Properties application performance

There is a significant gap of degradation rates and performance properties between the aliphatic and aromatic polyesters. However, taking some hints from nature can fill this gap. Mixtures of polyesters, molecular orientation, substitution of some functional groups, and macro structures have all been proposed as a means to provide a range of application performance properties versus degradation rates. 

The selection of solvents and solvent blends for use in coatings and inks is based upon solubility/viscosity characteristics and application/performance properties. Published solubility parameters and hydrogen bonding indexes are used to construct two-dimensional solubility maps. Methodology is described, and illustrations are shown. Data are provided on evaporation times of neat solvents, viscosities and dry times of polymer solutions, electrostatic characteristics of solvents, and on selected solvent blend recommendations for several polymers. Unpublished test methods for flow testing and for substrate testing are provided. Combination of the results from these areas provides a viable method for practical solvent blend selection this approach is faster than random trial-and-error and can result in superior, formulated solvent blends. 

Resin examples are limited to those polymers which either require or are benefited significantly by oxygenated solvents. Data are categorized into solubility/viscosity and application/performance properties. Specific test methods are included as needed. 

Application/Performance Properties. After the solubility/viscosity properties of a solution or a group of solutions have been determined, application and performance properties must be evaluated. In many cases, a close tie between these properties exists. Obviously, some thought has been given to limiting the potential solvents evaluated to get to this... 

Recent pigment technology has yielded a wide range of products which ate much mote specialized for individual end use applications. New polymers have been combined with improved dyestuffs to yield fluorescent pigments with better performance properties and economics, and more desirable environmental characteristics. 

The number of basic polymeric resin chemistries available for use as adhesives is large and each has their own set of application and performance properties. The ability to further modify these with other chemical or physical additives means that adhesives can be tailored for particular application or performance requirements quite readily. 

One may now ask whether natural systems have the necessary structural evolution needed to incorporate high-performance properties. An attempt is made here to compare the structure of some of the advanced polymers with a few natural polymers. Figure 1 gives the cross-sectional microstructure of a liquid crystalline (LC) copolyester, an advanced polymer with high-performance applications [33]. A hierarchically ordered arrangement of fibrils can be seen. This is compared with the microstructure of a tendon [5] (Fig. 2). The complexity and higher order of molecular arrangement of natural materi-... 

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. 

Detailed accounts of fibers and carbon-carbon composites can be found in several recently published books [1-5]. Here, details of novel carbon fibers and their composites are reported. The manufacture and applications of adsorbent carbon fibers are discussed in Chapter 3. Active carbon fibers are an attractive adsorbent because their small diameters (typically 6-20 pm) offer a kinetic advantage over granular activated carbons whose dimensions are typically 1-5 mm. Moreover, active carbon fibers contain a large volume of mesopores and micropores. Current and emerging applications of active carbon fibers are discussed. The manufacture, structure and properties of high performance fibers are reviewed in Chapter 4, whereas the manufacture and properties of vapor grown fibers and their composites are reported in Chapter 5. Low density (porous) carbon fiber composites have novel properties that make them uniquely suited for certain applications. The properties and applications of novel low density composites developed at Oak Ridge National Laboratory are reported in Chapter 6. 

P.R.32 is made in Japan and South America and enjoys only limited local significance. Its fastness properties and application performance largely parallel those of the chemically related Naphthol AS pigment P.R.31. 

The list of applications also includes decorative printing inks for laminated plastic sheets based on melamine or polyester resin. The required fastness and performance properties are very good the pigment does not, for instance, color the clear sheets. 8% gravure prints (20 pm cell depth) equal step 8 on the Blue Scale for lightfastness. 

A vast number of polymer compounds are available commercially. Generally they are known by their polymer type in full or abbreviated (e.g., acrylic, polyvinyl chloride or PVC, high density polyethylene or HDPE), and frequently by a manufacturer s trade name. There is little standardisation into classes based on chemical composition or physical performance, as there is for metals. In reality, a particular chemical composition does not fully define the physical properties, while each class of performance properties can be met by a range of competing polymer types. The current trend is towards further diversification polymer compounds are increasingly being tailored to a particular application. Only in industries where recycling is an issue is there pressure for a more limited number of polymers, which can be identified and separated at the end of product life. 

Copolyesters (such as BIOMAX ) which combine aromatic esters with aliphatic esters or other polymer units (e.g. ethers and amides) provide the opportunity to adjust and control the degradation rates. These added degrees of freedom on polymer composition provide the opportunity to rebalance the polymer to more specifically match application performance in physical properties, while still maintaining the ability to adjust the copolyesters to complement the degradation of natural products for the production of methane or humic substances. Since application performance requirements and application specific environmental factors and degradation expectations vary broadly, copolyesters are, and will continue to be, an important class of degradable polyesters. 

For some applications, a combination of materials may be required to achieve a composite with the desired properties and performance. Property-improved lignocellulosic fibers can be combined with materials such as metal, glass, plastic, natural polymers, and synthetic fiber to yield a new generation of composite materials. New composites will be developed that utilize the unique properties obtainable by combining many different materials. This trend will increase significantly in the future. 

Whereas the production flow charts of inoiganic pigments appear to be simple, the actual processes can be very complicated. Many pigments are not pure chemical compounds, but can be multiphase systems contaminated with various impurities and modifiers. Because pigments are fine powders, the physical properties are as critical to their application performance as are the chemical properties. 

Each class of sealants has certain attributes inherent to the. polymer on which it is based These attributes often define the sealant s applications and limitations. Future developments are likely to feature the production of more silicone sealants that do not pick up dirt, more latex acrylic sealants that have high performance properties. Urethanes that have improved uv stability, and high performance polysulfides that are made in the United States. 

The applications of glass/glass-ceramic matrix composites (CMC) can be divided into two specific categories aerospace applications and non-aerospace applications. In aerospace applications, performance is the prime consideration, while in non-aerospace applications cost-effectiveness is paramount. The characteristic properties of materials for aerospace applications should be... 

Reverse ethylene oxide/propylene oxide block copolymers (in which a hydrophilic core of PEO is terminated at both ends with hydrophobic PO moieties) are used in industrial applications. This is because of the different and unique performance properties compared to the conventional block copolymers, where a hydrophobic PO core is block copolymerized with EO. Dufour and Guyot [30] have built on this observation and synthesized Surfmers in which a PEG core (about 37 EO units) was tipped with about 10 PO units to further react with a chlorine-carrying polymerizable group or with maleic anhydride to produce reactive Surfmers. 

Organic titanates perform three important functions for a variety of industrial applications. These are (/) catalysis, especially polyesterification and olefin polymerization (2) polymer cross-linking to enhance performance properties and (3) Surface modification for adhesion, lubricity, or pigment dispersion. 

---