School of Agriculture, Food and Ecosystem Sciences - Theses

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The chemical modification of Pinus radiata (D.Don.) with furfuryl alcohol

Skewes, Brett Andrew. (University of Melbourne, 2006)

Wood blocks impregnated with furfuryl alcohol required a standing time of 48 hours to ensure complete swelling of the wood. Total penetration of the blocks was required for maximum swelling and water resistance in treated blocks. The presence of water in the treatment solution caused rapid swelling of the wood block, whereas 100% furfuryl alcohol created a slow rate of swelling. The presence of water in the cell walls accelerated the rate of swelling of 100% furfuryl alcohol, but not to the extent as when the water was present in the treatment solution. Dimensional stability decreased as the water content in the treating solution increased, but compared to the controls (6 - 8%) there was significant improvement in dimensional stability (2.5 - 4%). The resin forming efficiency varied with the amount of water present, but never dropped below 85%. Treated wood samples compressed to a density of 1200 � 1400 kg/m3 were more stable when exposed to water, and had increased hardness and MOE compared to untreated compressed samples. The curing of furfuryl alcohol in beakers gave a clear indication of catalyst performance with variable catalyst concentration and curing temperature. An increase in catalyst concentration increased the resin forming efficiency which was dependant upon the catalyst strength and number of pKa values. Of the catalysts stable at room temperature, oxalic acid, maleic acid and zinc chloride were the best performed for wood impregnation, with respect to the parameters investigated. The higher the resin forming efficiency the lower the volumetric swelling. The initial moisture content of the wood had a direct effect upon the swelling of wood blocks. All samples with an initial moisture content of 12% performed better than the corresponding treatments used with oven-dried blocks. Further, higher catalyst concentrations and curing temperatures improved performance. Oxalic acid at a 4% concentration with furfuryl alcohol and a 2% concentration with furfuryl alcohol � formaldehyde formulations produced the best resin forming efficiency, permanent swelling and water property results. Conditioning time between pressure impregnation and curing was unnecessary with no improvement in properties with the cured wood block. Furfuryl alcohol with a 4% oxalic acid concentration produced the most desirable overall results with resin forming efficiency (111%), permanent swelling (8%), water uptake (8%) and dimensional stability (2.8%), when cured for 24 hours at 120�C. Analysis of leachate by GCMS suggested that a minimum curing time of 12 hours is required with furfuryl alcohol and 6 hours with a furfuryl alcohol � formaldehyde formulation to substantially reduce the amount of leachable material from a treated wood block, confirmed by dimensional stability trials.
The chemical modification of Pinus radiata (D.Don.) with furfuryl alcohol

Skewes, Brett Andrew. (University of Melbourne, 2006)

Wood blocks impregnated with furfuryl alcohol required a standing time of 48 hours to ensure complete swelling of the wood. Total penetration of the blocks was required for maximum swelling and water resistance in treated blocks. The presence of water in the treatment solution caused rapid swelling of the wood block, whereas 100% furfuryl alcohol created a slow rate of swelling. The presence of water in the cell walls accelerated the rate of swelling of 100% furfuryl alcohol, but not to the extent as when the water was present in the treatment solution. Dimensional stability decreased as the water content in the treating solution increased, but compared to the controls (6 - 8%) there was significant improvement in dimensional stability (2.5 - 4%). The resin forming efficiency varied with the amount of water present, but never dropped below 85%. Treated wood samples compressed to a density of 1200 � 1400 kg/m3 were more stable when exposed to water, and had increased hardness and MOE compared to untreated compressed samples. The curing of furfuryl alcohol in beakers gave a clear indication of catalyst performance with variable catalyst concentration and curing temperature. An increase in catalyst concentration increased the resin forming efficiency which was dependant upon the catalyst strength and number of pKa values. Of the catalysts stable at room temperature, oxalic acid, maleic acid and zinc chloride were the best performed for wood impregnation, with respect to the parameters investigated. The higher the resin forming efficiency the lower the volumetric swelling. The initial moisture content of the wood had a direct effect upon the swelling of wood blocks. All samples with an initial moisture content of 12% performed better than the corresponding treatments used with oven-dried blocks. Further, higher catalyst concentrations and curing temperatures improved performance. Oxalic acid at a 4% concentration with furfuryl alcohol and a 2% concentration with furfuryl alcohol � formaldehyde formulations produced the best resin forming efficiency, permanent swelling and water property results. Conditioning time between pressure impregnation and curing was unnecessary with no improvement in properties with the cured wood block. Furfuryl alcohol with a 4% oxalic acid concentration produced the most desirable overall results with resin forming efficiency (111%), permanent swelling (8%), water uptake (8%) and dimensional stability (2.8%), when cured for 24 hours at 120�C. Analysis of leachate by GCMS suggested that a minimum curing time of 12 hours is required with furfuryl alcohol and 6 hours with a furfuryl alcohol � formaldehyde formulation to substantially reduce the amount of leachable material from a treated wood block, confirmed by dimensional stability trials.
Quantitative genetics of wood quality traits in Pinus radiata D. Don

