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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Reactive Modification of High Density Polyethylene in a UV-Initiated Process
Rheological properties of a high density polyethylene resin (HDPE) were modified by promoting long chain branching (LCB) through a novel photoinitiated reactive extrusion process (REX). Surface response methodology based on a central composite experimental design was employed with three processing variables, namely, photoinitiator concentration, polymer throughput, and extruder screw speed. The linear viscoelastic properties measured through oscillatory shear experiments indicated addition of LCB up to 0.055 branches per 1000 monomer units. The zero shear viscosity (?o) increased to a maximum of 11,600 Pa.s from a starting value of 1,900 Pa.s. Similarly, the average polymer relaxation time (?) increased from 0.05 s to 4 s. Both molecular weight (MW) and molecular weight distribution (MWD) slightly shifted toward higher values. However, the breadth of the distribution was not affected significantly.
Development of a Capacitive Transducer for Dimensions Prediction in Polymer Extrusion
On-line quality monitoring of the polymer extrusion is of great importance for process monitoring and product quality control. In view of the shortcomings of the existing hardware-based sensors, a novel low-cost capacitive transducer (CT) has been designed for polymer extrusion. In this project, the developed capacitive transducer has been successfully applied for thickness and diameter prediction in polymer extrusion. Experiments with various extrusion products show that the proposed transducer features broader application and the prediction results are quite accurate and robust. Therefore, this research paves the way for on-line quality monitoring and closed-loop quality control of polymer extrusion.
The Effect of Immiscibility on Biobased PLA/PHBV Foams
Biodegradable polymers are currently a critical global research topic as they may potentially serve as replacement to conventional petroleum based plastics. One key strategy to widen its range of application potential is by improving its physical and mechanical properties. Such characteristics can be engineered by blending two polymers of desirable properties together and by inducing a cellular morphology in the pure polymer or blend with the aid of a foaming agent. This paper examines the effect of blending PLA and PHBV on their overall miscibility as well as the effect of their miscibility on the resultant foam fabricated using carbon-dioxide as a blowing agent. PLA and PHBV blends were manufactured in various compositions via compounding and foamed, and their physical, mechanical and morphological properties were characterized. The results indicated that although PLA and PHBV are immiscible, the addition of small quantities of PHBV (at 15wt%) lead to a finer and more homogenous cellular morphology.
Paper Plastic Composites from Recycled Disposable Cups
The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs which has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). Samples were characterised using mechanical analysis and thermogravimetric analysis (TGA). The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.
Pipe Analysis for a Long, Deep Directionally Bored Installation under an Active Airfield in Portland, Oregon
Horizontal directional drilling (HDD) is a method of installing pipelines under obstacles without the need to excavate them. Used successfully to cross all types of impediments, a bore is directionally guided under the obstacle using a steerable drill. A pipeline is then pulled back through this excavation. Installation stresses on the product pipe when inserted into the borehole can be the limiting design factor for selecting pipe material, size, wall thickness, and joint configuration. These stresses may take precedent over traditional design parameters like long term hydrostatic strength or external loading capacity. This case study of a long and deep HDD insertion under an active runway and airfield at the Portland, Oregon International Airport provided a unique opportunity to compare common prediction techniques for stress estimates on thermoplastic pipe to what was experienced during the actual installation.
P.Y. 229: A Novel Pigment for Lead and Diarylide Replacement in Plastics
A new yellow pigment is developed to replace lead chromate and diarylide based yellow pigments in the plastics industry. Pigment Yellow 229 is a red shade yellow based on mono-azo chemistry and is free of heavy metals and halogens. This yellow pigment has high strength, heat stability, opacity, is non-warping, and non-bleeding in a masterbatch production. Formulators coloring plastics can select this pigment for indoor applications. This paper will discuss the properties of the new yellow pigment and compare the coloristic properties against lead chromate, diarylide and mono-azo based yellow pigments.
