Soybean protein has been considered as a potential biodegradable polymer in the manufacture of plastics. The purpose of this investigation was to characterize the effect of storage time on thermal and mechanical properties of soybean protein isolate (SPI) plastics. SPI was separated from defatted soy flour, modified with 1M or 2M urea, or plasticized with glycerol, and compression molded into plastics. Plastic made from SPI alone was used as a control. For all SPI plastics, glass transition temperatures and dynamic storage modulus increased and loss tangent decreased during storage. Excess enthalpy of relaxation of all SPI plastics had an exponential relationship with storage time, indicating a fast aging rate at the beginning of storage. All SPI plastics tended to be stiff and brittle during storage. The plastics with glycerol had the slowest aging rate and were fairly stable after 60 days, with about 8.8 MPa tensile strength and 168% strain at break. Plastics with the 2M urea-modification SPI also had a slow aging rate and became relative stable after 60 days, with about 10 MPa tensile strength and 72% elongation. 相似文献
Environmental Science and Pollution Research - The bacterial community of an anaerobic granular sludge associated with uranium depletion was investigated following its exposure to uranium under... 相似文献
Objective: This work aims at investigating the influence of some front-end design parameters of a passenger vehicle on the behavior and damage occurring in the human lower limbs when impacted in an accident.
Methods: The analysis is carried out by means of finite element analysis using a generic car model for the vehicle and the lower limbs model for safety (LLMS) for the purpose of pedestrian safety. Considering the pedestrian standardized impact procedure (as in the 2003/12/EC Directive), a parametric analysis, through a design of experiments plan, was performed. Various material properties, bumper thickness, position of the higher and lower bumper beams, and position of pedestrian, were made variable in order to identify how they influence the injury occurrence. The injury prediction was evaluated from the knee lateral flexion, ligament elongation, and state of stress in the bone structure.
Results: The results highlighted that the offset between the higher and lower bumper beams is the most influential parameter affecting the knee ligament response. The influence is smaller or absent considering the other responses and the other considered parameters. The stiffness characteristics of the bumper are, instead, more notable on the tibia. Even if an optimal value of the variables could not be identified trends were detected, with the potential of indicating strategies for improvement.
Conclusions: The behavior of a vehicle front end in the impact against a pedestrian can be improved optimizing its design. The work indicates potential strategies for improvement. In this work, each parameter was changed independently one at a time; in future works, the interaction between the design parameters could be also investigated. Moreover, a similar parametric analysis can be carried out using a standard mechanical legform model in order to understand potential diversities or correlations between standard tools and human models. 相似文献
The characteristics of bubble properties and the chaotic flow behavior of gas were investigated in an annular fluidized bed
(0.102 m in inner diameter and 2 m in height) because the behavior of gas flow in such a reactor is one of the important factors
governing reactor operation, reactor performance, and the reaction itself. Pressure fluctuations as a state variable for the
analysis of gas flow behavior were measured and analyzed. Bubble properties were determined by adopting the cross-correlation
function of pressure fluctuations. The resultant chaotic flow behavior of gas was interpreted by means of chaotic parameters
such as the Kolmogorov entropy. It was found that the Kolmogorov entropy could be utilized effectively to explain the nonlinear
dynamic behavior of gas-solid flow in the annular fluidized bed. The pierced length and rising velocity of bubbles increased
with increasing gas velocity, bed temperature, and particle size of the bed material. The bubble frequency increased with
increasing gas velocity and bed temperature, while it decreased with increasing particle size of the bed material. Correlations
to predict the bubble properties in annular fluidized-bed reactors were suggested. 相似文献
