Polyethylene terephthalate tensile modulus

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).

PLA compares well with petrochemical-based plastics used for packaging. It is clear and naturally glossy like polystyrene, it is resistant to moisture and grease, it has flavour and odour barrier characteristics similar to polyethylene terephthalate (PET). The tensile strength and modulus of elasticity of PLA is also comparable to PET. 

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.

Poly(a, -dimethyl-j3-thiopropiolactone) has been melt-spun at 185°C to give a fiber which, after drawing, had a tenacity of 1.4 g/den. (polyethylene terephthalate, 4-7 g/den.) and an initial modulus of 12 g/den. (30-130 g/den.) (16). Tensile recovery at 10% elongation was 80%. No information is available about poly (thiol esters) with higher melting points, such as poly(hexamethylene dithiolterephthalate). 

PBT/PC blends were commercialized by Dow, Mobay, Bayer, BASF, and GE Plastics with high modulus, heat resistance, tensile and impact strength, solvent resistance, and UV stability. Mobay and Dow commercialized polyethylene terephthalate (PET)/PC blends with solvent resistance, low-temperatnre impact, and tensile strength. PBT/PET blends with good surface appearance were introdnced by GE Plastics. 

Janik and Krolikowski [53] investigated the effect of Charpy notched impact strength and other mechanical properties such as tensile strength, flexural strength, elastic modulus, flexural modulus, melt viscosity, and fracture on the mechanical and rheological properties of PE-polyethylene terephthalate (PET) blends. 

Figure 6.6 Tensile modulus and loss factor tand for unoriented amorphous polyethylene terephthalate (a) and unoriented crystalline polyethylene terephthalate (b) as a function of temperature at 1.2 Hz (x) modulus ( ) land. (Reproduced with permission from Thompson and Woods, Trans. Faraday Soc., 52, 1383 (1956))...

Reinforced polymers that combine high tensile strength with high flexural modulus include polybutylene terephthalate, polyether ether ketone, polyamide-imide, and polyethylene terephthalate (see Table 3.3). 

As seen earlier, the incorporation of 30% glass fiber into polyethylene terephthalate increases the tensile strength from 55 to 100 MPa (Table 3.1), while increasing the flexural modulus from 2.3 to 5-17.9 GPa and decreasing the elongation of break from 250% to 2.2% (Table 3.3). 

PLA, also known as polylactide (i.e. polymerization of cyclic lactic acid, also called lactide), originally is a brittle material with lower impact strength and elongation at break, similar to another relatively brittle polymer—polystyrene (PS). However, its tensile strength and modulus are comparable to polyethylene terephthalate (PET). This is shown in Table 5. 2 as reported by Anderson et al (2008). Poor toughness limits its usage in... 

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