Papers by Author: Ping Qu

Abstract: Reinforcement of polymer with plant whiskers is a way of improving mechanical properties. Cellulose nanowhiskers (CNW) were separated from commercially available wood pulpboard. Different microscopy techniques, thermal gravimetric analysis, X-ray diffraction were used to study the structure and properties of the microcrystalline cellulose (MCC) and CNW. Because of the high specific surface area of CNW, the increases in total amorphous character of the cellulose decrease the relative degree of crystallinity. After chemical and physical treatment, the CNW in the length of several μm and diameters ranging from 20 - 50 nm was obtained. Both the initial decomposing temperature and temperature of maximum decomposing rate of CNW is higher than MCC, but lower than wood pulpboard.

Abstract: In this research, the urea-formaldehyde prepolymer and multilayer hot-press drying was used to obtain modified wood. The timbers were compressed and dried by the multilayer hot-press drying kiln. The combination of chemical modification and hot-press drying can improve the drying rate, which can also enhanced the physical and mechanical properties. Based on the findings, the basic density of modified wood improved 25.2 %, the bending strength and the bend elastic modulus improved 15.6 % and 25.0 % respectively. The dimensional stability of the treatment appeared to be slightly higher than that of untreated samples under the same conditions for processing temperatures and times. The improving dimensional stability of wood mainly was attributed to the prepolymer that changes wood cell wall components such as the degradation of the hemicelluloses and cellulose during hot-press drying treatment. The XRD results indicated that the degree of crystallinity increased to 35.45 %from 31.25 %. The TGA results show that the degradation of the samples can be divided into two step, both of the maximum weight loss velocity temperature of the two step increased to 266 °C, 355 °C from 244 °C and 341 °C.

Abstract: A preparation method of modifier with low molecular weight and high reactivity is presented. This modifier （called KFK in lab）can impregnate into polar wood along trachea from the ends with pressurized impregnation method. In the following heating and pressing processes of the polar wood, the KFK polymerizes, and it enhances stability and strength of the wood. It showed that the favorable conditions for synthetic reaction of the KFK are: molar ratio of U and F, 1:1; reaction temperature, 20°C; reaction time, 3 hours; dosage of ignition primer A: 5%. Results from test showed the degree of crystallinity tested by XRD were 30%, 32% in different dosage of the modifier. Utilizing a combination of low molecular weight resin impregnation and pressing resulted in a density increase of KFK resin-treated wood from 0.214 to 0.268g/cm3. At the same time, the Young’s modulus and bending strength increased from 1.407GPa to 1.759GPa and 64MPa to 74.5MPa, respectively. It can be concluded that the effective utilization of KFK resin impregnated in polar wood is a promising technique for the production of high-strength in the drying and pressing processing.

Abstract: One best way to harness the petroleum-based solid wastes is to develop biodegradable materials. Among which, PLA is the most important one, because it is made from renewable plant. But Poly(lactic acid) (PLA) is brittle and low impact resistance. The cellulose nanowhiskers are about 5-40 nm in diameter and the length can be from 100 nm to several micrometers depending on the source of cellulose and the processing technology. The cellulose nanowhiskers can act as efficient reinforcement because of the high aspect ratios, important surface areas and high modulus. The celluloses nanowhiskers are hydrophilic because of the abundant exposed hydroxyl (-OH) groups and PLA is hydrophobic. So we added the low molecular weight polymeric-poly (ethylene glycol) (PEG) to improve compatibility between PLA matrix and the cellulose nanowhiskers. The PLA/cellulose nanowhiskers composites were prepared by casting solution. The tensile strength and the elongation rate of the composites improved 56.7% and 48% comparing with the PLA/cellulose whiskers composites. The thermo gravimetric analysis indicated that the thermal decomposition of PLA/cellulose nanowhiskers/PEG composites include only one stage. The pictures of SEM showed the fracture morphology of the different kind of the composites. The structure of the PLA/cellulose nanowhiskers/PEG composites were characterized by AFM, which showed that the cellulose nanowhiskers dispersed evenly in the PLA matrix.

Abstract: In this study, pervaporation membranes were prepared from poly( vinyl alcohol) (PVA) with different amounts of cellulose nanocrystals as filler, and characterized by scanning electron microscopy (SEM). The characterization results demonstrated that cellulose nanocrystal particles dispersed homogeneously within the PVA matrix. Moreover, the pervaporation performance of these membranes was investigated using the separation of ethanol-water mixture as model system. Among all the prepared membranes, PVA/cellulose nanocomposite membrane containing 1 wt% cellulose nanocrystals exhibited the best pervaporation performance, whose averaged permeation flux reduced slightly but separation factor was increased from 83 to 163 for 80% aqueous solution of ethanol at 80 °C respectively.

Abstract: A series of natural materials used for oil absorption based on corn stalks have been prepared by acylation grafting with propionic anhydride in a solvent-free system at 100 and 140 °C for 2-6 h. It is found that the oil (benzene) sorption capacity of the grafted corn stalks is about 8.5- 12.6g/g (in 15 minutes), and the grafted material is significantly more hydrophobic than the raw corn stalks. The grafted corn stalk float on the surface of water, as the oil, can be easily to be removed when the application is completed. Fourier infrared (FT-IR) analysis is used to confirm the chemical reaction which takes place between corn stalks and propionic anhydride. Scanning electron microscope (SEM) analysis is used to determine the structure of the grafted corn stalk material.