Curing agents, analysis

Conventional rubber compound analysis requires several instrumental techniques, in addition to considerable pretreatment of the sample to isolate classes of components, before these selected tests can be definitive. Table 2.5 lists some general analytical tools. Spectroscopic methods such as FTIR and NMR often encounter difficulties in the analysis of vulcanised rubbers since they are insoluble and usually contain many kinds of additives such as a curing agent, plasticisers, stabilisers and fillers. Pyrolysis is advantageous for the practical analysis of insoluble polymeric materials. 

Deformulation of vulcanised rubbers and rubber compounds at Dunlop (1988) is given in Scheme 2.3. Schnecko and Angerer [72] have reviewed the effectiveness of NMR, MS, TG and DSC for the analysis of rubber and rubber compounds containing curing agents, fillers, accelerators and other additives. PyGC has been widely used for the analysis of elastomers, e.g. in the determination of the vulcanisation mode (peroxide or sulfur) of natural rubbers. 

Applications Conventional TLC was the most successful separation technique in the 1960s and early 1970s for identification of components in plastics. Amos [409] has published a comprehensive review on the use of TLC for various additive types (antioxidants, stabilisers, plasticisers, curing agents, antistatic agents, peroxides) in polymers and rubber vulcanisates (1973 status). More recently, Freitag [429] has reviewed TLC applications in additive analysis. TLC has been extensively applied to the determination of additives in polymer extracts [444,445]. 

Aromatic amines formed from the reduction of azo colorants in toy products were analysed by means of HPLC-PDA [703], Drews et al. [704] have applied HPLC/ELSD and UV/VIS detection for quantifying SFE and ASE extracts of butyl stearate finish on various commercial yarns. From the calibrated ELSD response the total extract (finish and polyester trimer) is obtained and from the UV/VIS response the trimer only. Representative SFE-ELSD/UV finish analysis data compare satisfactorily to their corresponding SFE gravimetric weight recovery results. GC, HPLC and SEC are also used for characterisation of low-MW compounds (e.g. curing agents, plasticisers, by-products of curing reactions) in epoxy resin adhesives. 

Cyanamides, 3 157-171 23 107 economic aspects, 3 162-163 health and safety factors, 3 163-164 manufacture, 3 161 shipping and handling, 3 162 specifications and analysis, 3 163 Cyanate ester curing agents, 20 411 Cyanate ester resins, production of, 23 769 Cyanation, 9 313 Cyanazine, 23 321-322 Cyan couplers, in chromogenic chemistry, 19 252-253 Cyan dyes... 

Thus, the analysis of the reactivity ratios of the primary and secondary amino groups indicates that for conventional curing agents this cannot be regarded as a serious factor affecting the network topology. 

One implication of Soualmia s result is that the curing agent plays a significant role in determining sr. This means that both the curing agent concentration and moment must be determined as part of the analysis. Sheppard71) has attempted this... 

The fact that a viscosity increase after phase segregation (for t > tp) is connected with such mechanism is evidenced by the results of gel chromatographic (GPC) analysis of solfi action in the network formation process of low-molecular siloxane rubbers (Fig. 15). As the reaction proceeds the molecular mass of the sol fraction decreases and so does its viscosity. However, network formation of a number of epoxy resins cured with amines or other curing agents conform the homogeneous model without microgel formation [88 a]. 

No traces of curing agents were found, further indicating a complete curing reaction. Triphenyl phosphate flame retardant was also found in this analysis. Since devices of this type are predominantly mounted on wooden utility poles, a flame retardant formulation may provide a desirable operating margin in the event of an electrical failure. However, as shown in Figure 10-14, this same insulator was also found to contain polybrominated biphenyls (PBBs), which are banned from manufacture or use in most countries. The analysis of this material protected the electric utility company from potentially inadvertent deployment of a hazardous material. 

Use Analysis (testing for amino acids, cobalt, iodine, urea), food additive (curing agent). 

Diaminobutane, DAB (Aldrich), Di-n-Butylamine, DBA (Aldrich), and Tri-n-Butylamine, TBA (Eastman Organic Chemicals), were used as curing agents. Each was distilled under Helium at one atmosphere and sealed. The amine analysis of Critchfield and Johnson (15)was conducted to determine purity. Table I. The purity and the theoretical equivalence were used to determine the weight of amine needed for a given weight of resin. 

Gonzalez, M. Cabanelas, J.C. Pozuelo, J. Baselga, J.(2011). Preparation of cycloaliphatic epoxy hybrids with non-conventional amine-curing agents. Journal of Thermal Analysis and Calorimetry, Vol.103, No.2, (February 2011), pp. 717-723, ISSN 1388-6150. 

Uses Reagent for detection of free chlorine in water reagent for analysis of gold curing agent for urethane resins intermediate in prod, of azo dyes... 

One-part, heat-curing epoxies require no mixing, since polymerization is initiated by heating the product to tri er the curative in the formulation. Dicyandiamide is a high-temperature curing agent that may be detected in an epoxy matrix by either IR or LC analysis, the latter being carried out on an aqueous methanolic extract of the sample. 

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