Residual Stress Development in the Injection Molding of Polymers

Isayev, A. I.; Crouthamel, D. L.

doi:10.1080/03602558408070038

Cited by 109 publications

(46 citation statements)

References 51 publications

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“…The generation of residual stresses (RS) is known to be effective for a toughening of PC, like for inorganic glasses. 3,4 RS are generated by quenching the polymer from a higher temperature than the glass transition temperature until a lower temperature. Then thermal stresses are parabolic in profile, compressive at the surface layer, and tensile inside.…”

Section: Introductionmentioning

confidence: 99%

Mechanical and thermal properties of polycarbonate. II. Influence of titanium dioxide content and quenching on pigmented polycarbonate

Rouabah

Fois

Ibos

et al. 2007

J of Applied Polymer Sci

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ABSTRACT:The effects of quenching temperature including different thermal histories on mechanical, physical, and thermal properties of pigmented polycarbonate (PC/ TiO 2 ) were investigated. Tensile test, Izod impact strength and heat distortion temperature (HDT) were performed on specimens of 3 mm thickness. Pigment content and quenching temperature are two key factors that affect the properties of the materials. A higher content of pigments results in an increase of modulus of elasticity and a decrease of unotched and notched Izod impact strength, as well as elongation at break. A maximum of yield stress and HDT is obtained at 3% of TiO 2 , which was considered as the optimum level of pigment. An additional second quenching at 408C has allowed to improve Izod impact strength and elongation at break of specimens with 3% of TiO 2 ; whereas modulus of elasticity, density, yield stress, and HDT were minimum at this quenching temperature.

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Section: Introductionmentioning

confidence: 99%

Mechanical and thermal properties of polycarbonate. II. Influence of titanium dioxide content and quenching on pigmented polycarbonate

Rouabah

Fois

Ibos

et al. 2007

J of Applied Polymer Sci

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“…One of the reasons of the ignorance of flow induced stresses is that they are at least one magnitude smaller than absolute value that of thermal residual stresses and a large part of flow stresses relax, since the relaxation is faster at the higher temperatures that prevail in filling stage [1,14,24]. However, they induce anisotropy of several properties of the final product; the most seen dimensional faults such as warpage and shrinkage are generally caused by thermal residual stresses [1,16,24]. As a consequence, in this study the effects of recycled material concentrations on thermal residual stresses along the flow direction were investigated.…”

Section: Residual Stress Distributions For Hdpe Blendsmentioning

confidence: 99%

“…These stresses are referred to as residual flow stresses. Second is thermal residual stresses resulting in differential shrinkage during cooling period in the mold and after the demolding [1]. During cooling of the melt polymer, as it passes through glass transition temperature or crystallization temperature, initially cooled surface layers become rigid or stiffen sooner than the core region.…”

Section: Introductionmentioning

confidence: 99%

“…Although flow induced stresses are at least one order of magnitude smaller than the thermal stresses in absolute value, they induce anisotropy in optical and some mechanical properties because of different molecular orientation in the directions of parallel and perpendicular to the flow direction. On the other hand, thermal residual stresses cause shrinkage, warpage and environmental stress-cracking [1][2][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

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

2008

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An 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.

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“…In a general case the residual stress in an injected molded part could include a number of contributions , including i. Flow-induced residual stress, generated as a result of shear, normal, and extensional¯ows during processing [4,5]; ii. Packing stress, resulting from the high pressures imposed during packing; iii.…”

mentioning

confidence: 99%

Approximate Model of Thermal Residual Stress in an Injection Molded Part

Zhang

Cheng

Stelson³

et al. 2002

Journal of Thermal Stresses

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A description and model of the thermally induced residual stress that forms in a`Injection molding is used in the fabrication of a wide range of plastic products. In the injection-molding process, molten polymer is injected into a mold and then is packed under pressure, solidi®ed, and then cooled to a uniform temperature. Figure 1 schematically illustrates the solidi®cation stage of a``platelike'' part.Injection molding introduces residual stresses, a stress state that exists in the bulk of a material without application of any external load, in the ®nal product [1,2]. It is important to know the residual stress state of the part to predict its performance under load. Depending on the situation, residual stresses can be either detrimental or

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Residual Stress Development in the Injection Molding of Polymers

Cited by 109 publications

References 51 publications

Mechanical and thermal properties of polycarbonate. II. Influence of titanium dioxide content and quenching on pigmented polycarbonate

Mechanical and thermal properties of polycarbonate. II. Influence of titanium dioxide content and quenching on pigmented polycarbonate

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

Approximate Model of Thermal Residual Stress in an Injection Molded Part

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