End-use Development

This led to the establishment of Du Font s Plastics Technical Service Laboratory in 1946 located in Arlington, N. J. and also to the formation of an end use development group. 

Mechanical Properties. Polyester fibers are formed by melt spinning generally followed by hot drawing and heat setting to the final fiber form. The molecular orientation and crystalline fine stmcture developed depend on key process parameters in all fiber formation steps and are critical to the end use appHcation of the fibers. 

The original yams were marketed as silk substitutes for use in apparel, hosiery, lace, home furnishings, ribbons, braids, and in a whole range of fabrics using blends with cotton or wool yams. As the end uses expanded beyond silk replacement, the harsh metallic luster of the yam proved disadvantageous and dull "matt" fibers had to be developed. Oil dulling was invented (11) in 1926, and an improved method using titanium dioxide was developed (12) in 1929. 

Other important properties that can be measured in the laboratory include sealabiHty, printabiHty, or coating adhesion. Many of these tests have been developed by the film manufacturer in cooperation with customers and are specifically designed to measure product performance in the end use. Some tests, like sealabiHty, can be standardi2ed to time, pressure, and temperature of sealing with instmment-measured peel values, but other tests are subjective, such as evaluations of printing loss to puUoff by adhesive tape. 

Considerable research and development effort is being placed on a chlorine-resistant membrane that wiU maintain permeabUity and selectivity over considerable time periods (years). This polymer activity is not limited to hoUow fibers, but the thick assymetric skin of hoUow-fiber constmction might offer an advantage in resolving the end use need as opposed to the ultrathin dat-sheet composite membranes. 

Textile finishing encompasses a broad range of approaches and may be directed toward needed properties such as shrinkage control or smooth-dry performance or toward developing properties for specific end uses such as flame retardance, soil release, smolder resistance, weather resistance, or control of static charges. 

Years of development have led to a standardized system for objective evaluation of fabric hand (129). This, the Kawabata evaluation system (KES), consists of four basic testing machines a tensile and shear tester, a bending tester, a compression tester, and a surface tester for measuring friction and surface roughness. To complete the evaluation, fabric weight and thickness are determined. The measurements result in 16 different hand parameters or characteristic values, which have been correlated to appraisals of fabric hand by panels of experts (121). Translation formulas have also been developed based on required levels of each hand property for specific end uses (129). The properties include stiffness, smoothness, and fullness levels as well as the total hand value. In more recent years, abundant research has been documented concerning hand assessment (130—133). 

Designing an experiment is like designing a product. Every product serves a purpose so should every experiment. This purpose must be clearly defined at the outset. It may, for example, be to optimize a process, to estimate the probabiUty that a component operates properly under a given stress for a specified number of years, to evaluate the relative effects on product performance of different sources of manufacturing and end use variabiUty, or to determine whether a new process is superior to an existing one. An understanding of this purpose is important in developing an appropriate experimental plan. 

Transportation end uses are expected to become a significant outlet. Products under development include an engine valve cover, as are various housings such as those for od pumps, water pumps, starter motors, and certain transmission parts. These end uses employ PPS because it resists high temperatures and is also chemically resistant. Fuel system parts can employ the excellent chemical resistance of PPS, replacing nylon, if alcohol-based fuels are adopted to reduce emissions. 

Chemical end uses employ the most exceptional property of PPS, chemical inertness. PPS is almost as chemically resistant as Teflon. It is used in pump impellers and housings and for down-od-weU end uses. New extmsion grades have been developed for potential piping end uses. Coatings of PPS are used extensively. 

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