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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

Research Credits For The Plastics Industry
Michael Devereux, May 2018

Abstract In this ever-changing world of tax laws, the plastic industry must keep abreast of tax incentives that will benefit their business. This presentation will explore the following topics:R&D Tax CreditOne of the most under-utilized tax savings opportunities for companies in the manufacturing sector is the U.S. Credit for Increasing Research Activities (R&D tax credit). The R&D tax credit rewards companies who invest resources in innovation, developing new designs, new techniques, and process development or improvement.The types of activities that may qualify for the R&D tax credit include, but are not limited to the following: Developing new part designs for manufacturability Experimenting with manufacturing variables to improve processes Improving manufacturing processes through automation Developing new fixturing or other tooling Testing new part or tool designs through testing, sampling or trialsThis presentation will also explore new legislation that will allow eligible small businesses (less than $50 million in sales) to offset the Alternative Minimum Tax (AMT), as well as new treasury regulations that expand upon eligible expenditures for custom plastic processors.

Determining Critical Stress For Ductile-Brittle Transition Of Polyethylene Pipe Under Creep Loading
Ben Jar, May 2018

A new test approach is proposed which uses multi-relaxation stages to determine critical stress for an unusual ductile-brittle (DB) transition of polyethylene (PE) pipe that may occur after subjecting the pipe to constant loading for a long period, often more than 50 years. This paper describes the key concept for the new test approach, and presents results for three PE pipes of which two are 1-inch PE4710 pipes and one 2-inch PE2708 pipe. The results suggest that critical stress for the unusual DB transition should be around 10 MPa for the two PE4710 pipes and 8 MPa for the PE2708 pipe. These values are consistent with their hydrostatic design bases (HDB) that needs more than 1 year to determine using the standard test method. Advantage of this new approach is not just for the short time needed to determine HDB (less than one week), but also for determining the time of occurrence for the unusual DB transition under constant loading. This part of work is on-going, and the results will be presented in the conference.

Fracture Mechanical Characterization Of Non-Virgin Pipe Materials
Andreas Frank, May 2018

For accelerated characterization of slow crack growth (SCG) properties of modern polyethylene pipe grades the Cyclic Cracked Round Bar Test has been developed. While many investigations on polyethylene are available with this test, only few studies have been published yet with other relevant pipe polymers such as polypropylene or polyvinyl chloride. Moreover, the increased use of non-virgin polymers for structural applications based on reprocessed or recycled resources is becoming a topic of increasing importance. The current paper presents an investigation of the general applicability of the Cyclic Cracked Round Bar Test to the mentioned polymers with a special focus on the sensibility to non-virgin materials. On the one hand the results show that this test can be used for accelerated SCG characterization of all materials. On the other it is demonstrated that the SCG resistance of non-virgin polymers is significantly lower than for virgin pipe grades.

Proposed Allowable Scratch Depth For High-Density Polyethylene (Hdpe) Pipes In Safety-Related Nuclear Applications
Prabhat Krishnaswamy, May 2018

