Quantitative wood–adhesive penetration with X-ray computed tomography

Paris, Jesse L.; Kamke, Frederick A.

doi:10.1016/j.ijadhadh.2015.05.006

Cited by 40 publications

(30 citation statements)

References 12 publications

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“…Fluorescently labelling the PLA produced clear distinctions of this polymer from both wood species as well as any wood fibres additionally contained within each bondline (Figures 1 and 4, with additional images available in Supplementary Materials). The microscopy cross sections of bondlines profile PLA mobility and migration into vesicular structures of the wood, similar to more traditional adhesive bondlines formed in plywood [9,14]. Examples of bondlines contrasting pure PLA and PLA containing 25% softwood fibres are shown in Figure 1.…”

Section: Fluorescence Microscopymentioning

confidence: 52%

Section: Discussionmentioning

confidence: 84%

“…This is distinct from liquid wood adhesive behaviours where cell wall infiltration is commonly observed [12,14]. This suggests that the greater molecular weight of PLA [14], together with polymer hydrophobicity [9] and/or high viscosity, may restrict PLA mobility into the wood cell wall compared to that of the water-soluble condensation polymers of typical wood adhesive systems [12,14]. Moreover with liquid wood adhesives, adhesive flow can be parameterised to measure adhesive penetration depth from bondlines.…”

Section: Discussionmentioning

confidence: 97%

“…In order to further develop a fundamental understanding of the PLA adhesion interface at a wood cellular level, further investigative analysis is required. A range of techniques are available to determine interfacial properties and behaviours at a wood ultrastructure level and include X-ray fluorescence microscopy, nanoindentation, scanning thermal microscopy and UV microscopy [9]. In the case of the latter, UV microscopy coupled with fluorescently tagged polyesters was initially applied to PLA-based WPCs to visualise interactions of PLA with wood fibre at microscale [10].…”

Section: Introductionmentioning

confidence: 99%

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Quantitative Assessment and Visualisation of the Wood and Poly(Lactic Acid) Interface in Sandwich Laminate Composites

Grigsby

Gager

Recabar

et al. 2019

Fibers

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Fluorescence microscopy was applied to understand adhesion interfaces developed within laminated composite sandwiches formed between poly(lactic acid) (PLA) and wood veneers. Composites formed with maple veneer had greater tensile bond strength when manufactured at 200 °C (10.4 N/mm2) compared to formation at 140 °C (8.7 N/mm2), while significantly lower bond strength was achieved using spruce veneers, at 5.2 and 3.5 N/mm2, respectively. Qualitative and quantitative confocal microscopy assessments revealed differing bondline thicknesses and PLA ingress within the wood ultrastructure. Forming maple veneer composites at 200 °C promoted greater PLA mobility away from the bondline to reinforce the wood–PLA interface and deliver associated greater composite bond strength. The addition of 25% wood fibre to PLA led to fibre alignment and overlap within bondlines contributing to relatively thicker, heterogeneous bondlines. Study outcomes show that the composite processing temperature impacts the adhesion interface and composite performance and will have broad application over veneer overlays, laminates and wood plastic composites (WPCs) using wood, particles or fibres with PLA.

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Section: Fluorescence Microscopymentioning

confidence: 52%

Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Quantitative Assessment and Visualisation of the Wood and Poly(Lactic Acid) Interface in Sandwich Laminate Composites

Grigsby

Gager

Recabar

et al. 2019

Fibers

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“…Contradictory results were observed from a study on PHB/ponderosa pine WF composites where the tensile strength and modulus increased with increasing pMDI content [Anderson et al, 2013]. It is suspected that the more concentrated pMDI solutions were prone to reacting with trapped moisture, producing CO2 [Paris & Kamke, 2015]. Thus, voids and porosity could be formed within the matrix leading to a worsened strength and strain at break.…”

Section: Effect Of Compatibilisation Techniquesmentioning

confidence: 93%

Development of bio-derived and biodegradable polyhydroxyalkanoate (PHA)-based wood plastic composites (WPCs)

Chan¹

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In response to the concerns over the accumulation of plastic wastes, the wood plastic composites (WPCs) industry has been in particular interest in replacing the petroleum-based polymer matrices with biopolymers. Polyhydroxyalkanoates (PHAs) are potential candidates as these biopolymers can be degraded readily under ambient conditions and can be synthesised intracellularly by bacteria from renewable/waste resources. Their low melt viscosity can also be an advantage in processing. While there is a considerable body of literature on PHA-based WPCs, the majority of the studies have focused on mechanical property optimisation but their mechanical stability and biodegradability were poorly understood. Therefore, this thesis explored the fundamental characteristics of PHA/wood flour (WF) composites with focus on the micro-structure-property relationship and end-of-life behaviour. The extrusion processing setup for composites of a commercially available poly(3-hydroxybutyrateco-3-hydroxyvalerate) (PHBV) and WF was first optimised. A logical next step involved the optimisation of mechanical properties through the use of carefully selected chemical compatibilisers and additives. The expected benefits of chemical compatibilisers were outweighed when compared to the alteration of micro-structure by the non-reactive micro-sized talc filler. An innovative approach for improving processabilty and toughness was then investigated through the inclusion of tougher PHA copolymers including an in-house mixed culture PHBV, for further cost reduction. The potential of this strategy was demonstrated by the improvement, albeit marginal, in composite strain at break. The real-time studies of mechanical stability and biodegradability brought new insights to this biocomposite. Uncoated PHBV/WF composites were stable under indoor ambient conditions for at least 1 year. Exposure to outdoor environment, however, led to reduced mechanical stability. It was determined to be solely associated with the mould growth on the exposed hygroscopic wood particles. The unique advantage of PHBV/WF composites was demonstrated with respect to their significantly higher biodegradation rate in soil than PLA/WF and PE/WF composites. The presence of wood accelerated the biodegradation and reduced the mechanical stability of the composites in soil. A micro-mechanical schematic model was used to illustrate the phenomena. In addition, it was shown that PHA-based WPCs are physically and mechanically stable unless they are exposed to colonies of microorganisms such as moisture-induced mould or those found in soil communities. Overall, this thesis provided better insights into the strong correlations between the micro-structure and the properties of PHA-based WPCs, both initially and in the long-term. Wood particles played an important role in both their performance and biodegradation. To conclude, this thesis has paved the way for development of novel bio-derived and biodegradable composites which provide utility what would otherwise be a low-value stream from the f...

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