Residual stresses in injection-molded amorphous polymers

1987 ◽  
Vol 27 (14) ◽  
pp. 1069-1078 ◽  
Author(s):  
A. Siegmann ◽  
S. Kenig ◽  
A. Buchman
Keyword(s):  
Residual Stresses ◽  
Amorphous Polymers ◽  
Injection Molded

Prediction and measurement of residual stresses in injection molded parts

2001 ◽  
Vol 2 (4) ◽  
pp. 203-211 ◽  
Author(s):  
Young Il Kwon ◽  
Tae Jin Kang ◽  
Kwansoo Chung ◽  
Jae Ryoun Youn
Keyword(s):  
Residual Stresses ◽  
Molded Parts ◽  
Injection Molded

Calculation on the Residual Stresses of Injection-Molded Conductive-Carbon-Fiber-Filled Polymer Composites

2012 ◽  
Vol 629 ◽  
pp. 55-59
Author(s):  
Ai Yun Jiang ◽  
Jing Chao Zou ◽  
Bao Feng Zhang ◽  
Hai Hong Wu
Keyword(s):  
Carbon Fiber ◽  
Residual Stresses ◽  
Polymer Composites ◽  
Injection Molding Process ◽  
Molding Process ◽  
Filled Polymer ◽  
The Core ◽  
Packing Pressure ◽  
Core Areas ◽  
Injection Molded

For conductive-carbon-fiber-filled polymer composites, the residual stresses developed during injection molding process may affect not only the molding’s conductive property, but its dimensional stability as well. In order to improve the conductivity of the molding fabricated with this kind of composites, we investigated, using layer removal method, the distribution of the residual stresses of injection-molded conductive-carbon-fiber-filled polypropylene in this paper. The residual stresses were obtained under the actions of different processing conditions. Our results indicate that processing pressures have more significant effects on the residual stresses at the skin areas than the core areas of the sample because of fiber orientation. The tensile stresses of the molding at the core areas drop under the action of packing pressure, but the compressive stresses at the skin areas increase. The results reveal that the action of packing pressure may decrease the anisotropy of the residual stresses in the molding.

Residual stresses determination in injection molded virgin and recycled HDPE blends: mechanical properties and morphology

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Mirigul Altan ◽  
Mehmet Emin Yurci ◽  
Nihan Nugay
Keyword(s):  
Elastic Modulus ◽  
Impact Strength ◽  
Residual Stresses ◽  
Thermal Stresses ◽  
Mold Temperature ◽  
Morphological Properties ◽  
Time Layer ◽  
Melt Temperature ◽  
Injection Molded ◽  
Recycled Hdpe

AbstractAn experimental study of residual thermal stresses has been carried out in injection molded virgin and recycled high density polyethylene (HDPE) blends. Effects of blend concentrations on residual stresses were investigated under different injection conditions such as melt temperature, mold temperature and cooling time. Layer removal technique was used for measuring residual stresses. In order to determine the relation between the residual stresses and material characteristic of HDPE blends, mechanical and morphological properties of the blends were also investigated. Elastic modulus and impact strength were important key factors for determining the blend characteristics. As a result, it was found that HDPE blends gave higher residual stresses but lower impact strength with higher elastic modulus when recycled concentration was increased. Furthermore, it was seen that shape and size of the crystallites were also effective on residual stresses. Small and spherulitic crystallite structured blends such as 30 % recycled HDPE induced reduction in residual stresses due to easier relaxation with lower elastic modulus and higher impact strength while lamellar crystallite structured blends such as 50 % recycled HDPE gave higher elastic modulus but lower impact strength with higher residual stresses.

Residual stresses in injection molded products

2014 ◽  
Vol 49 (13) ◽  
pp. 4399-4415 ◽  
Author(s):  
A. Guevara-Morales ◽  
U. Figueroa-López
Keyword(s):  
Residual Stresses ◽  
Injection Molded

Thermal Stresses in Nonlinearly Viscoelastic Solids

1992 ◽  
Vol 59 (2S) ◽  
pp. S43-S49 ◽  
Author(s):  
Giancarlo U. Losi ◽  
Wolfgang G. Knauss
Keyword(s):  
Glass Transition ◽  
Residual Stresses ◽  
Free Volume ◽  
Thermal Stresses ◽  
Morphological Changes ◽  
Polymer Chains ◽  
Transition Range ◽  
Rheological Models ◽  
Molded Parts ◽  
Injection Molded

Three different rheological models are applied to the study of transient and residual thermal stresses in amorphous polymers cooled across the glass transition. The models differ mainly in their treatments of the nonequilibrium (time-dependent) portion of the morphological changes in the polymer and their influence on the relaxation process. The interstitial volume between polymer chains (free volume) is found to play an important role in the residual stresses; they are affected by the relative time scale of thermal diffusion and thermoviscoelastic relaxation/creep. This result has implications for injection molded parts of different section dimensions and for extrusion products. This fact must also be accounted for in determining the thermomechanicalproperties in the glass transition range. The step cooling ofPVAc spheres (1 and 20 mm dia.) and a cylinder (20 mm dia.) have been considered; most of the results presented apply to the sphere(s). Residual stresses can vary by as much as 100percent depending on whether the interstitial molecular (free) volume is counted or not. It is also demonstrated that residual stresses can be higher than an elastic analysis based on the glassy properties would suggest; thus the “stressfree temperature” is found to be significantly above the glass transition.

Processing Optimization of Optical Lens in the Injection Molding

2013 ◽  
Vol 813 ◽  
pp. 161-164 ◽  
Author(s):  
Chao Ming Lin ◽  
Chih Kun Wang
Keyword(s):  
Residual Stress ◽  
Refractive Index ◽  
Residual Stresses ◽  
Processing Parameters ◽  
Processing Conditions ◽  
Fringe Order ◽  
Optimal Method ◽  
Optical Lens ◽  
Injection Molded ◽  
Processing Optimization

The processing conditions during the manufacturing have critical effects on the optical performances of the molded lenses including the refractive index, isochromatic fringe order, and the fringed pattern. The objective of this work is to investigate numerically some effects of the molding conditions on the residual stresses of injection molded lenses, and then to optimal the processing parameters for reducing the residual stresses using the Taguchi method. The results show the optimal method is able to improve the residual stress and to produce a good fringed pattern.

Analysis of polymer crystallization and residual stresses in injection molded parts

2014 ◽  
Vol 15 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Roberto Spina ◽  
Marcel Spekowius ◽  
Rainer Dahlmann ◽  
Christian Hopmann
Keyword(s):  
Residual Stresses ◽  
Polymer Crystallization ◽  
Molded Parts ◽  
Injection Molded
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