Mixed plastics dissolution

A hydrocyclone system has been proposed for the separation of mixed plastics including among others HIPS. Both water and calcium chloride solutions have been used. A procedure for the determination of the HIPS content in a ABS/HIPS material has been proposed. The analysis method relies on the selective dissolution in R-limonene (44). 

Ghebremeskel A, Vemavarapu C et al (2007) Use of surfactants as plasticizers in preparing solid dispersions of poorly soluble API selection of polymer-surfactant combinations using solubility parameters and testing the processability. Int J Pharm 328(2) 119-129 Gogos C, Liu H (2012) Laminar dispersive and distributive mixing with dissolution and applications to hot-melt extrusion. In Douroumis D (ed) Hot-melt extrusion pharmaceutical applications. Wiley, New York, pp 261-284... 

RPLC-PDA is frequently used for quality control, such as the determination of free Irganox 1098 in PA4.6 (at 278 nm after dissolution/precipitation), of free Irganox 1010/1076 in PP (at 278 nm after extraction with MTBE, thus avoiding dissolution of polymer waxes), of Luperco 802 in PP (at 218 nm, after extraction with HCC13), and of Tinuvin 122 in HDPE (at 225 nm as diol). The advantages of the use of HSLC over conventional LC in QC of plastics and additives have been demonstrated, e.g. for AOs in PE, mixed phthalate esters and residual terephthalic acid in PET and partially cured epoxy resins [557],... 

The ash is placed in a 100 ml Teflon beaker, containing 5 ml of HF (cone.) and 15 ml of HN03 (cone.). Dissolve the ash by warming, then evaporate just to dryness. Add water and 1 ml of HN03 to dissolve the salts and transfer to a 100 ml volumetric flask. Make to volume with water and mix. Immediately transfer to a plastic bottle and preserve as a stock solution for determining elements which do not require a specialized dissolution technique. 

Typically, finer granules with lower bulk densities can be obtained when a smaller volume of liquid is added during mixing. Moreover, these granules of smaller particle size yield tablets with faster dissolution rates and lower hardness values (75). The mechanical properties of a binder film are important as well and a good tablet binder should be able to offer flexibility and plasticity and yield without rupturing in order to absorb the effects of elastic recovery (62). 

Vane, L., and Rodriguez, F. "Selective Dissolution Multi-Solvent, Low Pressure Solution Process for Resource Recovery from Mixed Post-Consumer Plastics" Proceedings of the Society of Plastic Engineers Regional Technical Conference -Recvclint Technology of the 90 s. Chicago, IL. 1990. 

After the dispersion milling process is complete—that is, after 24 or more hours of milling—the mill is opened and the plasticizer or plasticizers are poured onto the top of the slip. Most plasticizers are liquids and quite fluid, and therefore this is not a complicated procedure. The plasticizer or plasticizers form a thin film on the surface of the slip in the mill. The weighed quantity of binder, either in powder form or dissolved in one or both of the solvents, is then added to the layer of plasticizer(s). Usually the binder is more soluble in the plasticizer(s) than it is in the solvent(s), so it is good practice to introduce the binder to the plasticizer first. Remember from Chapter 2 that the whole point of the Type I plasticizer is to react with (dissolve) the binder. The plasticizer wets the binder if it is in powder form and aids in the dissolution process. It is also good practice to make sure that the binder, if in powder form, is stirred into the slip mixture before the mill is sealed and returned to the rollers. We have found large clumps of undissolved binder after 12 hours or more of mixing if we didn t follow this simple procedure. 

In this case, we have an electrolyte identical to that which is present in lithium-polymer batteries, made of poly(ethylene oxide) (or PEO) in the presence of a lithium salt, solid at ambient temperature, and which needs to be heated above ambient temperature in order for the battery to work (T > 65°C for PEO). Thus, the electrolyte, in its molten state, exhibits sufficient ionic conductivity for the lithium ions to pass. This type of electrolyte can be used on its own (without a membrane) because it ensures physical separation of the positive and negative electrodes. This type of polymer electrolyte needs to be differentiated from gelled or plasticized electrolytes, wherein a polymer is mixed with a lithium salt but also with a solvent or a blend of organic solvents, and which function at ambient temperature. In the case of a Li-S battery, dry polymer membranes are often preferred because they present a genuine all solid state at ambient temperature, which helps limit the dissolution of the active material and therefore self-discharge. Similarly, in the molten state (viscous polymer), the diffusion of the species is slowed, and there is the hope of being able to contain the lithium polysulfides near to the positive electrode. In addition, this technology limits the formation of dendrites on the metal lithium... 

Polyvinyl chloride (PVC) has peculiar material characteristics because of its high level of syndiotactic vinyl chloride units. The polymer as a result has a low to modest level of crystallinity (-10%). The uncrystaUized regions in PVC are subject to dissolution by polar solvents. The solutions formed have exothermic heats of mixing and negative deviations from ideality. Non-volatile polar liquids, which dissolve amorphous PVC, are called plasticizers . PVC now becomes an elastomeric mixture of small crystalline regions and a solution phase. These materials are called plasticized polyvinyl chloride. 

---