Nyakuengama, John Gwinyai. (University of Melbourne, 1997)

In order to understand the variability of traits important in pulping and sawn timber (heartwood formation, moisture status, density and fibre cross-sectional dimensions, fibre coarseness and fibre specific surface), wood from 4 radiata pine (Pines radiata D. Don) plustrees, including parent 80055, and their progeny comprising of a small 4 x 4, 23 year-old, unthinned, diallel progeny test was studied. 80055 progeny is renowned for consuming low energy and producing bright newsprint during thermomechanical pulping. However, the newsprint is of low tear strength. No reciprocal or maternal effects were found in all the traits, probably because of the small number of reciprocal pairs in the diallel experiment. Otherwise, results imply that future wood quality experiments could be simplified by excluding reciprocal crosses. The study found that the o-anisidine and sodium nitrite method was useful to differentiate heartwood formation from sapwood in studies involving a large number of samples. A low narrow sense heritability (NSH) was found for heartwood and its formation was accompanied with a decrease in moisture content. This accounted for a strong inverse correlation found between heartwood formation and moisture content. 80055 progeny had the most heartwood and this explained why its corewood was the driest in the diallel experiment. Technologically, drier heartwood is undesirable in refining because its pulp fibres have a lower wettability, are more brittle and produce newsprint of inferior strength and lower brightness than wetter sapwood. Wood microstructure was studied using a recently commissioned Silviscan 1 system which incorporates an X-ray densitometer and video-microscope. Protocols were set up in this pioneer study for future CSIRO-Forestry and Forest Products progeny tests (and silvicultural studies). Area-weighted fibre size (ie., fibre perimeter, fibre radial and tangential diameters) and density had the highest NSH among traits but these had large standard errors due to a narrow genetic base. The NSH of fibre coarseness was intermediate while those of area-weighted fibre wall thickness and ring width were the lowest. Additive genetic variance was high in all arbitrary classes of fibre diameters, unlike in density and fibre coarseness where it was high in all but an intermediate class representing the transition zone between earlywood and latewood. 80055 progeny had the least dense wood and the highest fibre coarseness in the diallel experiment on account of possessing the largest amount of fibres with large diameters (tangential and radial) or earlywood (as defined as wood with a density less than 400 kg m-3). Technologically, this wood microstructure could translate to low strength in sawn timber. Density and fibre traits had different genetic structures, which accounted for difference in age-age correlations and selection efficiencies at a juvenile age in relation to those at a mature age in these traits. Results indicate that fibre coarseness increased with fibre size only, in 80055 progeny. Fibre coarseness increased directly with increases in fibre wall thickness only in progeny of other parents. Technologically, this implies that fibres of 80055 progeny have thinner fibre walls at a comparable fibre coarseness than non-80055 progeny. This finding could explain why make 80055 fibres make somewhat weak refiner pulp. NSH estimates of density and fibre traits calculated in whole-cores and individual growth rings from parent-offspring regressions were generally more conservative than those from sib analysis of the diallel progeny test but the magnitude of estimates was comparable. Despite large standard errors associated with NSH estimates which were caused by the narrow genetic base of the study material, estimates tended to differ between traits and with physiological and chronological age of parents and offspring. A holistic study based on principal component analysis concluded that fibre diameter and fibre coarseness, but not density, were directly related to tree height and diameter (growth traits). Heartwood formation was directly related to the growth traits, implying that selection of one trait would influence the other.
Quantitative genetics of wood quality traits in Pinus radiata D. Don

Nyakuengama, John Gwinyai. (University of Melbourne, 1997)

