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Cooling polymer/substrate

In the final step, the embossed substrate is cooled to a temperature below the Tg, where the plastic material transitions back to the rigid state. After reaching this lower cycle temperature, the embossing master is mechanically separated from the polymer substrate that now contains the desired microfeatures. Separation is a critical step due to the large forces that act on the polymer structure and mold. This is particularly tme for microstructures with vertical sidewalls and high aspect ratios. The overall cycle time of the embossing process is typically 1-10 min. [Pg.2110]

It should be noted that in the CVD method with laser activation, the method of cooling the substrate during polymer deposition is also effective. This cooling method creates conditions that hamper the polymer s degradation and allows for a considerable increase in the deposition rate. For example, by irradiating a cooled substrate with an excimer laser in an organic gas environment, polymethylmethacrylate (PMMA) films have been selectively deposited with a high deposition rate (Takashima et al. 1994). [Pg.424]

Magnesium hydroxide and aluminum trihydrate are utilized as flame retardants in polymers. They function as flame retardants by releasing water during a fire. The water release cools the substrate and dilutes the combustible gases and oxygen that are required for the fire to continue. The concentration of magnesium hydroxide and aluminum trihydrate... [Pg.174]

Embossing parameters were varied at different levels (from 4kN to 8kN for apphed force and from 160°C to 200°C for embossing temperature). After embossing, the polymer substrate was retained in the chamber and cooled down to 130°C, after which it was separated from the mold. The total cycle time was between 20 to 30 minutes. After de-molding, the rephcation accuracies of the embossed nticro-feature for the micro channel depth were examined by 3D laser microscope and compared with the depth of the stamp. Five measurements at each position were carried out and the average values from these five measurements were used for analysis and correlation. [Pg.960]

The generation of PPV and corresponding derivatives via the dihalide approach is possible not only in solution reaction, but also - via the gas phase -in a so-called chemical vapor deposition (CVD) process. In this process, the vapor of a dichlorinated para-xylene (a,a or a,a) is pyrolyzed at moderately low pressures (0,1-0,2 torr) to form a chlorinated para-xylylene intermediate, which then condenses and polymerizes on a suitable, cooled substrate. The coating of the chlorinated precursor polymer can be heated to eliminate HCl, to form PPV 60 (or a PPV derivative) [88]... [Pg.196]

Fig. 1 Melting temperatures of polymers k%Tm/Ec) with variable Ev/Ec values. The line is calculated from Eq. 10 and the circles are the simulation results obtained from the onset of crystallization on the cooling curves of disorder parameters, in a short-chain (r = 32) system (occupation density is 0.9375 in a 32-sized cubic box) with a template substrate (Hu and Frenkel, unpublished results)... Fig. 1 Melting temperatures of polymers k%Tm/Ec) with variable Ev/Ec values. The line is calculated from Eq. 10 and the circles are the simulation results obtained from the onset of crystallization on the cooling curves of disorder parameters, in a short-chain (r = 32) system (occupation density is 0.9375 in a 32-sized cubic box) with a template substrate (Hu and Frenkel, unpublished results)...
The substrates were admixed with 50 mol% of copper(I) chloride and small amounts of l-(2-propyl)-3-methylimidazolium hexafluorophosphate (pmimPF6) in dioxane. The mixture was heated to 110 °C within 2 min and kept at this reaction temperature for an additional 1 min. After cooling to room temperature, the product was rapidly released from the polymer support employing 20% trifluoroacetic acid (TFA) in dichloromethane, furnishing the corresponding bis-TFA salt in moderate yield. [Pg.335]

Si-H bonds add across olefins over platinum catalysts. This reaction (hydrosi-lation) is used in silicone polymer manufacture, when the silane is a hydrogen bearing oligo(alkylsiloxane). With some types of olefin there have been reports of runaways to explosion because of unexpectedly fast reaction. Dangerous substrates recorded are 2-allylphenols and ethenylsiloxanes. Very low levels of catalyst (ppm) and good cooling are recommended. [Pg.381]


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See also in sourсe #XX -- [ Pg.215 ]




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