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

Synergistic Effects of Antioxidants (AO) on Properties of Homo Polypropylene
Mazen Ageely, May 2017

Antioxidants (AO) are used to protect the polymer from deterioration either during extrusion or after production. Probably two types of Antioxidants are used to protect polymer, primary antioxidant (phenol type) and secondary antioxidant (phosphate type). The performance ratio of both the antioxidants is depend on its process technology, processing conditions and its application. To understand the effect of each antioxidants on HomoPP, different samples at different AO dosage were extruded. Relevant product properties such as mechanical, physical and rheology were measured. The test result obtained elucidates that the polymer recipe is a balance of additives to meet the requisite end product properties under the employed processing conditions.

Lateral Torsional Buckling of Anisotropic Laminated Thin-Walled Rectangular Simply Supported Composite Beams Subjected to Pure Bending
Habiburrahman Ahmadi, Hayder A. Rasheed, May 2017

In this paper, a generalized analytical approach for lateral-torsional buckling of simply supported anisotropic, thin-walled, rectangular beams under pure bending condition was developed using the classical laminated plate theory as a basis for the constitutive equations. Buckling of such type of members has not been addressed in the literature. A closed form buckling expression is derived in terms of the lateral, torsional and coupling stiffness coefficients of the overall composite. These coefficients are obtained through dimensional reduction by static condensation of the 6x6 constitutive matrix mapped into an effective 2x2 coupled weak axis bending-twisting relationship. The stability of the beam under different geometric and material parameters was investigated. The analytical formula is verified against finite element buckling solutions using ABAQUS for different lamination orientation showing excellent accuracy.

Bimodal Poly(Ethylene Terephthalate) Blends: Effect of Molecular Weight Distribution on Material Properties
Artemis Ailianou, Sudheer Bandla, Jay C. Hanan, May 2017

This study presents an investigation of bimodal poly(ethylene terephthalate) blends using injectionmolded parts. The blends were characterized for intrinsic viscosity, molecular weight distribution, crystallization, and tensile mechanical properties. The data shows that injection molding preserves the intended bimodal molecular weight distribution, despite typical inherent material degradation from processing. Our results show that the maximum effect was observed when the high molecular weight component is at 10 wt.%.

Effects of Processing Parameters on Colour Variation and Pigment Dispersion during the Compounding in Polycarbonate Grades
Jamal Al-Sadi, May 2017

The objective of this work is to study the variations of how independent processing parameters such as temperature, speed, and feed rate affect the dependent responses for consistent output colour (L*, a*, b*, dE*). In this study, the compounded material was processed on an intermeshing twin-screw extruder (TSE) and injection molded to evaluate their effect on the colour stability, rheology and dispersion of the polycarbonate resins. Focus was extended to the interaction of the speed, which correlates to the dispersion and colour changes.

Analytical and Finite Element Buckling Solutions of Fixed-Fixed Anisotropic Laminated Composite Wide Plates under Axial Compression
Rund Al-Masri, Hayder A. Rasheed, May 2017

Using Rayleigh-Ritz approximation, a generalized analytical buckling formula was developed of generally anisotropic laminated fixed-fixed composite plates. Using the generalized constitutive equation, the effective extensional, coupling, and flexural stiffness coefficients of the anisotropic layup are determined using dimensional reduction by static condensation of 6x6 composite stiffness matrix. The resulting explicit formula is expressed in terms of the flexural stiffness coefficients as well as the plate geometry. In order to decrease some of the discrepancy in some of the results, the coupling and extensional effect was considered through the substitution of the pre-buckling solution into the bifurcation expression to yield a new formula. The analytical results are verified against finite element Eigen value solutions for a wide range of anisotropic laminated layups yielding high accuracy. A parametric study is then conducted to examine the effect of ply orientations, material properties and type of element in FE analysis. Relevance of the numerical and analytical results is discussed for all these cases.

Optimizing Fused Deposition Modeling 3D Printing Process for Fracture Resistance
Nahal Aliheidari, Josef Christ, A. Ameli, R. Tripuraneni, S. