Cure profile

Mooaey viscosity, ML + 4 at 100°C, ASTM D1646 cure profile usiag ASTM D3187 compouad, ASTM D2084 total volatile matter, total ash, and total extractables, ASTM D1416 and bound ACN. 

When formulating a silicone adhesive, sealant, or coating, based on hydrosilylation addition cure, one must consider the following properties of the uncured product pot life, dispensing technique, rheology, extrusion rate, cure performance. These characteristics directly affect the processing properties of the polymer base or crosslinker parts. The degree of cure conversion at the temperature of interest is determined by properties such as tack free time, cure profile and cure time. Once... 

Thermocouples were placed in the curing part so that the model could be compared to the actual process. The model accurately predicted the cure time and temperature curing profiles for several parts with different geometries and curing conditions. 

At an A/E ratio of 1.05, wind time of 3.8 minutes and molding temperature of llO C, the curing profiles of the part were simulated varying the press temperature until the maximum exotherm temperature occurred at the center of the part. This condition was achieved at a press temperature of 135 C. The minimal cycle time at the optimal processing conditions was simulated to be eight minutes. 

From the cure profile recorded after a short and intense UV or pulsed laser exposure 18, one can evaluate the actual rate at which the polymer chains are growing. By calculating the ratio Rp/[R ], where [R ] is the number of initiating radicals generated by the UV exposure, we found that 5.104 acrylate double bonds have polymerized per second, for each initiating radical. From this value, the average time for the addition of one monomer unit was calculated to be 20 jlls. 

Epoxy system curing profile, 10 17-18 Epoxy systems, post-cure for, 10 423 Epoxy vinyl ester composites, 10 452 Epoxy vinyl ester resins, 10 349 Epoxy vinyl esters, 10 383 Eprosartan, 5 187... 

The FTIR cure profiles of some I mixtures using the overlap and the acrylate bands (Figure 2) show a fast initial rate followed by a slow down with extended irradiation times. The change in cure regime takes place at... 

Figure 5.8 Temperature and degree of cure profiles in the curing section at Y = 1.5. X is the fraction of the total length of the curing section (i.e., X = 0 denotes the entrance to the curing section). (Top) temperature profile (bottom) degree of cure profile...

In general, upon exposure to UV radiant energy, a photoinitiator can generate free radicals or ions, as pointed out earlier. These are generated at a rapid rate, and their depth profile corresponds to the inverse photon penetration profile. Similar to electron penetration, the final cure profile often deviates from the initial radical or ion distribution, since they can live much longer than the exposure time. The mechanisms of the processes for the generation of reactive species are discussed in detail in Davidson. ... 

The Versamid series of curing agents were the original and best known polyamide curing agents. Current commercial polyamide curing agents and their properties are shown in App. D. More recently developed polyamides provide lower viscosity, better compatibility with epoxy resins, and better cure profiles under adverse conditions. 

The typical application situation is where a new material or structure is being implemented. The question to be resolved is what thermal cure profile (time, temperature, pressure) should be specified. The current approach has been to expend much time and material producing simulated panels for validation. This process is neither rigorous... 

Fig. 8 The DMA cure profile of a two-part epoxy showing the tyrpical analysis for minimum viscosity, gel time, vitrification time, and estimation of the action energy. (From Ref l) (View this art in color at www.dekker.com.)...

The simplest way to analyze a resin system is to run a plain temperature ramp from ambient to some elevated temperature. This cure profile allows collection of several vital pieces of information as shown in Fig. 8. Samples may be run neat or impregnated into fabrics in techniques that are referred to as torsional... 

From the cure profile seen in Fig. 8, it is possible to determine the minimum viscosity the time to... 

Concentration-cure profiles have been determined for acrylate... 

In this the way the effect of the rate of temperature ramping may be taken into account in the total cure profile. In such studies the empirical E data may be adequate, but for detailed kinetic modelling it is generally recognized that isothermal experiments are appropriate, and even they may have limitations, as discussed later. 

Both materials were subjected to the same processing conditions. The cure profile consisted of heating from room temperature to 2 60°C at 5°C/min, holding at 260°C for 2 hours, then cooling to room temperature at 5°C/min. As can be seen in Figure 3, their stress-temperature profiles are quite different. Both films left the spin-coater with approximately zero stress. Upon heating, the polyimide film developed substantial tensile stress due to film contraction from solvent evaporation while the BCB film exhibited only mild tensile stress buildup. The stress in the BCB film relaxed at 260°C while the stress in the polyimide did not. 

The material properties (moduli and relaxation times) are then calculated from knowledge of network structure and free volume. Strains imparted by processing and reaction are determined. These inputs are then applied to a viscoelastic bi-Maxwell model, whereby stress in the polymer is determined. Time is then incremented and the procedure repeated until the cure profile is complete. 

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