Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed wood

Wu, Yanmei; Qin, Li; Huang, Rongfeng; Gao, Zhiqiang; Li, Ren

doi:10.1186/s10086-019-1791-7

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 1 Density profile characteristics of sandwich compressed wood formed under different preheating conditions

From: Effects of preheating temperature, preheating time and their interaction on the sandwich structure formation and density profile of sandwich compressed wood

Preheating parameters		Mean density of wood (g/cm³)	Mean density of sandwich compressed wood (g/cm³)	The characteristic parameters of compressed layer
Time (min)	Temperature (°C)	Mean density of wood (g/cm³)	Mean density of sandwich compressed wood (g/cm³)	Number	Thickness (mm)	Mean density (g/cm³)	Maximum density (g/cm³)
4	75	0.439 (0.028)	0.537 (0.030)	2	7.52 (0.48)	0.666 (0.026)	0.771 (0.232)
	90	0.432 (0.026)	0.550 (0.038)	2	8.56 (0.97)	0.674 (0.032)	0.773 (0.056)
	105	0.423 (0.022)	0.531 (0.032)	2	8.68 (1.18)	0.658 (0.037)	0.768 (0.061)
	120	0.434 (0.021)	0.564 (0.043)	2	7.86 (0.66)	0.685 (0.038)	0.802 (0.053)
	135	0.452 (0.020)	0.549 (0.026)	2	7.78 (0.66)	0.664 (0.027)	0.747 (0.036)
	150	0.442 (0.024)	0.539 (0.029)	2	7.45 (0.44)	0.653 (0.017)	0.751 (0.025)
	165	0.457 (0.027)	0.539 (0.016)	1	10.30 (0.09)	0.609 (0.036)	0.688 (0.030)
	180	0.423 (0.027)	0.516 (0.035)	1	10.21 (0.46)	0.613 (0.038)	0.702 (0.056)
	195	0.439 (0.030)	0.536 (0.043)	1	9.70 (0.72)	0.627 (0.043)	0.713 (0.031)
	210	0.417 (0.021)	0.511 (0.025)	1	9.36 (0.58)	0.575 (0.043)	0.689 (0.017)
8	75	0.422 (0.023)	0.554 (0.034)	2	8.99 (0.83)	0.665 (0.028)	0.760 (0.033)
	90	0.435 (0.009)	0.556 (0.025)	2	9.23 (0.78)	0.660 (0.023)	0.761 (0.033)
	105	0.441 (0.008)	0.567 (0.033)	2	8.61 (1.10)	0.684 (0.025)	0.782 (0.043)
	120	0.426 (0.024)	0.537 (0.035)	2	9.23 (0.83)	0.642 (0.020)	0.741 (0.032)
	135	0.431 (0.026)	0.538 (0.032)	2	8.22 (0.36)	0.619 (0.030)	0.695 (0.035)
	150	0.426 (0.017)	0.519 (0.024)	1	8.06 (1.20)	0.618 (0.017)	0.688 (0.040)
	165	0.442 (0.035)	0.531 (0.026)	1	8.11 (1.16)	0.64 (0.027)	0.689 (0.034)
	180	0.427 (0.011)	0.517 (0.026)	1	7.51 (0.96)	0.652 (0.016)	0.718 (0.023)
	195	0.436 (0.022)	0.515 (0.024)	1	5.25 (1.04)	0.632 (0.029)	0.718 (0.043)
	210	0.454 (0.041)	0.542 (0.038)	3	4.67 (0.79)	0.627 (0.044)	0.703 (0.035)
12	75	0.423 (0.026)	0.537 (0.049)	2	9.28 (0.82)	0.640 (0.026)	0.725 (0.051)
	90	0.427 (0.016)	0.557 (0.018)	2	10.21 (0.43)	0.654 (0.020)	0.758 (0.026)
	105	0.443 (0.029)	0.554 (0.033)	2	9.17 (0.64)	0.661 (0.030)	0.760 (0.045)
	120	0.432 (0.015)	0.547 (0.034)	2	10.75 (1.44)	0.626 (0.017)	0.695 (0.038)
	135	0.439 (0.025)	0.530 (0.025)	1	8.83 (0.41)	0.610 (0.034)	0.697 (0.034)
	150	0.451 (0.039)	0.543 (0.043)	1	7.97 (0.72)	0.647 (0.047)	0.687 (0.047)
	165	0.438 (0.025)	0.516 (0.023)	1	5.56 (0.94)	0.628 (0.028)	0.707 (0.033)
	180	0.433 (0.021)	0.518 (0.028)	1	5.18 (0.72)	0.600 (0.071)	0.666 (0.071)
	195	0.448 (0.026)	0.534 (0.040)	3	3.76 (1.27)	0.599 (0.021)	0.669 (0.024)
	210	0.447 (0.047)	0.511 (0.051)	3	3.12 (0.15)	0.565 (0.043)	0.588 (0.035)

Each value in parenthesis is standard deviation of six specimens; italic emphasizes preheating at 135 °C for 12 min, 150 °C for 8 min, and 165 °C for 4 min are conditions for the convergence of the compressed layers; when there are three compressed layers, the thickness, mean density, and maximum density of the compressed layer are the results of the central compressed layer

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