Mechanical properties

Mechanical properties

The crystallinity of TORAYCON™ PBT resin falls within the range of 35% to 45% when molded using standard conditions. The mechanical properties of TORAYCON™ are less dependent on molding conditions than other crystalline resins. Also, its water uptake is extremely low, so the effects of water absorption on its mechanical properties are negligible.

Ⅰ. Tensile properties

The breaking elongation of TORAYCON™ 1401X06 is 300% at room temperature—a very large value that explains the resin's resilient characteristics.
While TORAYCON™ also has superb heat-resistance properties, its tensile properties are affected by environmental temperatures, as is the case with other thermoplastic resins. Figure 1 shows the temperature dependence of tensile strength in 1401X06 and 1101G-30. Figure 2 shows the strain-rate dependence of tensile strength in 1401X06. The glass-fiber reinforced grade (1101G-30) exhibits favorable mechanical properties, but limited breaking elongation of only 3-5%.

• Figure 1: Temperature dependence of tensile strength
• Figure 2: 1401X06 strain rate

Ⅱ. Flexural properties

The flexural properties of TORAYCON™ PBT resin are influenced by environmental temperatures, as is the case with other thermoplastic resins.
Figure 3 shows the temperature dependence of flexural strength in TORAYCON™. Figure 4 shows the temperature dependence of flexural modulus.

• Figure 3: Temperature dependence of flexural strength
• Figure 4: Temperature dependence of flexural modulus

Even at high temperatures, the 1101G-30 grade exhibits superb mechanical properties—at 130°C, its flexural strength is 95 MPa and its flexural modulus is 3.5 GPa.

Ⅲ. Impact strength

TORAYCON™ PBT resin is resilient to impact, too. Table 2 shows the impact strength of each grade.
Although the resin's Izod impact strength (using a notched sample) cannot be categorized as high compared to other engineering resins, TORAYCON™ is extremely strong against falling-dart impact, a better measure of impact strength in practical applications. For example, the falling-dart impact strength of TORAYCON™ is 40 times that of polyacetal.

a) ASTM D1822 S Type dumbbell 1/8" thickness
b) 40mmφ, 22mm t disc, falling dart tip 5 mm R
c) 1/8" thickness
d) 1/2" thickness

Figure 5 shows the temperature dependence of impact strength. TORAYCON™ retains excellent impact strength even at low temperatures.

Ⅳ. Creep-resistance properties

Ⅴ. Fatigue resistance

Ⅵ. Resistance to friction and wear

TORAYCON™ PBT resin withstands friction and wear superbly. See Table 3 for a comparison to polyacetal resin.

a) ASTM DIO44, Wheel CS-17, Load 1000 g
b) Suzuki abrasion tester, non-lubricating, counterpart material S45C
c) Okoshi abrasion tester, load 3.7 kg, travel distance 100 m

Ⅶ. Weatherability

TORAYCON™ PBT resin degrades little when exposed to ultraviolet rays. Figures 8-12 show the results from accelerated weathering and outdoor exposure tests performed on 1401X06 and 1101G-30.
Both 1401X06 and 1101G-30 exhibit minimal physical degradation or dimensional change when exposed to the outdoors. That said, as is the case with other resins, applying white or black coloration is recommended for applications requiring exposure to direct sunlight for extended durations of time.

• Figure 8: Change in physical properties resulting from exposure to outdoors (Part 1)
• Figure 9: Change in physical properties resulting from exposure to outdoors (Part 2)
• Figure 10: Change in water absorption resulting from exposure to outdoors
• Figure 11: 1401X06 weatherability (irradiation under Sunshine Weather Meter)
• 

  Figure 12: 1101G-30 weatherability (irradiation under Sunshine Weather Meter)

Ⅷ. Heat-cycling resistance properties

Tables 6 and 7 show the heat-cycling resistance properties of TORAYCON™ PBT resin. Both the 1401X06 and 1101G-30 grades exhibit superb heat-cycling resistance, with little physical degradation or dimensional change.
However, exercise caution before using TORAYCON™ in applications requiring exposure to hot water for extended durations of time. See below for more details.
That said, as the hot-cold heat-cycling test results in Tables 6 and 7 show, TORAYCON™ can be used in applications where the product is exposed to hot water intermittently or for short durations of time.

a) 1 cycle constitutes: room temperature (1 hour) → boiling water (1 hour) → room temperature (1 hour)

a) Heat cycling conditions
　 3 cycles, where 1 cycle constitutes: boiling water (2 hours) → 0°C water (2 hours).
b) Test specimen 1/2"thickness