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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Evaluation of Different Injection Molding Screw Designs for Better Color Mixing
Improved color mixing for injection molding can be improved by different variables. Screw speed, melt temperature, backpressure, barrel temperature profiles, screw design, dispersion discs, etc. can all influence color dispersion. This study will focus on the screw design and its affect on color mixing and its affect on other process parameters.
Modeling of Non-Isothermal High Stalk Film Blowing Process by Using Variational Principles for Non-Newtonian Fluids
In this work, the high stalk film blowing model derived by using variational principles has been used to investigate the effect of cooling on the HMW – HDPE bubble formation with respect to final film properties. Moreover, the effect of the molecular weight and long chain branching has been theoretically studied by the help of the newly proposed generalized Newtonian model.
Extrusion and Spinning of Nylon-6,6 / Supercritical Carbon Dioxide Mixtures
This work had two aspects. In the first one, the interaction between CO2 and nylon-6,6 melt is explored by investigating by the effects of CO2 on nylon-6,6 shear viscosity and hydrogen bonding. In the second one, an attempt is made to establish feasible conditions for spinning of nylon-6,6/CO2 mixtures, to produce nylon filaments. Extrusion and spinning experiments of nylon- 6,6 / CO2 were conducted on a twin- screw extruder line and the effects of carbon dioxide on viscosity and spun filaments morphology and tensile properties were investigated.
Engineering Plastics for Laser Welding
The use of laser light energy to very locally weld plastic surfaces together has opened new possibilities for flexible design and assembly of plastics parts. However, this poses the challenge of applying a combination of transparent and absorbing plastic parts in order to use the laser light efficiently for local melting at the interface. Transparency is still a challenge in some cases, due to the scattering nature of certain plastics. This paper will focus on the optical requirements of the welded parts, but also on the physical aspects of the interface to form a strong weld.
Plane Stress Rapid Fracture Resistance of Pipe Grade PE: Estimation from Tensile Drawing Data
The Rapid Crack Propagation régime in pressurised polyethylene pipe is limited by a critical temperature, which is determined mainly by the increasing resistance of the material to plane stress fracture. The Reversed Charpy and ASTM F2231 ‘Thin Charpy’ test methods are designed to index this property, at appropriately high rates, for quality control and material development purposes. This paper demonstrates that equivalent information can be derived from a procedure based on basic tensile drawing tests, via material properties which are more accessible to material design.
Development of Semi-Interpenetrating Polymer Network Electrolytes of Polyurethane and Polysiloxane
A novel semi-interpenetrating polymer network (semi-IPN) electrolyte of polyurethane (PU) and polyether modified polysiloxane (PEMPS) with salt, LiClO4, were developed by using a solvent-free reactive process. The dissolution of LiClO4 in monomer and PEMPS was studied by using optical microscopy (OP), differential scanning calorimeter (DSC) and Fourier transform infra-red (FTIR) spectroscopy. The semi-IPN electrolytes of TPU/PEMPS were characterized by DSC and FTIR. The effect of PEMPS on the ionic conductivity of PU was also determined by using the modified LCR meter.
Comparison of N2 and CO2 in Extrusion Foaming of Wood-Fiber Composites
Producing cellular wood-fiber/plastic composite (WPC) with physical blowing agents (PBA) offers unique advantages over chemical blowing agents (CBA). This paper compares the foaming behaviors of two environmentally benign PBAs, namely N2 and CO2, to help understand PBA-based foaming mechanisms in WPC. This understanding will help in making proper choices about PBAs and foam processing parameters.
High Heat Ductile (HHD) Copolymers by Reactive Extrusion
A blend of two polycarbonate copolymers, high-heat poly(ester-carbonate) (PEC) and polycarbonate-polydimethylsiloxane copolymer (PC-PDMS) provided an opaque, pearlescent blend. However, when a transesterification catalyst was used, the blend becomes miscible and translucent/transparent. The high-heat, ductile (HHD) materials were analyzed for a range of properties including optics, rheology, heat performance, flame retardance, and mechanical properties. The hydrolytic stability of the HHD materials was also measured by comparing the ductility of the blends before and after autoclaving.
Extrusion Foaming Behaviors of PET with CO2
This paper investigates the extrusion foaming behaviors of Polyethyleneterephthalate (PET) blown with supercritical CO2. The evolution of the foam's morphology once it exited from the die was recorded using a CCD camera and also characterized by SEM. Microcellular PET foams can be prepared by optimizing the PET properties as well as the processing conditions.
