Thermal stability, elastomer-modified

W. A. Romanchick, J. E. Sohn, and J. F. Geibel Synthesis, Morphology, and Thermal Stability of Elastomer-Modified Epoxy Resin, in ACS Symposium Series 221 — Epoxy Resin Chemistry II, R. S. Bauer (ed.), American Chemical Society, Washington DC, 1982, pp. 85-118. 

Synthesis, Morphology, and Thermal Stability of Elastomer-Modified Epoxy Resins... 

The objective of this section is to characterize the thermal stability of uncured solid rubber-modified epoxy resins. The effects of extended thermal history on melt viscosity and epoxide equivalent weight are discussed. The influence of the type and concentration of CTBN elastomer in the solid rubber-modified epoxy resin on melt viscosity and EEW is also discussed. Mechanistic considerations are proposed to explain the side reactions which influence the thermal stability of solid rubber-modified epoxy resins. 

Polyolefins A broad class of hydrocarbon-chain elastomers or thermoplastics usually prepared by addition (co)polymerization of alkenes such as ethylene. There are branehed and linear polyolefins and some are chemically or physically modified. Unmodified polyolefins have relatively low thermal stability and a nonporous, nonpolar surface with poor adhesive properties. Proeessed injection, blow, and rotational molding and extrusion. Polyolefins are used more and have more applications than any other polymers. Also called Olefinie Resins, Olefin Resins, and Polyolefin Resins. 

The specific composition of the TPO blend produced depends on the balance of flexural modulus (stiffness) and impact toughness (drop impact and notched Izod) properties needed to meet the target performance specifications. In the formulation of TPO blends, the polypropylene is used normally as the major component, i.e., as the matrix phase, to provide the needed rigidity and thermal stability, while the elastomer dispersion provides the low-temperature impact toughness. A minor amount of a mineral filler such as talc provides additional stiffness and dimensional stability to the TPO. Hence, the levels of elastomer and mineral filler modifiers are carefully adjusted to achieve the desired balance of properties in the TPO. 

The synthetic mbber is widely used, this type of elastomer have important properties and numerous application due to stability. These properties are favored when the synthetic mbber is reinforced with organic nanoparticle as carbon nanombes, nanofibers, graphene, and fuUerene, among other [78-80]. These may or may not be modified nanofiUers surface for subsequent incorporation in the matrix, promoting greater interaction between inorganic nanofillers and polymeric matrix, thus improving the thermal stability of the nanocomposite etc. [81, 82]. 

The reaction of carbenes with olefins to form cyclopropyl derivatives has been used to modify elastomers. Pinazzi and Levesque and Berentsvich et al. found that carbene addition had a significant influence on the properties of polydienes. Thermogravimetric analysis (TGA), flammability and oil resistance in NR and dichlorocarbene modified styrene butadiene rubber (DCSBR) blends were investigated by thermogravimetrie analysis as a funetion of different composition. The TGA plots confirmed the better thermal stability and flame resistance of DCSBR as well as its blends with NR. The amount of DCSBR in the blend significantly affected the properties of blends. 

Saengsuwan S, Saikrasim S (2012) Thermal stability of styrene-(ethylene butylene)-styrene-based elastomer composites modified by liquid crystalline polymer, clay and carbon nanotube. J Therm Anal Calorim 110 1395-1406... 

Besides HALS, another class of photostabilizers used commercially in plastics, elastomer-modified plastics and coatings include preventive stabilizers acting by a preferential absorption of the radiation and transforming the harmful radiation into harmless thermal energy. The role of UVAbs is to inhibit the photo-oxidation of polymeric materials, therefore, they are very important additives used to prevent plastics from photo-degradation by UV. The UVAbs include derivatives of ben-zophenone, triazole, triazine, V-(substituted phenyl) itaconimides, etc. [110-113]. Stabilizers embedded into the polymer matrix are the most photo-reactive components of the system [114—120]. 

Siloxane elastomers present an attractive alternative to the butadiene acrylonitrile elastomers most often used for epoxy modification. Poly(dimethyl siloxanes) exhibit glass transition temperatures well below those of butadiene acrylonitrile modifiers (minimum —123 °C vs. about —40 °C) and also display very good thermal stability13, 14). Other favorable and potentially useful attributes include good weatherability, oxidative stability, and moisture resistance. Finally, the non-polar nature and low surface energy of poly(dimethyl siloxanes) constitute a thermodynamic driving force... 

Processing Stability. As with elastomers or other rubber modified polymers, the presence of double bonds in the elastomeric phase increases sensitivity to thermal oxidation either during processing or end use. Antioxidants are generally added at the compounding step to ensure retention of physical properties. Physical effects can also have marked effects on mechanical properties due to orientation, molded-in stress, and the agglomeration of dispersed rubber particles under very severe conditions. Proper drying conditions are essential to prevent... 

In addition, the conventional division between thermoplastics and thermosets is often losing distinction, while hybrid materials (ionomers, and elastomers of the SBS block type) are appearing, which behave as thermoplastics at elevated temperatures and as thermosets (most important for elastomers) at ambient temperature. Moreover, many thermoplastics are now also modified by cross-linking (either by chemical or radiation process), so they can serve dual pvuposes—good workability as a thermoplastic is combined with the improved thermal and mechanical stability of a thermoset. 

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