In order to understand the variability of traits important in pulping and sawn timber (heartwood formation, moisture status, density and fibre cross-sectional dimensions, fibre coarseness and fibre specific surface), wood from 4 radiata pine (Pines radiata D. Don) plustrees, including parent 80055, and their progeny comprising of a small 4 x 4, 23 year-old, unthinned, diallel progeny test was studied. 80055 progeny is renowned for consuming low energy and producing bright newsprint during thermomechanical pulping. However, the newsprint is of low tear strength. No reciprocal or maternal effects were found in all the traits, probably because of the small number of reciprocal pairs in the diallel experiment. Otherwise, results imply that future wood quality experiments could be simplified by excluding reciprocal crosses. The study found that the o-anisidine and sodium nitrite method was useful to differentiate heartwood formation from sapwood in studies involving a large number of samples. A low narrow sense heritability (NSH) was found for heartwood and its formation was accompanied with a decrease in moisture content. This accounted for a strong inverse correlation found between heartwood formation and moisture content. 80055 progeny had the most heartwood and this explained why its corewood was the driest in the diallel experiment. Technologically, drier heartwood is undesirable in refining because its pulp fibres have a lower wettability, are more brittle and produce newsprint of inferior strength and lower brightness than wetter sapwood. Wood microstructure was studied using a recently commissioned Silviscan 1 system which incorporates an X-ray densitometer and video-microscope. Protocols were set up in this pioneer study for future CSIRO-Forestry and Forest Products progeny tests (and silvicultural studies). Area-weighted fibre size (ie., fibre perimeter, fibre radial and tangential diameters) and density had the highest NSH among traits but these had large standard errors due to a narrow genetic base. The NSH of fibre coarseness was intermediate while those of area-weighted fibre wall thickness and ring width were the lowest. Additive genetic variance was high in all arbitrary classes of fibre diameters, unlike in density and fibre coarseness where it was high in all but an intermediate class representing the transition zone between earlywood and latewood. 80055 progeny had the least dense wood and the highest fibre coarseness in the diallel experiment on account of possessing the largest amount of fibres with large diameters (tangential and radial) or earlywood (as defined as wood with a density less than 400 kg m-3). Technologically, this wood microstructure could translate to low strength in sawn timber. Density and fibre traits had different genetic structures, which accounted for difference in age-age correlations and selection efficiencies at a juvenile age in relation to those at a mature age in these traits. Results indicate that fibre coarseness increased with fibre size only, in 80055 progeny. Fibre coarseness increased directly with increases in fibre wall thickness only in progeny of other parents. Technologically, this implies that fibres of 80055 progeny have thinner fibre walls at a comparable fibre coarseness than non-80055 progeny. This finding could explain why make 80055 fibres make somewhat weak refiner pulp. NSH estimates of density and fibre traits calculated in whole-cores and individual growth rings from parent-offspring regressions were generally more conservative than those from sib analysis of the diallel progeny test but the magnitude of estimates was comparable. Despite large standard errors associated with NSH estimates which were caused by the narrow genetic base of the study material, estimates tended to differ between traits and with physiological and chronological age of parents and offspring. A holistic study based on principal component analysis concluded that fibre diameter and fibre coarseness, but not density, were directly related to tree height and diameter (growth traits). Heartwood formation was directly related to the growth traits, implying that selection of one trait would influence the other.
Impregnation of wood with stains

Kwiatkowski, Aleksander ( 2007)
A study of the creep performance of microwave-modified radiata pine in different external environments

Dang, Lam Dien ( 2007)

A new innovative timber treatment developed at the CRC Wood Innovations, which involves high intensity microwave application and resins impregnation, is intended to provide products for a range of applications including structural engineering members. This study has been undertaken to obtain experimental data and provide better understanding of the creep performance and long-term behaviour of the new products. In the experiment, fifteen samples, five untreated, five treated with MUF resin and five treated with Isocyanate resin were loaded in four-point bending at 30 percent of the matched samples' failing stress, in a protected external environment in Brisbane, Australia for a period of nine months to date. The treated samples were found to produce lower relative creep deformations than the untreated sample. The samples treated with MUF resin showed better creep resistance than the samples treated with Isocyanate resin. Data from the first 90 days were used to obtain parameters for the two chosen models: the power law model and the 5- parameter model. While both models provided good fitting for the data, the 5-element model was found to possess better extrapolation capacity beyond the regression period. An increase in the period of regression data from 90 days to 150 days significantly lowered the errors in both of the models.
Towards association studies in Pinus radiata D.Don - populations and wood property candidate-genes

Tibbits, Josquin Frederick George ( 2006)

