PET cords

Application of solubility parameter match is also demonstrated in adhesives for polyester tire cord. Whereas resorcinol-formaldehyde resin is used in conjunction with polyvinylpyridine latex as an adhesive for rayon tire cord, this composition is not suitable for poly (ethylene terephthalate) (PET) cord. However, using hexylresorcinol rather than resorcinol results in a match of the solubility parameters of adhesive and fiber with resultant increased adhesion (21). 

Tire 1. Truck tire reinforced with nylon 6 cord Tire 2. Truck tire reinforced with PET cord. 

Figure 9 illustrates the effect of twisting on the heat generation rate and dynamic modulus of PET cords. It is seen that an Increase in the number of twist per unit length caused decrease both In the heat generation rate and dynamic modulus. 

Figure 8. Heat generation rate of high stress spun PET cords.

Figure 9. Effect of twist on viscoelastic properties of PET cords. Reproduced with permission from Ref. 2. Copyright 1979 ASIH,...

The engineering applications of PET resins include blow-molded botties, films, mol ding, and extmsion. Resins made for the latter two uses and related purposes are called mol ding resins in this article. The huge volumes of PET resin used for textile filaments and industrial fibers, eg, tire cord, are not included here. The PBT resins are mainly used for mol ding and related appHcations. 

The performance properties of PEN present opportunities for replacement of rayon or polyamide in carcass construction. The use of PEN cord in these applications is currently being evaluated in both Asia and Europe. PEN has demonstrated acceptable flexural fatigue equivalent to polyethylene terephthalate (PET) and rayon. It has equivalent toughness to rayon, which is important for sidewall impact resistance. PEN s superior mechanical properties also afford opportunities to use less fiber in carcass construction enabling production of lighter-weight, more fuel-efficient tires. 

More than 2 billion kilograms of PET are produced in the United States each year. This polymer is used to make tire cord, beverage bottles, home furnishings, small appliances, and many other common items. 

The processing requirements for a PET-SSP plant for tyre cord are very different to those for a bottle-grade plant First, the raw material is typically a homopolyester with a melting point of 260 °C or higher, secondly the final viscosity of 1.0 to 1.2 is much higher, and thirdly the plant throughputs, typically between 30 and 90 t/d, are much smaller. These three differences result in a rather simplified process, as shown in Figure 4.19. 

Polymers are real and all around us. We can look at giant molecules on a micro or atomic level or on a macroscopic level. The PET bottles we have may be composed of long chains of poly(ethylene terephthate) (PET) chains. The aramid tire cord is composed of aromatic polyamide chains. Our hair is made up of complex bundles of fibrous proteins, again polyamides. The polymers you study are related to the real world in which we live. We experience these large molecules at the macroscopic level everyday of our lives and this macroscopic behavior is a direct consequence of the atomic-level structure and behavior. Make pictures in your mind that allow you to relate to the atomic and macroscopic worlds. 

---