Table 6 shows strength properties of the handsheet produced
from DPM and WS as compared with those made
from J. procera. Overall strength properties of the
specimens made from the two raw materials are signifi-
cantly lower than those made of J. procera pulp. Generally,
the differences between the properties of handsheet made
from DPM and WS were significant. Wheat straw handsheets
had higher strength properties than those made
from DPM except for tear index where the differences
between them were not significant. The tensile indices
recorded in the current work were slightly lower than
those of the values for date palm rachis soda-AQ pulps
(61–70 Nm g1
) reported by Khristova et al. [23] and
Abdel-Aal [5]. The tensile strength of the samples
increased with increasing cellulose content of the raw
materials [14,27] also found that, increasing of the cellulose
content would increase the strength of the paper.
The tearing index of the specimens made from DPM and
WS were comparable to those reported for date palm
rachis [7]. Table 6 also shows the average values of the
air porosity and brightness of the samples made from the
three raw materials. As can be seen, the highest brightness
value and air porosity were determined for the samples
made from WS, while DPM resulted dark samples. The pulp
brightness ranged from 14.1% to 37.3% for the samples.
Brightness values of the specimens were comparable to
those values reported by Madakadze et al. [6] for kraft
pulps from switch grass (Panicum virgatum L.) and elephant
grass (Pennisetum purpureum Schum). The values of
air porosity of the paper had a wide range from 7.3 s for
DPM to 67 s for WS suggesting that the porosity of the
sheets made from WS was very high while of DPM sheet
had very low porosity. Increasing the porosity of the handsheet
made from WS could be attributed to the fine structure
of the fibres as compared to that of the other
materials. As can be seen from Table 4, WS have the lowest
values of fibre length (1.02 mm), fibre width (11 l), cell
wall thickness (1.2 l) and lumen diameter (8.6 l). The
brightness value recorded for WS (37%) was high than
those reported by Khristova et al. [23]. Such results are
similar to those determined on a previous work [32].