Proposed Allowable Scratch Depth for High-Density Polyethylene (HDPE) Pipes in Safety-Related Nuclear ApplicationsAuthor(s): P. Krishnaswamy1, S. Kalyanam1, Y. Hioe1, S. Pothana1, P. Raynaud2Affiliation:1Engineering Mechanics Corporation of Columbus3518 Riverside Drive, Suite 202, Columbus, OH 43221kswamy@emc-sq.com, sureshk@emc-sq.com, yhioe@emc-sq.com, spothana@emc-sq.com2United States Nuclear Regulatory CommissionRockville, Maryland Patrick.raynaud@nrc.gov The topic of flaw acceptance for HDPE pipes installed in safety-related applications of a nuclear power plant has been of interest over the last decade. From initial analysis and tests on slow crack growth (SCG) in coupon specimens to hydrostatic Notched Pipe Tests (NPT), verification studies have been conducted by several researchers. Recently, the Electric Power Research Institute (EPRI) proposed a flaw acceptance criterion for HDPE pipe based on observations from several rounds of tests on various HDPE resins. The present study proposes acceptable flaw sizes for a range of pipe diameters and thicknesses. The flaw acceptance analyses use the renowned Brown model to transfer PENT values to service life/failure time estimations, evaluate the stress-intensity factors (SIF or KI) for infinitely long axial outer diameter (OD) surface cracks (most conservative approach for flaw acceptance determination), and analyze EPRI NPT data. It is also noted that the Brown PENT model does not accurately incorporate pipe or component geometry effects, and hence needs to be modified to predict the service life of pipes. However, this model can easily be used to determine maximum allowable SIF (KI) for pipes with the same geometry but different PENT values at the same service temperature, using NPT data. The allowable flaw size (scratch depth) analysis method is presented, and the flaw acceptance criteria for various postulated pipe geometries are discussed. In addition, the allowable flaw size method is demonstrated with the example of the largest pipe diameter with the thickest wall installed to-date. In summary, a rigorous conservative approach has been developed using existing data (from EPRI), the Brown PENT model, and a fracture mechanics approach for KI, to determine the maximum allowable axial external scratch depths (flaw sizes) in HDPE parent pipe for all diameters, all wall thicknesses, and PENT ratings from 2,000 to 10,000 hours.

Effects Of Primer On Mechanical Behavior Of Cpvc Pipe
Bingjun Chen, May 2018

This paper compares mechanical properties for CPVC pipe with and without the exposure to primer that is commonly used for surface treatment before the pipe joining, using coupon specimens of different geometries, including round notched pipe ring (NPR) specimens with notch radii from 1 mm to 3.18 mm, flat NPR specimens and ring specimens. All specimens were subjected to the split disc tensile test at a crosshead speed of 1mm/min. The results show a strong influence of the immersion in primer on the mechanical behavior and the level of influence depends on the specimen geometry. Typically, round NPR specimens with the biggest notch radius suffers the most from the immersion in primer. Based on the results, it is believed that the primer weakens CPVC pipe material by reducing its ultimate tensile strength and decreasing the strain required to generate cracking. The study also found that such an influence is more on ductility reduction than on the strength drop, but the influences are interrelated.

Innovative Millimeter Waves Technology For Measuring Diameter, Ovality, Wall Thickness And Sagging Of Large Plastic Pipes
Katja Giersch, May 2018

Technical innovation at the manufacturing of plastic pipes with diameters from 90 to 3,200 mm and large wall thicknesses lead to impressive progress in product quality and reduction of material costs. Norms precisely define the minimum and maximum permissible diameter and wall thicknesses of a specific pipe dimension and require repeatable processes. To meet these standards and growing demands in the pipe extrusion requires the use of innovative measuring and control systems already in the production process. This paper introduces a new technology based on millimeter waves. It provides a non-contact, non-destructive, online measurement of inner and outer diameter, ovality, wall thicknesses and sagging (sagging of the melt during solidification at a too high viscosity) of large plastic pipes during the extrusion process.The measurement via millimeter waves technology is based on the FMCW (Frequency Modulated Continuous Waves) runtime method. One or two constantly rotating transceivers continuously send and receive frequency modulated millimeter waves thus ensuring the complete recording of the wall thickness over 360 degrees of the entire pipe circumference. From the runtime difference the inner and outer diameter, ovality, wall thickness and sagging is defined. The measuring principle does not require any coupling media and is not influenced by temperature or the plastic material. There is no need for calibration. In the paper we will at first outline the reasons for the development of the system with regards to the demands of the market. We will introduce the new technology as well as the functional principle, technical features and advantages of the millimeter waves technology for the user compared to other available measuring methods. The technology presented leads to repeatable and optimized production processes, increased product quality and cost savings for higher efficiency during pipe extrusion.

