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Article

Comparative Studies on Tensile Mechanical Properties of Water-Saturated Earlywood and Latewood within the Same Growth Ring from Masson Pine

by
He Huang
,
Zhu Li
,
Yuan Li
,
Jiali Jiang
and
Ruiqing Gao
*
Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China
*
Author to whom correspondence should be addressed.
Forests 2024, 15(4), 589; https://doi.org/10.3390/f15040589
Submission received: 30 January 2024 / Revised: 14 February 2024 / Accepted: 19 February 2024 / Published: 25 March 2024
(This article belongs to the Special Issue Measurement and Improvement of Wood Mechanical and Chemical Properties)
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Abstract

:
The tensile mechanical behavior of water-saturated earlywood (EW) and latewood (LW) within the same growth ring of Masson pine (Pinus massoniana) was investigated in the hydrothermal environment and discussed with respect to the density and microfibril angle (MFA) of the wood specimens. The tensile modulus, tensile strength, and strain at failure of EW and LW in the longitudinal (L) and tangential (T) directions were determined at different temperature levels ranging from 30 °C to 80 °C. Major differences in the tensile mechanical properties were found between EW and LW in the L and T directions. Compared to LW, EW showed a smaller density and a larger MFA, resulting in a lower tensile modulus, lower tensile strength, and higher strain at failure. Compared to the L specimens, the T specimens showed lower tensile modulus, lower tensile strength, and higher strain at failure. As the hygrothermal temperature increased, the MFAs, tensile modulus, and tensile strength of EW and LW specimens decreased, except for the MFAs of LW, while the strain at failure of the specimens showed the opposite trend. Variations in the tensile mechanical behavior between EW and LW were mainly influenced by the density and MFA of the specimens, and are closely associated with the hydrothermal softening properties of wood. These findings contribute to a further understanding of the structural–mechanical relationships of Masson pine wood at the cell wall level, and provide a scientific basis for the better utilization of plantation softwood in the hydrothermal environment.

1. Introduction

Wood is one of the most common renewable natural materials that have traditionally been used as a structural component of buildings. Masson pine (Pinus massoniana) is one of the main commercial plantation conifer tree species in China, which can widely be used for wooden buildings and industrial materials [1,2]. Conifers consist mainly of axial tracheids, serving for support and for transport of water and dissolved minerals. Their anatomical structure, chemical composition, and the spatial arrangement of polymers in the wood cell walls determine the mechanical properties [3,4,5]. Conifers contain two main types of tracheids: earlywood (EW) tracheids, which have thin cell walls and large cell cavities, and latewood (LW) tracheids, which have thick cell walls and small cell cavities. Therefore, information about the mechanics of EW and LW tracheids can be helpful to deepen our understanding of the structural–mechanical relationships of wood at the cell wall level.
Numerous scholars have extensively explored the differences in the tensile mechanical properties between EW and LW at a given temperature and moisture content (MC) level [6,7,8,9,10,11,12]. Roszyk [7] reported on the tensile mechanical behavior of the EW and LW of pine wood (Pinus sylvestris) in the longitudinal (L) direction in the wet and air-dry states, and found that tensile strength, modulus of elasticity, and stress at the proportionality limit of EW and LW decreased generally as the MC increased. Compared with EW, the tensile mechanical parameters of tensile strength and tensile modulus for LW are larger. However, the relationship for the strain at break of EW and LW was uncertain. A similar observation was made for previous research [8,9]. It is well known that wood strength decreases with temperature. The wood cell wall polymers are provided with heat energy for segmental motion, resulting in the decrement of wood stiffness [11,12]. Differences in density, microfibril angle (MFA), chemical compositions, and cell structure might be the reasons for the differences in the tensile mechanical properties of EW and LW [13,14,15,16]. Wood density and MFA are generally the key factors determining wood properties and have a significant impact on the stiffness and strength of wood.
Likewise, the tensile mechanical behavior of wood differs vastly in the L direction and in the transverse directions [17,18,19]. In general, previous comparative studies on the tensile mechanical behavior of EW and LW mainly focused in the L direction [7,8,9,10]; little research had been conducted on the tensile mechanical properties of EW and LW in the tangential (T) direction [12]. Horiyama et al. [12] investigated the tensile dynamic mechanical properties of water-saturated EW and LW within an annual ring in the T direction in the temperature range from 20 °C to 100 °C, and found that the dynamic modulus of LW was larger than that of EW for all wood species, regardless of softwood or hardwood. Therefore, information on the mechanics of EW and LW in the L and T directions exposed to different temperature levels is of particular interest.
While datasets about EW and LW in the L direction exist, to the best of our knowledge nothing is known about the static tensile mechanical properties of EW and LW in the T direction despite their frequent occurrence within an annual ring. In the present study, the tensile mechanical behavior of EW and LW within the same growth ring in the L and T directions was investigated in the hydrothermal environment ranging from 30 °C to 80 °C. The absolute dry density as well as the MFA of EW and LW were determined to reveal the structural–mechanical relationships of wood at the cell wall level. A deep understanding of EW and LW tracheids tensile mechanical properties at different temperature levels is necessary for the better processing and utilization of fast-growing softwoods.

