Q2. What is the main reason for the growing interest in finding alternative uses for rice straw?
As climate change is extensively recognized as a threat to development, there is a growing interest to find alternative uses for rice straw.
Q3. What are the possible uses for rice straw?
Possible uses for rice straw are limited by its low bulk density, a slow degradation in thesoil, the harboring of rice stem diseases (the possible transmission of diseases to the future crop), and a high ash content which can be a problem for subsequent ethanol or energy production (Binod et al., 2010).
Q4. How much water evaporation was observed in the twin-screw extruder?
When the liquid/solid ratio in the twin-screw extruder reduced from 1.02 to 0.43, the extrudate flow rate (QR) decreased progressively from 26.8 to 19.0 kg/h.
Q5. How long did the extrudate take to be collected?
Upon achieving steady operation, the extrudate was immediately collected over a period of 10 min to avoid any variability of the outlet flow rate.
Q6. How much inlet flow rate could be accessible from a twinscrew machine?
because the maximal screw speed of the Clextral Evolum HT 53 twinscrew extruder is 800 rpm, it is reasonable to assume that a 80 kg/h maximal inlet flow rate could be accessible from such a twin-screw machine.
Q7. How much water was used to reduce the morphology of the treated fibers?
for the morphology of these treated fibers, a slight decrease in their mean length, their mean diameter and their mean aspect ratio was observed when the quantity of water was reduced.
Q8. Why was the fibers entangled between them more favored?
On the contrary, because fibers originating from the highest L/S ratios were longer, their entanglement between them was favored, leading to a bulkier and therefore to a less dense pulp.
Q9. Why was the water favored in the twin-screw reactors?
This was due to the fact that the capability of the water to be diffused inside the solid plant matrix is clearly favored inside the twin-screw reactors thanks to the quality of the contacting between the liquid and solid phases (Evon, 2008; Bouvier and Campanella, 2014).
Q10. What was the effect of the lower aspect ratio on the fibers?
this illustrated the fact that higher mechanical shear and higher self-heating of the material at the level of the reversed screws caused by low L/S ratios contributed in more cutting of the fibers.
Q11. What was the effect of the ratio of the two screw extruders on the heating power?
As a consequence, the total heating power supplied by the twin-screw extruder tended to drop linearly when the liquid/solid ratio was reduced.
Q12. How much densities of pulps are decreasing when the L/S ratio increases?
Looking at the influence of the liquid/solid ratio used on the apparent and tapped densities of pulps, both densities are slightly decreasing when the L/S ratio increased: from 53 to 48 kg/m3 and from69 to 63 kg/m3, respectively.
Q13. What was the effect of the decreasing aspect ratio in the twin-screw extruder?
In addition, a slight decrease in the aspect ratio was observed with a decreasing liquid/solid ratio in the twin-screw extruder, especially for its two lowest values (i.e. 0.55 and 0.4), and such phenomenon was previously observed for thermo-mechanical pulps produced using steam plus a mechanical defibration treatment (Alila et al., 2013; Flandez et al., 2012; Theng et al., 2015a).
Q14. What was the effect of the alteration of the structure of rice straw fibers?
Such darkening was also observed in the case of extrudates (Table 5), and this was the consequence of the alteration of the structure of rice straw fibers inside TMP.