High-density polyethylene behavior

Short fiber reinforcement of TPEs has recently opened up a new era in the field of polymer technology. Vajrasthira et al. [22] studied the fiber-matrix interactions in short aramid fiber-reinforced thermoplastic polyurethane (TPU) composites. Campbell and Goettler [23] reported the reinforcement of TPE matrix by Santoweb fibers, whereas Akhtar et al. [24] reported the reinforcement of a TPE matrix by short silk fiber. The reinforcement of thermoplastic co-polyester and TPU by short aramid fiber was reported by Watson and Prances [25]. Roy and coworkers [26-28] studied the rheological, hysteresis, mechanical, and dynamic mechanical behavior of short carbon fiber-filled styrene-isoprene-styrene (SIS) block copolymers and TPEs derived from NR and high-density polyethylene (HOPE) blends. 

Various authors—for example, Dole, Milner, and Williams (15) and Lyons (25)—have suggested that the decay of vinyl groups initially present in some types of high density polyethylene involves an end-linking process, these authors disagreeing only about the mechanism involved. If such were the case, some difference in solubility or elastic behavior above 140 °C. would be expected between low and high density poly-... 

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. 

FIGURE 13-85 Schematic representation of the (10 second) modulus versus temperature behavior obtained from a sample of high density polyethylene. 

When a block copolymer is blended with a homopolymer that differs in composition from either block the usual result is a three-phase structure. Miscibility of the various components is not necessarily desirable. Thus styrene-butadiene-styrene block copolymers are recommended for blending with high density polyethylene to produce mixtures that combine the relative high melting behavior of the polyolefin with the good low temperature properties of the elastomeric midsections of the block polymers. 

The data in tables 9.1 and 9.2 were taken from Watkins et al. (1991) who demonstrate the impact of the crystallization boundary on the fractionation behavior of high-density polyethylene (HOPE). The second critical end point temperature for this sample of HOPE in propane is approximately 125°C. The data in table 9.3 show that HDPE can be selectively fractionated with respect to molecular weight across its entire molecular weight distribution using an isothermally increasing pressure profile in the liquid-gas region of the phase diagram. 

Figure 9.5 Effect of molecular weight on the pressure-composition behavior for the high-density polyethylene (1.3% methyl content)-propane system at 110°C.

N.S. Allen, A. Parkinson, F.F. Loffelman, and P.V. Susi, Photo-stabilizing action of a p-hydroxybenzoate compound in polyolefins. Part II. Thermal and photochemical behavior in high density polyethylene film, Polym. Degrad. Stab. 1984, 6, 65-79. 

In order to improve properties and compatibility of PP/EPDM blends, ternary blends and composites are sometimes prepared from the PP/EPDM blends. For instance, Sanchez et al. (10) prepared ternary blends of PP, high density polyethylene and EPDM with several blending ratios and investigated the melt rheological behaviors. They discussed the effect of the shear rate on the viscosity and flow curve in terms of the exponent of low power for a non-Newtonian liquid. They showed that addition of an elastomer to the polyolefin blends changes the shape of the viscosity-composition curve, and they discussed it in terms of the possible morphology of the blend. Similar works have been also reported by Ha et al. (11,12). 

Role of Fillers in the Friction and Wear Behavior of High-Density Polyethylene... 

The objective of this paper is to investigate the role of some potential fillers in modifying the friction and wear behavior of high density polyethylene. It has been studied in terms of the transfer film formation capability and its bonding to the counterface in view of the surface texture and chemical reaction possibilities. ... 

Since iron can react with sulfur and form sulfide films which can affect the tribological behavior significantly, CuS as a filler in high density polyethylene was next investigated. With 30% CuS,... 

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