Pipe Quick Burst Pressure Investigations Of Sample Length On Two Plastics
Bryan Hauger, May 2018

ASTM D1599 quick burst testing is a test used by plastic pipe manufacturers for various plastic materials. Requirements on the length between end closures relating to pipe nominal outside diameter (OD) are included in the test method. For larger sizes, the minimum length between end closures is 300% of the OD provided this value is not less than 30 inches. Samples require a length between end closures not less than 500% of the OD for pipe of 6 inch nominal OD or less. This presentation contains results on PE piping of 1 inch nominal OD and PVC piping of 12 inch nominal OD at various sample lengths for both materials to determine the effect, if any, of length between end caps on quick burst pressure. To the best of our knowledge, no publication exists in the literature detailing the effects of sample length on burst pressure has important consequences for material qualification and implications for composite piping systems.

Fracture Mechanic Principles For Multi-Layer Pipe-Wall Design
Florian Arbeiter, May 2018

To overcome the competitive nature of stiffness and toughness, multi-layered structures are a potential solution. By using intelligent design criteria, it is possible to severely increase toughness while keeping the stiffness of the structure at a sufficiently high level. This method can be used for smart pipe-wall design in demanding applications. First multi-layer composites of pure and also highly reinforced thermoplastic materials have been produced and tested with regard to their toughness-increase. As expected, interface properties and mechanical property mismatch play a key role in the development of optimized structures.

Comparison Of Real And Simulated Failure Times Based On The Slow Crack Growth Behavior Of Electrofusion Sockets Made Of Polyethylene
Isabelle Berger, May 2018

Previous laboratory studies have shown that brittle cracks in Electrofusion sockets (E-sockets) typically initiate in the inner cold zone between the pipe and the socket and lead to brittle failure of the pipe connection. Therefore, a profound understanding of the slow crack growth (SCG) behavior is essential to predict an accurate lifetime for welded joints. Internal pressure tests (IPT) on E-sockets made of different PE grades were conducted to create brittle failure curves in a first test run and to investigate the characteristics of crack initiation and SCG by the use of additional optical analyses in a second test run. Based on these test results and by using a fracture mechanical material law for SCG for one of the investigated PE grades a model for the stress intensity factor KI characteristics in E-sockets at elevated temperature was developed by finite element methods (FEM). The current results demonstrate that a reliable prediction of minimum lifetime of E-sockets with the fracture mechanics approach is possible.

Performance Of Pe Pipe Resins In Chlorine Dioxide Containing Aqueous Solution
Márton Bredács, May 2018

The resistance of polymer pipes in drinking water application against chlorine dioxide (ClO2) is crucial to ensure long-term functionality. The strong oxidative nature of ClO2 can cause an accelerated degradation of polyethylene (PE) resins and eventually shorten mainly the crack initiation time. To study the effect of ClO2 1 mm thick samples from six PE resins were subjected to exposure in 1 and 0.5 ppm ClO2 at 50 and 60 °C. Blank samples were also immersed in distillated water at 60 °C. Advanced material embrittlement with decreased elongation at break was observed in less than 5 weeks of exposure for each PE. Comparing the mechanical properties and the thermal stability various material performance was found. Furthermore unchanged properties of the blank samples point out the immense impact of ClO2 on the degradation of PE grades. The applied fast ranking methodology in terms of ClO2 resistance can serve as a valuable tool for material and stabilizer development.

Assessment Of Polybutylene Plumbing Installations After Long-Term Service
Dale Edwards, May 2018

Several investigations were undertaken involving polybutylene (PB) plumbing systems that had been in service for more than 20 years. A variety of tests were performed on the pipes, including ASTM test that were required for new PB pipe. Various PB pipe samples were submitted for analysis, including pipes from seven different locations around the U.S. The laboratory testing of the PB pipe samples included one or more of the following tests: a visual and microscopic inspection of the samples, dimensional measurements, quick burst testing, oxidation induction time testing, long-term hydrostatic pressure testing, and Fourier Transfer Infrared Spectroscopy (FTIR). The pipes analyzed did not reveal any significant degradation as a result of the long time service (>20 years) in hot and cold-water plumbing systems. This data was consistent with earlier investigations that showed that 18-year-old PB pipe still met the ASTM requirements for new pipe.

