Search

In order to fabricate green composites without the emission of toxic volatile compounds, wood fiber (WF) biocomposites reinforced with polylactic acid (PLA) were prepared utilizing the traditional hot-press manufacturing process. The effect of adding ammonium lignosulfonate (AL) on the mechanical and dimensional properties of the biocomposites was investigated. When the mass ratio of WF to PLA is 7:3 and the AL mass percentage is in the range from 1 to 20 wt%, the modulus of rupture of the WF/PLA/AL composites ranged from 21.95 to 36.96 MPa, the modulus of elasticity ranged from 3078.6 to 4157.8 MPa and the internal bonding strength ranged from 0.69 to 1.71 MPa, which showed a 4.0–75.1% increase in modulus of rupture, a 3.5–39.8% increase in modulus of elasticity and a 21.5–201.2% increase in internal bonding strength compared to the corresponding WF/PLA composites due to the reinforcing effect of AL. However, AL negatively affected the dimensional properties of the biocomposites. The thickness swell of the WF/PLA/AL composites ranged from 18.7 to 43.5% and the water absorption ranged from 47.1 to 78.9%. The thickness swell, water absorption and contact angle of the WF/PLA/AL composites increased with the AL mass percentage due to its high hydrophilicity, resulting in a 1.1–132.6% and a 3.4–67.4% increase in thickness swell and water absorption, respectively. AL had a positive effect on the crystallinity of the biocomposites due to its good surface activity as long as the AL mass percentage was below 20 wt%. The fractured surface of the WF/PL/AL composites clearly showed that a strong bond (mechanical interlocking and/or chemical bonding) exists at the interface resulting in an effective stress transfer.

Modified ammonium lignosulfonate (MAL) and polyethylenimine (PEI) were combined and used as a binder in the manufacture of a wood-based green composite. The effects of hot pressing temperature (150 oC to 190 oC), hot pressing time (3 min to 11 min), binder content (10 wt.% to 30 wt.%), and MAL/PEI weight ratio (1:1 to 1:9) on the physico-mechanical properties of the composites were investigated. The composites met the mechanical property requirements for furniture grade medium density fiberboard (MDF-FN REG) under the following parameters: hot pressing temperature of 170 oC, hot pressing time of 7 min, binder content of 20 wt.%, and MAL/PEI weight ratio of 7:1. Under optimum processing, although the X-ray diffraction analysis showed that the addition of either unmodified ammonium lignosulfonate (UMAL) or MAL did not change the crystalline structure, this addition markedly improved the relative crystallinity of the composites in comparison to that of pure wood fiber. The DMA results indicated that the MAL/PEI composites had higher storage modulus and tanδ values than did the UMAL/PEI composites. Moreover, SEM analysis showed that the MAL/PEI composites had better bonding strength characteristics than did the UMAL/PEI composites.

To pack a certain quality ratio ammonium lignosulfonate / urea as a filler into the natural wood fiber, Using flat pressure process fiberboard materials, Optimize the hot pressing technique that the filler is 20% (The quality ratio of lignosulfonate/ urea is 5: 3), slab moisture content is 13%, hot-pressing temperature is 190°C; hot-pressing time is 7 minutes, hot-pressing pressure is 2MPa and 1% paraffin emulsion. Verifying test results show that mechanical performance is stable and reliable process. Analyze the reactivity of fiberboard packing, fiber gathered, the microstructure of interface properties with the application of FTIR, XRD and ESEM and other modern instrument analysis technology.

In our research, a commercial poly (lactic acid) (PLA) film was used in combination with wood fiber matrix to generate biodegradable composites by a film stacking technique and hot-press. The results showed the flexural properties and water resistance increased with the increasing of PLA addition. Silane-treated wood fiber composites significantly improved the flexural properties compared to untreated composites. In experiment range, the physical and mechanical properties of composites were better in higher hot-press temperature. The optimal parameters are determined by PLA addition 20%, silane addition 3%, the hot-press temperature 190°C, the hot-press time 10min.Under these parameters, the flexural properties of composites exceeded the requirement of the outdoor boards’ standard, but the water resistance was a little low.

Dyeing experiment was conducted to explore the effects of dyeing concentration, Penetrant concentration, ash concentration, salt concentration, dyeing temperature and dyeing time, Fixing time, liquor ratio on surface coloration of Pinus sylvest var. mongolica as test material and reactive brilliant red X-3B as reagents. Color difference was measured by amulti-lightsource spectrophotometer, and results showed that dye concentration for the effects of color difference was monotonous relationship, and the other the impact of changed in both convex and concave, and finally to determined the optimal color for the dyeing process: dyeing concentration1%, Penetrant concentration0.1%, ash concentration, 2.5% salt concentration1.5%, dyeing temperature85°C and dyeing time60min, Fixing time40min, liquor ratio17:1.

Standing wave tube was used to test the sound absorption abilities and analyze the influence factors of perforated medium density fiberboard (MDF). The test results show that bore diameter, perforated rate and different depth of space from the structure are the key factors influencing the absorption performance of wooden perforated panels, but decorative facing and bore shape have a little contribution to absorption abilities. Research finds that absorption peak will move towards high-frequency with decreasing the bore diameter so as to increase absorption effect in high-frequency, and excellent high-frequency absorption performance can be achieved by increasing perforated rate. On the other hand, larger depth of space from the structure will raise the absorption abilities in low-frequency of the panel.