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Fiberboards were manufactured from filled phenolic resins (lignin-formaldehyde or glyoxal) and petiole date palm fibers. Lignin was obtained from paper industry waste black liquor. To improve lignin reactivity and increase the bonding strength between matrix and fiber, phosphogypsum (PG) was used as a filler in the resin formulation from 1 to 3 wt%. Phosphogypsum exhibited excellent performance as binder; this was verified by a decrease in the gelation time and an increase in internal bond (IB) in fiberboards. The analysis confirmed that resin reactivity depends on aldehyde types (glyoxal or formaldehyde) and PG proportion. Most of the obtained boards were of good quality [modulus of elasticity (MOE) up to 1230 MPa; modulus of rupture (MOR) up to 25 MPa; internal bond (IB) up to 0.23 MPa; water absorption (WA) up to 28%].

Different composites panels were prepared using two granulometrys of fibers from date palm petiole (PDPF) and bio-matrix from lignin-glyoxal-resin (LGR). The composites panels were manufactured at different PDPF percentages ranging from 10 to 70 wt%. Mechanical properties of the prepared samples were evaluated by measuring tensile strength, Young`s modulus and elongation. The obtained results showed that the sample made from fibers/thermo pressed resin 50/50 wt% has the best mechanical properties. The increase of the granulometry of the fibers from 250 to 500 µm results in an improvement of the tensile strength and Young`s modulus values. However, the LGR matrix reinforced with PDPF showed high values of water diffusion coefficient when compared to the unreinforced LGR.

International audience; Large mineral fillers have long been used in papermaking for many reasons. The finish of the writing and printing paper depends on using the fillers as internal or surface treatments. During this study, Tamarisk sp. and Prunus amygdalus pulp-filled papers with raw phosphogypsum (PG) and calcined PG (CPG) at different percentages were studied. First, the prepared minerals (treated and untreated ones) were characterized by different analytical methods such as SEM and EDS. Subsequently, different handsheets with a basis weight 60 g−2 were prepared on a Rapid Khöten sheet former following the standard method. The added amounts of PG and CPG fillers were included from 0% to 15% based on the pulp. The effects of incorporation as well as the quality fillers into physical and optical properties were assessed. It can be deduced that the incorporation of CPG at 800 °C improved filler retention by as high as 92%, and the optical properties of the filled paper was strikingly enhanced, while the strength properties were practically negatively influenced. It was clear that calcinationstepsreduce the fiber–filler–fiber bond. Thus, results are in accordance with the SEM observation, which confirmed the obtained physical properties.

This work presents a promising way to investigate the valorization of natural residual from Tunisian industrial wastes. In fact, large quantities of phosphogypsum which are obtained from Tunisian Chemical Group "TCG" are accumulated every year in Tunisia. The rational valorization of these available renewable resources fits very well with the recent sustainable approach, established nowadays. This work aims at ascertaining the chemical composition of this inorganic residue and structural characterization for use as a reinforced plaster. Several thermal treatments from 100°C to 800°C were established to prepare from phosphogypsum various qualities of this material to be characterized by numerous techniques such as the FTIR, XRD, SEM, DSC, DTG and TGA in order to apply in potential application. Calcination temperature that gave the best value for the beginning and the end of setting was 200°C. The experimental tests showed height values of flexural strength for thecalcined PG at 200°C (0.45 MPa). Original Research Article Mechi et al.; BJAST, 16(3): 1-10, 2016; Article no.BJAST.25728 2