Mechanical Properties of Polybutylene Terephthalate

As seen earlier, the incorporation of 45% glass fibers into polybutylene terephthalate increases the tensile strength from 52 MPa to values between 80 and 196 MPa (Table 3.1), giving it a superior tensile strength to polyethylene terephthalate. 

At the same time, the flexural modulus (Table 3.2) increases from 2.3 MPa to 

Elongation decreases dramatically from 250% for unreinforced polybutylene terephthalate to 2.3% for 45% glass fiber-reinforced polybutylene terephthalate (Table 3.4). Izod impact strength is virtually unaffected by the incorporation of glass fiber into the formulation. 

The incorporation of glass fiber info polyamide 6 increases the tensile strength from 40 to 145 GPa (Table 3.1), accompanied by an increase in flexural modulus (Table 3.2) from 1.0 to 1.6 MPa and hardly any change in elongation at break (Table 3.4). 

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At the beginning of a thermal loading condition, the mechanical properties of polybutylene terephthalate are often influenced by the increase in crystallinity, so that, e.g., impact strength decreases because of the higher degree of crystallization. Subsequently, oxidation will cause property changes. Figure 5.199. 

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