Characterizing the Melting Behavior of Different Shaped Polymer Bulk Solids by Utilizing a Model Experiment with an Optical Measuring System
The solids conveying and the melting behavior of polymers in single screw plasticizing units are crucial factors for further processing steps. This work deals with the melting behavior of different shaped polymer bulk solids, which is characterized by a new method that uses a model experiment comparable to Tadmor's “drag induced melt removal” model. The melting behavior is characterized with an optical measuring system. Finally, the results are compared to the temperature development and the mass flow rate of a single screw plasticizing unit. The results show that the shape and size of the granules are important factors for the melting process in single screw plasticizing units. Virgin material melts much faster than cylindrical shaped pellets.
Effects of Painting on the Mechanical Properties of Injection-Molded Plastics
Paint can have significant effects on the mechanical properties of plastic substrates. The selection of a paint system that is not properly matched to a given plastic substrate can lead to premature failure. While anecdotal accounts are plentiful, quantitative data regarding effects of coating on plastics is relatively scarce. This paper describes the effect of a high-solids acrylic topcoat paint, with either of two different adhesion promoters or no adhesion promoter, on the mechanical properties of four different plastic substrates: general-purpose acrylonitrile-butadiene-styrene (ABS), high-impact ABS, weather-resistant acrylonitrile-styrene-acrylate (ASA), and mineral-filled polyethylene ionomer/polyamide-6 blend.
Development and Characterization of Bio-Based PA Composites for Electronic Packaging Applications Using Micro Fillers
Since electronic devices are constantly becoming smaller and more powerful [1,3], heat dissipation plays a very important role in electronic packaging applications. By using highly thermal conductive materials, it is possible to manage the heat dissipation on electronics to improve their efficiency. In addition, it is possible to avoid the use of mechanical fans by avoiding the heat sink cooling method. Thus, electronics can be made cheaper, lighter, and more compact [4-8]. Recycling of electronics is also another concern because millions of devices are used and produced every day. This research is aimed at making a polymeric composite that has high thermal conductivity, is electrically isolative, and is bio-based: a suitable as a replacement candidate for current electronic packaging materials. In this study, Polyamide (PA) with at least 60% bio-based content in composite with hexagonal boron nitride (hBN) was studied. Significant improvement in thermal conductivity was found relating to the size of conductive network, which has direct relationship with numbers, length, and direction of thermal pathways, rather than amount of filler particles.
Mechanical Considerations of Textiles Applied as Geotubes for Coast Erosion Control and Shoreline Protection
Nowadays geotextiles play a significant part in coastal protection and erosion prevention design and maintenance techniques. The growth in their use worldwide as geotubes for recovering damaged coastal due to its easiness of manipulation and excellent mechanical properties has been extraordinary. The focus of this paper is on better understanding of the importance of the textile architecture/geometry and the mechanical properties when applied as geotubes for sand recovery. The paper provides an overview of the current erosion in the Yucatan coast and the solutions shoreline protection as well as the effect of geotextile architecture on mechanical behavior.
Improvement of Replication Fidelity in Injection Moulding of Nano Structures Using an Induction Heating System
In today’s industry, applications involving surface pattering with sub-?m scale structures have shown a high interest. The replication of these structures by injection molding leads to special requirements for the mold in order to ensure proper replication and an acceptable cycle time. A tool insert with functional surface geometry in the sub-micrometer range was produced using aluminum anodization and subsequent nickel electroforming. For the complete replica of the pattern, elevated mold temperatures are required. For this purpose a new mould set-up was developed, which allows rapid heating of the cavity wall by an induction heating system. The capability of the injection molding process to replicate the patterned surfaces into polycarbonate was investigated. Process optimization was carried out in terms of mold temperature/time variation and injection velocity. The replicated surfaces were quantitatively characterized by atomic force microscopy comparing the measurement in the nickel insert with the corresponding polymer nano-features. The experimental results show that the use of the induction heating system is an efficient way to improve the pattern replication.
Optimization of a Coat Hanger Die Geometry Considering Flow Induced Deformation
This study highlights the feasibility of designing a coat hanger die considering the expected flow induced deformation. A combined fluid and structural model is created to represent the flow field inside the die cavity as well as the steel of the die. A parametric two-way fluid structure interaction model is created which has two geometrical parameters affecting the tear drop cross section of the manifold as well as the manifold angle. The baseline analysis indicated that the flow induced die deformation does affect the flow uniformity substantially and should be considered when optimizing the die geometry. Then, a response surface based optimization algorithm is used to optimize the die geometry taking into account the flow induced die deformation. The optimization loop hence considers the non-Newtonian fluid flow inside the die cavity as well as the elastic deformation of the die body itself. Finally, a comparison is made between the baseline and the optimized designs and the improvements in flow uniformity, shear stress variation, and the pressure drop is made.
