Tensile strength of HDPE

Figure 3. Tensile strength of HDPE containers exposed to toluene at room temperature versus solvent exposure time. + symbols represent containers not exposed to solvent.

Tensile strength of HDPE generally decreases when filled to become HDPE-based composite materials. Tensile strength moves from 2900-4400 psi (neat HDPE) to 800-2800 psi in composite materials. 

Figure 11.16. Tensile strength of HDPE vs. the erucamide concentration. [Data from Percell, K. S. Tomlinson, H. H. Walp, L. K, Coatings Technology Handbook, 2nd Ed.,Marcel Dekkerim.]...

Fig. 4. Tensile strength of HDPE/POE at differing levels of POE content...

As shown in Table 12.1 the impact resistance and tensile strength of ultrahigh-molccular-weight polyethylene (uhmwpe) are superior to those of hope, but uhmwpe is more difficult to process, uhmwpe is also slightly harder than hdpe. 

Gao et al. (158) showed that LDPE-g-PS prepared based on Friedel-Crafts alkylation reaction could increase the impact strength, elongation at break and tensile strength of LDPE/PS blends. Wang et al. (159) reported that adding dicumyl peroxide (DCP) into HDPE/PS/SBS blends can obviously increase their impact and tensile strength. The mixing order affected the blend properties very much. However, DCP did not show such effect with HDPE/PS blends. 

High-density polyethylene (HDPE)/ultra-high molecular weight polyethylene (UHMWPE) blends are possible by direct compounding, and use of UHMWPE could improve the impact strength or tensile strain of HDPE. The effect of the UHMWPE content on the mechanical properties of the HDPE/UHMWPE blends is improved by compounding due to homogenisation of the mixture [35-39]. 

As much as 30% of all polyolefin products involve blends (Robeson 2007). It has been found, for example, that blending metallocene-catalyzed linear low-density polyethylenes (mLDPEs) with HDPE improves the Izod impact strength and some tensile properties of HDPE. Adding mLLDPE to LDPE increases the ductility of LDPE (Cran and Bigger 2009). In general, PE blends can be divided into three categories (1) PE lots blended to meet standard specifications for density and melt flow, (2) PE modified with <15 wt% of other polymer(s), and (3) PE bends with other thermoplastics or thermoplastic elastomers. 

Panthapulakkal and Sain [10] reported that incorporation of compatibilizer resulted in 15-25% increase in tensile strength of wheat straw, corn stalk or corncob-filled HDPE composites and 20% increase in flexural strength of wheat straw-filled HDPE composites. 

Table 2.5 clearly Indicates that the mechanical properties of solid-state extruded HOPE are much superior to the melt extruded HDPE. In fact, the tensile strength of solid-state extruded HDPE is about the same as carbon steel There are some other interesting benefits associated with solidstate extrusion of polymers. There is essentially no die swell at high extrusion ratios (extrusion ratio is the ratio of the area in the cylinder to the area in the die). Thus, the dimensions of the extrudate closely conform to those of the die exit. The surface of the extrudate produced by hydrostatic extrusion has a lower coefficient of friction than that of the un-oriented polymer. Above a certain extrusion ratio (about ten), polyethylene and polypropylene become transparent. Further, solid-state extruded polymers maintain their tensile properties at elevated temperatures. Polyethylene maintains its modulus up to 120°C when it is extruded in the solid state at a high extrusion ratio. The thermal... 

Chen J, Yang W, Yu G P, Wang M, Ni H Y and Shen K Z (2008) Continuous extrusion and tensile strength of self-reinforced HDPE/UHMWPE sheet, J Mater Process Technol 202 165-169. 

Although the tensile strength of PLA films decreased slightly after compounding with nanoclays, those of the composite films were still comparable to those of widely used plastic films such as high-density polyethylene (HDPE), polypropylene, and polystyrene (PS). 

The rigidity and tensile strength of HOPE are considerably higher than in LDPE and medium DPE (MDPE). HDPE s impact strength is slightly lower, as is to be expected in a stiffer material, but its overall values are high, especially at low temperatures, compared to the other TPs. 

It can be seen from Table 1 that the flexural modulus and tensile strength of PP is lower than most of the plastic materials except LDPE and HDPE. However, PP offers an advantageously high flexural modulus to cost ratio which makes it an ideal candidate for replacement material to many engineering plastics on the cost reduction basis. 

Therefore, in many cases, the main research objective is how to improve the properties of one - usually widely available and cheap - plastic material by the addition of another plastic. The most common examples of these are PE-PA, PP-PA, PE-PET, PE-ABS and so on, e.g., recycled PET and HDPE composites were prepared with different proportions of raw materials in the work of Avila and co-workers. It was found that changes in the ratio of raw materials significantly influenced the characteristics of the composites. The properties of the final products could also be improved by the application of compatibilisers however, the tensile strength of the composites was typically below 30 MPa [24]. 

When analyzing the data of the Table 4.1 it was observed that the tensile strength of composites reinforced with modified fibers by mercerization was increased compared to pure HDPE and the others composites. However, an increase in the strength of composites occurred when compared to the pure matrix. 

For linear polyethylene fibers made in this fashion, a tensile modulus of 44 GPa (6.4 x 10 psi) (steel is about 206 GPa (30 x 10 psi) but has a density 7.6 times as great ) and a tensile strength of 1.8 GPa (2.6 x 10 psi) have been claimed Compare these figures with those for ordinary, quiescently crystallized HDPE in Table 5.1. 

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