Blending ratios

Blending ratio Green coke yield, wt% TGA yield, u[Pg.225]

The chain arrangement of this morphology was schematically proposed as in Fig. 10. The cell of the microsphere has a hexagonal surface, and the AB diblock copolymers form a bilayer between the microspheres. From this schematic arrangement, the optimal blend ratio of the AB block copolymer in this system was calculated as 0.46. This value was very close to the blend ratio of the AB type block copolymer 0.5 at which the blend showed the hexagonal packed honeycomb-like structure. 

Variation of apparent viscosity with the blend ratio for both preblends and preheated blends is shown in Fig. 1. Comparing preblends and preheated, the viscosity of preheated 50 50(NBR-Hypalon) blends becomes maximum, whereas the prebends show a continuous decrease in viscosity from 100% Hypalon to 100% NBR in all shear rates studied. This decrease is explained by the difference in viscosity between two virgin polymers. Preheating of the blends may result in interchain cross-linking and it seems to be maximum at a 50 50 ratio. 

The non-Newtonian index is plotted against the blend ratio in Fig. 2. There are three distinct stages of the change of value with %NBR in the preblend. First, a decrease of up to 40% of NBR, a rapid rise of up to 60% of NBR, and beyond this ratio a further decrease are observed. Heating of blends shows the only minimum at 50 50 ratio. It is obvious that 60-50% of Hypalon in the NBR-Hypalon blend is an optimum range where maximum extent of interchain crosslinking reaction is expected, and this blend is supposed to be more pseudoplastic. 

Shear modulus also changes with the blending ratio (Fig. 5), such as the relaxation time. Preblends show an... 

Earlier studies [14,15] clearly reveal that there is a reaction between two polymers and that the extent of reaction depends on the blend ratio. As 50 50 ratio has been found to the optimum (from rheological and infrared studies) ratio for interchain crosslinking, the higher heat of reaction for the NBR-rich blend may be attributed to the cyclization of NBR at higher temperatures. There is an inflection point at 50 50 ratio where maximum interchain crosslinking is expected. Higher viscosity, relaxation time, and stored elastic energy are observed in the preheated blends. A maximum 50-60% of Hypalon in NBR is supposed to be an optimum ratio so far as processibility is concerned. 

Variations of melt viscosity with the blend ratio for both the preblends and preheated blends are shown in Fig. 

The non-Newtonian index is plotted against the blend ratio in Fig. 8. We see that for both the preblends and the preheated blends, the w value increases with NBR content up to about 50% of NBR. Beyond this while the preblend shows a continued increase in n value at a slower rate, the preheated blends seem to show a saturation in n value. The low values of may be attributed to the interchain crosslinking at higher levels of NBR in the blends. 

A representative example of the extrudate swelling behavior is shown in Fig. 15 as a function of blend ratio... 

Rheological parameters, such as relaxation time, shear modulus, and stored elastic energy, are determined from the extrudate swell and stress-strain data as previously described. Representative examples of the variation of these parameters with blend ratios for both blends are shown in Figs. 16-18. Figure 16 shows that relaxation time for both preblends without heating and... 

Variation of melt viscosity for both the preblends and preheated blends with the blend ratio are shown in Fig. 19. There are two distinct regions in viscosity change with the addition of polyacrylic rubber (ACM) in the blends. First, in the higher shear rate region, the viscosity increases with the addition of the ACM (up to 40% ACM) in the blend and then it decreases. In the lower... 

The non-Newtonian index is plotted against the blend ratio in Fig, 20. It is observed that for both the... 

The plot of the rheological parameters (relaxation time, shear modulus, and stored elastic energy) are shown in Figs. 22-24. The relaxation time increases as the ACM content is increased to attain a maximum at 60 40 = ACM XNBR blend ratio for the preblends. For lower shear rate the rise is sharp and after 60 40 blend ratio, // remains almost constant, whereas for the higher shear rate region the rise is not sharp and after 60 40 blend ratio ty decreases as ACM percent increased in the blend. In the case of the preheated blends the /y increases up to 50 50 blend ratio and then decreases with the addition of ACM in the blend. The preheating increases the ty in both shear rate regions. 

The shear modulus, G varies with the blend ratios. In the preblend system, the shear modulus decreases sharply with the addition of ACM up to the 50 50 blend ratio and then it remains constant with the further addition of ACM in the blend. In the case of preheated blend, the shear modulus decreases gradually with the addition of ACM. In both the preblend and preheated blends it is observed that the shear modulus at higher shear rate and lower shear rate gradually converge as the ACM content in the blend is increased. 

The stored elastic energy, W (Fig. 24) increases with the increase of ACM content in the blend up to 50 50 blend ratio and then it decreased with the further... 

The plot of the rheological parameters (relaxation time, /r shear modulus, G and stored elastic energy, W ) are given in Figs. 28-30. The relaxation time of both preblends and preheated blends remains almost constant up to 50 50 blend ratio and then shoots up drastically at both shear rates. Up to 50 50 blend ratio it is observed that the relaxation time is more at lower shear rate. Preheating of blends lowers the values. 

The shear modulus varies with the blend ratios in the preblend system, G remains constant up to 50 50 blend ratio and then it decreased with the further addition of AU in the blend at higher shear rate. At lower shear rate, G increased up to the 50 50 blend ratio and then it fell. Preheating of the blends resulted in increasing the G values. At both shear rates G increased up to 50 50 blend ratio and then decreased with further addition of AU in the blends. 

The stored elastic energy, VV , decreases drastically with the addition of AU in the blends up to 50 50 blend ratio for both the preblends and preheated blends at both shear rates. After 50 50 blend ratio at both shear rates the W does not change for preheated blends. For preblends the W increase up to 60 40 AU-XNBR blend ratio for both the shear rates and then remain constant at lower shear rate, whereas at higher shear rates it decreased further with the addition of AU in the blend. At lower shear rates, the W gradually converge to the same value as the AU is added to the blend. 

Figure 7 Experimental viscosity curves of PA, TLCP, and their blends of different blending ratios [1].

Figure 6 Theoretical viscosity function versus viscosity ratio 8 = 771/770 at different blending ratios .

These generally defined requirements are met quite comprehensively by microfiber glass fleeces. These are blends of C-glass fibers of various diameter, which are processed in the usual way on a Foudrinier paper machine into a voluminous glass mat. The blending ratio gains special importance since cost aspects have to be balanced against technical properties. The... 

De Sarkar et al. [52] have reported a series of new TPEs from the blends of hydrogenated SBR and PE. These binary blends are prepared by melt mixing of the components in an internal mixer, such as Brabender Plasticorder. The tensile strength, elongation at break, modulus, set, and hysteresis loss of such TPEs are comparable to conventional rubbers and are excellent. At intermediate blend ratio, the set values show similarity to those typical of TPEs (Table 5.5). 

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