Inorganic fillers, surface technique

In addition, modem fabrication techniques demand good molding characteristic, i.e., low melt viscosity, in order to enhance the shaping cycle and increase the productivity. When a layered silicate, e.g., montmorillonite is added as an inorganic filler, the fluidity and the surface properties can be improved (24). 

The SEM is also used to do X-ray/elemental analysis. This technique is qualitative. X-ray analysis and mapping of the particular elements present is useful for the identification of inorganic fillers and their dispersion in compounds as well as inorganic impurities in gels or on surfaces and curatives, e.g., aluminum, silicon, or sulfur in rubber compounds and Cl and Br in halobutyl blends. (Figure 9)... 

Simple tests can only indicate which polymer type the plastic contains. To identify materials more precisely, it is necessary to use instrumental analytical methods. Each technique provides specific information either about which polymers or which additives are present, so it is usually necessary to use several in combination. For example, gas chromatography-mass spectrometry (GC-MS) is a destructive technique which allows identification of the polymer, plasticizer and other organic components. X-Ray Fluorescence (XRF) spectroscopy is an effective, non-destructive surface technique for identifying inorganic fillers, pigments and metal components, but carmot be used to identify polymers. 

Most plastic products contain additives or other components, whose purpose is to modify the properties of the base resin, change its appearance, or lower the cost. Blends of more than one polymer are common, and composites contain inorganic fillers. Additives are incorporated into polymers for many reasons, such as altering transition temperatures, improving stability, or enhancing surface properties. NMR is very useful for characterizing the composition of blends, and solid-state techniques provide insight into compatibility and phase structure. Since NMR s sensitivity is limited, its utility for filler and additive analysis is limited, as they are often used at very low (pg/g) levels. In specific cases, however, NMR can be useful even for these components. 

The surface modification technique of inorganic fillers directly affects the filling modification. The common surface modification methods can be classified into three types inorganic filler pretreatment, blending, and masterbatch methods. 

Commercial pyrolyzers are available for the controlled thermal degradation of materials which are difficult to prepare for transmission spectroscopy because of toughness, surface texture, or composition, including certain polymers and rubbers.Carbon-filled rubbers are best identified by this technique. The condensate from the destructive distillation process can be collected on a plate and run by transmission or internal reflection techniques or the gas formed in the chamber can be run directly. The condensate spectra from pyrolysis should be compared with a library of pyrolyzates since they may differ somewhat from that of the starting material. Polymer pyrolyzates, for example, may show new monomer bands whereas any inorganic fillers originally present will be missing. 

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