Elastomers reactive

Polyepichlorohydrin (PECH) is well known as a reactive elastomer. Displacement at the carbon-chlorine bond of PECH has been accomplished with a wide variety of nucleophilic reagents, for the purposes of polymer modification, grafting and crosslinking (1, 2). On the other hand, the PECH structure (1) is hardly optimal from the point of view of its reactivity as a substrate for nucleophilic... 

Reactive impact modifiers are preferred for toughening of PET since these form a stable dispersed phase by grafting to the PET matrix. Non-reactive elastomers can be dispersed into PET by intensive compounding but may coalesce downstream in the compounder. Reactive impact modifiers have functionalized end groups. Functionalization serves two purposes - first, to bond the impact modifier to the polymer matrix, and secondly to modify the interfacial energy between the polymer matrix and the impact modifier for enhanced dispersion. Some examples of commercially available reactive impact modifiers for PET are shown in Table 14.3. An example of a non-reactive elastomer that can be used in combination with reactive impact modifiers is ethylene methyl acrylate (EMA), such as the Optema EMA range of ethylene methyl acrylates manufactured by the Exxon-Mobil Chemical Company (see Section 4.2). 

The chemical reaction between glycidyl methacrylate (GMA) end groups on the reactive elastomer and the carboxylic acid end groups of PET is shown in... 

Figure 14.7 Schematic highlighting the microstructure of rubber-toughened PET and performance improvements when non-reactive elastomers are blended with reactive elastomers (adapted from Atofina literature entitled Lotader and Lotryl )...

E-EA-GMA (see Table 14.3) and EEA are often used in combination as a toughening system. The optimum blend ratio of reactive elastomers non-reactive elastomers (e.g. Lotader Lotryl) is 30/70. Since the E-EA-GMA terpolymer and EEA copolymer are mutually miscible, when blended together with PET the mixture acts as a single elastomeric phase, which is interfacially grafted to the PET continuous phase. 

Hence a low molecular weight, reactive elastomer is normally used for impact modification of thermosets. The low molecular weight of the mbbery prepolymer aids its easy dissolution or dispersability in the thermosetting resin. The reactive functionality couples the rubber covalentiy to the growing polymer network during the curing reaction. Hence the rubber toughened thermosets may also be considered as co-reacted thermosets and not true blends. 

Rubber toughened epoxy resins are the well known examples of impact modified thermosets utilizing reactive rubbery prepolymers. Epoxy resins can be toughened or flexibilized by any one of the following types of oligomeric reactive elastomers ... 

Many anaerobie adhesives and sealants may require a relatively low strength so that the eomponents can be disassembled for repair or replacement. Many liquid plasticizers have been used for this purpose [62], but the use of a low-molecular-weight polyester has been found to be advantageous [63]. The toughness properties of anaerobic adhesives can be enhanced by the addition of a reactive elastomer [64]. The heat resistance of anaerobic adhesives and sealants can be enhanced by the addition of a bismaleimide... 

Accelerators similar in solubility parameter to less reactive elastomers (Amidon and Gencarelli, 1972 Mastromatteo et al., 1971 Sumitomo Chemical Company, 1973 Woods and Mars, 1974). 

Accelerators similar in solubility parameter to less reactive elastomers [35g-j]... 

PA 6/elastomer Elastomers EPR-g-MA, SBS-g-MA, VP701, EPR, E-MA-GMA, PE-GMA, PP-g-MA 95/5 Cloisite 30B PA 6 phase Reactive elastomers, mainly EPR-g-MA and SBS-g-MA, result in better improvement in toughness compared to other elastomers. A tensile property increases in the presence of organoclay Kelnar et al. 2005, 2006... 

Metal Detectable, 100% Metal Detectable and non metal detectable. All PATENTED models are manufactured with a unique, Ultra-Soft, heat-reactive elastomer that starts soft and continues to get softer once it is inserted into the ear canal until within a matter of one -two minutes there is virtually no pressure. 

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