Rubber—thermosetting blends

Vlassopoulos et al. (1998) examined the gelation of three epoxy-rubber thermoset blends (based on TGDDM/DDS/(acrylonitrile/butadiene rubber/methacrylic acid copolymer) of the same chemistry but different pre-cure treatments. The pre-treatments used heat and catalysts to promote epoxy-carboxyl reactions, and there was some evidence of a decrease in gelation time and an effect on pre-gel rheology with these treatments. 

Structural applications of rubber base adhesives were also obtained using rubber-thermosetting resin blends, which provided high strength and low creep. The most common formulations contain phenolic resins and polychloroprene or nitrile rubber, and always need vulcanization. 

Blends of the commodity polymers with more specialty polymers are limited although many specific examples exist in the patent/open literature. In the design of polymer blends for specific application needs, countless opportunities can be envisioned. Examples may include PE/poly(s-caprolactone) (PCL) blends for biodegradable applications (proposed), polyolefin (PO)/poly(vinyl alcohol) (PVAL) blends for antistatic films, PO/silicone rubber blends for biomedical applications, PO/thermoplastic polyurethane TPU (or other thermoplastic elastomers) for applications similar to plasticized PVC, functionalized PO/thermoset blends. 

When a rubber is crosslinked in the absence of a plastic, as the degree of crosslinking in the rubber increases the viscosity increases and eventually it becomes a thermoset that will not flow at all or melt at higher temperatures. In rubber/plastic blends, when... 

Natural rubber based-blends and IPNs have been developed to improve the physical and chemical properties of conventional natural rubber for applications in many industrial products. They can provide different materials that express various improved properties by blending with several types of polymer such as thermoplastics, thermosets, synthetic rubbers, and biopolymers, and may also adding some compatibilizers. However, the level of these blends also directly affects their mechanical and viscoelastic properties. The mechanical properties of these polymer blended materials can be determined by several mechanical instruments such as tensile machine and Shore durometer. In addition, the viscoelastic properties can mostly be determined by some thermal analyser such as dynamic mechanical thermal analysis and dynamic mechanical analysis to provide the glass transition temperature values of polymer blends. For most of these natural rubber blends and IPNs, increasing the level of polymer and compatibilizer blends resulted in an increase of the mechanical properties until reached an optimum level, and then their values decreased. On the other hand, the viscoelastic behaviours mainly depended on the intermolecular forces of each material blend that can be used to investigate the miscibility of them. Therefore, the natural rubber blends and IPNs with different components should be specifically investigated in their mechanical and viscoelastic properties to obtain the optimum blended materials for use in several applications. 

Thermosetting Blend Systems with Rubbers and Thermoplastics... 

Further information in particular areas can be obtained by using recent reviews. For example, readers who would like to obtain more information on the use of waste rubber in blends with thermoplastics, thermosets and virgin rubber compounds can obtain it in an extensive review that has been produced recently by Karger-Kocsis, Meszaros and Barany [1], This review also surveyed the methods available to reclaim waste rubber, the surface treatment of rubber particles to improve interfacial adhesion in blends, and the principals underlying the compatibilisation of waste rubber within the host matrix. 

The cloud point curves of the epoxy monomer/PEI blend and BPACY monomer/PEI blend exhibited an upper critical solution temperature (UCST) behavior, whereas partially cured epoxy/PEI blend and BPACY/PEI blend showed bimodal UCST curves with two critical compositions, ft is attributed to the fact that, at lower conversion, thermoset resin has a bimodal distribution of molecular weight in which unreacted thermoset monomer and partially reacted thermoset dimer or trimer exist simultaneously. The rubber/epoxy systems that shows bimodal UCST behavior have been reported in previous papers [40,46]. Figure 3.7 shows the cloud point curve of epoxy/PEI system. With the increase in conversion (molecular weight) of epoxy resin, the bimodal UCST curve shifts to higher temperature region. 

Very often particles are blended into polymers, in thermoplasts as well as in thermosets and in synthetic rubbers. This is done for various reasons the aim may be stiffness, strength, hardness, softening temperature, a reduction of shrinkage in processing, reduction of thermal expansion or electric resistance, or, simply, to reduce the price of the material. The fillers used are wood flour, carbon black, glass powder, chalk, quartz powder, mica, molybdene sulphide, various metal oxides, etc. etc. 

Compression moulding of rubbers is not essentially different from that of thermosets. The starting material is a blend of a rubber, vulcanisation ingredients and... 

A plastic foam is a heterogeneous blend of a polymer with a gas. The gas cells are between 1 mm and 0.1 mm. Foams are made from thermoplasts, thermosets and rubbers. In all these cases the foam structure is generated in the fluid condition with thermoplasts it is fixed by solidification, with thermosets and rubbers by the curing or vulcanisation reaction. 

This specification covers expanded unicellular elastomeric plastic material in sheet form intended for use in shock-absorbent containers, impermeable extreme-cold-weather jackets, and decorative insulations. The material specified is a blend of vinyl and a butadiene-acrylonitrile rubber or other thermosetting elastomeric material. Recycled material use is encouraged. 

Much work has been reported on studying the structure of thermoset resins via SAXS, especially focussing on interpenetrating network polymers (IPNs), thermoset nanocomposites, rubber-modified thermosets and thermoset-thermoplastic blends. Most recently Guo et al, (2003) have examined the use of SAXS to monitor the nanostructure and crystalline phase structure of epoxy-poly(ethylene-ethylene oxide) thermoset-thermoplastic blends. This work proposes novel controlled crystallization due to nanoscale confinements. 

The term synthetic polymer refers equally well to linear, saturated macromolecules (i.e., thermoplastics), to unsaturated polymers (i.e., rubbers), or to any substance based on crosslinkable monomers, macromers, or pre-polymers (i.e., thermosets). The focus of this handbook is on blends of thermoplastics made of predominantly saturated, linear macromolecules. 

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