Blend analysis

Conduct blend analysis on batches by extensively sampling the mix in the blender and/or intermediate bulk containers. 

Synergism occurs with fructose (Hyvonen el al., 1978), aspartame, cycla-mate (Bakal, 1987) and sucralose (Tate Lyle Pic, 1986). Negative synergy (i.e. suppression) occurs with acesulfame K blends. Analysis of saccharin is usually done using HPLC (Halm Gilikson, 1987) or spectrophotometric methods (Ramappa Nayak, 1983). 

Dietrick, J. Special forum on blend analysis. Presentation sponsored by PDA, Rockville, MD, Jan. 1996. 

Oils and lubricants Mineral and synthetic oils, greases, coolants, hydraulic fluids Blending analysis Additive chemistry Oil degradation monitoring... 

The objective of blend analysis is to determine whether the blend is uniformly mixed or not (very similar to CU, except BU is for powders and CU is for dosage units). What one needs is quick answers during blend analysis, so fast and simple methods are preferable. There is no need to develop a new HPLC method for blend analysis, since the CU method can easily be employed here. 

The focus of automation is not solely on HPLC anymore (since it is automated), but also includes the sample preparation procedure for drug products since it involves many labor intensive steps (weighing, addition of sample solvent, extraction procedure, mixing, filtration, additional dilutions, second mixing, etc.). So, if the sample preparation procedures are automated and combined with HPLC, then the entire analysis is said to be fully automated whether it is for assay, CU, blend analysis, or even for dissolution testing. Such automated workstations are currently available from number of vendors (Caliper Life Science, SOTAX Inc.), but their ability to integrate with HPLC or UV spectrophotometer is left to the end users. This open-ended option depends on the end user requirements. 

Data Analysis. A tacit assumption that the support material contributes little or no retention to the observed retention by the polymeric coating is usually made in the IGC literature. In a published work (17), and from a large body of recently gathered data, it has been confirmed that retention by the so-called inert support may actually account for up to 10% of the observed retention of the column. Furthermore, the support retention was found to be a function of the amount of probe injected, especially for strongly polar probes. It became clear that this factor alone could undermine the blend analysis if it were not handled properly. 

Kadla, J.F. Kubo, S. Lignin-based polymer blends analysis of intermolecular interactions in lignin-synthetic polymer blends. Composites, Part A Appl. Sci. Manuf. 2004, 35 (3), 395-400. 

Lbonard, C., Halary, J. L., Moimeiie, L., (1988), Crystallization of poly(vinylidene fluoride)-poly(methyl methacrylate) blends analysis of the molecular parameters controlling the nature of p>oly(vinylidene fluoride) crystalline phase. Macromolecules, Vol 21, No. 10, (October 1998) pp. 2988-2994, ISSN 0024-9297. 

Kelusky et al. [11] have also applied TREF for EVA copolymer analysis. Their interest was mainly in the use of TREF for blend analysis involving these copolymers. They did, however, evaluate a series of six EVA copolymers in the range of 8 to 24 wt.%, showing how the TREF separation was dependent on the total branching, polyethylene type as well as VA. The resins analysed are listed in Table 4 which includes the analysis of all branches by NMR. The TREF curves (Fig. 23) clearly show the sensitivity of the separation to the total SCB level. 

Blend analysis by TREF was first described by Knobeloch and Wild [14] and was specifically directed toward the evaluation of LLDPE/LDPE blends. This type of blend is sold commercially and is very difficult to analyse because the two components overlap both in terms of molecular weight and more importantly with respect to the level of short-chain branching. However, there is considerable difference in overall SCB distribution of the two types of PE (Fig. 34). There is a part of the low branched region of a LLDPE which has no counterpart in a similar density LDPE and is thus free from any overlap from the LDPE component. As a result, the high separation temperature peak in such a blend can be used as a measure of the LLDPE component. 

In this necessarily convoluted approach to blend analysis, the authors pointed out that there are three crucial requirements for success. First it is important that there be a high level of reproducibility in the TREF analysis. In order to achieve this they introduced some modifications to their experimental TREF technique. They included ... 

As indicated in the introduction there is a distinct correlation between the commercial growth of linear low density polyethylene and the resurgence of interest in the temperature rising elution fractionation technique. It is clear, however, from the wide variety of examples noted in this review that the scope of TREF extends well beyond the LLDPE area. Since the TREF technique is becoming available to many more research workers it is anticipated that there will be continued growth and development which will lead to greater sophistication in the way the technique is utilized, particularly in the polyolefin area. The power of TREF for blend analysis and cross-fractionation is certain to be exploited in the coming years. 

Crystaf has also started to gain recognition as an efficient technique to analyze polyolefin blends quantitatively, as it is considered to be superior to the conventional DSC method. It is quite certain that its use for blend analysis will become more common in the near future. 

It is a common practice in textile manufacturing to blend fibers of two or more generic types to achieve desired fabric characteristics. For example, cotton is often blended with polyester terephthalate (PET) fibers to enhance durability and make the fabric easy to care for. The proportion of each type of fiber in the total blend must remain constant in the manufacturing process. Normally, polyester/cotton blend analysis is performed by dissolving cotton in 70% H2SO4 solution. This procedure requires 8 h before the final result is obtained. NIRA is used to perform a blend analysis within 2 min in textile laboratories. 

In analogy with the conformationally and interaction asymmetric thread blend analysis discussed in Section VI.C, Schweizer has derived analytic results for the microphase spinodal based on the R-MMSA and R-MPY/ HTA closures. The focus here is not on the rather universal fluctuation stabilization phenomenon discussed above but the influence of system-specific block stiffness and attractive interaction differences on the location of the (spinodal) microphase separation temperature. 

Three major error sources may be indicated the inaccuracy in the determination of the P content, the variability in the blend composition (at macro or micro level) and the stability of the standards. Irganox B220/B225 blend analysis based merely on P analysis (with XRF) translates a 5 ppm uncertainty... 

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