In this study the effect of heat treatment on some physical properties of Douglas fir (Pseudotsuga menziesii) was investigated. Wood specimens were subjected to heat treatment at 160, 180, 200 and 220°C for 1, 2, 3 and 4h. The results show that heat treatment resulted in a darkened color, decreased moisture performance and increased dimensional stability of wood. Compared with untreated wood, equilibrium moisture content (EMC), water absorption (WA) and volume swelling (VS) for treated wood decrease up to 42.63%, 34.93% and 67.47%. The higher the treatment temperature and the longer the treatment time, the lower EMC, WA and VS. The VS of treated specimens has a more significant reduction than EMC and WA when the heat treatment temperature is above 180°C. The visual color changes were more distinct after heat treatment above 180°C. Temperature has a greater influence than time on these properties of specimens.

Summary Poplar samples were impregnated with ammonium polyphosphate fire retardant at various pressures and durations after they were pretreated with microwave heating. The effects of the pressure and duration on the flame‐retardation and smoke‐suppression properties were investigated with cone calorimeter analysis. The peak heat release rate (pk‐HRR), total heat release (THR), and total smoke product (TSP) of treated woods were measured for samples of pretreated and untreated with microwave. After the impregnation, the poplar wood showed the significant improvement in its fire resistance. Compared with non‐impregnation wood, the pk‐HRR, THR, and TSP of wood impregnated with ammonium polyphosphate at pressure of 0.4 MPa and duration of 10 min were 48.29%, 35.58%, and 68.64% less, respectively. The pk‐HRR, THR, and TSP of microwave pretreated wood was 15.89%, 5.69%, and 13.59% less than those without microwave pretreated sample. The microwave pretreatment of wood can increase fire retardant effectiveness of ammonium polyphosphate‐impregnated wood. Copyright © 2015 John Wiley & Sons, Ltd.

In this study, eucalyptus wood was subjected to thermal treatment with super-heated steam under various conditions. The effects of temperature and exposure time on the functional groups and degree of cellulose crystallinity of the eucalyptus wood (Eucalyptus grandis × Eucalyptus urophylla) were analyzed. The results showed that the thermal treatment caused significant changes in the chemical composition and structure of wood. The Fourier transform infrared spectroscopy (FTIR) absorption peaks of the hydroxyl group decreased from 3,425 to 3,250 cm−1 for all thermally treated samples. Higher treatment temperature and extended exposure led to the lower methyl levels, with almost no methyl present at 220°C. The aromatic ring first increased and then decreased with increasing temperature and exposure time. The carbonyl group maintained the same intensity, with small fluctuations, across the different thermal treatment conditions. Compared with the untreated wood sample, the X-ray diffraction peak position of thermally treated samples shifted slightly left from 22.02° to 21.06°, and the distance between crystal planes increased. The degree of cellulose crystallinity of eucalyptus wood was affected significantly by treatment temperature with a confidence level of 99 percent.

The study tested the short-term bending creep curves of Eucalyptus Plantation Wood under different loads, moisture contents and temperatures, analyzed the influence of load, moisture content and temperature on creep of Eucalyptus. Guided by the rheological theory, the study adopted the Burger rheological model to do the curve fitting and solved the model parameters. A defect found from Burger model in simulating long-term creep properties of wood was preliminary discussed and remedied. The equivalence of creep test and relaxation one was discussed.

Straw fiber (SF)/polylactic acid (PLA) composites were prepared from SF and PLA. The effects of the composite SF/PLA mass ratio investigated in terms of mechanical properties, water resistance, crystal structure, and thermal properties were investigated. These composites were characterized by scanning electron microscopic (SEM), X-ray diffractometric (XRD), differential scanning calorimetric (DSC), and thermogravimetric analyses (TGA). The results showed that, when the SF/PLA mass ratio was 3/7, the mechanical properties and water resistance of these composites were the best. When the mass ratio exceeded 3/7, the interface compatibility in the composites decreased. As the SF/PLA mass ratio increased, the crystallinity and the heat resistance of the composites were decreased.