Commercial blends, examples

A commercially important example of the special case where one monomer is the same in both copolymers is blends of styrene—acrylonitrile, 1 + 2, or SAN copolymers with styrene—maleic anhydride, 1 + 3, or SMA copolymers. The SAN and SMA copolymers are miscible (128,133,144) so long as the fractions of AN and MA are neatly matched, as shown in Figure 4. This suggests that miscibility is caused by a weak exothermic interaction between AN and MA units (128,133) since miscibility by intramolecular repulsion occurs in regions where 02 7 can be shown (143) by equation 11. 

Figure 8.16 Analysis of selected areas of the best laboratory blend (Tablet E) and the commercial blend (tablet F). (a) Truncated PLS score imaged for the API component (depicted as white) from the central region of the tablets showing that on a local scale, the blending in both samples is uniform and (b) histograms and resulting %SD of the distribution from the truncated images. Note that both examples display nearly normal distributions.

Examples of Commercial Blends. In this subsection we will review some of the commercial activity in polymer blends. We find it interesting and informative to categorize examples into specific areas that relate to both technical issues associated with these mixtures, such as miscibility or crystallinity, and the intended commercial applications, such as rubbers or fibers. Other schemes of classification could be used, and the present one is not intended to be exhaustive. Likewise, there is no intent to mention all of the commercially interesting polymer blends, but rather, the present purpose is to illustrate some of the possibilities. Information about the examples used here was obtained from product literature supplied by the companies who sell these blends and from various literature references that have attempted to review commercial developments in polymer blends (70-76). 

In addition to the conventional listing of major constituents, a commercial blend may be formulated to contain one or more of the secondary constituents, calcium, magnesium, or sulfur, which are used to correct local soil deficiencies. These are normally specified in a separate listing. The importance of these, too, cannot be overlooked as, for example, fertilization of a sulfur deficient soil with soluble sulfate has given over 1100% rapeseed (canola) crop improvement [69]. 

Ethanol is the most successful biofuel and, for example, already supplies 40% of Brazil s transportation fuel needs. Its main advantage is that there is a well-established infrastructure for its production and use. Techniques for its production by the fermentation of sucrose are in place, large-scale distillation technologies have been developed, and it can be used in so-called flexible-fuel vehicles. In addition, the logistics for its distribution are well-established. Every gas station in Brazil supplies it, with gasoline being provided in a commercial blend containing up to 24% ethanol. 

Most specialty resins require high processing temperatures, while PP usually has T < 250°C. Thus, only few blends of this type are known, none commercial. For example, addition of PP enhanced throughput of PAES [Gowan, 1969] PEI PC/PEST blends, etc. 

PA s are excellent candidates for blending with PPE — each ingredient compensates for deficiency of the other. Since the resins are immiscible and brittle, they must be compatibilized and toughened. In consequence, PA/PPE blends comprise minimum four polymeric components PA, PPE, a styrenic modifier and an acidic com-patibilizer. Usually PA is the matrix in which PPE/styrenic resin domains are dispersed. As time progresses, these blends are getting more complex — examples are shown in Table 1.57. Commercial blends are Artley, Dimension , Luranyl , Lynex A and Xyron , Noryl GT, Remarry , Ultranyl , Vestoblend , etc. 

Since most of the applications of the PMMA type acrylic resins are based on their high degree of transparency and UV resistance characteristics, there has been little commercial interest or motivation in developing acrylic blends. This is understandable because unless there is complete, molecular level miscibility between the components, it is not possible to maintain a high degree clarity in the blends. Nevertheless, several examples of commercial blends of acrylic resins are known. These will be discussed under separate headings. 

As previously mentioned, several commercial hybrid thermosets are known to be co-reacting thermosets, i.e. when the mixture of two different thermosetting monomers or prepolymers is cured, there is a simultaneous graft or co-reaction between the components along with the crosslinking reactions. These systems may therefore be considered as co-polymerizing thermosets and not as true blends. Examples of such systems are phenolic novolak/epoxy resin (or epoxy novolaks) ... 

The last several decades have seen an exponential increase in the activity of engineering polymer blends. While this activity will continue, the area that will probably show the most future increase in commercial activity will be in high temperature systems. These blends include LCP and molecular composites as subsections that will be discussed separately. The activity in high temperature polymer blends has been primarily in the patent and published literature. Several examples of developmental and specialty commercial blends have emerged and many more are expected to follow in the future. 

Some of the methods (a) i) are used for the production of commercial blends, but others have so far been used mainly on an experimental scale. An example of the latter is (a), because the production of small quantities of the specific graft or block copolymer is very expensive. 

Multiphase polymer blends are of major economic importance in the polymer industry. The most common examples involve the impact modification of a thermoplastic by the microdispersion of a rubber into a brittle polymer matrix. Most commercial blends consist of two polymers combined with small amounts of a third, compatibilizing polymer, typically a block or graft copolymer. 

Blending PPE with either PEST or PC poses similar problems - the polymers are immiscible and brittle, hence require compatibilization and toughening. The PEST/ PPE blends are multicomponent systems, with > 5 components PEST, PPE, styrenic copolymer, compatibilizer, and impact modifier. Examples of commercial blends are Dialoy X, Gemax , or lupi-ace . For improved modulus and dimensional stability, they are usually reinforced with GF. These alloys are known for excellent processability, high solvent resistance, and dimensional stability. Evolution of these systems is outlined in Table 1.64. 

In a majority of cases, the thermoset/thermoset blends are actually formulated by the fabricator or the end user during the fabrication and processing of such materials as composite prepregs, printed circuit boards, laminates, and adhesives. The formulations and compositions are often kept proprietary and are designed to meet their own individual requirements. The following are some commercially important high-performance thermoset/thermoset blend examples ... 

The processability of the final material may also be improved, included here the resistance to chemical decomposition during processing, among other features. Examples of commercial blends are modified starch + PEAT (e. g., Novamont - MaterBi Com Products/Basf - Ecobras) for films, thermoformed and injection moulded parts PEAT + PLA (e. g., BASF - Ecovio) for films, thermoformed and extmded parts PLA + starch (e. g., Cereplast - Cereplast Compostables) for bags and packaging, injection moulded and extmded articles for food, pens, etc. 

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