Extrusion-calendering method was developed to prepare single-polymer composites（SPCs） of ultrahigh molecular weight polyethylene（ UHMWPE） fabric reinforcing low density polyethylene（LDPE）.Differential scanning c...Extrusion-calendering method was developed to prepare single-polymer composites（SPCs） of ultrahigh molecular weight polyethylene（ UHMWPE） fabric reinforcing low density polyethylene（LDPE）.Differential scanning calorimeter（DSC） experiments were executed to determine the setup of extrusion temperature.Effects of the die temperature on the tensile and interfacial performances of SPCs were studied through the tensile and T-peel tests,respectively. The results showed that both tensile strength and modulus increased initially and decreased afterwards as the temperature increased. The peak values of tensile strength and modulus of PE SPCs,which are 10. 8 and 3. 5 times as high as those of the unreinforced LDPE respectively,were obtained at 150 ℃. Higher temperatures also give a positive effect on peel strength. Scanning electron microscopy（ SEM） and camera were also used to observe the morphology of the SPCs samples.展开更多
The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with ...The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.展开更多
基金Supported by the National Natural Science Foundation of China(51403019)
文摘Extrusion-calendering method was developed to prepare single-polymer composites（SPCs） of ultrahigh molecular weight polyethylene（ UHMWPE） fabric reinforcing low density polyethylene（LDPE）.Differential scanning calorimeter（DSC） experiments were executed to determine the setup of extrusion temperature.Effects of the die temperature on the tensile and interfacial performances of SPCs were studied through the tensile and T-peel tests,respectively. The results showed that both tensile strength and modulus increased initially and decreased afterwards as the temperature increased. The peak values of tensile strength and modulus of PE SPCs,which are 10. 8 and 3. 5 times as high as those of the unreinforced LDPE respectively,were obtained at 150 ℃. Higher temperatures also give a positive effect on peel strength. Scanning electron microscopy（ SEM） and camera were also used to observe the morphology of the SPCs samples.
文摘The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base(CMDB)propellant.Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process.To improve the accuracy of the simulation results,material parameters and model structure were corrected based on actual conditions,and adaptive grid technology was applied in the local mesh refinement.In addition,the rheological behavior,motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps,rotational rates and temperatures of two rollers.The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet.Compared with the gap,the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging.Meanwhile,under the synergistic effect of contact heat transfer as well as convective heat exchange,heat accumulated near the outlet and diffused along the reflux movement,which led to the countercurrent heat dissipation behavior of CMDB propellant slurry.The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored,which provided theoretical guidance and reference data for the optimization of calendering process conditions.Based on the simulation results,the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.