2. Materials and Methods

2.1. Materials

Clear wood specimens without any visible defects or knots were cut from the 17th growth ring of the heartwood of a 41-year-old Masson pine (Pinus massoniana) obtained from a demonstration forest of Hunan Province in China. The EW and LW from the 17th growth ring were selected because they had representative absolute dry density. Moreover, the 17th growth ring was wider than the other growth rings, which allowed for obtaining more wood specimens of EW and LW. The absolute dry density of the EW and LW from the 17th growth ring was 0.388 g/cm3 and 0.836 g/cm3, respectively. Microtome cuboidal slices were cut to a thickness (radial) of 0.1 mm and a section of 30 mm (L) × 2 mm (T) for the L specimens and 30 mm (T) × 2 mm (L) for the T specimens; see Figure 1. The L specimens of EW and LW are named as LT-EW and LT-LW, and the T specimens of EW and LW are named as TL-EW and TL-LW, respectively. The LT-EW and LT-LW specimens were used to determine the MFA and to conduct tensile mechanical analysis, respectively, while the TL-EW and TL-LW specimens were obtained for tensile tests. Before testing, all specimens were stored in distilled water at room temperature for more than 3 months until the water-saturated state of the specimens was achieved. The wood specimens did not float in distilled water following this treatment.

2.2. Experimental Methods

The MFA values of the specimens were evaluated via a D8 Advance X-ray diffractometer (Bruker AXS, Karlsruhe, BW, Germany). Before testing, the wood specimens were placed in an electro-thermostatic water bath with an aim to obtain different temperature levels of 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C, respectively. After that, the specimens were fixed with double-sided tape in a holder, and the direction of the zero scale of the holder was parallel to the fiber axis of the specimens. The main parameter settings were as follows: 2θ = 22.4°, 40 kV, 40 mA, continuous circle scanning, sample rotation angle of 360°, and a measuring time of about 6 min. The mean MFA was calculated based on the 0.6T method [20], where T is the half-width of the maximum peak, taken from the tangents drawn at the points of inflection. For LT-EW and LT-LW, three replicate specimens were evaluated, respectively.
Tests were performed in tensile mode on a dynamic mechanical analyzer (DMA Q800; TA Instruments, New Castle, DE, USA) equipped with submersible configuration. The submersion clamp was fixed in such a way that the water-saturated specimens were put into a stainless-steel cup that maintained the specimens immersed and tested directly in distilled water. The span between the supporting points was fixed at 15 mm. During the DMA test, the tensile stress was applied along the length of the L or T specimens. Wood specimens of LT-EW, LT-LW, TL-EW, and TL-LW were measured at different temperature levels of 30 °C, 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C, respectively. A preload force of 0.01 N was applied, and then the tensile force was applied at the rate of 1.0 N/min for the specimens. When the specimens were loaded to 18 N (the maximum load of DMA Q800), the tensile force applied would be stopped automatically. The parameters of stress, strain, and time were automatically recorded by the DMA, and the wood specimens studied were subjected to measurements of tensile modulus, tensile strength, and strain at failure. Three replicates were performed for each condition.

3. Results and Discussion

3.1. Microfibril Angle (MFA)

The values of the MFAs for EW and LW in the 17th growth ring at various temperature levels ranging from 30 °C to 80 °C are listed in Table 1. The variability of results was calculated based on the coefficient of variation (COV) obtained from the average of three specimens for each test condition. The results clearly indicate that the MFA of EW was larger than that of LW at each temperature level, in agreement with findings in previous studies [8,9,21]. Interestingly, the values of the COV for EW at any temperature level were larger compared to those of LW, which might be related to the greater number of pits in EW and to the fact that the cellulose microfibrils around these pits are distorted in the length direction [22]. The MFAs of EW gradually decreased from 15.28° to 14.12° with increasing temperature, while the MFAs of LW were slightly affected by the change in temperature. Hydrothermal treatment caused the hydrolysis or abscission of some pit membranes, leading to the more regular orientation of the microfibrils in the pit area [23,24]. The number of pits of the EW tracheids (approximately 89 on average) were approximately 3.5 times greater than that of the LW tracheids (approximately 26 on average) [22]. Consequently, compared to LW, the MFAs of EW gradually decreased with increasing temperature, and the effect of temperature on the reduction in MFAs was more pronounced in EW.

