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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A New Methodology for Measuring Flammability Parameters of Plastics
A methodology that separately reproduces the gas and condensed phase processes of flaming combustion in a single laboratory test is described. Anaerobic pyrolysis of solid plastics under controlled heating conditions and thermal oxidation (nonflaming combustion) of the volatile products provides the rate and amount of heat released by the solid during burning. The physical basis for the methodology, the measurement of flammability parameters, and their relationship to fire response and flame resistance of plastics are described.
Multi-Objective Velocity Profile Optimization
A methodology is presented for optimizing multiple stages in an injection velocity profile between critical junctions in the runner and cavity geometry. During a short shot study, the injection velocity is sequentially optimized for each consecutive velocity stage by minimizing the total injection molding cost. The results indicate that velocity profiling has a marginal role on nominal molding costs, but a significant role on part quality (the part thickness in this study) and processing yields.
Effect of Molecular Weight on the Interfacial Properties of GF/PP Injection Molded Composites
For the fabrication of GF/PP injection molded composite, 3 types of PP with different molecular weights were used in order to simulate the recycling process of PP. Effects of weight-average molecular weight on interfacial adhesion between GF and PP were investigated. Moreover, effects of fiber length was also examined through high-back and low-back pressure at the injection molding condition.
In Mold Punching - Processing and Mechanical Properties
The effects of punching and injection molding conditions on the amount of deformation and the tensile strength for punched polycarbonate parts in a mold during injection molding were investigated. Both punching and injection molding conditions affected the amount of deformation. Only punching conditions have been found to influence the tensile strength. Two ways could be proposed to secure small degree of deformation and high tensile strength.
Hygrothermal Ageing of GF/PP Injection Molded Composites
The effects of hygrothermal ageing on mechanical interfacial shear properties of injection molded glass fiber (GF) reinforced polypropylene (PP) composites (GFPP) were elucidated. The degradation at the interface initially occurred during the aging process. The interfacial shear strength of GF/PP before and after immersion was investigated by using the Kelly-Tyson formula. As the immersion time increased, the interfacial shear strength became lower.
Prediction of Modulus by Considering Distribution of Cell Shape
The distribution of the cell shape in the polyurethane foam was measured by using the image processing method. In addition, the cell shape was simply modeled. The analysis limited within the range of elasticity was done by using this model. As a result, the prediction of the mechanical properties was tried by applying the rule of mixture to the foam. The validity was examined.
Morphology in WPC during Extrusion Foaming with N2
Incorporating a fine-celled structure in wood-fiber/plastic composites (WPC) foam is important for achieving improved ductility and impact strength. This paper investigates the effects of processing and materials parameters on the morphological changes of WPC during extrusion foaming with N2.
Real-Time Diagnosis for Micro Powder Injection Molding Using Ultrasound
Real-time diagnostics of ceramic powder injection molding with a micromolding machine was performed using ultrasound. Miniature ultrasonic sensors were integrated onto the mold insert. Melt front, solidification and part detachment of the feedstock inside the moldcavity were observed. The assistance of ultrasonic velocity in feedstock inside the mold cavity, the ultrasonic contact time during which the part and mold are in contact and holding pressure may minimize part dimension variation.
Rheology and Thermoforming of Rigid Medical Packaging Materials
Rheological properties were measured on two materials to evaluate their behavior in the thermoforming process. An impact-modified acrylic-based terpolymer compound displayed higher extensional viscosity and melt strength measurements versus a copolyester. The findings in this study showed that lower extensional viscosity and melt strength led to higher molded-in-stress and thinner walls of thermoformed parts.
Mechanical Testing and Characterization of Biopolymers
Biopolymers are generally defined as polymers that are found in nature, derived from nature, or utilized as medical implants. Polymeric biomaterials which are utilized as medical implants are typically characterized for end-use performance as well as processability. While lactic acid is found in the human body, polylactic acid is derived from natural resources and utilized as medical implants. This paper will utilize poly(lactic acid) as an example of a biopolymer where the morphological and isomeric structure has an influence on end-use properties such as mechanical properties, biodegradability, and biocompatibility.