Determination Of Flame Retardant Materials In Plastics Using A Combination Of Analytical Techniques
Yanika Schneider, May 2018

Flame retardant compounds serve an important purpose in society and are particularly critical in plastics, which are more flammable than other materials. To evaluate the efficacy of flame retardants in commercial products, it is important to know both the concentration and composition. However, due to the variability of flame retardants, the appropriate analytical method is not always obvious. In this publication, we analyze an unknown plastic box advertised to have flame retardant properties. We use a series of analytical techniques and evaluate their compatibility with one another.

Effects Of Biodegradable Additives On The Nucleation Intensity And Growth Rate Of Isotactic Polypropylene Spherulites
Yousef Mubarak, May 2018

The effect of biodegradable additive (Biosphere) on the spherulite growth rates of isotactic polypropylene was studied by means of polarized light microscopy. It has been found that the addition of biodegradable additive to isotactic polypropylene matrix increases the intensity of the spherulites at all covered isothermal crystallization temperature in the range from 125 to 145 oC. In comparison with the neat isotactic polypropylene spherulites, much smaller spherulites were obtained at all crystallization temperatures for the isotactic polypropylene/biodegradable composite. The obtained results show that the presence of the biodegradable additives enhances spherulite growth rate at low crystallization temperatures (below 135 oC) while the effect of these additives is almost negligible at high crystallization temperature (above 135 oC).

Thermal Investigation Between Pressure Conditioning And Thermal Annealing In Aging Studies Of Glassy Thermosets
Brendan Ondra, May 2018

This communication presents comparative results between two separate techniques to accelerate physical aging in polymeric glasses: pressure conditioning and thermal annealing. Four different epoxy-based glassy thermosets were synthesized with specific molecular and network structures for further comparison and discussion. The epoxy compositions were synthesized to form glasses with comparable glass transitions but with different crosslink density and backbone stiffness. To analyze the glasses and the extent of aging, Differential Scanning Calorimetry was employed. Additionally, in order to perform the pressure conditioning, a pressurizable dilatometer was designed and built. The results show fundamentally different responses between thermal annealing and pressure conditioning. These differences are detailed and discussed.

Observed Particle Migration During Processing Of Polypropylene With Glass Beads
Jose Luis Colon Quintana, May 2018

Extrusion and injection molding of filled polymers are widely used in industry due to their high strength-to-weight ratios and for their ability to manufacture a variety of geometries while improving the overall mechanical properties. However, filler migration during processing is not fully understood. To gain an improved understanding of this phenomena, samples of polypropylene with different concentrations of glass beads were manufactured using the extrusion process, injection molding process and a screw-less extruder that was built in house. Computed Tomography scanning was performed on the samples to observe particle position and distribution after solidification.

Analytical Characterization Of Commercial Products: Cool Comfort Technologies For Bedding Products
Praveenkumar Boopalachandran, May 2018

Dow polyurethane (PU) business is investigating into cool comfort technologies for bedding products (pillows, mattresses), as it is a major driver in the market. Recently, there have been many enquiries around the commercial benchmark products (‘commercial product A’ and ‘commercial product B’) that sparked the interest for the Dow PU marketing team. There is an overwhelming interest to understand these materials and its composition. Analytical techniques utilized in this study for the deformulation of the two commercial products identified the presence of styrenic block copolymer (SEBS) as the major polymeric species. In addition, long chain aliphatics identified as mineral oil was observed in both products. Furthermore, a filler identified as talc was present in ‘commercial product B'.

