Variability in Wood Density and Wood Fibre Characterization of Woody Species and Their Possible Utility in Northeastern Mexico

Context: Preliminary screening has been undertaken by woody species of Tamaulipan thornscrub for wood density and its utilization northeastern Mexico for different purposes and to find possible relationship of density with wood fibre characteristics. This technique can be used in the selection of species with high wood density for possible utility. Aims: It is to determine the variability in wood density and in fiber cell morphology and its length and among wood species of the Tamaulipan thornscrub, northeastern Mexico. Methods: Wood density and wood fibres are characterized in these woody species following standard methodology. Results: The results reveal large variability in wood density and in fibre cell morphology h. The species have been classified on the basis of wood density and its fibber cell morphology and has been recommended for their possible utilization for different purposes. Conclusions: Species desirable for strong furniture making, paper pulp, soft furniture, fence etc. can be selected on the basis of fibre length to breadth ratios as strong fibres for furniture and fibre cells with broad lumen and thin cell wall use for fabrication of paper pulp and other utilities.

Additive manufacturing of mechanical testing samples based on virgin poly （lactic acid） （PLA） and PLA/wood fibre composites

3D printing in additive manufacturing is con-sidered as one of key technologies to the future high-pre-cision manufacturing in order to benefit diverse industriesin building construction, product development, biomedicalinnovation, etc. The increasing applications of 3D printedcomponents depend primarily on their significant merits ofreduced weight, minimum used materials, high precisionand shorter production time. Furthermore, it is very crucialthat such 3D printed components can maintain the same oreven better material performance and product quality asthose achieved by conventional manufacturing methods.This study successfully fabricated 3D printed mechanicaltesting samples of PLA and PLA/wood fibre composites.3D printing parameters including infill density, layer heightand the number of shells were investigated via design ofexperiments （DOE）, among which the number of shells wasdetermined as the most significant factor for maximisingtensile strengths of PLA samples. Further, DoE workevaluated the effect of material type （i.e., neat PLA andPLA/wood fibres） and the number of shells on tensile,flexural and impact strengths of material samples. It issuggested that material type is the only predominant factorfor maximising all mechanical strengths, which howeverare consistently lower for PLA/wood fibre compositeswhen compared with those of neat PLA. Increasing thenumber of shells, on the other hand, has been found toimprove almost all strength levels and decrease infillcavities.

Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid(Eucalyptus grandis 3 E. urophylla)clones

We studied two clones of Eucalypt urograndis hybrid （Eucalyptus grandis × E. urophylla）, GR283 and GR330, grown in Tumkur district of Kamataka （India）, and felled 5-6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 （37 %）. Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.

Recycled fibres and fibrous sludge as reinforcement materials in injection moulded polypropylene(PP)and poly(lactic acid)(PLA)composites

Wood flour or sawdust is often used as filler in conventional wood plastic composite(WPC)materials.However,there has been an increasing interest to the use of wood pulp fibres in reinforced plastic applications,because they can provide enhanced strength properties and better biodegradability characteristics for the composite.This research compares the effect of recycled fibres or side streams of paper as reinforcement in poly(lactic acid)(PLA)or polypropylene(PP)composites.Fibres from liquid packaging board and non-deinked old newspapers,and fibrous sludge from recycling processes are compared with virgin softwood kraft pulp fibres.Composites were produced by melt processing to a fibre content of 30%(or 10%fibrous sludge),and the mechanical properties were investigated.Recycled fibres provided comparable,or even higher,plastic reinforcement than virgin softwood fibres.In PP composites,the differences in mechanical properties between different fibre types were relatively small.Fibrous sludge decreased the mechanical performance of composites but can be considered as cheap filler in cases when mechanical properties are not crucial.The possibility to use low-cost materials like recovered paper or deinking sludge in wood plastic composites is an interesting option for future sustainable applications.