Mixing torque

The kinetics of the reactive compatibilization of nylon-6-PP by acrylic acid modified PP was investigated by Dagli et al. [47]. The compatibilization reaction in this system involved the reaction between the acid group of acrylic acid modified PP and the amine group of nylon-6. A typical intensive batch mixer torque (t) vs time (t) trace for a ternary blend showing an increase in mixing torque upon the addition of PP-g-AA to a binary PP-NBR (85 7.5) blend is shown in Fig. 3. The kinetic... 

Prud HGMMti, R. K. and Shaqfeh. E. A.l.Ch.E. Jl 30 (1984) 485 Effect of elasticity on mixing torque requirements for Rnshton turbine impellers. 

The waste PP/GRT blends were prepared using a Haake internal mixer at a temperature of 180 C and a rotor speed of 30 rpm for 8 min (Egodage et al., 2009). Blends of nine different compositions with GRT concentrations up to 70 wt.% were prepared. Mixing torque was increased with an increase in the GRT content. The tensile strength, modulus, and tear resistance decreased with the GRT content, while the elongation at break and the impact failure energy increased. 

ESR signals increases with increasing initial strain. The intensity of ESR signals of filled and unfilled SBR vulcanizates are dilferent from each other due to the dilference in the degree of chain scission caused by the considerably higher mixing torque for silica filled system than that for unfilled system. 

NBR/PP/Zn dimethacrylate/ peroxide RI Melt mixing/torque rheometry/mechanical properties/TEM/SEM/TGA Xu et al. 2013a... 

It was obvious that the mixing torque of the NR/HDPE blends corresponded to the apparent shear viscosity curve in which the mixing torque and apparent shear viscosity of the NR/HDPE blends can be arranged in the following sequence 80/20 >60/40 >50/50 >40/60 >20/80 as shown in Figure 18.3. 

The mixing torque and apparent shear viscosity of the blends increased with increasing amounts of NR might be due to the natural characteristics of ADS that is produced from NR latex without shear cutting in the production process and it was dried at low temperature using the heat from sunshine. Therefore, ADS itself will have high Mooney viscosity in comparison with those other NR block types. 

Figure 18.2 Mixing torque-time of NR/HDPE blends at various blend ratios without compatibilizers.

Figure 18.5 shows comparative torque time curves for NR/HDPE blends at a fixed blend ratio of 80/20 with three types of blend compatibilizers added. It can be seen that the torque increased in the absence of a compatibilizer. Also, the phenolic resin with active hydroxymethyl (methylol) groups gave the highest mixing torque at the final mixing stage. 

Figure 18.55 Effect of molecular weights of natural rubber on mixing torque of LLDPE/NR (60/40) blends.

During mixing, the mixing torque and temperature were measured and plotted as functions of mixing time. For both the N-330 and N-326 carbon blacks, similar temperature and mixing torque profiles were obtained. The mixing torque reaches a maximum very rapidly. The mixing torque then drops continuously at first rapidly, and then more slowly. This type of behavior has been observed before [33] with respect to oil-extended butadiene rubber. However, in that case and in other previously reported work, two power peaks (torque maxima) were observed. 

Agitator in mixing Torque and power Mixing speed. Possible inferential data Unusual torque and/or power... 

Scott et al. compared the development of the phase morphology in non-reactive and reactive polymer blends based on the reaction of maleic anhydride (MA) with amine and oxazoline (OX), respectively. The increase in the mixing torque and decrease in the average particle size were less pronoimced and delayed in time in the case of the MA/OX reactive pair compared to the MA/NH2 one, consistently with the lower reactivity of the former pair [46]. 

The interfacial chemical reaction changes the dynamics of the phase inversion process. Sundaiaraj et al. [25] systematically studied the phase inversion process in a reactive polyarylate/ethylene-ethyl acrylate-glycidyl methacrylate rubber blend where the extent of interfacial chemical reaction was controlled by the addition of stearic acid. The primary effects of the interfacial reaction were to delay phase inversion and increase the mixing torque rise associated with it. Figure 5.6 illustrates both of these points. They attributed these effects to the fact that in reactive blends steric stabilization of the... 

Figure 5.8 (a) Mixing torque vs time for blends with 30wt.% rubber (O) PA/EP nonreactive blend, (A) PA/EP-MA reactive blend [41] (b) Temperature vs time for blends with 30wt.% rubber (O) PA/EP nonreactive blend, (A) PA/EP-MA reactive blend [41]... 

As described above in the section on morphology development, there are several separate mechanisms responsible for the effects of the interfacial reaction on the final morphology. Empirical means may be used to separate some of these simultaneous effects. For example, Scott and Macosko [41] successfully separated the effects of increased mixing torque and changing component rheologies as a fimction of temperature from other effects of the chemical reaction. They utilized Wu s [55] empirical equation for rubber particle diameters in reactive blends with polyamide 66 and poly(ethylene terephthalate) prepared in twin screw extruders ... 

Figure 5.17 Mixing torque as a function of time for (O) PS/EP-MA and (A) PS-Ox/EP-MA. Data from eight runs are overlaid on each curve [S]...

Figure 5.17 [5] compares the torque as a function of time in a batch intensive mixer for non-reactive and reactive blends of polystyrene/ethylene-propylene rubber. These results are typical for a relatively slow interfacial reaction. As the room temperature pellets of the blend are added to the hot mixer, the mixing torque rises rapidly in the melting regime. The torque for both blends then begins to fall as the temperature increases and the polymers soften. In the case of the non-reactive blend, the torque continues to fall and levels out to a reasonably constant value. However, in the case of the reactive blend there is a second peak in the torque due to the chemical reaction. The interfacial chemical reaction builds molecular weight, and in some cases may result in local crosslinking. This increases the viscosity of the blend relative to a non-reactive blend. 

Figure 5.22 Effect of oxazoline concentration in the polystyrene phase for blends with 20 wt.% EP-MA ( ) weight fraction gel (A) normalized mixing torque ( ) normalized G (0.1 rad/s, 180°C)...

Based on the mixing torque data, it is quite apparent that maleated EPR is by far the fastest reacting system, with >4 fold torque increase within one minute due to a rapid reaction between the anhydride group of the rubber and the amine chain end of PA6... 

---