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

An Innovative Method to Increase the Charge Storage Capability of Polymer Nanocomposites

Aboutaleb Ameli, Nemat Hossieny, Davoud Jahani, Chul B. Park, Petra Pötschke, May 2014

Microcellular polypropylene-multiwalled carbon nanotube (PP-MWCNT) composites exhibiting high dielectric permittivity and low dielectric loss at low MWCNT content are reported. Nanocomposites were foamed using N2 in injection molding process. The electrical and dielectric performances of the foamed samples are compared against those of compressionmolded and injection-molded solids. In addition to 35% density reduction, the introduction of cellular structure provided a unique arrangement of MWCNTs around cells favorable to enhancing the dielectric properties. Therefore, foams containing 1.25 vol.% MWCNT presented a dielectric permittivity of ?'=68.3 and a dielectric loss of tan ? =0.05, highly superior to those of the compression-molded (?'=14.1 and tan ?=0.39) and injection-molded (?'=17.8 and tan ?=0.04) solids. The results of this work reveal that high performance dielectric polymer nanocomposites can be developed using foaming technologies for charge storage applications.

One-Step Nanocellular Foaming of Clarified Polypropylene Using Supercritical CO2

Mehdi Saniei, Aboutaleb Ameli, Nemat Hossieny, Davoud Jahani, Chul B. Park, May 2014

Nanocellular foams of clarified isotactic polypropylene (iPP+clarifying agent) were prepared through one-step batch foaming process with supercritical carbon dioxide (CO2). Clarifying agent, Millad NX8000, was used in order to promote cell nucleation. Clarified iPP was prepared using twin-screw microcompounder. Crystallization behavior of iPP and clarified iPP was studied using DSC. Cellular structure of the foam was also characterized. Depending on the foaming condition, foam structure was obtained in both micro and nano scales. Nanocellular foams with the cell size distribution of 33-260 nm and cell density of about 1014 cells/cm3 was achieved by controlling the size of the crystals within iPP. An optimum foaming temperature was found wherein the smallest cell size with highest cell density could be produced.

Accelerated Weathering Insights into ASA Polymers UV Resistance

Steve Blazey, Brian Struchen, May 2014

ASA polymers (Acrylonitrile-Styrene-Acrylate) represent one family of weatherable polymers often used in outdoor applications requiring long term color and physical properties retention. Their resistance to UV degradation is achieved through the selection of the ASA rubber modifier, choice of SAN (Styrene Acrylonitrile) copolymer, colorants, antioxidants and UV stabilizers along with other additives optimized for the application performance. Accelerated weathering testing offers valuable insights into the UV resistance of colored ASA polymers.

Morphology and Mechanical Properties of Polylactic Acid/Cellulose Nanofiber Composite Foams

WeiDan Ding, Peiyu Kuo, Chul B. Park, Mohini Sain, May 2014

This paper investigates the foaming behaviors of polylactic acid (PLA)/cellulose nanofiber composites and the mechanical properties of the composites and their foams. The composites were fabricated by mixing PLA and nanofibers in a solvent with different fiber contents, followed by drying and hot pressing into test specimens. The composites were then foamed via a batch foaming process with CO2 as a blowing agent at different foaming conditions. The effect of nanofiber content on the cell morphology of PLA was studied. The impact strength and thermo-mechanical properties of PLA composites and their foams were also investigated.

Performance Attributes of Thermoplastic Polyurethane Golf Ball Covers

Shane R. Parnell, Nimitt G. Patel, May 2014

Injection moldable thermoplastic elastomers (TPE) have been used in golf ball constructions since the 1960s. They provide an attractive combination of performance, processability, and cost when compared to thermoset materials. In particular, ionomer based TPEs are well suited for use in golf ball cover layers as they exhibit attractive properties such as high rebound resilience, good durability, excellent UV stability, and hydrophobicity. However, in multilayer golf ball constructions where the goal is maximum performance, thermoplastic polyurethanes (TPU) are better suited for use as cover materials. In this study, the thermal properties, mechanical properties, dynamic mechanical-thermal properties, and final golf ball performance attributes of a polyether based TPU were characterized and compared to a relevant ionomer based golf ball cover composition.