3-Dimensional Injection Stretch Blow Simulation of PET Bottle with 2 Intra-Divisional Spaces for Storage
3D injection stretch-blow simulation was conducted for the PET bottles that have intra-divisional spaces. Tensile test was conducted as the material model for this and its results became the basis for adopting an appropriate visco-plastic model. Also, the initial temperature distribution of the preform was predicted by conducting the heat transfer analysis that includes convection and radiation. The temperature distribution was applied as initial condition in the injection stretch blow molding. After conducting the initial injection stretch blow simulation, analysis was conducted by adopting the design of experiment to study the incompletely molded areas. Here, the 4 process parameters selected were the position of the heat source, maximum temperature, maximum pressure and the increasing rate of blowing pressure. The parameters that greatly influence the blow simulation were derived through such molding analysis and the optimal blow analysis that can restrict the incompletely molded areas was carried out.
Benefits of Servo-Driven Ultrasonic Welding for Critical Assemblies
Ultrasonic welding is one of the most widely used processes for bonding polymers, valued for its speed, flexibility, and low cost. Recently, there has been a call for more controlled and consistent ultrasonic welding processes, as part designs become more complex and requirements more stringent, especially in the medical field and for complex packaging applications. Additionally, the processes used to meet these increasing demands must be consistent and repeatable over time. Dukane has worked to meet this demand through the development of a new iQ series Servo-Driven Ultrasonic Welder with Melt-Match® technology, which is protected by US and international patents with other US and international patents pending [1, 2, 3, 4]. This study explores the potential benefits of the features solely available with Dukane’s servo-driven welders, such as Melt-Match® (matching welding speed with the melt flow rate of the plastic). A full scale Design of Experiments has been undertaken to identify the relational effects of these speed and distance control features and how they can be used to optimize the welding process. An effort has been made to detail and quantify the improvement to the weld joint based both on previous research, including a joint study with Value Plastics, a large medical device manufacturer, and new experimentation in collaboration with Parker Hannifin.
Aspects of Physical Aging and Thermal Annealing in a New Copolyester
Long-term effects of physical aging and thermal annealing are monitored through dynamic mechanical properties of an amorphous glassy polymer. These phenomena are investigated through dynamic mechanical testing that evaluates in-situ the evolution of the storage modulus with time during annealing and physical aging. Comparisons are made on samples with different thermal histories. The polymer characterized in this contribution is a new commercially available copolyester under the trade name of Tritan™. The results are discussed in context to different aging rates obtained from the various thermal treatments.
Influence of Ultrasonic Treatment in PP/CNT Composites Using Masterbatch Dilution Method
Multiwalled carbon nanotube (CNT) filled polypropylene (PP) composites of various concentrations were prepared by a twin screw extruder using direct compounding (DC) method without and with ultrasonic treatment. In addition, a masterbatch of 20 wt% PP/CNT composites were prepared without and with ultrasonic treatment and diluted to the same concentration as in the DC method without ultrasonic treatment. This is called the masterbatch dilution (MD) method. The rheological and electrical properties were investigated. The increased storage modulus and viscosity as well as the electrical conductivity indicates a better dispersion of CNT in PP matrix prepared by the MD method than by the DC method. The fractal dimension of CNTs, D, and the backbone fractal dimension, x, of the CNT network was determined by fitting the rheological data to the scaling model. The lower fractal dimension of CNT and higher backbone fractal dimension of CNT network in composites prepared by MD method compared with composites obtained by DC method indicates a better dispersion of CNT. Additionally, a lower value of D and a higher value of x as well as a higher storage modulus, viscosity and lower electrical percolation were achieved when the ultrasonic treatment at an amplitude of 13 ?m was applied in the MD method, indicating an advantage in use of the ultrasonic treatment in preparing the PP/CNT masterbatch. The macrodispersion was determined using optical microscopy to correlate the processing, properties and structure. It was shown that the MD method provided better dispersion of CNT in PP matrix than the DC method.
