Papers by Author: De Gao

Abstract: This paper concerned nanocrystalline cellulose(NCC)’s isolation from microcrystalline cellulose(MCC) by sulfuric acid hydrolysis, meanwhile centrifuging, ultrasonic treatment and freeze-drying were carried out afterwards. It covered the effect of reaction conditions on the yield of NCC. It indicated that hydrolysis time was the factor that matters most and it was possible to obtain the largest yield with hydrolysis time being 108min, hydrolysis temperature being 43oC and sulfuric acid concentration being 33%. It also investigated the microcosmic morphology of NCC by Transmission Electronic Microscopy(TEM). MCC and NCC’s thermal properties were studied further.

Abstract: The basic parameters of calcium carbonate-plastic composite packaging materials, such as tensile strength and flexural strength, were obtained by means of mechanical properties test at different temperatures. Through the experimental tests, the best processing temperature was determined at 190°C and the test data were fitted and optimized. Also, the residual of fitting curves was calculated by using the mathematical analysis software of MATLAB. Besides, mathematical models were established between temperatures and target parameters, from which the mechanical properties of materials at any other temperatures can be predicted theoretically. So, it provides a scientific basis for the regulation of processing temperatures.

Abstract: In this paper, the characteristics of B-flute corrugated paperboard is obtained by quasi-static compression experiment on a universal testing machine. The constitutive relationship is identified. Then, according to the relation, we calculate the energy absorption curve of corrugated paperboard with B-flute. At last, a bearing example of the paperboard is given to introduce its application.

Abstract: Mechanical properties of the calcium-plastic composite have a great influence on the containers. The main factors affecting the mechanical properties are the process and material formulations. This paper mainly describes its impact of the addition of coupling agent. Under the usage of analysis of variance on single factor experiment, the mechanical properties of the calcium carbonate-plastic composite with three different coupling agents (silane, titanate and aluminate) were studied in the same test conditions. The results show that: The type and quantity of the coupling agent effect a lot on the mechanical properties of the composite. The silane coupling agent is the most suitable for calcium carbonate-plastic composite packaging materials, and the compatibility of calcium carbonate and polyethylene can be improved. When the silane coupling agent was at a 2.25 wt. % concentration, the tensile and flexural strength were improved obviously, especially the tensile strength increased by 23.24%, but the impact strength improved slightly.

Abstract: The paper describes the production and the mechanical characteristics of composites made completely from renewable raw materials, the corn straw fiber and the biodegradable plastic, poly(lactic acid). The effect of straw fiber content on the mechanical properties of the composites was studied and the optimum mass fraction was 15%. To enhance the mechanical properties of the composites, two different methods were tested. Maleic anhydride as the compatilizer was introduced into the composites but the changes of the mechanical properties were small. While the other method, pre-treatment for straw fiber before blending, the mechanical properties increased obviously. The tensile strength and the impact strength were 35.6 MPa and 1.67 kJ/m2, respectively.

Abstract: In situ melt copolycondensation was proposed to prepare biodegradable copolyester nanocomposites based on degradable components poly(L-lactic acid) (PLA), rigid segments poly(butylene terephthalate) (PBT), and nanoparticles polyhedral oligomeric silsesquioxanes (POSS). The morphologies and dispersions of two POSS nanoparticles (POSS-NH₂ and POSS-PEG) in the copolyester PLABT matrix and their effects on the mechanical properties were investigated. The results demonstrated that the morphologies and dispersions of POSS-NH₂ and POSS-PEG showed quite different characteristics. POSS-PEG took better dispersion in the PLABT, while POSS-NH₂ had poor dispersions and formed crystalline microaggregates. Due to the good dispersion and strong interfacial adhesion of POSS-PEG with the matrix, the tensile strength and Young’s modulus were greatly improved from 6.4 and 9.6 MPa for neat PLABT up to 11.2 and 70.7 MPa for PLABT/POSS-PEG nanocomposite. Moreover, the incorporation of POSS-PEG could impart macromolecular chains good flexibility and improve the mobility of the chains, so the the elongation at break of PLABT/POSS-PEG nanocomposite dramatically increased from 190 to 350 % compared with neat PLABT.

Abstract: Through the test of mechanical properties of the straw-biodegradable tableware, the relationship between performance and processing technology was analyzed and the optimal solution was obtained. And using finite element analysis software, the internal stress distribution under the specific load was obtained based on mechanical properties, more valuable reference method about tableware design was provided through studying the changing intensity.

Abstract: The basic flat compression cushioning performance of corrugated board was studied according to the measured data from static and dynamic flat compression tests. Based on the experimental data, the nonlinear visco-elastic-plastic model of the cushion was established. The establishment of the model and successful identification of its parameters solve the problem of flat compression dynamic calculation of corrugated board, make it possible to optimize the design of cushion packaging and avoid the great amount of measuring work.

Abstract: This paper proposes to model cushioning materials by combining hyperbolic tangent function and tangent function together. Based on the proposed model, the kinetics equations for cushion packaging system under excitation of half-sine acceleration pulse shock have been derived, where the rotation due to product’s eccentricity in center of mass has been taken into account. The law for coupling between rotation and translation is discussed. Numerical analysis shows that it may lead to a certain degree’s excessive packaging and thus causes waste if the rotation effect is not considered in design. The proposed model and the established kinetics equations with consideration of coupling between translation and rotation provide much better description regarding the characteristics of practical cushion packaging systems, and thus can be taken as reference in design optimization for packaging structure. The proposed approach can also be directly applied in analyzing the shock responses of packaging systems with multiple degrees of freedom.

Abstract: This paper presents a laser trigonometry system measuring a micro cantilever’s vibration. The system includes a semiconductor diode laser, a short-focus optical system, PSD (Position Sensitive Detectors) and its signal enlarging system, and data collection system. The system can be used to measure the vibration data of micro frictional pairs. Compared with image method, the measuring frequency is higher and more accurate.