Quantitation, additives Fillers

We used a new silane which readily permits quantitative conversion of silanol-terminated fluids into aminopropyl-terminated fluids. The reaction between aminopropyl-terminated fluids and diisocyanates proceeds smoothly within a few minutes, either in solution or in the melt. The preparation of siloxane-urea block copolymers is performed in either a two- or a three-component process. By carefully choosing the inorganic segment defined by the corresponding silicone fluid, it is possible to obtain silicone mbbers with different material characteristics. The mechanical properties can be tuned from very soft to very hard. Those materials display tensile strengths up to 14 MPa without requiring additional fillers and can be used for diverse applications. 

An unknown commercial detergent may contain some combination of anionic, nonionic, cationic, and possibly amphoteric surfactants, inorganic builders and fillers as weU as some minor additives. In general, the analytical scheme iacludes separation of nonsurfactant and inorganic components from the total mixture, classification of the surfactants, separation of iadividual surfactants, and quantitative determination (131). 

Principles and Characteristics Mass-spectral analysis methods may be either indirect or direct. Indirect mass-spectral analysis usually requires some pretreatment (normally extraction and separation) of the material, to separate the organic additives from the polymers and inorganic fillers. The mass spectrometer is then used as a detector. Direct mass-spectrometric methods have to compete with separation techniques such as GC, LC and SFC that are more commonly used for quantitative analysis of polymer additives. The principal advantage of direct mass-spectrometric examination of compounded polymers (or their extracts) is speed of analysis. However, quite often more information can be... 

Applications The general applications of XRD comprise routine phase identification, quantitative analysis, compositional studies of crystalline solid compounds, texture and residual stress analysis, high-and low-temperature studies, low-angle analysis, films, etc. Single-crystal X-ray diffraction has been used for detailed structural analysis of many pure polymer additives (antioxidants, flame retardants, plasticisers, fillers, pigments and dyes, etc.) and for conformational analysis. A variety of analytical techniques are used to identify and classify different crystal polymorphs, notably XRD, microscopy, DSC, FTIR and NIRS. A comprehensive review of the analytical techniques employed for the analysis of polymorphs has been compiled [324]. The Rietveld method has been used to model a mineral-filled PPS compound [325]. 

Volume swelling measurements have produced erratic results even under the most carefully controlled conditions. One important contribution in this regard is the work of Bills and Salcedo (8). These investigations showed that the binder-filler bond could be completely released with certain solvent systems and that the volume swelling ratio is independent of the filler content when complete release is achieved. Some thermodynamic problems exist, however, when such techniques are used to measure crosslink density quantitatively. First, equilibrium swelling is difficult to achieve since the fragile swollen gel tends to deteriorate with time even under the best conditions. Second, the solubility of the filler (ammonium perchlorate) and other additives tends to alter the solution thermodynamics of the system in an uncontrollable manner. Nonreproducible polymer-solvent interaction results, and replicate value of crosslink density are not obtained. 

Raman and IR spectroscopic studies dealing with the qualitative and/or quantitative determination of rubber compounding ingredients, i.e., the elastomer itself [22, 26-31], fillers [32, 33], vulcanisation chemicals and other additives [34-37], are not included here. The same applies to studies dealing with the crosslinking of elastomers by means of chemicals other than sulfur or peroxide [38-41], self-crosslinking of elastomers blends [42-44], crystallisation (strain-induced) [45-48] and oxidation/ageing [49-53]. 

Carbon black filled NR vulcanisates have been studied by high-resolution solid-state 13C NMR at 75.5 MHz. It is shown that the detection of poly- and mono-sulfidic crosslinks with 13C MAS spectroscopy is also possible in the case of carbon black filled NR vulcanisates. Quantitative results suggest that the addition of carbon black leads to a decrease in crosslink density with increasing filler content [55]. 

Very often, processed plastic materials contain additives plasticizers, stabilizers, fillers, or coloring agents such as pigments. Such additives usually do not interfere with the simple, not very specific, screening tests. For a quantitative determination or for the definite identification of a plastic... 

In addition to spectroscopic techniques, DC has been studied indirectly using micro-hardness methods, either Vicker s or Knoop hardness. There is a good relationship between the DC and micro-hardness [37,40], though the relationship is complicated because micro-hardness is affected not only by DC but also be extent of crosslinking [41], It can also be affected by accidentally placing the micro-hardness in-denter directly on a filler particle. A further disadvantage of the use of micro-hardness is that measurements cannot provide quantitative information on the fraction of double bonds that have undergone polymerization. 

The reactivity and the kinetics of a UV curable system is affected by numerous parameters i.e. nature and amount of photoinitiator and functionalized monomers and oligomers, thickness, light intensity, concentration of O2, the presence of fillers or additives etc. RT-FTIR has been extensively used for the rapid and quantitative assessment of the effect of such parameters on the UV curing kinetics. Further down characteristic examples of the use of this powerful analytical technique are listed. 

As with the predictions of mechanical behavior, predictions of permeability by different models require additional experimental verification to determine the limitations of the expressions proposed. Another interesting point—and one which complicates the quantitative application of permeability expressions— is the possible role of filler-polymer interactions (see also Section 12.3). The mechanism of permeation in polymers is believed to depend upon the ability of segments to move in such a way as to create a hole which can accommodate a penetrant molecule. Thus any restriction or enhancement of mobility would be expected to alter the permeability (Crank and Park, 1969), just as such effects are known to alter the relaxation behavior and hence the glass temperature of a polymer. 

PVC additives such as plasticizers, stabilizers and fillers can be analyzed by this method." " A one gram sample of PVC is extracted in a jacketed Soxhlet apparatus with ethyl ether for 6 hours. After extraction, the solvent is evaporated and a dry plasticizer determined by gravimetry. This quantitative method of analysis is not very precise because stabilizers are other additives that may be extracted together with the plasticizer. 

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