Polymer granules plastic containers

The BFS technology is an advanced aseptic processing technique which allows plastic containers to be formed by means of molded extruded polymer granules, filled, and sealed in one continuous process. This differs from conventional aseptic processing where container formation, preparation, and sterilization, and container filling and closiu e are all separate processes. 

Even more interest exists in direct in-polymer analysis of intact bulk samples as delivered (powder, granulate, sheet, film, etc.). This is by no means a simple matter. In fact, as plastic materials usually contain several components, analysis of the levels whilst still in the plastic is usually difficult. Some additives can be analysed without extraction... 

There are different types of plastics that are usually identified by their composition and/or performance. As an example there are virgin plastics. They are plastic materials that have not been subjected to any fabricating process. NEAT polymers identify plastics with Nothing Else Added To. They are true virgin polymers since they do not contain additives, fillers, etc. They are very rarely used. Plastic materials to be processed are in the form of pellets, granules, flakes, powders, flocks, liquids, etc. Of the 35,000 types available worldwide there are about 200 basic types or families that are commercially recognized with less than 20 that are popularly used. Examples of these plastics are shown in Table 1.1. 

Film-coating was developed early in the 1950s to help resolve many of the problems associated with sugar-coating. It involves the application of a film-forming polymer onto the surface of a substrate (such as tablets, granules, and capsules). In addition to the polymer, the film contains plasticizers and colorants, which are needed to achieve the desired properties in the final dosage form. 

The crystallization kinetics of native P(3-hydroxyalkanoic acid) (PHA) granules isolated from the strains of A. eutrophus and P. oleovorans have been studied by measurements of the glass-transition temperature with a differential scanning calorimeter [36]. The comparison is made between PHA in vivo and the isolated polymer. It is demonstrated that the native granules do not contain a plasticizer and the amorphous state of in vivo PHA can be explained by straightforward crystallization kinetics. 

The physical form of the polymer affects the ease of additive dispersion. Powder blending is a low energy process, so polymers like PVC, that need large proportions of additives, are sold in powder form. Pigments or stabilisers, needed in proportions of 1% or less, are often dispersed in an extruder. Granules of a masterbatch, which contain 50% of the additive mixed into the relevant polymer, are mixed with granules of the polymer. Universal masterbatches are becoming more common the host polymer is compatible in small amounts with the major plastics. 

More efficient density separation is possible by introducing plastic granules into a pressurised vessel containing a supercritical fluid. By altering pressure and composition the density of such fluids can be controlled to within +0,001 g/cm. This allows separation of all polymers with the exception of those with overlapping densities [6]. Productivity remains a problem, however, since this is a batch process. 

The mechanical compatibilisation of polymer blends is conceptually an attractive route, leading to unique property combinations and the recycling of mixed polymer scrap. There is considerable impetus behind discovering polymers that exhibit such compatibilising effects and to understand the mechanisms by which they function. Blends would result if certain types of plastic soft-drink bottles were granulated and processed. A bottle type of interest consists of a PET container with an HOPE pedestal, which is needed because the blown bottle has a rounded bottom. It is quite obvious that PET and any PO would be grossly incompatible and that a very effective compatibiliser would be needed to give the blend adequate mechanical properties for any subsequent application [76]. 

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