Advanced Materials Research Vols. 87-88

Abstract: according to the poor quality situation that tire building machine presses tire in current market, the thesis analyses the reasons that press roll presses tire uncompactedly and tire layer has bubbles in the process of tire building machine repression. A new design method that is the optimal design of oscillating oil cylinder mechanism of tire building machine is presented. In the premise of meeting the movement performance of mechanism, it not only can maintain that the pressing roll fits in the best pressure, but also enables wave motion of fitting tire pressure in the allowable scope when mechanism is in the dynamic movement. The article cites examples of the design, demonstrates the superiority of the new design method fully.

Abstract: In connection with the phenomenon that the quality of products is affected seriously， because the connecting nut on the pillar of pillar flat vulcanizing machine is easy to loose， where no reliable connection， and the problem that lines between the flat are not parallel is often caused。In this paper, a kind of threaded connection to achieve reliable locking anywhere and benign dismountability is presented. The connection bases on ratchet wheel movement principle. The ratchet-shaped trench is designed on the contact surface of nut and gasket. The trench is circular uniform distribution and its axial section is triangular cone. This combination ensures that the fastening can be connected for the relative movement when the thread is rotated directly and for the self-locking when the thread is rotated reversely. The dismountability can be achieved by tilting the side wing of ratchet-gasket to remove the circumferential fix.

Abstract: Pressure-Volume-Temperature (P-V-T) properties of two amorphous polymers (ABS and PS) were measured by an on-line testing measurement in the temperature ranges from 20 to 150 °C and pressures from 20 to 120 MPa. The on-line testing measurement is based on an injection molding machine (IMM), and it can be used to get P-V-T data of polymers directly with a special testing mold under normal processing conditions. The experimental P-V-T results of amorphous polymers under industrial processing conditions were presented. A new modified two-domain Spencer-Gilmore equation of state (EOS) was developed. The P-V-T properties were correlated by the modified Spencer-Gilmore EOS and a modified two-domain Tait EOS, showing a good agreement with measurements. The effects of sample forms were investigated. A sample with large length diameter ratio is the best one to be measured.

Abstract: While the transfer from filling to packing is particularly crucial during injection molding, the transfers from packing to holding and holding to screw recovery also significantly affect part quality. In this study, the control of the transfer from holding to screw recovery, that is the control of the end-point of the holding phase, was examined. The holding end-point control by time, cavity pressure and cavity temperature were presented. The purpose of this study was to validate the feasibility of the control methods of holding end-point by cavity pressure and cavity temperature. The qualities of injection-molded parts, weight, will serve as measures to probe their process capabilities. Recently found to be a good indicator of product quality, both cavity pressure and temperature profiles are applied here to obtain more precise control. Change of mold temperature was specially considered. After the experimental verification is conducted, the results reveal that the innovative holding end-point control by cavity temperature yields a more uniform product weight with mold temperature. It proved that the holding end-point control by cavity temperature can be used to obtain the optimum holding time and accommodate the product weight to the change of mold temperature, which is the other holding control methods cannot obtain.

Abstract: To enhance the mechanical property and the bioactivity of composites, nano-hydroxyapatite (n-HA) modified monomer casting nylon-6 (n-HA/N) composites were prepared by in situ polymerization. During the synthesis of n-HA/N composite, the n-HA and caprolactam were mixed, melt and placed in the field of ultrasonic radiation. The differences between composite with ultrasonic and without ultrasonic were investigated. The tensile strength and the viscosity average molecular weight of the nylon matrix were measured. The results show that the molecular weight of the nylon matrix decreased firstly and it had the lowest value when the content of nano-hydroxyapatite was 1.6 wt.%. After that the molecular weight increased and then it began to decrease when it reached the highest value. But the tensile strength of the n-HA/N composite were improved. The ultrasonic dispersion made the n-HA more evenly dispersed in the nylon and increased the mechanical properties of the n-HA/N composites significantly. The bioactivity and moisture absorption of n-HA/N composites in simulated body fluid (SBF) were examined and compared to pure nylon. What's more, Fourier transform infrared spectrometer was used to characterize the structure of the materials formed on the surface of the composite. The results showed that moisture absorption of the n-HA/N composites was lower than that of the pure nylon. After composites impregnated 16 days in SBF, a layer of carbon hydroxyapatite (CHA) with weak crystalline was formed on the surface of sample. This phenomenon showed that the n-HA/N composites have good bioactivity.

