Weekly topic: 8 Wealth points for correct answers, 2 Wealth points for participation； Question 126
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What are the adverse effects of the inlet effect and outlet effect on polymer processing? How can they generally be reduced? Answer 1) The entrance effect and the swelling effect away from the membrane are generally unfavorable for polymer processing. Especially in injection, extrusion, and fiber spinning processes, they can lead to deformation and warping of the products, reduce dimensional stability, and may introduce internal stresses within the products, thereby decreasing their mechanical properties. (2) Increase the tube length, increase the tube diameter, increase the L/D ratio; reduce the convergence angle at the inlet end; appropriately reduce processing stress, increase the processing temperature, and apply drawing force to mitigate the adverse effects of elastic deformation.
What are the adverse effects of the inlet effect and outlet effect on polymer processing? How can they generally be reduced? Answer: (1) The entrance effect and membrane expansion effect are generally unfavorable for polymer processing, especially in processes such as injection, extrusion, and fiber spinning. They can cause deformation and distortion of the product, reduce its dimensional stability, and introduce internal stresses that diminish the product’s mechanical properties. (2) Increasing the length and diameter of the pipe, as well as the L/D ratio, reduces the convergence at the entrance; this helps to lower stresses. Raising the processing temperature and applying drafting forces can also help to reduce these issues
I couldn’t find any problematic information; no matter how I tried to make changes, it didn’t work. In the end, I had to convert it to English – it was not easy at all to get it sent out.
Okay, I’ll know next time. Thank you.
Answer: Both effects are detrimental to polymer processing; particularly in injection molding, extrusion, and fiber spinning, they cause deformation and warping of the finished products, reduce their dimensional stability, and may even lead to internal stresses in the products. Methods to reduce it include: 1. Increasing the processing temperature ； 2. Appropriately reduce shear stress ； 3. Increase the L/D by lengthening the pipe, increasing its diameter, or reducing the convergence angle at the inlet end ； 4. Properly pull the extrudate.
Answer: The inlet effect and outlet effect cause deformation and warping of polymers during processing, reduce the dimensional stability of the products, and may even induce internal stresses in them. Methods to reduce it: 1. Increase the processing temperature ； 2. Appropriately reduce shear stress ； 3. Increase the L/D ratio and reduce the convergence angle at the inlet ； 4. Apply appropriate tension to the extrudate.
Solutions: 1) Slightly reduce processing stress and increase the processing temperature. 2) Slightly decrease shear stress. 3) Increase the L/D ratio (increase the tube length, increase the tube diameter, and reduce the convergence angle at the inlet end). 4) Apply appropriate traction to the extrudate
Polymer molecules are subjected to tensile forces during flow; their elastic deformation is hindered by viscosity, and they can only return to their original state after passing through the exit die. This affects the appearance, dimensions, yield, and quality of the final product. Its impact can be reduced by the following methods: (1) increasing the length of the straight sections of the tube or die ； (2) Appropriately reduce the pressure during molding ； (3) Increase the molding temperature ； (4) A forced setting device is used, and the extruded material is pulled or stretched at an appropriate speed.
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Polymer molecules are subjected to tensile forces during flow; their elastic deformation is hindered by viscosity, and they can only return to their original state after passing through the exit die. This affects the appearance, dimensions, yield, and quality of the final product. Its impact can be reduced by the following methods: (1) increasing the length of the straight sections of the tube or die ； (2) Appropriately reduce the pressure during molding ； (3) Increase the molding temperature ； (4) A forced setting device is used, and the extruded material is pulled or stretched at an appropriate speed.