3.2. Temperature-Dependent Tensile Mechanical Properties

3.2.1. Tensile Modulus

The values of the tensile modulus for the L specimens and T specimens at different temperature levels ranging from 30 °C to 80 °C are depicted in Figure 2a,b, respectively. The tensile modulus of LW was significantly higher than that of EW at each temperature level, irrespective of the grain orientation, which has been observed in some previous studies [8,9,11]. Structurally, the absolute dry densities of LW (0.836 g/cm3) within the same growth ring were 2.2 times larger than those of EW (0.388 g/cm3). Similar observations were made for wood specimens at the macroscopic scale, in which results showed that the tensile modulus values in the L and T directions were positively linear with the wood densities [25,26]. In addition, the MFA of LW was smaller than that of EW at each temperature level, which was also an important contributing factor for the higher tensile modulus values in LW. Furthermore, the tensile modulus of the L specimens was significantly higher than that of the T specimens. In tensile tests, the crystalline cellulose microfibrils are orientated in the L direction, and the matrix of lignin and hemicelluloses is the load-bearing polymer in the T specimens [27,28]. Therefore, it should be noted that the orientation of cellulose microfibrils in the L direction explains the higher tensile modulus of the L specimens.
At the measured temperature of 30 °C, the tensile modulus was determined as 1680 MPa, 5553 MPa, 25 MPa, and 132 MPa in LT-EW, LT-LW, TL-EW, and TL-LW, respectively. It was found that the tensile modulus of LT-LW was 3.3 times greater than that of LT-EW, and the tensile modulus of TL-LW was 5.3 times greater than that of TL-EW. A similar observation was made for EW and LW at all temperature levels. As also seen in Figure 2, the tensile modulus of the wood specimens showed a decreasing trend as the hygrothermal temperature increased. When the temperature increased from 30 °C to 80 °C, the decrement in tensile modulus for LT-EW, LT-LW, TL-EW, and TL-LW was 32.4%, 29.1%, 84.0%, and 76.8%, respectively. Under water-saturated conditions, heat energy is provided for the Brownian motion of polymer molecules and chain segments, resulting in the decrement in tensile modulus with the rising temperature [11,12]. Accordingly, the decrements in tensile modulus for EW were larger than those for LW in both the L and T directions. This result may be related to the quantity of lignin in the wood cell walls, which was the determining factor for the thermal softening properties of water-swollen wood [29]. Compared to LW with a lignin content of 28.31%, EW had a higher lignin content of 33.88% [30]. Consequently, the tensile modulus for EW was more sensitive to temperature changes compared to LW. Furthermore, the decrement in the tensile modulus of the L specimens was significantly lower than that of the T specimens. The cellulose microfibrils dominated the tensile modulus of the L specimens, while the matrix of lignin and hemicelluloses played the more dominating role for the tensile modulus of the T specimens [31]. The cellulose microfibrils are more stable and resistant to heat than the matrix, which is more pliable and sensitive to temperature in the hydrothermal environment [32,33], accounting for the larger values of the decrement in the tensile modulus of the T specimens.
To obtain more detailed information about the relationship between the tensile modulus and the hygrothermal temperature, the parameter of relative tensile modulus was calculated as follows: the tensile modulus at any temperature level (30~80 °C) was divided by the tensile modulus at 30 °C. The relative tensile modulus values of the L specimens and T specimens are visible in Figure 2c,d, respectively. It was seen that the relative tensile modulus of the specimens decreased as the hygrothermal temperature increased, and a clear inflection point was exhibited at 50 °C or 60 °C. In the hydrothermal environment, the softening properties of wood reflect to a large extent the properties of lignin. In general, water-saturated wood specimens were found to soften around 60 °C, corresponding to the relaxation of lignin [34,35,36,37]. Therefore, it should be concluded that the softening of wood played a significantly important role in the decrease in tensile modulus in the hydrothermal environment.

