Polyester films specific materials

Polyester-styrene resins have a low raw material price and are used in wood finishing. Disadvantages are the presence of volatile styrene and the low cure speed. Products with methacrylic groups are used where line (cure) speed is less important, mainly in combination with acrylates in special end uses (e.g., in the electronics industry and in photopolymer printing plates) to improve adhesion or to obtain specific physical properties. Thiol- thiene mixtures can lead to very flexible cured films but their odor seriously limits their use. 

In 2000, we have begun our research on this topic paying particular attention to the possibility of finding new chemical systems able to frontally polymerize and new FP applications. Specifically, we have studied polyurethanes (19, 20), polyester tyrene resins (21), polydicylopentadiene (22) and its BPNs with polyacrylates (23), Furthermore, we were able to prepare films (24) and to apply FP to the consolidation of porous materials (i.e. stones, woods, flaxes, papers), in particular -but not only- those having a historical-artistic interest (24), In this chapter we present a brief overview of these recent findings. 

A principle advantage of organic electronics is that large, flexible and low cost substrates can be used. Polymer films, such as polyester, are the most widely used today but paper, cardboard, thin glass and stainless steel are also potential candidates. Special surface treatments or barrier layers can be added if necessary. The material best suited for a specific application depends on the process conditions, surface roughness, thermal expansion, and barrier properties. 

The flexible materials used for medical device packages include a plastic film that is usually a lamination or extrusion-coated material. The material most commonly used for flexible packaging applications is oriented polyester (e.g.. Mylar ), which is used as a base for properties such as dimensional stability, heat resistance, and strength with an adhesively laminated se layer such as low-density polyethylene, which provides the film structure with heat sealability. The variety of film combinations is virtually unlimited and the performance properties of the film can be customized to meet the requirements of the package specifications and the medical device. Other examples of film constructions are... 

Both IR and Raman spectroscopies are vibrational spectroscopies that provide a unique identification of the substance, or a fingerprint. They are used extensively to determine the composition of materials as discussed by Koenig [3]. Lang et al. [4] showed that IR and Raman provided complementary information about the fibers. They comment that sample preparation is far easier for these methods than the traditional characterization methods based on the solubility of the fibers. In this mode, Raman is used to determine whether a film or fiber is nylon, polyester, polypropylene, cotton, wool, and so forth. Each type of material will have Raman bands specific to the type of polymer of which it is composed. If copolymers are present, the Raman spectra can be used to determine the ratio of comonomers. Many comonomers are strong Raman scatterers (aromatics, double and triple bonds, carbonyls, etc.). Others are weak Raman scatterers (NH, OH, etc.) and are better determined by IR. In either case, an appropriate calibration is required and the spectroscopist needs to make an educated selection between IR and Raman or perhaps use both. 

These materials can be joined by mechanical self fastening methods or by mechanical fasteners. Polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) parts are generally joined by adhesives. Surface treatments recommended specifically for PBT include abrasion and solvent cleaning with toluene. Gas plasma surface treatments and chemical etch have been used where maximum strength is necessary. Solvent cleaning of PET surfaces is recommended. The linear film of polyethylene terephthalate (Mylar ) surface can be pretreated by aUcahne etching or plasma for maximum adhesion, but often a special treatment is unnecessary. Commonly used adhesives for both PBT and PET substrates are isocyanate cured polyesters, epoxies, and urethanes. Polyethylene terephthalate cannot be solvent cemented or heat welded. 

The material characteristics (polysaccharide, protein, polyester, plasticised or not, chemically modified or not, used alone or in combination) and the fabrication procedures (casting of a film forming solution, thermoforming) must be adapted to each specific agricultural product and usage condition (irrigation, temperature, cultivation duration, etc.). 

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