Abstract: Dispersion polymerization of acrylamide and acrylic acid was successfully carried out in aqueous salt solutions using anionic polyelectrolytes as stabilizers. The influences of aqueous solution of salt concentration, molecular weight and concentration of the stabilizers on the apparent viscosity and stability of the dispersions, and on the molecular weight of the polymers prepared were investigated. The results showed that stable dispersions could be obtained on condition that salt concentration was between 26%~30%, concentration of stabilizers between 8%~12%, and intrinsic viscosity of stabilizers between 2.977~3.740 dL/g. With salt concentration ranging from 26% to 30%, molecular weight of products increased first and then decreased. Molecular weight of products was hardly changed when concentration of stabilizer was between 8%~12%. When intrinsic viscosity of stabilizer was between 2.977~3.740 dL/g, increase of the molecular weight of stabilizer resulted in a decrease in the molecular weight of the products.

Abstract: HDPE and UHMWPE were blended in the twin screws extruder with two kinds of screws scheme and the HDPE/UHMWPE films were prepared in the blown film extruder. The mechanical properties, rheological property and crystallization behavior of the blends were discussed. The results showed that UHMWPE could improve the mechanical properties of HDPE film, but made the melt torque of the blends increase. The surface morphology and crystallization behavior of the blends were observed by polarized light microscope. It was found that the dispersion and molten degree of UHMWPE in the blends made by the screws scheme B were improved greatly.

Abstract: By analyzing the technology process of all steel radial truck tire building machine, the author finds that there is a big potential of improvement both in stitching effect and efficiency. A new kind of stitching and control device is designed to replace the original. The new device can realize the soft stitching of tire, which reduces redundant actions and thus optimizes the process and improves the stitching efficiency. It is found in tests that the optimized process reduces the blister defectives greatly. Both productivity and quality of tires are improved significantly. It shows a big economic benefit.

Abstract: Ultra High Molecular Weight Polyethylene(UHMW-PE) pipe is a kind of pipe of thermoplastic engineering plastic with excellent comprehensive performance, but the difficulty in molding is a technical bottleneck which has already affected the extensive application of pipe of pure UHMW-PE. Molding in barrel on the Single screw extruder is a new technology of extrusion molding method, which can continuously carry out pipe of pure UHMW-PE, the most significant advantages of the technology are as follows: under the circumstances of no need to feed any additives in the whole forming process, it can continuously carry out pipe of pure UHMW-PE, and the extrusion molding speed of it is up to 12 m/h above. During the process of it based on molding in barrel technology, one of the main factors influencing to whether UHMW-PE pipe can be successfully molded or not is whether the melting process of raw material is adequate and appropriate or not. This article will elaborate melting characteristics of raw material of UHMW-PE, establishment of mathematical model of melting process, and numerical simulation of melting process, which belong to the forming process of molding in barrel, and will provide a theoretical basis for correctly designing the structure of single screw extruder and temperature control system of single-screw extruder, based on Molding in Barrel Technology.

Abstract: The article analyses the main factors such as the species and character of the carbon black, the conveying pressure and gas-flow rate which influence the flow character of carbon black during pneumatic conveying. And also studies the flow character of carbon black in dense phase pneumatic conveying system with experiment. It raises the view that the carbon black with narrow particle diameter distribution, especially with bigger size is favorable for saving energy and reducing fragmentation; the conveying pressure approach lowest point should be chosen during carbon black pneumatic conveying, and the quantity of elbow pipe should be used as less as possible; on condition that the conveying capacity is guaranteed, the lower air feeding volume is preferable; the higher the conveying pressure is, the lower the fragmentation of the carbon black will be. The article also supplies the reference for technology parameter choosing and carbon black conveying system design.