Compounding process colorants

Quality Control. Reproducible production of perfumes requires careful quality control of all materials used as well as the compounding process itself. The use of analytical tools has iacreased over the years with their availability, but there can be no substitute for organoleptic evaluation. The human nose is far more sensitive than any analytical instmment for certain materials, yet it is also quite limited as a quantitative tool and is subject to fatigue. There are also weU-documented examples of specific anosmias ia iadividuals, ie, iaability to smell certain odor types, which is somewhat analogous to color-blindness. 

Odriozola-Serrano I, Soliva-Fortuny R and Martin-Belloso O. 2008. Effect of minimal processing on bioactive compounds and color attributes of fresh-cut tomatoes. LWT Food Sci Technol 41(2) 217-226. 

Compounding—Processing operation in which fillers, plasticizers, coloring agents, and other additives are mixed with a polymer, often in an extrude to obtain desired properties. 

Although a masterbatch can be more expensive because of the cost of raw materials, the advantages of advanced color development, higher productivity, easier housekeeping, and process cleanout and the option of a less complicated compounding process can help offset higher raw material costs. 

Now, it is not commonly realized that by moving from a neat HDPE to a filled composite material, the lifetime of the resulting composite dramatically lowers, often by 50-100 times. That is, the OIT in Table 15.2 for composite materials can decrease to as low as 0.3-0.5 min, if no antioxidants are added in the composite manufacturing process. Actual drop in the OIT value largely depends on the compounding process (on shearing and heating effects first of all), on type of fillers, colorants, lubricants, and, of course, type and amount of added antioxidants, if any. 

Some acids (e.g., acetic and citric) have a sour taste. In fact, sourness had been a defining property since the 17 " century an acid was any substance that had a sour taste reacted with active metals, such as aluminum and zinc, to produce hydrogen gas and turned certain organic compounds characteristic colors. (We discuss indicators later and in Chapter 19.) A base was any substance that had a bitter taste and slippery feel and turned the same organic compounds different characteristic colors. (Please remember NEVER to taste or touch laboratory chemicals instead, try some acetic acid in the form of vinegar on your next salad.) Moreover, it was known that when acids and bases react, each cancels the properties of the other in a process called neutralization. But definitions in science evolve because, as descriptions become too limited, they must be replaced by broader ones. Although the early definitions of acids and bases described distinctive properties, they inevitably gave way to definitions based on molecular behavior. 

Features Improves color and processing stability during compounding, processing and end-use synergistic with hindered phenols and other stabilizers... 

To produce the broad variety of finished products fiom PVC formulations nearly always requires the incorporation of colorants. Most often, pigments (insoluble particulates) are employed in PVC rather than dyes, although the latter are employed in a few speeial cases. Pigments selected for use in PVC must be acid-degradation resistant, and can be added to the formulation as dry powders, dry dispersions, or concentrates in either liquid or solid carriers. The seleetion of the physical form of the colorant often depends on the formulation (e.g. rigid versus flexible), the compounding process, and the requirements of the appUcation. 

Similarly, introduction of carbazole in 174 also leads to a polymer presenting distinct redox processes and hence optical states [297,298]. Unlike electrochromic materials based on pure PEDOT, these compounds are colored in the oxidized state and colorless in the neutral one. The exploitation of the complementary properties of these two types of polymers has led to electrochromic devices exhibiting a large variety of colors [122],... 

Precolored compounds are delivered ready for final processing. Prior to delivery to the extruder, they have been mixed to the final ratio of polymer to colorant. This is the easiest form in which to color polymer because it requires no additional materials or hardware other than what is typical for single-material extrusion. Additionally, the imiformity of color is usually excellent as a result of the compounding process. However, this form is generally expensive because another processor performs the compounding work. 

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