Effect of Moisture Absorption on the Properties of Clay-Reinforced Polypropylene Nanocomposites
The behavior of two polypropylene nanocomposites when immersed in distilled water or sea water at four different temperatures was studied and compared with that of neat PP. The nanocomposites showed a higher water diffusion rate and equilibrium moisture content. Nevertheless, because of their superior initial mechanical properties, after 42 days exposure they were still equivalent to unexposed PP. X-ray diffraction and infrared spectroscopy were applied to characterize the surfaces of the exposed specimens.
Phase Separation in Thermotropic Liquid Crystalline Polymer/Polycarbonate Blends under Shear
The effect of shear on the temporal development of phase separation in thermotropic liquid crystalline polymer (LCP)/polycarbonate (PC) blends was examined. Experiments were performed using a polarized-light microscope, equipped with a shearing hot stage. Phase separation, with and without shear, in blends containing 50 wt % LCP were analyzed. The results showed that the speed and amount of phase separation increased when shear was applied.
Foaming Dynamics of Immiscible Polymer Blends
To better understand the underlying mechanisms of immiscible blend polystyrene/poly (methyl methacrylate) (PS/PMMA) foaming, a simple bilayer representation is examined. Visual observation of batch foaming of this system is conducted and a quenching method is used to study foams with different bubble growth time. These help understand the effects of blend morphology on foaming in a more quantitative way.
Rheology of Heterogeneous Polymer Melts
Heterogeneous polymers represent an important class of plastics that comprise polymer blends, alloys, and fiber or mineral filled plastics. The rheology of these melts is dominated by the transient morphology that is produced during fabrication into finished products. Standard laboratory rheological tests do not take into account morphology. Combined measurements of a capillary viscometer and controlled stress rotational rheometer can provide a better understanding of the processing behavior of these complex rheological plastics
Cluster Performance Measurement: A Case-Study of Plastic Clusters in the Czech Republic
The topic of clusters has emerged as a crucial idea in competitiveness and economic development in the last years. This paper shows and discusses (basing on concrete plastic cluster in the Czech Republic) possible approaches to the cluster performance measurement. There are analyzed problems related to the performance measurement and suggested suitable performance measures. This case-study also shows the possibilities for mutual cooperation and ways in which the research results can be transferred into working practice.
Prediction of Continuous Kneader Reactor Processes from Batch Data
Batch trials were performed on a kneader reactor where a bulk co-polymerization was carried out. Polymerization conversion, viscosity build, reaction kinetics, and heat transfer calculations were performed using the experimental data from the batch trials. A continuous process was proposed for this bulk copolymerization and the models and results from the batch trials were used in designing the continuous process. Predictions of the continuous process using the batch trial data are compared to the actual continuous process, with a focus on polymer conversion, heat transfer, and torque prediction.
Injection-Molding Degradation of Biodegradable Polylactide
The effects of degradation on the mechanical and aesthetic properties of injection-molded biodegradable polylactide (PLA) parts were studied. Standard tensile test specimens were molded from NatureWorks 3051D injection-molding grade PLA. Barrel residence time, machine nozzle temperature, and shear rate were varied during the injection-molding process. The resulting specimens were analyzed in a tensile testing machine. Tensile strength, tensile modulus and visual inspection were used to characterize the extent of degradation that occurred during each process.
Investigation of Failures in a Polypropylene Water Piping System
Polypropylene pipe and fittings were selected for a high-purity, highly chlorinated water system in a medical research facility. In the first four years of operation, the system sustained an excessive number of leaks. This paper is an account of the investigation of the causes of those leaks.
High-Energy Electron Beam Processing of Wood Composites
For high doses, a DMA analysis of wood and composites revealed a change in lignin resulting in reduced Tg, and that electron scavenging from lignin's aromatic structure could hinder the cure. An investigation of purified cellulose revealed changes at higher doses in the physical response to moisture and thermal stability without a change in the degree of crystallinity as measured by wide-angle X-ray scattering (WAXS).
Developments in Water Assisted Injection Molding Process Technology and Simulation
A preliminary account is given of issues involved in numerical simulation of water assisted injection molding (WAIM), extending techniques used previously for gas assisted molding. An industrial scale, instrumented process is used to guide and validate the simulations. Novel sensor technologies, including ultrasound, are used at process to monitor the position of the water bubble during filling, together with melt pressures and temperatures as well as the residual wall thickness.
In-Mold-Fabric Decorated Parts with a Plastic Trimmed Edge
Several processes currently exist that produce a thin-walled part with a fabric-covered surface. These processes, however, are limited by cost, low production volumes, and durability of the part. A new process is described here that produces a high-quality and durable, thin-walled part using low-cost mass production techniques.
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