Specialty polymers examples

One major use of HF is in the manufacture of fluorinated hydrocarbons. Fluorinated ethylene is used for several specialty polymers. For example, the Teflon coating on nonstick cookware is made from polytetrafluoroethylene (PTFE). This polymer is made from tetrafluoroethylene. 

Similarly, low volume chemicals are classified according to whether they are sold primarily on the basis of specification or performance. Specialties are generally formulations that are sold on the basis of their performance and their prices reflect their value rather than cost of production. Producers of specialty chemicals often provide extensive technical service to their customers. Examples of specialty chemicals include pharmaceuticals, pesticides, flavours and fragrances, specialty polymers, etc. Fine chemicals, on the other hand, are produced to customer specifications and are often intermediates or active ingredients for specialty chemicals, e.g. pharmaceutical and agrochemical intermediates and bulk actives. 

The resist materials that have emerged from these studies are the first examples of resist materials tailored specifically for use in the microelectronics industry. They are specialty polymers that are produced in very low volumes, and have been developed as a result of research carried out in industrial laboratories. In the following sections, we will examine the chemistry of selected examples of these new systems. 

Examples of applications in eight areas, ranging from adhesives to specialty polymers, are listed in Table 11.11. 

In the area of specialty polymers, we are seeing an explosion of new polymer blends, alloys, and composites. The properties of novel polymer alloys, for example, are significantly better than those of the materials from which they are blended, but many aspects of these alloys are not well understood. Most of the materials consist of multiple polymer phases. But there is still uncertainty as to the desired characteristics and size of the polymer domains and the mechanisms by which forces are transferred through the material. All of these questions will benefit from the chemical engineering approach. 

Fermentation-derived organic acids and their esters are potentially important chemical feedstocks for polymers and specialty polymers, but most significantly as alternative solvents for industrial and consumer applications. For example, lactate esters are derived from renewable carbohydrate raw materials such as cornstarch. They exhibit much lower toxicity compared with halogenated hydrocarbons and ethylene glycol ethers and are environmentally benign. Some studies suggested that lactate ester solvents have the potential of replacing petroleum-based solvents... 

There are practical problems associated with many of the above processes for example, there are many materials that are difficult to process by grinding or solution techniques for one reason or another. Certain dyes, chemical intermediates, biological and pharmaceutical compounds which are "waxy" or "soft , certain specialty polymers, and explosives are a few categories of difficult to process materials. 

Discussion of polytetrafluoroethylene is included here as one example of a high value, relatively low volume specialty polymer to illustrate the diversity... 

Fluoropolymers are notoriously immiscible with any other polymer. Usually, they are dispersed in blends of engineering and specialty polymers either to improve processability or to induce lubricity and abrasion resistance. Examples of the PC/Specialty resin blends are listed in Table 1.68. 

Blends of the commodity polymers with more specialty polymers are limited although many specific examples exist in the patent/open literature. In the design of polymer blends for specific application needs, countless opportunities can be envisioned. Examples may include PE/poly(s-caprolactone) (PCL) blends for biodegradable applications (proposed), polyolefin (PO)/poly(vinyl alcohol) (PVAL) blends for antistatic films, PO/silicone rubber blends for biomedical applications, PO/thermoplastic polyurethane TPU (or other thermoplastic elastomers) for applications similar to plasticized PVC, functionalized PO/thermoset blends. 

For example, in anionic polymerization, careful selection of solvent, initiator, and temperature are important for successful polymerization. Sensitivity of anionic species toward oxygen and moisture remains an inconvenient factor inherent in anionic polymerization. On the other hand, many novel block copolymers and functional polymers can be prepared by living anionic polymerization, providing access to a variety of specialty polymers. The problem of controlled anionic polymerization of highly reactive monomers remains a challenging target in the field of anionic polymerization. 

A first group of specialty polymers prepared by aluminium alkoxides are end-fimctionalized polylactones. Many examples are available, which can be divided in two groups. A first method is to prepare a functionalized polymer by using a functionalized aluminium alkoxide (Eq. 11). 

More recently, in the last 25 years, it has become increasingly apparent that, in addition to the major commodity synthetic plastics, water-soluble commodity and specialty polymers and plastics, such as poly(acrylic acids), polyacrylamide, poly(vinyl alcohol), poly(aIkylene oxides), and even some modified natural polymers, for example, cellulosics and starch, may potentially contribute to environmental problems and should also be targets for biodegradable substitutes. 

Most specialty resins are processed at temperatures that limit the possibility of blending them with PE. The PE/specialty resin blends usually contain low concentration, < 5 wt%, of either component. Addition of PE improves the processability, surface finish, chemical, solvent, and impact resistance. Addition of specialty polymer to PE may improve rigidity and processability (viz. PE/LCP). Examples are given in Table 1.46. 

Addition of low concentration of PP, w(PP) 15 wt.%, was found to be beneficial for processability and performance of several specialty polymers. For example, it improved the notched Izod impact strength of PEI as well as its ultimate flexural strength, but it decreased the unnotched impact strength, modulus and the tensile properties. Added to PAES, it improved processability as well as solvent resistance and impact strength. 

This review gives most attention to those phosphorus pol5oners which have attained commercial use or which have been (or currently are) the subject of serious development efforts. Other reviews encompass phosphorus polymers of mainly academic interest (3,4). The commercial examples tend to be specialty polymers and none have attained large volume usage. One reason is cost. In addition, those pol5miers having P—0 links are usually more hydrolyzable than corresponding C—O bonded poljmiers, and moreover the phosphorus acids which are liberated tend to catalyze further hydrolysis. Hydrolytically stable phosphine oxide... 

In recent years the focus has been on the high performance, specialty resins. For example, polyetherimide, PEI, was commercialized in 1983. In tlie ensuing two years its blends with most engineering and specialty polymers were patented. Since 1990 PEI C blends, Ultem LTX , have been available from GEC. 

---