Influence of Phase Segregation on the Physical Properties of Polyethylene Blends
Phase segregation in melt-extruded blends of polyethylenes that differ considerably in molecular weight was found to exert diverse degrees of influence on various measured physical properties. The instantaneous tensile deformation properties were insensitive to phase segregation while the high-strain tensile deformation behavior is strongly and adversely influenced by phase segregation. Phase segregation of select blend components can favor the plane stress fracture resistance.
Polymer Composites of Modified Carbon Nanofibers Prepared by Chaotic Mixing
Surface-modified carbon nanofibers were used using a chaotic mixer to prepare composites of poly (methyl methacrylate). The quality of dispersion, and electrical and thermo-mechanical properties were determined and compared with similar composites containing non-treated carbon nanofibers. Composites of treated nanofibers showed improved dispersion, and better mechanical properties even at high temperatures, but their electrical conductivity was lower than composites of nanofibers without surface treatment.
Increasing the Feasible Bonding Strength in Micro Assembly Injection Molding Using Surface Modifications
Polymers offer a wide range of properties that can be modified according to the needs. An offline joining process can be avoided by overmolding the components to create a hybrid micro system. New research at IKV shows a significant increase in the feasible bonding strength in micro assembly injection molding by using plasma treatment for the inlay parts.
Bead and Fiber Morphologies during Electrospinning of Polystyrene
The cumulative effects of polymer molecular weight and concentration on the structure of electrospun fibers and beads were investigated. A significant change in fiber diameter and shape was observed as the molecular weight was varied keeping Berry number, [?]C, constant. Below the entanglement concentration, various types of beads including wrinkled beads, cups, dishes and toroids were produced.
Polystyrene/Clay Nanocomposites by Melt Intercalation
Polystyrene nanocomposites were obtained via melt compounding, using montmorillonite modified with various surfactants. The interlayer distance, thermal stability and surface tension of the resulting organoclays were determined. Moreover, the resulting PS nanocomposites were evaluated using X-ray diffraction and thermogravimetric analysis (TGA). The mechanical and barrier properties were also determined. The results show significant differences in thermal stability, and mechanical and barrier properties of the nanocomposites depending on the composition and interfacial properties of the surfactant.
Photoviscoelastic Behavior and Residual Thermal Birefringence in Polycarbonates
The stress-optical coefficient function of two optical grade polycarbonates (PC) has been determined by simultaneous measurements of the relaxation modulus and strain-optical coefficient function. Based on these measurements, linear viscoelastic and photoviscoelastic constitutive equations were applied to evaluate residual thermal birefringence in quenched PC plates. Numerical results have been compared with the measurements.
Influence of Compounding Conditions on Mechanical Properties of Recycled Poly(Ethylene Terephthalate)
We have prepared several types of recycled materials from waste poly-(ethylene terephthalate) (PET) through different compounding conditions. As a result, modified recycled- PET (R-PET) with strength similar to virgin PET has been successfully developed. In this paper, structure and mechanical properties of the modified R-PET immersed in hot water were investigated on the basis of tensile test, impact test, Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC).
Characterizing Fiber Diameter and Deformation Using Diffraction Techniques
A common experimental obstacle encountered during mechanical testing of fibers is that the cross-section area and transverse strain are difficult to assess directly. A laser diffraction technique has been found adequate to measure fiber diameters within the range of 10-100 um during tensile testing with a precision of ±10%. Fiber transverse strain is evaluated by SAXD and used to determine Poisson’s ratio and study deformation at different length scales of fibers with hierarchical structure.
Effect of Plug Design on Thermoformed Polypropylene Parts
In this study the influence of plug design, namely plug volume, plug taper, plug depth and plug temperature on the wall thickness distribution, weight and compression strength in thermoformed polypropylene cups was investigated. It was observed that the plug volume was the most importance factor for part shape. Plug depth had a significant effect on the bottom and corner thicknesses and part weight. Plug temperature and plug taper had a significant effect only on the compression strength.
Electrospun PVA Fibers as Precursor to Synthesize Hydroxyapatite
PVA (Polyvinyl alcohol) with various molecular weights (Mw) were electrospun with a Calcium Phosphate based sol. Fibers on the order of 2 ?m with uniformly distributed sol particles were obtained. Electrospinning process may be facilitated with high molecular weight polymers. The distribution of sol in the electrospun structure may depend on polymer/sol ratio. XRD results indicate that the fibers after calcination consisted predominantly of hydroxyapatite.
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