In Australia and New Zealand Pinus radiata D. Don wood quality is receiving increasing interest from tree breeders. This is partly due to declining resource wood quality associated with more advanced generation breeds leading to increased rejection and product downgrading in processing. While log segregation and wood grading at mill-door yields immediate benefits to processors the underlying cause is not addressed. The only long-term solution is to include wood quality in breeding programs. Wood quality traits are costly and difficult to measure. Marker-assisted selection offers a potential solution and quantitative trait loci (QTL) mapping studies have been undertaken with the aim of facilitating this. It is becoming increasingly clear that in widely outcrossing species with long generation times and very large genomes these approaches will not work. The identification of the underlying genetic sites, or tightly linked marker sites, would rectify this and in model species linkage-map based cloning has been used extensively. This approach is also not practical in species such as P. radiata. Association testing combined with a candidate-gene approach is therefore widely believed to be one of the only methods remaining. This approach uses a priori information to select and then test the phenotypic effects of variants within candidate-gene loci. Implementation of these studies relies heavily on the results of other investigations, especially those that generate DNA sequence information. Also required is detailed knowledge of the genetic population structure, the patterns of nucleotide diversity and the patterns of linkage disequilibrium. On a more practical level suitable populations need to be identified while the current methods for the collection and handling of samples for molecular investigations are limiting. The selection of candidate genes is also a non-trivial process. For candidate-gene association studies to be successful in P. radiata all these factors need to be addressed. This formed the main aim of this thesis. A multi-pronged approach was used. Firstly, at the population level, the genetic resources available for association studies were identified and the underlying genetic population structure of these resources and the patterns of nucleotide diversity and linkage disequilibrium were investigated. Secondly, improved methods for the collection and isolation of genomic DNA were developed and thirdly, a small set of wood quality candidate-genes were selected and further characterised with the aim of identifying those with the most promise of harbouring causative variation for inclusion in future association studies. This was achieved by literature based review, linkage mapping onto wood property QTL maps and neutrality testing. Results include support for previous population genetic studies showing P. radiata to have a complex genetic structure compared to most pine species. This study also indicated significant levels of migration between the three mainland populations. Within the candidate-genes two, cinnamyl alcohol dehydrogenase and sucrose synthase, showed interesting patterns of population differentiation and/or nucleotide diversity while the results for one other gene, korrigan, did not agree with previous investigations.
The role of plant functional traits in determining the response of vegetation to land-use change on the Delatite Peninsula, Victoria

Meers, Trevor Lawrence ( 2006)
Some aspects of the symbiotic association of Pinus Radiata D. Don with Mycorrhizal fungi

Theodorou, C ( 1970)
Mechanical properties of wood following microwave and resin modification

Muga, Meshack Odera ( 2002)

The influence of microwave and resin modification of wood on its density, modulus of elasticity (MOE), modulus of rupture (MOR) and surface hardness is the subject of this thesis. Microwave energy has been used in industrial processing for many years. Microwave energy is an attractive option for wood processing and drying. Recent studies have shown that microwave energy can be used to modify wood by rupturing ray cells to form a large number of cavities in its radial/longitudinal planes resulting in micro voids of various sizes throughout its cross-section. The resultant wood (`Torgvin') is more permeable and more flexible but has a lower density and mechanical properties (MOE, MOR and surface hardness) compared to the original wood. Further treatment to restore initial density and mechanical properties by addition of resin has resulted in a new timber product `Vintorg'. Initial trials of Vintorg production employed isocyanate resin. An increase in MOE, an increase in surface hardness and a 100% restoration of MOR of P. radiata heartwood was achieved. Despite being a tough adhesive, isocyanate has some drawbacks that may not make it acceptable for the production of Vintorg. This study therefore focused on melamine formaldehyde (MF) and furfuryl alcohol (FFA) resins as potential substitutes for isocyante resin in the manufacture of Vintorg. The study evaluates Vintorg produced by soaking P. radiata and E. regnans in these two resins. A factorial design is used to evaluate the effect of wood species, resin type and duration of soaking on resin uptake, resin loss, increase in density of Torgvin, density of Vintorg and mechanical properties of Vintorg. The results show that wood species and duration of soaking and resin type have significant effects on resin uptake. The increase in the density of Torgvin during the manufacture of Vintorg is found to be influenced by wood species, duration of soaking and resin type. A higher overall increase in the density of Torgvin was obtained in E. regnans compared to P. radiata. Melamine formaldehyde resin tends to have a greater effect on the increase in the density of E. regnans than P. radiata. Torgvin samples impregnated with FFA had a greater effect on increasing the density of P. radiata than E. regnans. Vintorg in the timber species tested is found to be the same or higher in MOE, much higher in density but lower in MOR than natural wood from the same species, irrespective of wood species, resin type or soaking time. Vintorg produced from P. radiata is also higher in surface hardness than natural wood from the same species irrespective of resin type and soaking time. It is interesting to note that surface hardness of Vintorg is lower in E. regnans as compared to natural wood from the same species. It is also evident that FFA and MF Vintorg are the same or higher in MOE but lower in MOR than isocyanateVintorg from the same species irrespective of wood species tested and the duration of soaking used. The FFA and MF Vintorg from are also the same or higher in surface hardness in the case of P. radiata but same or lower in the case of E. regnans. It is concluded that it may be possible to substitute the two resins for isocyanate resin in the production of Vintorg provided that a way is devised to ensure that the MOR of the resultant Vintorg is at least same or higher than that of original wood. It is recommended that further research be carried out to establish a microwave regime for optimal wood permeability and whilst minimizing the reduction in MOR, and that low cost, environmentally friendly resin systems are developed with low viscosity. These resins need to be tough enough to result in Vintorg with characteristics similar to Vintorg produced with isocyanate resin and superior to natural wood in terms of mechanical properties.

School of Agriculture, Food and Ecosystem Sciences - Theses

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