Physical properties

Physical properties

Ⅰ. Melting point and crystallization properties

The melting point of Toray's TORAYCON™ polybutylene terephthalate (PBT) resin is 224°C—a high melting point that is on par with that of nylon or polyethylene terephthalate (PET).
That high melting point contributes to a very high deflection temperature under low loads-1401X06 has a deflection temperature of 154°C under a load of 0.45 MPa.
TORAYCON™ crystallizes much faster than PET, making it possible to obtain aesthetically appealing molded products with superb mechanical properties and stable dimensional properties even when using a low mold temperature in an injection-molding process.

Ⅱ. Water-absorption properties

TORAYCON™ PBT resin exhibits the lowest water-absorption properties among thermoplastic resins, so there is little need to consider the effects of water absorption in a TORAYCON™ molded product.

Ⅲ. Gas and water permeability

Table 1 shows the gas and water permeability of several films. 1401X06 is the non-reinforced grade of TORAYCON™ PBT resin. Its gas permeability is mostly equivalent to that of polyethylene terephthalate. Moreover, 1401X06 expanded film exhibits gas permeability equivalent to that of polyvinylidene chloride. Although inferior to polypropylene and polyvinylidene chloride, the water vapor barrier properties of 1401X06 are superior to those of nylon.

Table 1: Gas and water permeability of films
Resin Properties
Specific gravity O2 permeability CO2 permeability N2 permeability H2O permeability
ml·mm/m2·d·Mpa g·mm/m2·d
PBT (not expanded) 1.31 30 120 6 1.2
PBT (expanded in two dimensions) 1.31 17 70 4 0.7
PET (expanded in two dimensions) 1.4 19 74 4 0.7
LDPE (not expanded) 0.92 2,000 8,900 720 0.5-0.6
PP (not expanded) 0.89 900 2,700 160 0.3-0.4
PVDC (copolymer expanded in two dimensions) 1.66 17 91 - 0.15
Nylon 6 (not expanded) 1.13 5-15 50 5 7.5

1. Gas permeability was measured per the GENERAL FOOD method using 25°C dry gas.
2. Water vapor permeability was measured per JlS Z0208 at 40°C and 90%RH.