Rheological Methods For Characterizing The Degree Of Long Chain Branching In Polyethylene
Greg Kamykowski, May 2018

Branching in polymers contributes many unique rheological properties in polymer processing. Polymer branching enhances chain entanglements, increases relaxation times, and increases the extensional flow viscosity as evidenced by the strain hardening phenomenon. For many years, researchers have used different rheological methods to quantify the degree of branching in polymer chains. The most commonly used rheological techniques for differentiating linear and long chain branched polymers include traditional small amplitude oscillatory shear testing (SAOS), such as frequency sweeps at multiple temperatures, followed by time-temperature superposition (TTS), extensional viscosity testing, and large amplitude oscillatory shear testing (LAOS). However, polymer chain entanglement and relaxation are not only affected by branching but also by molecular weight (Mw) and molecular weight distribution (MWD). The common rheological methods may not be able to distinguish whether the rheological property contributions are from long chain branching or Mw and MWD effects. In this paper, we describe commonly used melt rheological methods for studying polymer long chain branching and their respective benefits and limitations.

TGA-FTIR Unleashed At Last - Introducing A Fully-Integrated, Transfer Line-Free Coupling For Evolved Gas Analysis Of Polymers
Bob Fidler, May 2018

Evolved gas analysis improves the value of TGA data by allowing the identification of the chemical species evolved during decomposition. FTIR is particularly advantageous when organic molecules and IR active gases are being analyzed from the TGA sample. This lecture will introduce an innovatively designed TGA-FTIR and STA-FTIR (STA = Simultaneous DSC-TGA) for evolved gas analysis. The unique coupling system has the FTIR now mounted directly above the sample cell, eliminating the need for a long transfer line. The system allows immediate response from the FTIR when the sample loses mass. The lack of the transfer line allows for analysis of gas species that would ordinarily condense in a standard heated transfer line in addition to dramatically reducing bench space normally required for TGA-FTIR.

Effect Of HNTs Dispersion In PVDF On Morphology And Its Formation Mechanism Of Tensile Fractured Surfaces
Han-xiong Huang, May 2018

Poly(vinylidene fluoride) (PVDF) nanocomposites containing unmodified halloysite nanotubes (HNTs) are prepared by using extrusion with and without water injection. Transmission electron microscopy micrographs show that better HNTs dispersion is obtained in the PVDF matrix with water injection. The Halpin-Tsai equation is employed to quantitatively estimate the HNTs dispersion, indicating that the nanocomposites prepared with water injection possess large fitting aspect ratio of the HNTs owing to improved HNTs dispersion. The tensile fractured surfaces for the neat PVDF, P-Hm, and P-Hm-W samples exhibit different fractured morphologies, as evidenced by scanning electron microscopy, indicating that different fracture mechanism occurs. This is because the crystallization behavior of PVDF and the HNTs dispersion induced by injected water result in the formation of the voids, wedges, and ridges, and so cracks initially form at different locations.

Pellet Shape Classification Using Deep Neural Networks
Brenda Colegrove, May 2018

In this paper, the task of image-based product classification is considered. This is a supervised learning problem where the input is an image of a polyethylene pellet and the output is a unique label attributed to the image from a finite set of labels corresponding to useful classes. This is a prevalent and highly relevant industrial challenge and recent developments in deep learning have proven to be successful in increasing the image classification accuracy. Thus, in this work, we leverage deep neural networks’ (DNN) ability to automatically learn features from images and test their performance in a real industrial context for describing the pellet shape. Furthermore, other machine learning techniques such as partial least squares discriminant analysis (PLS-DA) and random forests (RF) are also explored in order to assess the benefits of adopting DNN as opposed to current classifiers. PLS-DA, RF, and DNN models were developed for two classification tasks: pellet body shape classification (distinguishing good and bad pellets), and detecting tails in a pellet (distinguishing whether a pellet has tails or not). After developing these models, the results were consistent for both classification objectives: compared to the classification system currently in use, RF was able to better utilize the same pre-defined morphometric features and improve prediction accuracy significantly, while PLS-DA presented slightly better performance. DNN obtained the highest accuracy overall, with the advantage that there is no need to specify a priori which image features to use. Rather, they are directly extracted from the raw images.

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