Transparent amorphous polymer

The polysulfones are transparent, amorphous polymers but possess good mechanical properties due to the rigid polymer chains. The glass transition temperatures are in the 180-230°C range, and polysulfones are rated for continuous use in the 150-200°C range. 

Transparent amorphous polymers such as poly(methyl methacrylate) (PMMA) have been found to be useful materials for polymer optical fibers (POFs) (1,2), waveguides (3), lenses (4), optical disks (5), and other optical components because of their excellent mechanical properties and easy processing. Many recently developed optical applications utilizing polarization techniques need optical polymers for maintaining more accurate polarization. However, applications of optical polymers are limited by birefringence which occurs in the process of device fabrication. 

In a thermoplastic, the macromolecules are not cross-linked so that the material can melt, i.e., above the glass transition temperature, the material begins to soften. Thermoplastics can be amorphous or semicrystalline. In microfluidics, amorphous polymers are often preferred because of their optical transparency. Amorphous polymers include polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), and cyclic olefin polymers (COP) and copolymers (COC). COP and COC, unlike most other polymers, are also transparent for UV Ught... 

Polymethyl methacrylate (PMMA) is a typical transparent amorphous polymer. It has been widely used as an important material in optical devices. It has several advantages, including good flexibility, high strength and excellent dimensional stability however, it suffers from shortcomings such as poor heat resistance, a weak mechanical surface and low refractive index [41, 42]. 

Many crystalline polymers are translucent or opaque compared with transparent amorphous polymers (e.g. PS, PMMA). This is because the refractive index of the crystalline region is often different from the amorphous region. However, in the case of poly (4-methylpent-l-ene), the crystalline size can be made small by nucleation (by copolymerization with a-olefins)... 

In this study, the effects of polymer part characteristics such as surface defects and contamination on SDT are examined for polycarbonate (PC), a laser-transparent amorphous polymer. The measured SDT can be used as a reference when selecting the laser power and speed in LTW process development for PC. Some suggestions on how to maximize a polymer s SDT are also provided. 

Pure amorphous polymers, being homogeneous materials, are transparent. Atactic polystyrene is a good example. The crystalline syndiotactic form is not transparent. Alack of transparency does not necessarily indicate crystallinity, however. It can also be caused by inorganic fillers, pigments, gas bubbles (as in a foam), a second polymer phase, etc. 

Glassy amorphous polymers exhibit excellent dimensional stability and are frequently transparent. Everyday examples include atactic polystyrene, polycarbonate, and polymethylmethacrylate (Plexiglas ), which we encounter in such applications as bus shelters, motorcycle windshields, and compact disc cases. 

Crystalline polymers tend to have greater mechanical strength, higher melting points, and higher densities than amorphous polymers. On the other hand, they are usually much less transparent (more opaque) because light is reflected or scattered at the hour dary between the crystalline ana amorphous... 

Cast film extrusion of polyolefins has been developed to obtain flexible films with a high level of transparency by freezing the amorphous polymer structure of the melt on a chill roll. Cast films are mono-oriented in extrusion direction. 

Amorphous polymers are characterized by the following properties They are transparent and very often soluble in common organic solvents at room temperature. The following amorphous polymers have gained industrial importance as thermoplastic materials polyfvinyl chloride), polystyrene, polyfmethyl methacrylate), ABS-polymers, polycarbonate, cycloolefine copolymers, polysulfone, poly( ether sulfone), polyfether imide). 

Since at temperatures below the Tg the chains of an amorphous polymer are randomly distributed and immobile, the polymers are typically transparent. These glassy polymers behave like a spring and when subjected to stress, can store energy in a reversible process. However, when the polymers are at temperatures slightly above the Tg, i.e., in the leathery region, unless crosslinks are present, stress produces an irreversible deformation. 

They are atactic amorphous polymers which have good light transparency (92%) and yield transparent moldings and films. As was noted for polyalkyl acrylates, the solubility parameters decrease as the size of the alkyl groups increases. The flexibility also increases as one goes from polymethyl methacrylate (PMMA) to polyaryl methacrylate and then decreases as the size of the alkyl group is further increased. 

The most widely used polyvinyl acetal is polyvinyl butyrai (PVB). This transparent amorphous plastic is used as a plasticized polymer in the inner lining of safety windshield glass (Saflex). Because of the presence of hydroxyl groups, the commercial product, which is produced from 75% hydrolyzed PVAc, has a Tg of about 49 C and has excellent adhesion to glass. 

Fully amorphous polymers may be transparent, such as PVC, PMMA, PC and PS. They can, in principle, be applied in the optical industry for spectacles, simple photographic lenses etc. For precision optics they are less suited, since because of volume retardation as well as by the fact that they are often manufactured by injection moulding, they cannot meet the requirements of narrow dimension tolerances. Moreover, their low resistance to scratching is a disadvantage in optical applications. 

Thermal and Conducting Properties of Polymer-LiC104 Mixtures. Plots of the conductivity, a, of homogeneous, transparent mixtures of LiCl04 PMMS-8 and PAGS-12 exhibit distinct maxima at ratios of ethylene oxide units to lithium (EO/Li of 20-25 (Figure 2). This behavior is typical for amorphous polymer electrolyte complexes (7, 8). An increase... 

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