3.2.2. Tensile Strength

The values of the tensile strength of the L specimens and T specimens at different temperature levels ranging from 30 °C to 80 °C are depicted in Figure 3a,b, respectively. It can be observed that the tensile strength of LW presented a tendency to surpass that of EW at each temperature level, irrespective of the grain orientation, which was similar to previous reports [7,8]. At the measured temperature of 30 °C, the tensile strength was 22.63 MPa, 54.77 MPa, 1.32 MPa, and 1.94 MPa in LT-EW, LT-LW, TL-EW, and TL-LW, respectively. The values of the tensile strength of LW were found to be 2.42 to 2.69 times higher than those of EW in the L direction. Similarly, in the T direction, the values of the tensile strength of LW were seen to be 1.43 to 1.59 times higher than those of EW. It is generally acknowledged that the relationship between tensile modulus and tensile strength is proportional, which was similar to previous reports [25,38]. The difference in tensile strength between EW and LW has been determined not only by the wood density but also by the MFA values [13,14,15,16]. At each temperature level, compared to LW, EW showed a smaller density and a larger MFA, resulting in the lower tensile strength of EW.
Furthermore, with the increase in temperature from 30 °C to 80 °C, the tensile strength of LT-EW, LT-LW, TL-EW, and TL-LW decreased by 20.76%, 16.39%, 52.02%, and 49.46%, respectively. Obviously, the decrement in tensile strength was less pronounced than that in the tensile modulus of the wood specimens (the corresponding values were 32.4%, 29.1%, 84.0%, and 76.5%). Accordingly, the decrements in the tensile strength for EW were larger than those for LW in both the L and T directions, indicating that the tensile strength for EW was more sensitive to temperature changes compared to LW. In addition, the decrements in the tensile strength of the L specimens were significantly lower than that of the T specimens. The cellulose microfibrils dominating the tensile strength of the L specimens are more stable and resistant to heat than the matrix, which is more pliable and sensitive to temperature in the hydrothermal environment [32,33], accounting for the larger values of the decrement in tensile strength of the T specimens.
To obtain more detailed information about the relationship between the tensile strength and the hygrothermal temperature, the parameter of relative tensile strength was calculated as follows: the tensile strength at any temperature level (30~80 °C) was divided by the tensile strength at 30 °C. The relative tensile strength values of the L specimens and T specimens are illustrated in Figure 3c,d, respectively. It was evident that the response of tensile strength to temperature exhibited a similar trend to that of the tensile modulus. Specifically, as the measured temperature increased, the relative tensile strength of all wood specimens diminished, and a distinct inflection point was clearly observed at approximately 50 °C or 60 °C. Similar to the discussion of tensile modulus, the softening of lignin contributed greatly to the decrement in the tensile strength of the specimens. Furthermore, for the L specimens (Figure 3c), the relative tensile strength of LT-EW was lower than that of LT-LW at all temperature levels (40~80 °C), while the relative tensile strengths of TL-EW and TL-LW were approximately the same (Figure 3d), indicating that the response of tangential tensile strength to temperature was similar for EW and LW. The matrix of lignin and hemicelluloses is the load-bearing polymer in the T specimens [27,28], and the response of the matrix to the hygrothermal environment was similar for the tensile strength of EW and LW.

