Polyethylene tensile strength data

The major feature of the tensile strength data for highly drawn polyethylene is the markedly larger values of strengths recorded for the fibres prepared from dilute solu-... 

Figure 10.7 shows that the tensile strength is improved as polystyrene is incorporated. Data for conventional melt-blended samples (Fayt et al., 1989) are provided for comparison. We note that the ductile-to-brittle transition for our system is shifted toward much higher polystyrene content. Fayt and others have shown that conventionally prepared polyethylene/ polystyrene blends are relatively poor materials (Barentsen and Heikens, 1973 Wycisk et al., 1990). Blends of most compositions are weaker than polystyrene or polyethylene homopolymers because of the poor interfacial adhesion between the two immiscible polymers. The electron micrographs and the mechanical data for the blends described here indicate that poly-... 

Fig. 19.11A,B presents, as an example, data of drawing series of nylon 6 and polyester filaments (Van der Meer, 1970). The additional data for the polyester (polyethylene terephthalate) are given in Table 19.8 by stretching the Young modulus increases by a factor 8 and the tensile strength by a factor 5.5 (Fig. 19.13).

Table VI compares the key properties of these two types of thermotropic polymers category by category. The samples compared had the same melting ranges, but were very different in reduced viscosities and solubility characteristics. The data compared were those processed under the most favorable conditions. Interestingly enough, the as-spun fibers from the polyester-carbonate can be heat-treated more efficiently than those fibers (of same tenacity) spun from the polyester. Both of them gave fiber properties far superior to those of nylons and polyethylene terephthalate. These two classes of polymers also had comparative properties (such as tensile strength, tensile modulus, flex modulus, notched Izod impact strength) as plastics and their properties were far superior to most plastics without any reinforcement.

Good models are needed because information on important properties such as heat capacity and elastic modulus can be derived from the force constants, The elastic modulus data is particularly useful since it allows the ultimate tensile strength of polyethylene to be determined. Based on present estimates of this, it is apparent that it is still possible to improve existing materials. 

Tensile strength measurements were made for untreated and phosphonylated polyethylene films in order to ensure that the bulk tensile properties of the treated polymer were not affected by the surface modiHcation. Twenty samples of both treated and untreated films were pulled until failure. The average ultimate tensile strength for untreated polyethylene was 2,437 psi with a standard deviation of 308 and the average for the treated fflms was 2,339 psi with a standart deviation of 729. A student s t-test revealed no statistically significant difference in the tensile strength between the two polymers. This tensile data, coupled with the percentage of die material affected by the surface treatment as calculate from ESCA data confirms that the material modification was limited to the material surface and did not penetrate the bulk of the material. 

HDPE/bamboo composites with different nanoclay and maleated polyethylene (MAPE) contents were fabricated by melt compounding. The compounding characteristics, clay dispersion, HOPE crystallization, and mechanical properties of the composites were studied. The X-ray diffraction (XRD) data showed that the clay was exfoliated only when 1% clay was added to pure HOPE wifliout MAPE. For HDPE/bamboo systems, MAPE was necessary to achieve clay exfoUatiOTi. For the HDPE/bamboo fiber composites, tensile strength, bending modulus, and strength were improved with the use of MAPE however, the use of the clay in the system led to reduced mechanical properties [27]. 

For polyethylene, the tensile data have the shape as shown in Figure 1.9. The initial slope of the curve gives the value of tensile modulus. The tensile strength can be defined as the stress at the yield point or at the break point... 

The use of n-alkane properties (with suitable equations) to estimate amorphous polyethylene properties has the advantage the ra-alkanes (unlike the polyolefins) ean be prepared pure, and accurate properties can be determined. The use of n-alkane data has the limitations, however, that some properties (e.g., boiling points) are irrelevant for polymers and some polymer properties (e.g., tensile strength) are lacking in the lower alkanes. This method treats the main backbone polymer chain as the functional group and the pendant alkyl groups or repeat units as the homolog chain for correlation purposes. 

Examination of Table 1 indicates that an increase in the acrylic acid content reduces softening point and modulus, which are normally correlated with crystallinity. In addition, tensile strength and adhesion to metallic substrates are increased. Cemia " reported similar data on the bulk polymerization of ethylene and acrylic acid which was accomplished at a temperature of — 200°C and a pressure of 171.6 MPa. The acrylic acid content of the copolymers ranged from 2.1-16%. When used as adhesives for bonding aluminum, the strength of straight polyethylene was 0.003 N/cm as compared to >0.59 N/cm for 16% acrylic acid copolymer. 

The mechanical data for this rubbery material are a low modulus (0.71 GPa), low tensile strength (0.07 GPa) and high elongation to break (32%). A yield point was not found and the majority of the elongation was reversible (20%). These are most unusual properties for polyethylene. 

Figures VII.3 and VII.4 show the experimental values of the Young s modulus and the tensile strength, respectively, for thick films of undoped trans-polyacetylene as a function of draw ratio (all samples were derived from the same polymerization batch). Although there is some scatter in the data, the modulus and tenacity increase approximately linearly with the draw ratio, as is commonly observed for most polymers drawn to moderate draw ratios. The modulus and tensile strength of trans-polyacetylene films stretched up to 15 times are 50 GPa and 0.9 GPa, respectively. These values are essentially equivalent to those observed for ultra-high molecular weight polyethylene [83] drawn to the same draw ratio. Recently, Akagi et al.[78] reported remarkable mechanical properties for drawn polyacetylene films prepared by non-solvent polymerization (100 GPa and 0.9 GPa for the modulus and tensile strength, respectively). The origin of difference in the modulus (in the two studies) is unknown.

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