Utilization of bio-waste cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) in wood-based composite particleboard

The objective of this study was to investigate some mechanical (modulus of rupture, modulus of elasticity and internal bond) and physical (thickness swelling and water absorption) properties of wood-based three-layer particleboard containing different cotton (Gossypium hirsutum L.) stalks and underutilized paulownia (paulownia fortunie) wood particle ratios (30, 50 and 70%) using urea formaldehyde resin. Addition of cotton stalk and paulownia wood in particleboard improved mechanical properties of resulting composites boards significantly. However, the water resistance decreased with increasing cotton stalk and paulownia wood particle contents. The highest mechanical properties were obtained at cotton stalk and paulownia wood particle loading of 50 and 70%, respectively. Conclusively, valuable underutilized natural resources, cotton stalk and paulownia wood can be used with the mixture of industrial wood particles in the production of particleboards with high mechanical properties.Keywords: Wood, resin, urea-formaldehyde, mechanical properties, physical propertie

A decentralized control strategy to bring back frequency and share reactive power in isolated microgrids with virtual power plant

In this paper, a novel Power-Frequency Droop Control (PFDC) is introduced to perfectly bring back the system frequency and share the reactive power in isolated microgrid with virtual power plant (VPP). The frequency-based power delivery must be essentially implemented in VPP which can operate as a conventional synchronous generator. It has been attained by enhancing the power processing unit of each VPP to operate as an active generator. The inverter coupling impedance which has been assigned by the virtual impedance technique has reduced the affected power coupling resulting from line resistance. The reference has been subsequently adjusted to compensate the frequency deviation caused by load variation and retrieve the VPP frequency to its nominal value. In addition, the line voltage drop has compensated the voltage drop and load sharing error to obliterate the reactive power sharing imprecision resulting from the voltage deviation. The voltage feedback confirms the correct voltage after compensating the voltage drop. As an illustration, conventional PFDC after a load change cannot restore the system frequency which is deviated from 50 Hz and rested in 49.9 Hz while, proposed PFDC strategy fades away the frequency deviation via compensating the variation of the frequency reference. Likewise, the frequency restoration factor ( γ) has an effective role in retrieving the system frequency, i.e., the restoration rate of the system frequency is in proportion with γ. As a whole, the simulation results have pointed to the high performance of proposed strategy in an isolated microgrid

Effect of organoclay platelets on the mechanical properties of wood Á plastic composites formulated with virgin and recycled polypropylene

Abstract This study investigated the effects of organoclay platelet contents (0, 3 and 5 wt%) and polypropylene type (virgin and recycled) on the mechanical properties of polypropylene/wood flour composites. Composite samples were made by melt compounding and consequent injection moulding. The tensile, flexural and impact properties of resultant composites were determined. X-ray diffraction (XRD) analysis of composites with 3 and 5% nanoclay content was also conducted. The results indicated that tensile and flexural properties of the composites increased with the addition of nanoclay particles up to 3 wt% and decreased thereafter. The impact strength of the composites, however, decreased with the incorporation of nanoclay. The mechanical properties of the recycled polypropylene-based nanocomposites were statistically comparable with those based on virgin polypropylene. XRD analysis revealed that the degree of intercalation in the nanocomposites containing 3% nanoclay was higher than in those containing 5%. Based on these results, it can be concluded that recycled polypropylene could be used instead of virgin polypropylene in the production of value-added products with no significant adverse effects on the mechanical properties

Investigation of physical, mechanical properties and formaldehyde emission of medium density fiberboard manufactured from urea formaldehyde resin reinforced with nanocrystalline cellulose

The purpose of this study was to evaluate the physico-mechanical properties and formaldehyde emission of medium density fiberboard (MDF) made from modified urea formaldehyde resin. In this study, nanocrystalline cellulose (NCC) (0, 0.5, 1, 1.5 and 2 percent) based on the dry weight of resin was applied to modify urea formaldehyde resin. The results of mechanical properties indicated that MOR and IB of the MDF panels significantly increased as the NCC incorporated into the UF adhesive up to 1%wt. However, further increment in the NCC content (1.5 and 2 wt%) decreased the MOR and IB of the panels. Water absorption and thickness swelling after 2 h were significantly increased when the NCC content increased from 1% to 2%, but no significant differences were observed between the panels after 24 h. Also, the formaldehyde emission significantly decreased with increasing the amount of nanocrystalline cellulose