3.2.3. Strain at Failure

The values of the strain at failure of the L specimens and T specimens at different temperature levels ranging from 30 °C to 80 °C are depicted in Figure 4a,b, respectively. The strain at failure of EW was extremely higher than that of LW at each temperature level, irrespective of the grain orientation, which was similar to previous reports [8,9]. At the measured temperature of 30 °C, the strain at failure was 1.82%, 1.00%, 8.59%, and 1.01% in LT-EW, LT-LW, TL-EW, and TL-LW, respectively. It was found that the values of the strain at failure of EW were 1.82 times greater than those of LW in the L direction, while the strain at failure of EW was 8.51 times greater than that of LW in the T direction. In the hydrothermal environment ranging from 30 °C to 80 °C, the strain at failure of EW was found to be 1.43 to 1.82 times higher than that of LW in the L direction, and the strain at failure of EW was seen to be 4.87 to 8.51 times higher than that of LW in the T direction.
Compared to LW, EW with a larger MFA appeared to have a greater strain at failure under the same conditions, which was similar to previous reports [7,8]. Observed differences in the strain at failure between EW and LW in the L direction could be closely related to the MFA [8,21,39]. The MFA is probably the most important structural parameter on the cell wall scale influencing the mechanical performance of tracheids in their axial direction [40]. Roszyk [8] found that the strain at break of wet wood with a moisture content above the fiber saturation point was observed to increase with increasing MFA. In addition, differences in the types of breaks were observed between EW and LW in the L direction. For EW, a typical break was an easy break, while it was more often a jagged break for LW. In the T direction, the value of the strain at failure in EW was higher than that in LW at each temperature level, which may be related to the higher relative lignin content and lignin-rich middle lamella in EW [28,41]. Furthermore, at each temperature level, the values of the strain at failure in the TL-EW specimens were significantly higher than those of the LT-EW specimens, while the values of the strain at failure in the TL-LW specimens were slightly higher than those of the LT-LW specimens. The softening of the matrix was pronounced for EW in the hygrothermal environment compared to LW, accounting for the larger values of the strain at failure in EW.
An increasing trend of the strain at failure was manifested with increasing temperature for all wood specimens, which displayed an opposite trend for the tensile modulus and tensile strength. These results were in agreement with previous studies [8,9]. As the temperature increased from 30 °C to 80 °C, the strain at failure of EW and LW increased by 20.9% and 53.0% in the L specimens and 76.1% and 144.6% in the T specimens, respectively. The higher temperature level will provide more heating energy for segmental motions in the wood cell wall, and the molecular motion of the wood cell walls will become active and have decreased resistance to external tensile stress [28,38]. Therefore, for water-saturated EW and LW specimens, higher values of strain at failure were observed at higher temperatures.
To obtain more detailed information about the relationship between the strain at failure and the hygrothermal temperature, the relative strain at failure was calculated as follows: the strain at failure at any temperature level (30~80 °C) was divided by the strain at failure at 30 °C. The values of the relative strain at failure of the L specimens and T specimens are illustrated in Figure 4c,d, respectively. Obviously, all curves of EW and LW exhibited a monotonically increasing trend as the temperature increased, and a distinct inflection point was clearly observed at approximately 30 °C or 40 °C for the T specimens (Figure 4d). Similar to the discussion of tensile modulus and tensile strength, the softening of wood contributed to the increase in strain at failure. The relative strain at failure of EW was lower than that of LW at each temperature level (40~80 °C), irrespective of the grain orientation. Furthermore, the relative strain at failure values of the L specimens were lower than that of the T specimens, indicating that the effect of softening on the T specimens was pronounced in the hygrothermal environment.

4. Conclusions

The structural characterization and tensile mechanical properties of water-saturated EW and LW within the same growth ring of Masson pine wood were investigated and compared. Structurally, the absolute dry densities of LW within the same growth ring were 2.2 times larger than that of EW. In addition, the MFA of EW was larger than that of LW at each temperature level.
Compared to LW, EW showed a smaller density and a larger MFA, resulting in a lower tensile modulus, lower tensile strength, and higher strain at failure. Compared to the L specimens, the T specimens showed lower tensile modulus, lower tensile strength, and higher strain at failure. In the hydrothermal environment ranging from 30 °C to 80 °C, for the L specimens, the tensile modulus and tensile strength values of LW were 3.31 to 3.57 and 2.42 to 2.69 times greater than those of EW, while the strain at failure values of EW were 1.43 to 1.82 times greater than those of LW, respectively. Furthermore, in the T direction, the values of tensile modulus and tensile strength were 5.29 to 8.79 and 1.43 to 1.59 times greater than those of EW, while the strain at failure values of EW were 4.87 to 8.51 times greater than those of LW, respectively.
The MFAs of EW gradually decreased with increasing temperature, while the MFAs of LW were slightly affected by temperature. As the hygrothermal temperature increased, the tensile modulus and tensile strength of EW and LW in the L and T directions decreased, while the strain at failure of the wood specimens showed the opposite trend. Compared with LW, EW was more sensitive to temperature in the MFA, tensile strength, and tensile modulus, while EW was less sensitive to temperature in the strain at failure. Variations in tensile mechanical behavior between EW and LW are mainly influenced by the density and MFA of the specimens, and are closely associated with the hydrothermal softening properties of wood. The results of this study are important for better understanding the tensile mechanical properties of wood tracheids, and can serve as a valuable reference for the selection of experimental parameters and process optimization of hydrothermal treatment in the practical production of wood products.

Author Contributions

Conceptualization, Y.L. and H.H.; methodology, Y.L.; formal analysis, H.H. and Z.L.; investigation, J.J. and R.G.; data curation, H.H. and Z.L.; writing—original draft preparation, H.H.; writing—review and editing, Z.L., J.J. and R.G.; supervision, J.J. and R.G.; funding acquisition, Z.L. and J.J. All authors have read and agreed to the published version of the manuscript.

Funding

This work was funded by the Major Projects of Scientific and Technological Innovation 2030 (2023ZD0405905) and the National Natural Science Foundation of China (32071689).

Data Availability Statement

The datasets generated during and/or analyzed in this study are available from the corresponding author upon reasonable request.

