Viscosity profile

Melt Viscosity. Viscosities of resins at standard temperatures yield information about molecular weight and molecular weight distribution, as weU as valuable information with respect to appHcation logistics. Some customers prefer to receive resins in molten form. Melt viscosities help to determine the required temperature for a resin to be pumpable. Temperature—viscosity profiles are routinely suppHed to customers by resin manufacturers. In general, a molten viscosity of 1—1.1 Pa-s (1000—1100 cP) or less at process temperatures is convenient for the pumping and handling of molten resin. 

Solution The numerical integration techniques require some care. The inlet to the reactor is usually assumed to have a flat viscosity profile and a parabolic velocity distribution. We would like the numerical integration to reproduce the paraboUc distribution exactly when q, is constant. Otherwise, there will be an initial, fictitious change in at the first axial increment. Define... 

A plot of Tvs. G yields a rheogram or a flow curve. Flow curves are usually plotted on a log-log scale to include the many decades of shear rate and the measured shear stress or viscosity. The higher the viscosity of a liquid, the greater the shearing stress required to produce a certain rate of shear. Dividing the shear stress by the shear rate at each point results in a viscosity curve (or a viscosity profile), which describes the relationship between the viscosity and shear rate. The... 

Fig. 3 Newtonian and non-Newtonian behaviours as a function of shear rate (a) flow profile (b) viscosity profile. (From Ref. 65.)...

This defines a stress-dependent packing fraction. This is shown as a function of stress in Figure 6.7, which is sigmoidal in form, mimicking a mirror image of the viscosity profile. 

Diffusion Rate Controlled Process If the rate of chemical reaction is much faster than the diffusion of water and EG through the solid amorphous phase, then the reaction can be considered to be at equilibrium throughout the pellet [21], The reaction rate is dependent upon the pellet size, the diffusivity of both water and EG, the starting molecular weight, and the equilibrium constants Ki and K5. In addition, the pellet can be expected to have a radial viscosity profile due to a by-product concentration profile through the pellet with the molecular weight increasing as the by-product concentrations decreases in the direction of the pellet surface [22-24],... 

In this study, we present evidence for the first time of a three-way interaction among starch, protein, and lipid that alters starch paste viscosity profiles. (Adapted from Zhang and Hamaker, 2003)... 

Adsorption isotherms for AMP-QS onto kaolin, titania and calcium carbonate are shown in Figure 4. Viscosity profiles obtained when AMP is used to disperse titania and kaolin are shown in Figures 5-7. 

Figure 6 Viscosity profile for kaolin dispersed with AMP and polyacrylate...

Fig. 23 Viscosity profiles of (a) native starch, (b) Native starch heated up at 50°C for 24 h. (c) Telomerized starch with DS = 0.055. (d) Telomerized starch with DS = 0.1. Dotted line. temperature profile...

In all above- and below-cited publications in this field (e.g. 84 ) the problem was solved in order to calculate the tensors of strain velocity and stress, to prognosticate alteration of longitudinal viscosity, profile of alteration of the thickness of material over the height of the film sleeve (by coordinate on the central line of the sleeve counted from the outlet face of the extrusion head) and configuration of the sleeve ( bubble ) and also to solve thermal problems in order to determine the dependency of melt temperature upon height (or time) and to forecast the position of the crystallization... 

Figure 11.24 RFM viscosity profile (Pa-s units) between the rolls using a power law viscosity model with a power law index, n, of 0.5.

Barley starch (see Chapter 16) has a viscosity profile similar to that of potato starch and also has a similar range of applications.159 Seib and Wu160 claimed excellent freeze-thaw stability in a hydroxypropylated waxy barley starch. 

Figure 3 Viscosity profile of a 0.05% CMC sol, showing the effect on viscosity of order of addition of tartaric acid (TA) to water (a) before and (b) after dispersion of CMC.

An initial negative slope of iq, vs ct in a dilute water dispersion (electroviscosity) of a polysaccharide is indicative of polyanionic character. Electroviscosity disappears in excess electrolyte solution and is nonexistent in neutral polymer viscosity profiles. 

Figure 2 Viscosity profile of selected samples of pectin in aqueous dispersions, as a function of ethanol content.

Figure 6 Viscosity profile of gellan in water (1), gellan in 0.04-M tartaric acid (2), locust bean (3) and methylcellulose (4) in water, and CMC in 0.04-M tartaric acid (5).

Figure 7 Viscosity profile at 28°C of 0.05% CMC in different molal concentrations (M) of tartaric acid.

Figure 8 Viscosity profile at 28°C of aqueous CMC at different concentrations (c) in 0.35 M tartaric acid solution.

Waxy com starch contains only amylopec-tin com starch contains both amylopectin and amylose. This results in a different viscosity profile (Figure 8-37). Com starch shows a lower peak viscosity and less breakdown during heating. After cooling, the viscosity continues to increase, probably because the amylose interlinks with the amylopectin. On further storage at 25°C, the slurry sets to a firm gel. Tapioca starch is intermediate between com and waxy com starch (Figure 8-37). This is explained by the... 

Note For adhesive film samples, this is not practical. Samples are cut to the appropriate diameter (generally 25 mm parallel plates, due to their high viscosity profile) and 2 to 3 plies placed on the fixture. 

Figure 1. Viscosity profiles for the BF3MEA accelerated TGDDM/...

The material parameters for a resin system are determined from a series of viscosity profiles as displayed in Figure 1. 

It is obser ed that upon reaching the isothermal temperature, the viscosity profiles exhibit two relatively linear regions as demonstrated by the 115 and 135 C isothermal profiles. The viscosity corresponding to t=0 at each isothermal temperature is calculated using a linear least squares analysis on the linear viscosity region directly after the point of minimum viscosity. An Arrhenius plot of the values versus 1/T is constructed to ob-... 

Figure 3. Correlation of the predicteci and experimental viscosity profiles for a ramping temperature cure.

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