Impact of Natural Degradation on the Aged Lignocellulose Fibers of Moroccan Cedar Softwood: Structural Elucidation by Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD)

In plain language

This research evaluates the natural degradation of historical Moroccan cedar softwood samples dating from the sixteenth, seventeenth, nineteenth, and twenty-first centuries. By combining infrared spectroscopy and X-ray diffraction, structural changes in hemicellulose, cellulose, and lignin were identified to measure deterioration over time. Hemicellulose breakdown was evidenced by the loss of specific acetyl groups beginning in nineteenth-century timber. Cellulose crystallinity dropped significantly from fifty-one point eight percent in modern wood to twenty point two percent in the oldest specimens, matching declines in crystalline cellulosic bands. Significant alteration of the lignin aromatic structure occurred in the sixteenth- and seventeenth-century samples, forming new carbonyl compounds. The degree of deterioration depended on whether the timber surface was internally or externally exposed to weathering agents alongside the overall duration of natural aging.

Key takeaways

Combining infrared spectroscopy and X-ray diffraction reveals structural degradation patterns across Moroccan cedar softwood aged from the sixteenth to the twenty-first century.
Hemicellulose breakdown begins from the nineteenth century onward through the loss of specific acetyl groups.
Cellulose crystallinity falls from 51.8 percent in modern wood to 20.2 percent in the oldest samples.
Lignin undergoes chemical alteration in sixteenth- and seventeenth-century wood, shifting from aromatic structures toward new carbonyl compounds.
The extent of decay depends on exposure to weathering agents on internal versus external surfaces and the duration of aging.

Why it matters

Understanding how ancient timber decays helps heritage specialists assess structural integrity and preservation needs in historical wooden structures and artefacts. By tracking precise chemical alterations across centuries of natural exposure, researchers can pinpoint how essential structural components, including cellulose, hemicellulose, and lignin, break down over prolonged periods under environmental conditions.

Commercialisation angle

This analytical approach could assist heritage conservation practitioners, timber restorers, and cultural institutions in diagnosing the decay level of historic wooden structures. The study represents early-stage diagnostic research rather than an applied commercial tool, relying on laboratory-based spectroscopy and diffraction techniques to characterise degradation mechanisms without outlining direct commercialisation pathways.

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Abstract

The aims of this study are to investigate the structure of four historical Moroccan cedar softwood samples of different aging time duration (16th, 17th, 19th, 21st centuries) and compare among these four samples, using two analytical methods, FTIR and XRD, in order to confirm some structural changes and determine the degree of deterioration. The pronounced hemicellulose deterioration was highlighted by a breakdown of IR acetyl groups at 1738 cm−1 from the 19th century sample until aged ones. The cellulose XRD crystallinity index showed an important decrease from recent to oldest samples (51.8 to 20.2%) justifying the damages mainly in the two oldest samples (17th and 16th centuries), also confirmed by FTIR. The alteration of lignin was manifested in the case of the two ancient samples (16th and 17th centuries), proven by the decrease in IR bands related to aromatic nuclei (1595, 1500, 1230 cm−1) evolving towards a new diconjugate C=O formers at 1647 cm−1 (quinone, Ar-CO-Ar, Ar-CO-C=C). For accurate elucidation, the data of two combined techniques were compared and correlated. The obtained results depended on the part of the wood exposed to weathering effects (internal or external) and were influenced by both extended time of aging and effects of natural deterioration agents. The effects of natural aging were investigated in four historical Moroccan cedar softwood samples (16th, 17th, 19th, 21st centuries) using two analytical tools: FTIR and XRD. The pronounced hemicellulose deterioration was highlighted by a breakdown of IR acetyl groups at 1738 cm−1 and declines in the absorption signal at 1268 cm−1 from the 19th century sample until aged ones. The cellulose XRD crystallinity index (CrI) estimation showed an important decrease from recent to oldest samples (51.8 to 20.2%) justifying the damages mainly in the two oldest samples (17th and 16th centuries). These data were also confirmed by FTIR showing a significant reduction in both area profiles of C-O-C (1150–1000 cm−1) and C-H crystalline cellulosic bands (1375, 1318, and 1268 cm−1), respectively. The lignin alteration in both old samples (16th and 17th centuries) was proven by the decrease in IR aromatic skeleton (1595, 1500, and 1230 cm−1) evolving towards a new diconjugate C=O formers at 1647 cm−1 (quinone, Ar-CO-Ar, Ar-CO-C=C). To determine the structural difference and the degree of deterioration, the IR area of C=O band intensities ranging from 1550 to 1800 cm−1 was exploited. For accurate elucidation, the data of two combined techniques were compared and correlated. The obtained results depended on the part of the wood (internal or external) exposed to weathering effects and were influenced by both extended time of aging and effects of natural deterioration agents.

Research topics

Lignin and Wood Chemistry
Cultural Heritage Materials Analysis
Wood Treatment and Properties

Sustainable Development Goals

15Life on Land

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