Acknowledgments

The authors gratefully acknowledge the laboratory of the Research Institute of Wood Industry at the Chinese Academy of Forestry for providing testing materials and machines, and the technical staff for assisting in our experiment.

Conflicts of Interest

The authors have no relevant financial or non-financial conflicts of interest to disclose.

References

  1. Huang, Q.J. Analysis on planting technology and economic benefit of Masson pine. Mod. Agric. Res. 2020, 26, 88–89. [Google Scholar]
  2. Zhang, C.Z. Analysis on planting technology and economic benefit of Pinus massoniana in Guangxi. South China Agric. 2020, 14, 9–10. [Google Scholar]
  3. Chen, C.; Kuang, Y.; Zhu, S.; Burgert, I.; Keplinger, T.; Gong, A.; Li, T.; Berglund, L.; Eichhorn, S.J.; Hu, L. Structure–property–function relationships of natural and engineered wood. Nat. Rev. Mater. 2020, 5, 642–666. [Google Scholar] [CrossRef]
  4. Li, Z.; Zhan, T.Y.; Eder, M.; Jiang, J.L.; Lyu, J.X.; Cao, J.Z. Comparative studies on wood structure and microtensile properties between compression and opposite wood fibers of Chinese fir plantation. J. Wood Sci. 2021, 67, 12. [Google Scholar] [CrossRef]
  5. Wang, S.D.; Chen, D.S.; Chu, J.Y.; Jiang, J.H. Effect of growth ring width and latewood content on selected physical and mechanical properties of plantation Japanese larch wood. Forests 2022, 13, 797. [Google Scholar] [CrossRef]
  6. Pearson, H.; Gabbitas, B.; Ormarsson, S. Tensile behaviour of radiata pine with different moisture contents at elevated temperatures. Holzforschung 2012, 66, 659–665. [Google Scholar] [CrossRef]
  7. Roszyk, E.; Kwiatkowski, T.; Moliński, W. Mechanical parameters of pine wood in individual annual rings under tensile stress along the grains in dry and wet state. Wood Res. 2013, 58, 571–580. [Google Scholar]
  8. Roszyk, E. The effect of ultrastructure and moisture content on mechanical parameters of pine wood (Pinus sylvestris L.) upon tensile stress along the grains. Turk. J. Agric. For. 2014, 38, 413–419. [Google Scholar] [CrossRef]
  9. Roszyk, E.; Moliński, W.; Kamiński, M. Tensile properties along the grains of earlywood and latewood of Scots pine (Pinus sylvestris L.) in dry and wet state. BioResources 2016, 11, 3027–3037. [Google Scholar] [CrossRef]
  10. Büyüksarı, Ü.; As, N.; Dündar, T. Mechanical properties of earlywood and latewood sections of Scots pine wood. BioResources 2017, 12, 4004–4012. [Google Scholar] [CrossRef]
  11. Li, A.X.; Jiang, J.L.; Lu, J.X. Differences in the viscoelastic properties between earlywood and latewood in the growth rings of Chinese fir as analyzed by dynamic mechanical analysis (DMA) in the temperature range between −120 °C and 120 °C. Holzforschung 2019, 73, 241–250. [Google Scholar] [CrossRef]
  12. Horiyama, H.; Miyoshi, Y.; Kojiro, K.; Furuta, Y. Thermal softening properties of various wood species within an annual ring. J. Wood Sci. 2023, 69, 30. [Google Scholar] [CrossRef]
  13. Dong, F.; Olsson, A.; Salmén, L. Fibre morphological effects on mechano-sorptive creep. Wood Sci. Technol. 2010, 44, 475–483. [Google Scholar] [CrossRef]
  14. Bonnet, M.; Courtier-Murias, D.; Faure, P.; Rodts, S.; Care, S. NMR determination of sorption isotherms in earlywood and latewood of Douglas fir. Identification of bound water components related to their local environment. Holzforschung 2017, 71, 481–490. [Google Scholar] [CrossRef]
  15. Kurata, Y.; Mori, Y.; Ishida, A.; Nakajima, M.; Ito, N.; Hamada, M.; Yamashita, K.; Fujiwara, T.; Tonosaki, M.; Katayama, Y. Variation in hemicellulose structure and assembly in the cell wall associated with the transition from earlywood to latewood in Cryptomeria japonica. J. Wood Chem. Technol. 2018, 38, 254–263. [Google Scholar] [CrossRef]
  16. Sun, B.L.; Zhang, Y.M.; Su, Y.Y.; Wang, X.Q.; Chai, Y.B. Effect of vacuum heat treatment on larch earlywood and latewood cell wall properties. Forests 2023, 14, 43. [Google Scholar] [CrossRef]
