Applied Mechanics and Materials Vols. 275-277

Abstract: A new type of sound absorbing material, which was made from super strength polyurethane and mass fiber, was investigated. And the sound absorption coefficient of the material was tested by standing wave tube method. Experiment results manifested that content of glass fibers, blowing agent and thickness have great effects on the sound absorbing performance of the sample. When the content of glass fiber and blowing agent are separately 3% and 0.4%, the performance of the material reaches optimum. The noise reduction coefficient of the material is 0.6, and the sound absorption property at middle-low frequency is good.

Abstract: In this paper, Brookfield viscometer was used to test the rheological properties of sodium alginate solution and blends of sodium alginate/polyethyleneglycol（PEG）/molecular sieve in which the molecular weight of sodium alginate solution was respectively 1.59*105Da and 3.27*105Da. Besides, thermal stability and the thermal property of alginate fibers were also investigated by TGA and DSC. The fracture strength of blended alginate fibers was discussed by electronic monofilament tensile strength tester. The results showed that the system was a typical kind of non-Newtonian fluid. The apparent viscosity declined with the increase of shear rate. Rheological properties were affected by temperature and contents of the blends, at the same time, non-Newtonian index and structure viscosity index also changed. Research results were very important to the choice of wet spinning process. The thermal property and energy storage effect of alginate fibers was good, so was the fracture strength.

Abstract: Multi-membrane hydrogels are newly promising carriers in biomedical fields for their gentle gel condition and excellent biocompatibilities. In this study we focused on the dual control release property of alginate-based onion-like multi-membrane hydrogels hybrid with polylactic acid microspheres. The results indicated that the PLA microspheres evenly distributed in each of the hydrogel membranes. And the drug delivery in physiological saline is well controlled which can be promising in transport drugs, genes, protein, etc.

Abstract: Two diamine monomers 2-tert-butyl-1,4-bis(4-nitro-2-trifluoromethylphenoxy)benzene and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene were reacted with the alicyclic dianhydride monomers 1,2,3,4-cyclobutanetetracarboxylic dianhydride to synthesize the poly(amic acid)s, and then obtain the corresponding polyimide films through thermal imidization. The structure and properties were characterized by fourier transform infrared spectroscopy (FT-IR), ultraviolet visible spectroscopy (UV-vis), thermogravimetic analysis (TGA), solubility test and so on. The effect of introduction of bulky tert-butyl and trifluoromethyl to the polyimide backbone on the properties of polyimide films was investigated. The experimental results showed that polyimides with tert-buty group exhibit excellent solubility, but their thermal and optical properties decreased slightly.

Abstract: Safflower seed oil is known to be one of the richest natural sources of linoleic acid (LA), with values of up to 69.5% of the total fatty acids. Linoleic acid is known to has important biological activity and its absence in a normal diet has been described as responsible for the development of a wide variety of diseases. This work reported purified LA from safflower seed oil could lower blood liquids level of rats with hyperlipidemia. It showed that purified LA from safflower seed oil could decrease the serum total cholesterol and triglyceride concentration significantly, as well as increase the serum high density lipoprotein cholesterol. The serum atherosclerosis index (AI) was decreased remarkably. It demonstrated purified LA from safflower seed oil could improve metabolism of serum lipids and it could play active role of preventing atherosclerosis.

Abstract: Natural short fiber reinforced polypropylene (PP) composite has great significance both in commercial and environmental and is widely used in motor industry. Its local inhomogeneity and interphase both affect the macroscopic properties of the composite. These phenomena are still difficult to observe and study accurately in the experiment. A cohesive zone model (CZM) based numerical simulation method is presented in this paper. The three-phase (matrix-interphase-fiber) model considering some different factors was developed to study the effects of interphase parameters on the mechanical properties of the composite.

Abstract: A novel three-phase (ceramic, epoxy resin and decoupling material) piezoelectric composite with multi-element in parallel connection has been developed by using dice-fill technology. This kind of composite consists of a large number of elements which can be seen as a single-sound radiation source. The space between elements is determined via a precise method of calculation. The ceramic elements are then cut using precision machinery to achieve exact results. A kind of decoupling material has been developed to decrease the cross coupling effect between elements. The vibration velocity curves of active elements and close elements were measured using a Scanning Laser Vibrometer (Polytec PSV-400). The results indicated that the decoupling materials induced in multi-element composites have a good decoupling effect. Vibration attenuations between adjacent elements are larger than 31 dB at resonance frequency.

Abstract: Detection of intermediates is the general way to investigate a reaction mechanism, because the intermediates connect the reactants and the products, the intermediates can reflect some internal relationships between the reactants and the products. By studying the the structures of intermediates, the reaction process and reaction mechanism can thus be understood. Ammonium polyphosphate (APP) is an effective material as halogen-free flame retardants, it has six crystalline forms.In preparation of APP, the factor of temperature raising rate is investigated, some intermediates are detected, the XRD spectra of these intermediates are discussed. The results are informative for controllable preparation of APP in industrial production.

Abstract: Ammonium polyphosphate have six crystalline forms, of them, form I and form II have industrial uses, their flame retardant properties have been studied extensively. Form V is seldom studied, its flame retardant is not fully known. In this paper, the flame retardant effects of ammonium polyphosphate with crystalline form II (APP-II) and crystalline form V (APP-V) in polypropylene were tested. Results show that the flame retardant effect of APP-V is better than APP-II, and has better mechanical strength that APP-II, meaning it should has a good market perspective in field of halogen-free flame retardation.

Abstract: This study aims to establish a natural cellulosic biomass pretreatment process using ionic liquid (IL) for efficient enzymatic hydrolysis and second generation bioethanol. The IL 1-Butyl-3-methylimidazolium Chloride/FeCl3 ([Bmim]Cl/FeCl₃) was selected in view of its low temperature pretreatment ability and the potential of accelerating enzymatic hydrolysis, and it could be recyclable. The yield of reducing sugars from sugarcane residue pretreated with this IL at 80 oC for 1 h reached 46.8% after being enzymatically hydrolyzed for 24 h. Sugarcane residue regenerated were hydrolyzed more easily than that treated with water. The fermentability of the hydrolyzates, obtained after enzymatic saccharification of the regenerated sugarcane residue, was transformed into bioethanol using Candida shehatae. This microbe could absorb glucose and xylose efficiently, and the ethanol production was 0.38 g/g glucose within 30 h fermentation. In conclusion, the metal ionic liquid pretreatment in low temperature shows promise as pretreatment solvent for natural biomass.