Literature has shown that cellulose nanocrystals (CNCs) which are produced through hydrochloric (HCl) acid hydrolysis catalyzed by inorganic chlorides can enhance the mechanical properties of organic polymers further than CNCs by pure HCl acid hydrolysis. The results have shown that the level of reinforcement may be negatively correlated to the dissociation constant of the inorganic chlorides. However, titanium tetrachloride’s dissociation constant is 1.3, lower than that of ferric chloride, 2.2, which is the lowest dissociation constant among the four inorganic chlorides that have been studied. Therefore, for this study, titanium tetrachloride was investigated along with ferric chloride. The only two variables in this study are reaction time and acid-to-microcellulose crystals (MCCs) ratio. The results of laser diffraction spectroscopy (LDS) show that the resultant solutions exhibit binomial size distributions which contain both MCCs and CNCs. At acid-to-MCCs ratio of 40 for ferric chloride, any increase in reaction time above 1.5 hours did not result in size reduction. The Fourier transform infrared (FTIR) spectroscopy results of CNCs showed that the catalyzed hydrolysis did not change the molecular structure of MCCs. The color of CNCs varies with increasing reaction time, but, based on the FTIR and LDS results, the color is not an indication of CNCs’ size nor their chemical composition.

Pedicle screws (PS) are frequently used in medical spinal column fixation. Despite 7 out of 100 pedicle screws fracture inside of the patients’ body and under the claim that lateral bending is the main failure mode, little research has addressed the stress characteristics and the fracture location of the PS under lateral bending. This study focuses on the effect of thread design on the magnitude and location of maximum stress concentration. Four types of thread shapes are considered including V-shape, square-shape, buttress, and reverse buttress. Three-dimensional (3D) finite element (FE) methods are used in this investigation. A load of 150 Newton is applied at the screw head to simulate lateral bending. The models are created in SolidWorks. The 3D FE analysis is performed using the standard coding of ANSYS Workbench 19.1. Based on this study, it is found that the high stress concentration is located at the cortical bone region rather than at the cancellous bone region. Although the general stress patterns are similar, the PS thread shape design and the thread fillet radius may significantly affect on the magnitude and location of maximum stress concentration.

Armor wires which are typical spiral wound structures are widely applied to flexible structures in ocean engineering, such as flexible pipes and umbilical cables. Birdcage buckling phenomenon would appear under the condition of damage of the cover sheath and strength tapes when armor wires are subjected to high axial compression which exceeding its critical load. In this paper a special experiment device is designed to simulate the armor wires winding a cylinder. Based on the experiment, the birdcage buckling mechanism of spiral wound steel wire is analyzed. The global configuration time-history of spirally wound steel wire is recorded to find the critical buckling load with the increasing compression displacement. At the same time, strain state at the critical position is analyzed, which could provide a reference for curved beam’s buckling research. Moreover, sensitivity analysis of critical buckling load is investigated with consideration of some influencing factors such as spiral wound radius, length and pitch. Finally, the relationships between them and critical buckling compression load are quantified. The experimental results could guide the anti-buckling design of armor wires for flexible pipe or umbilical cables.