CPVC Sprinkler Pipe in Contact with Suspected off-Ratio Urethane Foams

Ray L. Hauser, May 2014

This paper discusses failures in a residential fire sprinkler system using CPVC pipe surrounded by sprayed urethane foam insulation. The pipe had multiple circumferential cracks. The external surface had a brown coloration in cracked areas. Chemical analysis showed presence of chemicals in the polymer consistent with components that may have been present in the foam. These chemicals had solubility parameters and boiling temperatures consistent with causation of Environmental Stress Cracking of CPVC. Accelerated exposure of strained CPVC pipe sections to three of these chemicals showed rapid formation of suspected environmental stress cracks.

Feasibility of Double Melting Peak Generation for Expanded Thermoplastic Polyurethane Bead Foams

Nemat Hossieny, Aboutaleb Ameli, Mehdi Saniei, Davoud Jahani, Chul B. Park, May 2014

This study investigated the effects of dissolved CO2 on the crystallization of hard segment (HS) to generate double crystal melting peak for expanded thermoplastic polyurethane (ETPU) bead foam manufacturing. The double crystal melting peak is generated while annealing at elevated temperatures in a autoclave-based ETPU foaming process. The influence of saturation temperature, time, and pressure on the generation of double melting peak structure in TPU was investigated. It was observed that higher saturation temperature assisted in the improvement in the size and perfection of the smaller HS crystals and resulted in formation of double melting peak close to the melting point of TPU. However, the saturation pressure was the most critical parameter to enhance the double melting peak. Furthermore, in the presence of dissolved CO2, the saturation temperature required to generate the double melting peak in the TPU decreased significantly due to the plasticization effect of CO2. The longer saturation time increased the amount of perfected HS crystals with a high melting temperature.

Experiments with Hot Tool Joining of Thermoplastics to Metal

Kevin Faraone, Avinash W. Prabhu, Avraham Benatar, May 2014

With the requirements for increasing fuel efficiency of automobiles lightening of structures would require joining of dissimilar materials like metals to plastics. In this study, thermoplastics were joined to metal using a heated tool. The metal substrate was textured with a fine knurl pattern and heated for a preset time by pressing it against a hot tool that was kept at a high temperature. Then the metal part and hot plate were retracted, and the cool thermoplastic sheet was pressed against the hot metal surface for a preset time. The hot metal would then melt the thermoplastic surface resulting in flow and wetting and joining of the parts together. Increasing the heating time generally increased the joint strength until an optimum was reached. HDPE to steel joints were slightly stronger and more consistent than HDPE to aluminum joints. For a fixed heating time, the PC and HDPE steel joints were stronger than PP and acrylic to steel joints.

Polypropylene Crystallization in Bulk during an Extrusion Process: Effect of Molecular Weight and Supercritical Carbon Dioxide

Alireza Tabatabaei Naeini, Chul B. Park, May 2014

Through in-situ visualization, the crystallization behavior of two grades of polypropylene (PP) with medium and high melt flow index was investigated during an extrusion process in the absence and presence of the supercritical carbon dioxide. In all experiments conducted in this study, the crystalline phase (i.e., crystallite) was visualized in the melt during continues process by decreasing the processing temperatures. However, the crystallization onset and the crystallites’ morphologies vary from one condition to another depending on the material molecular weight and the presence of the gas. In the absence of blowing agent, effect of processing conditions (i.e., temperature profile, and flow rate) on the crystallization was studied. It was observed that increasing the flow rate didn’t show any significant changes on the crystallization onset for the lower molecular weight PP. On the other hand, the crystallization onset was shifted to a higher temperature profile for PP with higher molecular weight. The results indicate that the flow-induced crystallization (FIC) is more active in PP with higher molecular weight. In the presence of supercritical CO2, the onset of crystallization was lowered for both PPs studied here mostly due to the CO2 plasticization effect. However, this temperature depression was more pronounced in the higher molecular weight PP than that of lower molecular weight PP, suggesting that carbon dioxide also hinders the effect of FIC.

Metal Replacement with Specialty Thermoplastic Solutions in Heat-Sensitive Automotive Applications

Patricia Hubbard, Marc Mézailles, Michael Bosse, Renaud Maurer, May 2014

Automotive OEMs are facing immediate and continuous short- and mid-term targets to improve fuel economy. Light-weighting and energy efficiency are key enablers to reach these targets. Light-weighting primarily involves implementing material solutions with an appropriate performance/weight ratio for an application, without compromising quality and costs. Energy efficiency mainly comes from power-train innovations, including electrification of the car, with innovations in electronics (LED, power electronics, alternative energy, etc.) translated to automotive uses. Specialty thermoplastics have a key role to play in this respect. This paper/presentation from PolyOne will describe how thermally conductive thermoplastics can help achieve these targets, specifically in heat-sensitive automotive applications - from the fundamentals of thermal management and the corresponding material properties, to a case study of metal replacement in automotive LED lighting applications.

