PMMA films, thick Poly

In the cases of poly (methyl methacrylate) (PMMA) and poly (vinyl chloride-vinyl acetate) (PVC/PV Ac), these polymers generate much more gas during irradiation than polystyrene. Thus, even if the gases accumulated in microvoids, where their enhancement of creep rate might be lessened, the local gas concentration between the polymer chains should still be much higher than in the case of polystyrene. One would thus expect to see an effect of film thickness on creep rate for these polymers. 

Fig. 18. Induced open-circuit voltage in elongation plotted against amplitude at the end of film for as-cast films polypropylene (PP), high-density polyethylene (PE(H)), low-density polyethylene(PE(L)), polystyrene PS), and poly(methyl methacrylate) (PMMA). Span length = 3.6 cm. Electrode area=2.5 x 2.5 cm2. Film thickness =0.5 mm. Reproduced from Furukawa and others [J. Appl. Polym. Sci. 12, 2675 (1968)] by permission of John Wiley Sons, Inc.

Another type of dependence of effective interfacial width wD on film thickness D was observed [130] for immiscible mixture of deuterated polystyrene (dPS) and poly(methyl methacrylate) (PMMA) (at T TC) an increase, from wd=1.8(4) nm for a dPS layer thickness D=6 nm to wd(D=100 nm)=2.5(4) nm, follows the logarithmic dependence wD°clnD (intrinsic interfacial width w= 1.5 nm). This may reflect [6,224] long range forces acting from the external interfaces on the internal interface Ie(x,y). On the contrary, the relation wd D1/2 found for random olefines [121] corresponds [6,224] to short range forces. We note also that capillary waves in dPS/PMMA system were observed [130] already for the thickness-to-intrinsic width ratio D/w<85 ... 

The original resist used for the LIGA process was thick films of poly(methyl methacrylate) (i.e., PMMA). Because spin coating the very thick... 

Neckers and coworkers could, however, generate hexacene photochemically after the photoprecursor had been embedded in a poly(methyl methacrylate) matrix (PMMA) [29]. Due to immobilization of the molecules, this matrix prevents photodimerization of hexacene and minimizes contact with ambient oxygen. Within the PMMA film ( 0.5 mm thick), hexacene is stable under ambient conditions overnight, but it is slowly oxidized by diffusion of molecular oxygen into the PMMA matrix [29]. 

The influence of the monomer concentration on the film thickness of the surface-attached monolayer is shown in Fig. 9a using poly(methylmethacrylate) PMMA monolayers on glass substrates as an example. With increasing monomer concentration the molecular weight and the film thickness increase. Slight deviations from a linear relationship between monomer concentration and film thickness can be attributed to radical transfer to solvent. As an example for the good optical quality of the monolayers, a waveguide spectrum [29] of an approximately 1700 nm thick PMMA monolayer (100 vol% sample in Fig. 9a) is shown in Fig. 9b. 

Coextrusion is an important process for manufacturing layered plastic composites, such as film, sheet, and tubing (Middleman, 1977 Schrenk and Alfrey, 1983 Schrenketal., 1963). A costly alternative would be the fabrication of individual layers of plastics followed by conventional lamination and coating. An additional advantage of the coextrusion technique is its ability to handle extremely thin films on the order of 10 xm. One of the most colorful applications of this technique is the iridescent film, which consists of hundreds of very thin layers of alternating low and high refractive indices. A typical example of this type of film consists of 116 layers of poly(methyl methacrylate) (PMMA) with refractive index 1.49 and 115 layers of polystyrene (PS) with refractive index 1.59 and total film thickness of about 20 o.m (Radford et al., 1973). 

Russell et al. first observed the formation of multilayered parallel orientations of lamellae in films of symmetric polystyrene-Woc -poly(methyl methacrylate) (PS-b-PMMA) on silicon, referred to as surface-induced ordeting. No preferential orientation was observed in toluene-cast films, but parallel orientation was observed after thermal annealing. This was accompanied by film thickness forming in steps, also known as island and hole formation or terracing. Parallel orientation from selective interactions with walls also occurs for films of cylinders.In all of these films, films were formed on surfaces with a preferential interaction with one of the blocks. 

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