Polymer additive system

Unfortunately, extraction procedures are often elaborate and labour intensive since many of the polymer matrices are poorly soluble or insoluble. For this reason, substantial efforts have been directed towards additive analysis without prior separation from the polymer. Chapter 9 deals with direct methods in which such separation of polymer and additive can be omitted. Yet, this direct protocol still requires sample pretreatment (dissolution) of the polymer/additive system as before. 

The polymer/additive system in combination with the proposed extraction technique determines the preferred solvent. In ASE the solvent must swell but not dissolve the polymer, whereas MAE requires a high dielectric solvent or solvent component. This makes solvent selection for MAE more problematical than for ASE . Therefore, MAE may be the preferred method for a plant laboratory analysing large numbers of similar samples (e.g. nonpolar or polar additives in polyolefins [210]). At variance to ASE , in MAE dissolution of the polymer will not block any transfer lines. Complete dissolution of the sample leads to rapid extractions, the polymer precipitating when the solvent cools. However, partial dissolution and softening of the polymer will result in agglomeration of particles and a reduction in extraction rate. 

SFE has now been available long enough to allow an evaluation of its prospects for polymer/additive extraction. SFE is still around, but EPA and FDA approved SFE methods are still wanting. The main problem is strong matrix effects. SFE is not a cookbook method for one s matrix. Not unlike microwave extraction, SFE requires that a specific method be developed to optimise the recovery for each polymer/additive system. Therefore, the success of SFE depends on the polymer... 

Table 3.48 Comparison of extraction performance of polymer/additive systems...

Howard [772] has been amongst the first to show the usefulness of conventional SEC for polymer/additive systems. Coupek el al. [773] have also reported results with this technique in an early stage their work was limited to synthetic mixtures of additives. The use of open-column SEC in the analysis of plastics additives has been reported [774], Qualitative analysis of additives has been performed by stopped-flow SEC with IR detection [775]. Polypropylene oligomers were isolated from a PP/(Irganox 1010, Irgafos 168, DBS) matrix by dissolution (toluene)/precipitation (methanol) and Soxhlet... 

The applicability of alternative photothermal densitometric techniques, such as PAS, for characterisation of TLC plates with particular emphasis on the in-depth distribution of compounds in the sorbent, has been investigated [776], No specific applications for polymer/additive systems appear to have been reported so... 

Applications Multidimensional SEC techniques can profitably be applied to soluble polymer/additive systems, e.g. PPO, PS, PC - thus excluding polyolefins. A fully automated on-line sample cleanup system based on SEC-HRGC for the analysis of additives in polymers has been described, as illustrated for PS/(200-400ppm Tin-uvin 120/327/770, Irgafos 168, Cyasorb UV531) [982], In this process, the high-MW fractions are separated from the low molecular masses. SEC is often used as a sample cleanup for on-line analysis of additives in food extracts these analyses are usually carried out as on-line LVI-SEC-GC-FPD. 

Whereas the use of conventional fast atom bombardment (FAB) in the analysis of polymer/additive extracts has been reported (see Section 6.2.4), the need for a glycerol (or other polar) matrix might render FAB-MS analysis of a dissolved polymer/additive system rather unattractive (high chemical background, high level of matrix-, solvent- and polymer-related ions, complicated spectra). Yet, in selected cases the method has proved quite successful. Lay and Miller [53] have developed an alternative method to the use of sample extraction, cleanup, followed by GC in the quantitative analysis of PVC/DEHP with plasticiser levels as typically found in consumer products (ca. 30 %). The method relied on addition of the internal standard didecylphthalate (DDP) to a THF solution of the PVC sample with FAB-MS quantitation based on the relative signal levels of the [MH]+ ions of DEHP and DDP obtained from full-scan spectra, and on the use of a calibration curve (intensity ratio m/z 391/447 vs. mg DEHP/mg DDP). No FAB-matrix was added. No ions associated with the bulk of the PVC polymer were observed. It was... 

Principles and Characteristics Although it might appear that MALDI-ToFMS should perform particularly well only for the polymer part of polymer/additive systems, the technique also yields useful information about additives contained in UV-insensitive polymers, such as polyolefins. The latter materials are hardly an insignificant part of the total polymer market ... 

Howard, J.M. Gel permeation chromatography and polymer additive systems. J. Chromatogr. 1971, 55, 15-24. 

The book is an up-to-date coverage of the present state of knowledge on the subject of polymer additive systems and as snch shonld be extremely useful to workers in the field. 

The free-volume fluctuation model (43) which is based on the average free volume and its fluctuations has been successful in describing such differences in density fluctuations of different polsrmers as well as to explain the suppression of the intensity of sub-glass processes in polymer/additive systems. According to the model, the free volume is assiuned to have a Gaussian distribution characterized by two parameters (7) the average free volume (V) and (2) the distribution of free volume, which is given by the variance of the distribution P(5V). The... 

It is probably true to say that the more data are amassed on the correlation between laboratory weatherometers and direct sunlight, the more is there a tendency to use direct sunlight testing at suitably chosen sites in various parts of the world, and to restrict laboratory accelerated weatherometer work almost entirely to control testing, where a correlation has already been fully established on a given polymer/additive system. 

Creating the potentially useful components of intumescent polymer additive systems. 

Lykke et al. [177,262] have used L MS (ToF-MS, FTMS) in resonant and non-resonant mode for the molecular analysis of complex materials, including polymer/additive systems. Different wavelengths for the post-ionisation step (near-UV, far-UV, VUV) permit selectivity that provides important additional information on the chemical constitution of these complex materials. LDI techniques render more accessible analysis of complex materials such as polymers and rubbers containing a wide variety of additives and pigments. Lykke et al [218] also compared laser desorption, laser desorption/post-ionisation and laser ionisation in both direct and extract analysis of three vulcanised rubbers (natural rubber, SBR and poly(c/5 -butadiene)). Desorption (532, 308, 266 nm)/post-ionisation (355, 308, 266, 248, 213, 118 nm) was carried out with various lasers. Desorption (308 nm)/post-ionisation (355 nm) with REMPI detection allows preferential detection of various additives (antiozonant HPPD, m/z 268, 211, 183, 169 antioxidant poly-TMDQ, m/z 346, 311) over the ubiquitous hydrocarbons in a rubber (Fig. 3.13). 

A cautionary note is that, in addition to the polymer itself, the polymer additive system may contain elements other than carbon, hydrogen and oxygen. The detection of an element such as nitrogen, sulphur, halogens, phosphorus, silicon or boron in a polymer... 

In this chapter, we turn our attention to binary mixtures of different polymers. These are perhaps better termed pseudo-binary because here we do not consider molecular weight distribution effects of polymer chains of different molecular weights as independent species. Our hrst concern is with miscibility, as it was with polymer-solvent systems in Chapter 3 and with polymer-additive systems in Chapter 4. We consider which polymer structures are likely to lead to miscibility. This leads to a consideration of partially miscible systems and to mixtures involving copolymers. Finally, we consider immiscible polymer blends. Here we emphasize the role of interfacial tension between phases and the factors influencing phase morphology. 

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