Importance of Application Representative Sealant Test Methods

Mridula (Babli) Kapur, Mustafa Bilgen, Paul O'Connell, May 2014

Polyethylene (PE) based sealants are an integral part of the food packaging industry. Their use in packaging ranges from simple multi-layer PE film configurations to complex multi-polymer laminate structures. There is a constant drive to develop sealant resins that offer an improved balance of properties in terms of ease of processing, excellent sealant and physical properties. When developing new sealant resins, it is also essential that the performance be characterized by test methods relevant to converters and end-users. This study assesses the sealant performance of various PE resins in the context of molecular architecture, sealant performance test methods, and application specific packaging fabrication conditions.

Simulation of Single Fiber Motion and its Application to Short Fiber Orientation Predictions in Composites Processing

Douglas E. Smith, Dongdong Zhang, May 2014

A simulation-based approach is presented to predict the motion of a single fiber or a set of fibers in a viscous fluid with application to short fiber composites processing. This model is developed specifically to reconsider basic assumptions made in Jeffery’s model published in 1922 which forms the basis for nearly all polymer processing fiber orientation prediction today. Our approach computes the velocities in the fluid domain surrounding a fiber, and the fiber motion is determined to zero the forces and torques on the moving fiber. A numerical integration method is then used to determine the fiber’s position and orientation as a function of time. This approach is used to better understand the effect of fiber shape, far-field boundary condition, velocity profile, and neighboring fibers on fiber orientation. Special attention is given to the effect each of these have on recent observations that current fiber orientation models based on Jeffery’s equation tend to over-predict the rate of fiber alignment.

Review of Analytical Models of Anisotropy-Induce Spring Forward Effect via FEA Simulation and an Experimental Study

John R. Puentes, Brian LaQua, Lucas Iervolino, Keith R. Dahl, Martin Knott, Tim A. Osswald, May 2014

The increase of residual stresses during the phase change of thermoset fiber-reinforced composites causes unintended situations. A specific situation of interest is the angular distortion in curved fiber-reinforced thermoset parts, also referred to as the spring-forward effect or anisotropy induced curvature change. It has been identified that conventional analytical models deviate from experimental results when changing the part thickness. Therefore, it is of interest to study the effect of thickness variation on the final angle change. Some of these models neglect the effect of phase change in the distortion. This research relates the current scope of analytical and experimental models to predict spring-forward effect. It is necessary to extend the current models to involve the cure time-temperature-diagram (TTT) of thermoset resins.

Short Cellulose Nanofibril/Polyvinyl Alcohol Nanocomposite Fibers

Jun Peng, Tom Ellingham, Ronald Sabo, Lih-Sheng Turng, Craig Clemons, May 2014

Short cellulose nanofibrils (SCNF) were investigated as a reinforcement for polyvinyl alcohol (PVA) fibers. SCNF fibers were mechanically isolated from hard wood pulp after enzymatic pretreatment. Various levels of SCNF were added to PVA and gel-spun into continuous fibers. The molecular orientation of PVA was affected by a combination of wet drawing during gel spinning and post-hot-drawing at a high temperature after drying. A maximum total draw ratio of 27 was achieved with various SCNF contents investigated. The PVA crystal orientation increased when small amounts of SCNF were added, but decreased again as the SCNF content was increased above about 2 or 3%, likely due to SCNF percolation resulting in network formation that inhibited alignment. SCNF fillers were effective in improving PVA fiber tensile properties (i.e., ultimate strength and elastic modulus). Shifts in the Raman peak at ~1095 cm-1, which were associated with the C–O–C glycosidic bond of SCNF, indicated good stress transfer between the SCNF and the PVA matrix due to strong interfacial hydrogen bonding.

