Curative ingredients

Evidence of Interfacial Bonding. In these experiments compounded blends were composed of two elastomer phases that were first mixed with curative ingredients before blending in various ratios. This procedure was adapted to ensure proper initial distribution of the ingredients between the two phases. Blending was accomplished, with one exception, by mill mixing on a small laboratory two-roll mill. After blending, cured specimens in the form of small 0.025-inch thick pads were swollen in a common solvent to observe the over-all state of network... 

Curative ingredients are typically added to a batch late In the mixing cycle so that the processed rubber does not cure (start chemically crosslinking) until the rubber compound is deliberately raised to the elevated cure temperature. 

Approximately 1.5 billion worth of curatives were consumed in 2012 by the rubber industry worldwide. Typically, curative ingredients are used at small concentrations of from 0.2 to 5 parts per hundred rubber polymer (phr). 

There are different subgroups of curative ingredients that we will discuss. These include the following activators, vulcanizing agents, accelerators, and inhibitors. 

Induction period. The curatives react with themselves in preparation for the cross-linking reaction. This period allows the ingredients to be safely mixed avoiding premature curing ( scorch ). 

A chromatogram obtained for the examination of acetone extractables from an ethylene propylene-based rubber is shown in Figure 3. Excellent separation of the main hydrocarbon components from polar compounding ingredients and curative breakdown products is observed. 

For identification of other organic rubber compounding ingredients such as waxes, and most antioxidants/antiozonants, sample extraction with diethyl ether, followed by GC-MS of the resulting extract is commonly employed. Examination of volatile species can also provide information on the nature of curatives employed. 

The results demonstrate the versatility of plasma polymerization of various monomers onto rubber fillers and vulcanization ingredients. The largest effects are seen in blends of different rubbers with unequal polarities. Substantial improvements in mechanical properties are seen in comparison with the use of unmodified fillers and curatives. 

The Pure Food and Drug Act was passed mainly in response to widespread public concern about contaminated meat and other food, but patent medicines with dubious contents and misleading labels were also a significant problem. Among its other provisions this law required that any narcotic ingredients in a patent medicine be disclosed, and prohibited unwarranted claims of curative powers. 

In parts where amounts of entrapped air must be kept to an absolute minimum, the process may be carried out under full vacuum. The unit consists of two chambers, one for mixing the prepolymer, curative, and other ingredients, and the lower chamber for the mold. 

As the population increased, the use of patent medicines increased as well. During the late 1800s, few scientifically trained physicians were available, their fees were relatively expensive, and there was a general distrust of their curative procedures (e.g., bloodletting). However, patent products were readily available inexpensive and claimed to be panaceas for many ailments. Unfortunately, the ingredients in these products were not disclosed and many of the products were simply alcohol, water, or flavoring. ... 

These lists are not complete as it is recognised that rubber contains two important ingredients (antidegradants and curatives) that are reactive and so produce reaction and breakdown products. Recent work carried out at Rapra for the Food Standards Agency has shown that there are more than 1000 of these products originating from the 200 curative and antidegradant compounds in the Council of Europe rubber resolution inventory list. 

Apart from polymer and curatives, the other ingredients of epoxypolysulphide systems are fillers, pigments, reinforcing agents and solvents. 

The powdered seeds are made into a paste for drawing boils and, with or without cumin seeds and palm sugar, are prescribed for chroiuc diarrhoea and dysenteiy. The seed coat, too, is astringent, and is also specified for the latter disorders. An infusion of the roots is believed to have curative value in chest complaints and is an ingredient in prescriptions for leprosy (S). 

Green rubber is sometimes used as a primary or secondary binder in disk and drum formulations. Nitrile, styrene-butadiene and chlorinated rubbers have been used for this purpose. These rubbers are intimately mixed with curatives and other ingredients in intensive mixers. 

The effects of shampoos and conditioners on hair body depend on the ingredients and the type of hair. A cleaning shampoo can provide body by removing soils or styling residues that weigh down the hair. Alternatively, shampoos and conditioners can deposit materials on the hair surface that can depress hair volume. Straight fine hair is more sensitive to these effects than is curly coarse hair. 

Thus, the Mooney units measure the extent of mastication or the plastic flow of rubber to enable better dispersion and mixing of ingredients and curatives. In addition to this, the Mooney units can give an indication of the curing nature of compounded uncured rubbers. 

In the nineteenth and early twentieth century, with the increased urbanisation and industrialisation of the UK, the majority of medicines were the so-called patent medicines which contained few active ingredients but had extensive claims for their curative actions. Thus, the controls that had to be applied were on the advertising and claims for the product. It was only after 1935 that the therapeutic revolution brought products which actually had some proven and consistent efficacy. Unfortunately, along with the efficacy came side-effects and problems, since for every pharmacological activity which is beneficial there will inevitably also be side-effects. If we look back at the introduction of controls on medicines, it is generally a problem or disaster which leads to introduction of the specific control. 

We may conj ecture that this plant may possibly be the principal active ingredient of the mysterious Compound-X, described elsewhere in this book, for example, in Chapter 6. Then again, it may not be, depending on who is making up Compound-X. And if this plant is indeed curative, how in the world can a pharmaceutical company compete with what grows wild and free in the southwestern deserts )... 

Preparation of Vulcanizates. For filled compounds prepared from NR and NBR, a Brabender was used to mix the ingredients. A small laboratory mill was used to add the curatives and the antioxidants. The formulations are shown in Tables II and III. 

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