Ultrasonic Decrosslinking of Crosslinked High Density Polyethylene: Effect of Screw Design
In order to evaluate the performance of different screws designs, decrosslinking of the crosslinked high density polyethylene (XHDPE) is performed by means of an ultrasonic twin-screw extruder (TSE) with two screw configurations. Die pressure and ultrasonic power consumption during extrusion of XHDPE is recorded. Swelling test, scanning electron microscopy (SEM) and tensile test are used to investigate the structure and properties of the decrosslinked XHDPE. It is found that the screw configuration without kneading elements (decrosslinking screws) is more effective in decreasing the gel fraction and crosslink density of the decrosslinked XHDPE. The ultrasonic treatment significantly improves the processibilty of the decrosslinked XHDPE. The reason for the superior performance of this screw configuration for decrosslinking of XHDPE is explained by extrusion theory. The numerical calculation describes the effect of the residence time, the gel fraction and crosslink density of the initial polymer on the gel fraction and crosslink density of ultrasonically decrosslinked XHDPE. The mechanical performance of the decrosslinked XHDPE from TSE containing the decrosslinking screws is very close to those of the virgin XHDPE. The effect of the gel fraction and crosslink density on the morphology of the decrosslinked XHDPE is also identified.
Effect of Heater Surface Shape for Heat-Sealed Parts on Oriented Polypropylene/Cast Polypropylene (OPP/CPP) Film
In this study, oriented polypropylene/cast polypropylene (OPP/CPP) laminated films were heat sealed by various stainless mesh sheets in order to evaluating the effect of heat sealing bar shape on heat sealed properties. The heat sealed conditions were set at heat sealed time of 1.0 s with a pressure of 0.3 MPa at various heat sealed temperatures of 100 to 120 °C. The difference of higher order structure of these films was discussed on the basis of results of micro-Raman spectroscopy, DSC and peel test. From the result, it was found that peel strength were affected by the heat sealing bar surface shape. We can analyze the very small area and changes on the basis of the results of heat sealed part by using micro-Raman spectroscopy imaging.
Effects of Carbon Fiber Loading on the Conductive, Mechanical, EMI Shielding Effectiveness Properties of Microcellular Foams of PBT/Carbon Fiber Composites
This study investigated the carbon fiber loading on the mechanical/electrical conductivity/EMI shielding effectiveness properties of Polybutyele Terephthalate(PBT)/carbon fiber composites. The PBT/carbon fiber composites were compounded by twinscrew extruder as a master batch of 13 wt.% . Then composites were diluted into 1, 3, 5, 8, and 13wt% during the injection molding process. The results showed as the carbon fiber loading increased so is the tensile strength. It level off at the carbon fiber loading of 8wt. %. The conductivity test showed that as the carbon fiber loading increased so is the conductivity. And conductivity test were done at 3 different locations (surface, 0.3 mm under surface, and 1.5 mm under surface). For the different positions, the conductivity showed as the position is far from surface the conductivity increased. For the carbon fiber distribution, SEM results showed that there are more fibers on the PBT matrix when the location is far from sample surface. For the electromagnetic interference (EMI) shielding effectiveness(SE), the EMI SE for carbon fiber loading less than 13 wt% is almost zero. So the carbon fiber loading is increased to 20, 25, and 30 wt.% respectively. As the carbon fiber loading is increased from 20 ~ 30 wt%, so is the EMI SE value.
High Strain Rate Testing of Polymers for Impact Simulations
The increased use of polymeric materials in impact and high strain rate applications is motivating the use of impact simulations during design. Simulation of polymer impacts however requires difficult-to-measure stress-strain behavior at high strain rates. Complicating the measurement task further is the need to establish failure criteria associated with high strain rate deformations. Even when appropriate data is collected, appropriate high strain rate constitutive models need to be fit to the data before being incorporated into a simulation code. This article presents a testing and constitutive modeling process to achieve accurate impact simulations using polyether ether ketone (PEEK) as the example material. High and low strain rate data is presented over a large strain rate range. The resulting data and material model is used simulate a drop test which is then compared with an actual drop test data to validate the model.
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