WOOD FIBERS FROM SEVEN EUCALYPTUS SPECIES WERE COLLECTED TO INVESTIGATE THE RELATIONSHIPS AMONG SPECIES, FIBER BIOMETRY, AND NANOMECHANICAL PROPERTIES. THE RESULTS INDICATED SIGNIFICANT DIFFERENCES IN WOOD DENSITY, COARSENESS, FIBER LENGTH, FIBER WIDTH, AND CELL WALL THICKNESS AMONG THE DIFFERENT EUCALYPTUS SPECIES. THE NANOMECHANICAL PROPERTIES OF THE S2 CELL WALL LAYER ALSO SHOWED SIGNIFICANT DIFFERENCES AMONG THE EUCALYPTUS SPECIES. THE ELASTICITY MODULUS RANGED FROM 16 TO 19 GPA, THE HARDNESS SPANNED 0.24 TO 0.31 GPA, AND THE DUCTILITY RATIO WAS BETWEEN 54 AND 68. MOREOVER, SIGNIFICANT CORRELATIONS WERE OBSERVED FOR HARDNESS VERSUS CELL WALL THICKNESS (R = 0.87), AND ELASTICITY MODULUS VERSUS CRYSTALLINITY INDEX (R = 0.80) AND CRYSTALLITE SIZE (R = 0.68). AMONG THE EVALUATED SPECIES, E. DUNNII SHOWED THE HIGHEST ELASTICITY MODULUS, HIGHEST HARDNESS AVERAGE, AND THE HIGHEST CRYSTALLINITY INDEX. THE RANGE OF NANOMECHANICAL VALUES INDICATED THAT EUCALYPTUS WOOD FIBERS ARE SUITABLE FOR THE DEVELOPMENT OF NEW COMPOSITE MATERIALS OR ENGINEERING PRODUCTS BY SELECTING THE MOST ADEQUATE SPECIES FOR EACH USE ACCORDING TO ITS PROPERTIES.

EUCALYPTUS WOOD FROM ADULT TREES IS USED FOR SEVERAL PURPOSES; HOWEVER, THE WOOD OF YOUNGER TREES HAS LIMITED USE. THIS STUDY AIMS TO CHARACTERIZE AND PROPOSE USES OF TWO-YEAR-OLD EUCALYPTUS WOOD. SIX TWO-YEAR-OLD EUCALYPTUS GRANDIS × EUCALYPTUS UROPHYLLA CLONES HAVE BEEN SELECTED AND THEIR ANATOMICAL, ULTRASTRUCTURAL, PHYSICAL AND MECHANICAL WOOD CHARACTERISTICS EVALUATED. THE WOOD OF CLONE A SHOWS MORE ROBUST FIBERS WITH BETTER MICROFIBRIL ARRANGEMENT, RESULTING IN BETTER MECHANICAL PROPERTIES, AND THEREFORE, A BETTER PERFORMANCE FOR STRUCTURAL USE. CLONE F SHOWED A LOW VARIATION OF WOOD BASIC DENSITY IN THE RADIAL DIRECTION, FACILITATING ITS MACHINABILITY, AND WITH THE CLONE B, SHOWED A LOWER ANISOTROPY, AND THEREFORE, THE WOOD IS RECOMMENDED FOR LOCATIONS WITH HIGH VARIATIONS OF HUMIDITY. THE HETEROGENEITY OF THE WOOD CHARACTERISTICS OF THE EVALUATED CLONES CONFIRMS THE NEED FOR FURTHER STUDIES, TO CHOOSE THOSE MOST ADEQUATE TO EACH USE.

