SPE Library

The SPE Library contains thousands of papers, presentations, journal briefs and recorded webinars from the best minds in the Plastics Industry. Spanning almost two decades, this collection of published research and development work in polymer science and plastics technology is a wealth of knowledge and information for anyone involved in plastics.

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Conference Proceedings

EFFECT OF THE MOLDING PROCESS OVER THE ADJUSTABLE PARAMETERS IN CONSTITUTIVE EQUATIONS

R. Morales , O. Santana, May 2008

The mission of this study is to determine the effect of the orientation induced during the transformation process in the adjustable parameters of the constitutive equations for PP. In the hot tensile test different thermoforming conditions were simulated by changing oven temperature (sheet temperature) and crosshead speed (plug speed).Stressƒ??strain relations were derived. The model used involved eight adjustable parameters considering the effect of the process condition and process orientation.

TOWARDS QUALITY PRODUCTS FROM BIO-BASED PLASTICS

Rolf Koster, May 2008

The importance of three inter-dependent factors, i.e., (1) materials, (2) manufacturing, and (3) design and engineering, is generally recognized. All factors are indispensable and equally important for product development. Manufacturing is often the least structured factor and many designers and materials experts do not consider themselves capable to deal with it. Fortunately, expertise is sufficiently available and the best professionals are able to utilize plastics expertise properly in collaborative product development.

THE EFFECTS OF GRADUATED VERSUS CONSTANT RUNNER DIAMETERS ON FILLING AND PACKING OF A PLASTIC PART IN INJECTION MOLDING

Gregory L. Swanson , Matthew Weller, May 2008

This paper presents a study of the effects of various cold runner systems on filling and packing of a plastic part in injection molding. A comparison between graduated and constant runner diameters was the main focus of the paper. The study centered on the battle between minimizing runner volume and minimizing pressure drops. While many theories exist supporting one runner system over another this research attempted to collect enough data to prove when each should be used.

BIO-COMPATIBLE STRUCTURAL HYDROGEL CATHETER MATERIAL

Scott M. Epstein, May 2008

A new novel process that will produce a structural hydrogel catheter has been developed (1) resulting in biocompatible architecturally stable all hydrogel devices which can be used as an alternative to conventional TPE’s.

FAILURE ANALYSIS OF A PLASTIC SLIDE VALVE ASSEMBLY

Ahamed Shabeer, May 2008

Premature cracks were observed during service in the slide valve assembly molded from an acrylonitilebutadiene- styrene resin. The investigation focused on the determination of nature and cause of the failure. The results obtained during the evaluation indicated that the failure was due to environmental stress cracking which occurred as a consequence of the presence of the residual stress and the stress cracking agent. This paper will focus on the testing used to characterize the failure mode and identify the cause of the cracking of the slide valve assembly.

FAILURE ANALYSIS OF A PLASTIC SLIDE VALVE ASSEMBLY

Ahamed Shabeer, May 2008

Premature cracks were observed during service in the slide valve assembly molded from an acrylonitilebutadiene- styrene resin. The investigation focused on the determination of nature and cause of the failure. The results obtained during the evaluation indicated that the failure was due to environmental stress cracking, which occurred as a consequence of the presence of the residual stress and the stress cracking agent. This paper will focus on the testing used to characterize the failure mode and identify the cause of the cracking of the slide valve assembly.

MOLECULAR DYNAMICS SIMULATOIN OF VISCOELASTIC PROPERTIES AND SLIP BEHAVIOR OF THIN FILMS OF N-HEXADECANE IN THE SHEAR FLOW

Chen-Chieh Wang , Rong-Yeu Chang, May 2008

We investigate the viscoelastic properties of chain molecules (n-hexadecane) under steady state and oscillatory shear flow of ultra thin films by molecular dynamics simulation. The stress vs. strain rate diagram of the oscillatory shear flow system is used to determine the range of linear viscoelasticity. In addition interfacial slip is observed and discussed in both cases. The critical shear stress at which slip occurs is also found in our simulation.

RELATION BETWEEN BUBBLE STABILITY IN THE FILM BLOWING PROCESS AND MFI

Erika Palacios-Aguilar , Leonardo Cortés-Rodríguez , Jaime Bonilla-Ríos, May 2008

Several HDPE resins with different bubble film stability were tested in a melt flow indexer using the typical die (L = 8 mm D = 2.095 mm) and a zero die (L = 1.3 mm D = 2.095 mm) at two different loads (21.6 kg and 5 kg). A direct correlation was found between the MFI results and the bubble stability.

RELATION BETWEEN BUBBLE STABILITY IN THE FILM BLOWING PROCESS AND MFI

Erika Palacios-Aguilar , Leonardo Cortés-Rodríguez , Jaime Bonilla-Ríos, May 2008

Several HDPE resins with different bubble film stability were tested in a melt flow indexer using the typical die (L = 8 mm, D = 2.095 mm) and a zero die (L = 1.3 mm, D = 2.095 mm) at two different loads (21.6 kg and 5 kg). A direct correlation was found between the MFI results and the bubble stability.