  17. Ożyhar, T. Moisture and Time-Dependent Orthotropic Mechanical Characterization of Beech Wood; ETH: Zürich, Switzerland, 2013. [Google Scholar]
  18. Kuai, B.; Wang, X.; Lv, C.; Xu, K.; Zhang, Y.L.; Zhan, T.Y. Orthotropic tension behavior of two typical Chinese plantation woods at wide relative humidity range. Forests 2019, 10, 516. [Google Scholar] [CrossRef]
  19. Li, Z.; Jiang, J.L.; Lyu, J.X.; Cao, J.Z. Comparative investigation on the orthotropic viscoelastic properties of wood during cooling and heating variations. Wood Mater. Sci. Eng. 2023, 18, 262–268. [Google Scholar] [CrossRef]
  20. Cave, I.D. Theory of X-ray measurement of microfibril angle in wood. Wood Sci. Technol. 1997, 31, 225–234. [Google Scholar] [CrossRef]
  21. Eder, M. Structure, Properties and Function of Single Wood Fibres of Norway Spruce (Picea abies [L.] Karst); BOKU: Vienna, Austria, 2007. [Google Scholar]
  22. Bao, F.; Zhao, Y.; Lu, J. Relationship between permeability and fine structure of common Chinese fir and masson pine wood. J. Beijing For. Univ. 2003, 1, 1–5. [Google Scholar]
  23. Wang, X.M. Study on Permeability and Its Improvement about Two Kinds of Fast-Growing Plantation Species; NJFU: Nanjing, China, 2010. [Google Scholar]
  24. Kim, J.S.; Daniel, G. Developmental localization of homogalacturonan and xyloglucan epitopes in pit membranes varies between pit types in two poplar species. IAWA J. 2013, 34, 245–262. [Google Scholar] [CrossRef]
  25. Miyoshi, Y.; Kojiro, K.; Furuta, Y. Effects of density and anatomical feature on mechanical properties of various wood species in lateral tension. J. Wood Sci. 2018, 64, 509–514. [Google Scholar] [CrossRef]
  26. Darmawan, W.; Nandika, D.; Afaf, B.; Rahayu, I.; Dumasari, D. Radial variation in selected wood properties of Indonesian Merkusii pine. J. Korean Wood Sci. Technol. 2018, 46, 323–337. [Google Scholar] [CrossRef]
  27. Bergander, A.; Salmén, L. Cell wall properties and their effects on the mechanical properties of fibers. J. Mater. Sci. 2002, 37, 151–156. [Google Scholar] [CrossRef]
  28. Miyoshi, Y.; Kojiro, K.; Furuta, Y. Deformation properties of wood in lateral tension. Effect of tensile direction to the annual rings, moisture, and temperature on lateral tensile deformation of hinoki (Chamaecyparis obtusa). Mokuzai Gakkaishi 2014, 60, 241–248. [Google Scholar] [CrossRef]
  29. Furuta, Y.; Nakajima, M.; NakaniI, E.; Ohkoshi, M. The effects of lignin and hemicellulose on thermal-softening properties of water-swollen wood. Mokuzai Gakkaishi 2010, 56, 132–138. [Google Scholar] [CrossRef]
  30. Cai, S.; Guo, Y.; Li, Y. Intratree variation in viscoelastic properties of cell walls of Masson pine (Pinus massoniana Lamb). J. Renew. Mater. 2022, 10, 119–133. [Google Scholar] [CrossRef]
  31. Salmén, L. Micromechanical understanding of the cell-wall structure. CR Biol. 2004, 327, 873–880. [Google Scholar] [CrossRef] [PubMed]
  32. Åkerholm, M.; Salmén, L. Softening of wood polymers induced by moisture studied by dynamic FTIR spectroscopy. J. Appl. Polym. 2004, 94, 2032–2040. [Google Scholar] [CrossRef]
  33. Altgen, M.; Awais, M.; Altgen, D.; Kyyrö, S.; Seppäläinen, H.; Rautkari, L. Micro-tensile behavior of Scots pine sapwood after heat treatments in superheated steam or pressurized hot water. J. Mater. Sci. 2020, 55, 12621–12635. [Google Scholar] [CrossRef]
  34. Placet, V.; Passard, J.; Perré, P. Viscoelastic properties of green wood across the grain measured by harmonic tests in the range 0–95 °C: Hardwood vs. softwood and normal wood vs. reaction wood. Holzforschung 2007, 61, 548–557. [Google Scholar] [CrossRef]
  35. Placet, V.; Passard, J.; Perré, P. Viscoelastic properties of wood across the grain measured under water-saturated conditions up to 135 °C: Evidence of thermal degradation. J. Mater. Sci. 2008, 43, 3210–3217. [Google Scholar] [CrossRef]
