previous study on the mechanical properties of neat PLA by Jacobsen et al. [1] showed that PLA has great potential to be a substitute polymer for petroleum based plastics. The respective values of mechanical properties of PLA [2] with comparison of other petroleum based plastics e.g. polypropylene (PP) [3], polystyrene (PS) [4], high density polyethylene (HOPE) [5], polyamide (PA6) [6] shown in Fig. 11.2. 

Gupta, K., Rana, S.K., Deopura, B. Mechanical properties and morphology of high-density polyethylene/linear low-density polyethylene blend. J. Appl. Polym. Sci. 46, 99-108 (1992)... 

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)... 

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)... 

G. Madhu, H. Bhunia, P.K. Bajpai, Blends of high density polyethylene and poly(L-lactic acid) mechanical and thermal properties. Polym. Eng. Sci. (2013). doi 10.1002/pen.23764... 

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