Using Zemac® Copolymers to Upgrade Virgin Nylon Performance

Ashok M. Adur, Prasad Taranekar, May 2014

Nylon is widely used in many applications. At the 2013 ANTEC, our paper covered the results obtained with compounding primarily recycled nylon with the addition of small quantities of alternating copolymers of ethylene and maleic anhydride and specific property improvements for applications in injection molded compounds. The resulting compounds have performance that can match or exceed prime virgin nylon at 30-50% cost savings. This current paper will cover the unique chemistry of alternating copolymers of ethylene and maleic anhydride to provide several advantages for upgrading prime or virgin nylon. For example, this paper will cover results of increasing relative viscosity and the advantages that brings to various applications. Another set of results will cover the unique improvements obtained in impact-modified nylon-6 and nylon-6,6 by reducing the negative impact of traditional impact modifiers by offering synergistic set of properties.

Important Factors Impacting the Performance of Polyolefin Pipes

Roswell E. King III, Markus C. Grob, Andreas Thuermer, May 2014

The use of polyolefins in pipe applications has global acceptance. As such, polyolefin based pipes are expected to maintain their properties over an extremely long service life where the polymer must withstand climatic, extractive and mechanical forces. The success of polyolefin pipes has been enabled by the development of suitable resins with a defined molecular architecture plus stabilization systems which have enabled the protection of the polymer during both melt processing and the end use application. Through the proper development of the stabilizer systems for this challenging application it is possible to protect the polymer and also extend the service life of the pipe under various environmental factors.

Detection of the Brill Transition to Elucidate Localized Thermal History in Nylon 6/6 Injection Molded Samples

Alicyn M. Rhoades, Jason L. Williams, John P. Beaumont, May 2014

The semi-crystalline microstructure of nylon 6/6 is directly related to the shear and thermal history of the material. Injection molding freezes in a set microstructure distribution through the thickness of a quenched sample. The relationship between the amorphous and crystalline domains in nylon 6/6 injection molded samples was explored using DMA, Flash DSC and FTIR analysis. The rate of injection during molding was shown to have the most significant effect on final microstructure distribution through the part thickness. Areas within the test geometries were analyzed to determine if the microstructure had formed at conditions above or below the Brill transition temperature, providing insight to the condition of localized polymer melt just prior to quenching.

Recent Advances in Glass Bubble Polymer Compounds

Baris Yalcin, Steve E. Amos, Mark J. William, Stefan Friedrich, Friedrich Wolff, Dae-Soon Park, Takujirou Yamabe, Jean-Marie Ruckebusch, May 2014

Glass Bubbles (Hollow Glass Microspheres), due to their unique spherical geometry and low density, provide several benefits in thermoplastic composites. They help produce lighter weight parts in order to achieve stringent fuel economy targets for automotive and aerospace manufacturers. They also provide productivity benefits through shorter cooling times, enhanced dimensional stability and less warpage – helping to reduce waste and improve throughput. In this paper, we provide solutions to achieve high impact strength in glass bubble polyolefin composites through the combination of impact modifiers and compatibilizers as well as demonstrate how GBs can be combined with supercritical foaming technology to achieve double digit weight savings with well maintained properties primarily for glass fiber filled composites.

Development of Chaotic Mixing System for MWCNT/Polymer Nanocomposites

Majid TabkhPaz, Mehdi Mahmoodi, Simon Park, Jingsong Chu, May 2014

The aim of this study was the development of a novel chaotic mixing system utilizing two cylinder rotors rotating in a sinusoidal fashion to uniformly mix multi-walled carbon nanotubes (MWCNTs) with a polymer matrix. To investigate the influences of important mixing parameters and optimize the mixing conditions, four major parameters were selected; and, MWCNTs were mixed with polystyrene to fabricate nanocomposites. Electromagnetic interference shielding effectiveness (EMI SE) and electrical conductivity results of the chaotic mixed nanocomposites suggest that the chaotic mixer has a higher potential for mixing nano particulates into thermoplastics, compared to other types of melt mixing techniques.

Chemical Foaming Agents for Gap Bridging in Contour Laser Transmission Welding

Philip J. Bates, Fahmida Mamtaz, May 2014

The use of chemical blowing agents (CBA) as a means of bridging gaps in contour laser transmission (LTW) welding was investigated in this study. 5% 5 Phenyl Tetrazole CBA was mixed with low density polyethylene (PE) containing 0.05% carbon black (CB). The CBA-containing PE compound was able to bridge 5-10% larger gaps at a given laser power than PE without CBA. In addition, a tool for assessing CBA degradation during LTW was developed. It involved developing a kinetic model for CBA degradation using thermal gravimetric analysis (TGA) and determining the temperature-time history during LTW using a finite element method (FEM) simulation. The kinetic model and thermal history were then combined to yield the CBA degradation as a function of time and position in the assembly.