The Effect of Fountain Flow on Molecular Orientation in Injection Molding

1988 ◽  
Vol 32 (6) ◽  
pp. 639-663 ◽  
Author(s):  
H. Mavridis ◽  
A. N. Hrymak ◽  
J. Vlachopoulos
Keyword(s):  
Injection Molding ◽  
Molecular Orientation ◽  
Fountain Flow

scholarly journals FTIR Analysis of Molecular Orientation at Weldline Region in Thermoplastics Injection Molding.

1992 ◽  
Vol 49 (7) ◽  
pp. 591-600 ◽  
Author(s):  
Kiyotaka TOMARI ◽  
Toshihiko HARADA ◽  
Zenichiro MAEKAWA ◽  
Hiroyuki HAMADA ◽  
Akio HAMAMOTO
Keyword(s):  
Injection Molding ◽  
Molecular Orientation ◽  
Ftir Analysis

Product Strength and Orientation Manipulation via Vibration-Assisted Injection Molding

2002 ◽  
Author(s):  
David C. Angstadt ◽  
John P. Coulter
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Injection Molding ◽  
Molecular Orientation ◽  
Polymer Melt ◽  
Polymer Processing ◽  
Shear Yielding ◽  
Processing Methods ◽  
Improve Product

This investigation focuses on determining why polystyrene ASTM specimens exhibit an increase in tensile strength when processed by vibration assisted injection molding (VAIM) while polycarbonate parts do not. VAIM is one of several polymer processing methods that attempt to improve product properties via manipulation of the polymer melt. Observation of birefringence patterns in VAIM processed polystyrene samples show a significant impact on molecular orientation. The same studies were conducted on opaque polycarbonate and were unable to determine the degree of molecular orientation via birefringence measurement. It was theorized that VAIM did not produce significant orientation due to its higher thermal conductivity and stiffer backbone. It has been determined by this investigation that VAIM processing does impart significant molecular orientation in polycarbonate specimens but still does not increase its UTS. It is proposed that increased molecular orientation induced by VAIM processing inhibits crazes from growing into cracks. VAIM therefore favors polymers that fail by crazing (e.g., polystyrene) rather than those that fail by shear yielding (e.g., polycarbonate).

Analysis of Residual Stress in Thin Wall Injection Molding

2006 ◽  
Vol 306-308 ◽  
pp. 1331-1336
Author(s):  
H.K. Lee ◽  
J.C. Huang ◽  
G.E. Yang ◽  
Hong Gun Kim
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Injection Molding ◽  
Molecular Orientation ◽  
Polymeric Materials ◽  
Residual Stress Distribution ◽  
Thin Wall ◽  
Flow Paths ◽  
Wall Injection ◽  
Relationship Of

A relationship of residual stress distribution and surface molding states on polymeric materials is presented in thin-walled injection molding. The residual stress is computed by computational numerical analysis, observed with stress viewer and birefringence. The residual stress on polymeric parts can allude the surface quality as well as flow paths. The residual stress distribution on polymeric parts is related with thickness, gate layout, and polymer types. Molecular orientation on polymeric parts is also important in thin wall injection molding. The residual stress and molecular orientation are related to the surface molding states intimately. Analysis of the residual stress is validated through photo-elastic method and surface molding states..

Effect of complex flow kinematics on the molecular orientation distribution in injection molding of liquid crystalline copolyesters

Polymer ◽  
2004 ◽  
Vol 45 (15) ◽  
pp. 5341-5352 ◽  
Author(s):  
Stanley Rendon ◽  
Wesley R. Burghardt ◽  
Anthony New ◽  
Robert A. Bubeck ◽  
Lowell S. Thomas
Keyword(s):  
Injection Molding ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Orientation Distribution ◽  
Complex Flow

Residual Stress and Surface Molding Conditions in Thin Wall Injection Molding

2005 ◽  
Vol 9 ◽  
pp. 137-142
Author(s):  
H.K. Lee ◽  
G.E. Yang ◽  
Hong Gun Kim
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Injection Molding ◽  
Molecular Orientation ◽  
Polymeric Materials ◽  
Residual Stress Distribution ◽  
Thin Wall ◽  
Flow Paths ◽  
Wall Injection ◽  
Polymer Type

Residual stress distribution and surface molding state of polymeric materials are presented for thin-walled injection molding. The residual stress is computed by computational numerical analysis, observed with a stress viewer and birefringence. The residual stress on the surface of the polymeric part can indicate the surface quality as well as flow paths. The residual stress distribution of the polymeric part is related with the part’s thickness, the gate layout, and the polymer type. Molecular orientation, affected by flow paths, is simulated and validated by observing the birefringence of the polymeric specimens. The residual stress and molecular orientation are closely related to the surface molding states.

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