INFORMATION ON THE MORPHOLOGICAL AND PHYSICAL PROPERTIES OF BIOFIBERS IS NECESSARY TO SUPPORT THE MECHANICAL UNDERSTANDING OF THE BIOLOGICAL DESIGN OF PLANTS, AS WELL AS FOR THE DEVELOPMENT OF NEW TECHNOLOGY THAT ADDS VALUE TO NON-TRADITIONAL BIORESOURCES, SUCH AS THOSE BASED ON ULEX EUROPAEUS FIBERS. ULEX EUROPAEUS FIBERS WERE EXTRACTED THROUGH A CHEMICAL PULPING PROCESS AT 170 °C AND WITH 40 G/L NAOH. THE DIMENSIONS OF THE FIBERS PRODUCED WERE 0.97 ± 0.1 MM IN LENGTH AND 13 ± 2 ?M IN DIAMETER. PRESSED FIBER PAPER SHEETS WERE MADE TO EVALUATE THEIR MECHANICAL PROPERTIES. BURST AND TEAR INDICES OF 1.2 MN/KG AND 8.6 NM2/KG, RESPECTIVELY, WERE RECORDED. THE VALUES OBTAINED DID NOT COMPARE WELL TO FIBER PAPER SHEETS FROM PINUS RADIATA, PRESUMABLY DUE TO THE SIGNIFICANT AMOUNT OF NON-STRUCTURAL ELEMENTS OF WOOD PRESENT IN THE SAMPLES AND THE LOWER LENGTH OF ULEX EUROPAEUS FIBERS, WHICH RESULTED IN LOWER TENSILE STRENGTH. ADDITIONALLY, NANOINDENTATION TESTS WERE CONDUCTED TO ASSESS THE HARDNESS AND ELASTIC MODULUS OF THE FIBERS, OBTAINING AVERAGE VALUES OF 0.84 GPA AND 9.23 GPA FOR THE STEM, RESPECTIVELY. THESE VALUES WERE SIGNIFICANTLY LOWER THAN THOSE OF INDUSTRIAL BIOFIBER, PERHAPS DUE TO THE LOWER MORPHOGENIC MATURITY OF ULEX EUROPAEUS FIBERS COMPARED TO OTHER TRADITIONAL SOURCES OF FIBER.

THE OBJECTIVE OF THIS RESEARCH WAS TO STUDY THE CHEMICAL AND NANOMECHANICAL CHARACTERISTICS OF NATIVE WOODS GROWN IN SOUTHERN CHILE REGION. THE SPECIES ANALYSED WERE DRIMYS WINTERI, LAURELIOPSIS PHILIPPIANA, AEXTOXICON PUCTATUM, NOTHOFAGUS ALPINA, NOTHOFAGUS DOMBEYI, LAURELIA SEMPERVIRENS, AUSTROCEDRUS CHILENSIS AND FITZROYA CUPRESSOIDES. THE SAMPLES WERE COLLECTED FROM THE REGIONS OF BIOBÍO (37° S, 73° W), ARAUCANÍA (37° S, 71° W) AND LOS LAGOS (40° S, 73° W). CHEMICAL ANALYSIS REPORTED THAT GLUCAN CONTENT OF NATIVE WOODS WAS BETWEEN 39% AND 44% AND LIGNIN CONTENT BETWEEN 28% AND 35%. THE NANOMECHANICAL PROPERTIES ANALYSED IN THE SECONDARY CELL WALL (S2 LAYER) AND MIDDLE LAMELLA (ML) WERE ELASTIC MODULUS (E), HARDNESS (H) AND DUCTILITY RATIO (E/H). VALUES FOR ES2 WERE BETWEEN 12.0 AND 15.4 GPA AND FOR EML BETWEEN 4.3 AND 6.6 GPA. HARDNESS VALUES WERE SIMILAR IN ML AND S2 (?0.3 GPA). THE COMPILATION OF RESULTS SHOWED HIGH CORRELATIONS BETWEEN ES2 AND CARBOHYDRATE CONTENT (R = 0.80), BETWEEN ES2 AND HEMICELLULOSE CONTENT (R = 0.89), AND BETWEEN HS2 AND LIGNIN CONTENT (R = 0.88).