ELIMINATION OF DEFECTS FROM INJECTION MOLDED POLYSTYRENE PARTS VIA SCREW MODIFICATIONS

Mark A. Spalding , Joseph R. Powers, May 2008

Many injection molded part defects are caused by improper screw designs. Elimination of the defect and optimization of the process can often be performed via simple modifications to the screw. A case study is presented where a splay defect was caused by a screw with a low compression ratio with regions where resin can stagnate and degrade and with a limited melting capacity. Modification of the screw eliminated the defects and decreased the cycle time by 8% an improved the plant capacity by 14%.

ELIMINATION OF DEFECTS FROM INJECTION MOLDED POLYSTYRENE PARTS VIA SCREW MODIFICATIONS

Mark A. Spalding , Joseph R. Powers, May 2008

Many injection molded part defects are caused by improper screw designs. Elimination of the defect and optimization of the process can often be performed via simple modifications to the screw. A case study is presented where a splay defect was caused by a screw with a low compression ratio, with regions where resin can stagnate and degrade, and with a limited melting capacity.Modification of the screw eliminated the defects and decreased the cycle time by 8% an improved the plant capacity by 14%.

AN ENGINEERING APPROACH TO DESIGNING PLASTICATING SCREWS FOR SINGLE-SCREW EXTRUDERS

Mark A. Spalding , Gregory A. Campbell, May 2008

An engineering approach for the design of plasticating screws is presented with a case study. The approach uses a combination of experimental data and numerical simulations.

AN ENGINEERING APPROACH TO DESIGNING PLASTICATING SCREWS FOR SINGLE-SCREW EXTRUDERS

Mark A. Spalding , Gregory A. Campbell, May 2008

An engineering approach for the design of plasticating screws is presented with a case study. The approach uses a combination of experimental data and numerical simulations.

POLYCARBONATE HYDROLYSIS

Robert R. Gallucci, May 2008

The hydrolysis of polycarbonate (PC) is compared to polybutylene terephthalate (PBT). Phosphorus additives are shown to accelerate PC hydrolysis. Polycarbonate polyester (PEC) copolymers hydrolyze faster than PC however hydrolysis of the copolymer can be retarded by addition of a hydro stabilizer. Color clarity and mechanical properties are retained.

POLYCARBONATE HYDROLYSIS

Robert R. Gallucci, May 2008

The hydrolysis of polycarbonate (PC) is compared to polybutylene terephthalate (PBT). Phosphorus additives are shown to accelerate PC hydrolysis. Polycarbonate polyester (PEC) copolymers hydrolyze faster than PC, however hydrolysis of the copolymer can be retarded by addition of a hydro stabilizer. Color, clarity and mechanical properties are retained.

MORPHOLOGY STUDY FOR MICROCELLULAR INJECTION MOLDING

Jingyi Xu, May 2008

The morphology of microcellular injection molding is investigated for different materials at different processing conditions in current available equipments. Several morphology models are proposed based on this study. The conclusions provide the guidelines to select the best processing parameters for different materials to make the good morphology of microcellular foam by injection molding with the minimum material property changes.

MORPHOLOGY STUDY FOR MICROCELLULAR INJECTION MOLDING

Jingyi Xu, May 2008

The morphology of microcellular injection molding is investigated for different materials at different processing conditions in current available equipments. Several morphology models are proposed based on this study.The conclusions provide the guidelines to select the best processing parameters for different materials to make the good morphology of microcellular foam by injection molding with the minimum material property changes.

CAE SIMULATION AND EXPERIMENTAL INVESTIGATION ON WARP OF AN INJECTION MOLDED PART

Shijun Ni, May 2008

The warpage of an injection molded part was predicted by CAE injection molding simulation software using mid-plane Fusion and true three-dimensional analyses. An Arburg 320S Allrounder 55 ton injection molding machine was used for producing parts. The part deformation was then measured on a CMM. The predicted part warpage among three mesh models was compared to the measurement of part deformation. It was found that the predicted part warp using the true threedimensional model was in a good agreement with the measurement of the part.

CAE SIMULATION AND EXPERIMENTAL INVESTIGATION ON WARP OF AN INJECTION MOLDED PART

Shijun Ni, May 2008

The warpage of an injection molded part was predicted by CAE injection molding simulation software using mid-plane, Fusion and true three-dimensional analyses. An Arburg 320S Allrounder 55 ton injection molding machine was used for producing parts. The part deformation was then measured on a CMM. The predicted part warpage among three mesh models was compared to the measurement of part deformation. It was found that the predicted part warp using the true three-dimensional model was in a good agreement with the measurement of the part.

SCREW DESIGN CONSIDERATIONS FOR BIOBASED POLYMERS

Edward Steward, May 2008

The family of biobased polymers is ever growing in number and in popularity and the extruder/screw manufacturing businesses need to keep abreast of the machinery requirements of these polymers to insure that efficient processing is understood. This paper will look at the extrusion parameters and logic that are important to determining the most efficient screw designs and extrusion operating conditions for processing biopolymers. Vented and non-vented operation will be discussed. PLA data will be used as the basis for the conclusions.