Filler degradable

Fillers. Addition of fillers is not common in polychloroprene latex formulations. Fillers are used to reduce cost and control rheology, solids content and modulus. However, cohesion and adhesion are reduced. Calcium carbonate, clay and silica are some of the fillers than can be added. Alumina trihydrate is often used when resistance to degradation by flame is important. 

Fillers can also be used to promote or enhance the thermal stability of the silicone adhesive. Normal silicone systems can withstand exposure to temperatures of 200 C for long hours without degradation. However, in some applications the silicone must withstand exposure to temperatures of 280 C. This can be achieved by adding thermal stabilizers to the adhesive formulations. These are mainly composed of metal oxides such as iron oxide and cerium oxide, copper organic complexes, or carbon black. The mechanisms by which the thermal stabilization occurs are discussed in terms of radical chemistry. 

Certain fillers are commonly added to protect the urethane backbone from oxidative degradation. Carbon black and titanium dioxide are commonly used in conjunction with antioxidants to protect polyether polyurethanes in exterior adhesive applications that may be exposed to oxygen and light (Fig. 12). 

Modulus Rigid minerals Ductility Ductility produces a more rigid composite. Particulate fillers severely degrade impact strength. 

These fillers are soft and do not dramatically affect mechanical properties. PTFE loadings commonly range from 5 to 20% the others are usually 5% or less. Higher loadings can cause mechanical degradation. 

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

Thermal stability is a crucial factor when polysaccharides are used as reinforcing agents because they suffer from inferior thermal properties compared to inorganic fillers. However, thermogravimetric analysis (TGA) of biocomposites suggested that the degradation temperatures of biocomposites are in close proximity with those of carbon black composites (Table-1). 

In a reactor at low pressure (0.2-0.3 MPa) and moderate temperature (375 °C) the PVC is chemically and thermally degraded. A particular feature of the process is that the chlorine in the PVC reacts in part with the fillers in PVC and is neutralised with the formation of CaCl2. In similar vein, metal stabilisers in PVC are converted into the respective metal chlorides (lead, cadmium, zinc and/or barium). At current PVC waste compositions these chlorides consist of 60% lead which can be purified and re-used. The reaction in the end results in the following solid, liquid and gaseous products. 

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