SIX EUCALYPTUS NITENS FAMILIES FROM TWO SOILS IN THE 8TH REGION OF CHILE, CLAY AND TRUMAO, WERE STUDIED TO SELECT FAMILIES WITH LOWER DEGREE OF CRACKING. CRACKING PARAMETERS EVALUATED AT MESOSCALE, NEXT TO NANOMECHANICAL PROPERTIES OF THE CELULAR STRUCTURE, WERE RELATED IN A REPRESENTATIVE VOLUMEN ELEMENT OF THESE TREE, SUCH AS PERCENTAGE OF CRACKED AREA OF TREES RELATING THEM TO THE DUCTILITY RATIO (E/H) OBTAINED OF VALUES OF MODULUS OF ELASTICITY (E) AND HARDNESS (H) BY NANOINDENTATION AND THE MODULUS OF RESILIENCE (UR) OF THE MIDDLE LAMELLA AND S2-LAYER OF THE CELL WALL WERE ANALYZED. FURTHERMORE, IT WAS DETERMINED THAT THE DIFFERENCE BETWEEN THE MODULUS OF RESILIENCE (?UR) OF THE MIDDLE LAMELLA WITH THE S2-LAYER IS A GOOD INDICATOR OF THE INTERFACIAL STRESS INDUCING FRACTURES IN THE S1-LAYER. USING NANOCHARACTERIZATION IT WAS ESTABLISHED THAT THE MIDDLE LAMELLA IS MORE BRITTLE AND SUSCEPTIBLE TO GENERATE MICROCRACKS THAT SPREAD TO MESO SCALE. THE ?UR BETWEEN THE MIDDLE LAMELLA AND S2 LAYER SHOWN TO BE LOWER IN FAMILIES 2 AND 5. THESE FAMILIES SHOWED TO HAVE LOWER LEVELS OF SHEAR STRESS AT THE INTERFACE BETWEEN THE MIDDLE LAMELLA AND S2-LAYER, THEREFORE THE AMOUNT OF MICROCRACKS THAT OCCUR IS LOWER, THERE IS A GOOD RELATIONSHIP WITH THE PERCENTAGE OF MEASURED CRACKS IN THESE FAMILIES OF EUCALYPTUS NITENS. ACCORDING THESE FINDINGS, THE FAMILIES THAT SHOW LOW DEGREE OF INTERFACIAL TENSIÓN AT CELULAR LEVEL AND LOW CRACKS INDEX WERE FAMILY 2 AND FAMILY 5.

MULTI-LAYER SYSTEMS ARE FREQUENTLY USED AS ANTI-REFLECTIVE COATINGS (ARCS) DUE TO THEIR EXCELLENT OPTICAL PROPERTIES. HOWEVER, THESE SYSTEMS SUFFER FROM EROSIVE DEGRADATION (WEAR), THUS URGENTLY SEEKING ALTERNATIVE WAYS TO IMPROVE THEIR MECHANICAL PROPERTIES WHILE MAINTAINING THEIR OPTICAL RESPONSE. TO TACKLE THIS PROBLEM, WE PROPOSE TO DOPE MULTI-LAYER TIO2/SIO2 COATINGS WITH ZR-OXIDES TO ENHANCE THEIR CRYSTALLINE STRUCTURE AND DENSITY/COMPACTNESS, AS WELL AS TO FORM SI?ZR?O BONDS. WE EXPLORE THE EFFECT OF ZR-OXIDE DOPING ON THE MICROSTRUCTURE AS WELL AS THE OPTICAL AND MECHANICAL PROPERTIES OF MULTI-LAYER TIO2/SIO2 COATINGS WITH THE OVERALL AIM TO SYNERGISTICALLY INDUCE ENHANCED OPTICAL AND MECHANICAL PROPERTIES. THEREFORE, HOMOGENEOUS 250 NM THICK MULTI-LAYER TIO2/SIO2 COATINGS DOPED WITH ZR-OXIDES (DIFFERENT ATOMIC CONCENTRATIONS) WERE DEPOSITED ON GLASS SUBSTRATES BY MAGNETRON SPUTTERING. BASED ON OUR ANALYSIS, ZR-DOPING IMPROVES THE OPTICAL AND MECHANICAL PROPERTIES SIMULTANEOUSLY. AMONG ALL ARCS, THE SAMPLE ANNEALED AT 400 °C AND DOPED WITH 1 AT.-% ZR PRESENTED AN EXCELLENT ANTI-REFLECTIVE BEHAVIOR AND THE BEST MECHANICAL PERFORMANCE. THESE CHARACTERISTICS POINT TOWARDS AN IMPROVED MECHANICAL RESISTANCE (OUTSTANDING DURABILITY) AND OPTICAL EFFICIENCY THUS RENDERING THEM EXCELLENT CANDIDATES FOR THE PROTECTION OF GLASS COVERS ON SOLAR PANELS.