  36. Redman, L.A.; Bailleres, H.; Perré, P. Characterization of viscoelastic, shrinkage and transverse anatomy properties of four Australian hardwood species. Wood Mater. Sci. Eng. 2011, 6, 95–104. [Google Scholar] [CrossRef]
  37. Furuta, Y.; Okuyama, T.; Kojiro, K.; Miyoshi, Y.; Kiryu, T. Temperature dependence of the dynamic viscoelasticity of bases of Japanese cypress branches and the trunk close to the branches saturated with water. J. Wood Sci. 2014, 60, 249–254. [Google Scholar] [CrossRef]
  38. Ido, H.; Nagao, H.; Harada, M.; Kato, H.; Ogiso, J.; Miyatake, A. Effects of the width and lay-up of sugi cross-laminated timber (CLT) on its dynamic and static elastic moduli, and tensile strength. J. Wood Sci. 2016, 62, 101–108. [Google Scholar] [CrossRef]
  39. Wang, D.; Lin, L.; Fu, F.; Fan, M. Fracture mechanisms of softwood under longitudinal tensile load at the cell wall scale. Holzforschung 2020, 74, 715–724. [Google Scholar] [CrossRef]
  40. Reiterer, A.; Lichtenegger, H.; Tschegg, S.; Fratzl, P. Experimental evidence for a mechanical function of the cellulose microfibril angle in wood cell walls. Philos. Mag. A 1999, 79, 2173–2184. [Google Scholar] [CrossRef]
  41. Fredriksson, M.; Pedersen, B.N.; Thygesen, G.L. The cell wall composition of Norway spruce earlywood and latewood revisited. Int. Wood Prod. J. 2018, 9, 80–85. [Google Scholar] [CrossRef]
Forests 15 00589 g001
Figure 1. Sketch map of wood specimen sawing.
Figure 1. Sketch map of wood specimen sawing.
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Figure 2. Influence of temperature on the tensile modulus of the L specimens (a) and T specimens (b) and on the relative tensile modulus of the L specimens (c) and T specimens (d).
Figure 2. Influence of temperature on the tensile modulus of the L specimens (a) and T specimens (b) and on the relative tensile modulus of the L specimens (c) and T specimens (d).
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Figure 3. Influence of temperature on the tensile strength of the L specimens (a) and T specimens (b) and on the relative tensile strength of the L specimens (c) and T specimens (d).
Figure 3. Influence of temperature on the tensile strength of the L specimens (a) and T specimens (b) and on the relative tensile strength of the L specimens (c) and T specimens (d).
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Figure 4. Influence of temperature on the strain at failure of the L specimens (a) and T specimens (b) and on the relative strain at failure of the L specimens (c) and T specimens (d).
Figure 4. Influence of temperature on the strain at failure of the L specimens (a) and T specimens (b) and on the relative strain at failure of the L specimens (c) and T specimens (d).
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Table 1. The microfibril angle (MFA) of EW and LW at different temperature levels.
Table 1. The microfibril angle (MFA) of EW and LW at different temperature levels.
Temprerature (°C)EWLW
Mean (°)COV (%)Mean (°)COV (%)
3015.282.4712.371.98
4015.105.3112.354.28
5015.076.6212.343.29
6014.796.6612.333.63
7014.347.1012.286.33
8014.124.5812.252.15
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Huang, H.; Li, Z.; Li, Y.; Jiang, J.; Gao, R. Comparative Studies on Tensile Mechanical Properties of Water-Saturated Earlywood and Latewood within the Same Growth Ring from Masson Pine. Forests 2024, 15, 589. https://doi.org/10.3390/f15040589

AMA Style

Huang H, Li Z, Li Y, Jiang J, Gao R. Comparative Studies on Tensile Mechanical Properties of Water-Saturated Earlywood and Latewood within the Same Growth Ring from Masson Pine. Forests. 2024; 15(4):589. https://doi.org/10.3390/f15040589

Chicago/Turabian Style

Huang, He, Zhu Li, Yuan Li, Jiali Jiang, and Ruiqing Gao. 2024. "Comparative Studies on Tensile Mechanical Properties of Water-Saturated Earlywood and Latewood within the Same Growth Ring from Masson Pine" Forests 15, no. 4: 589. https://doi.org/10.3390/f15040589

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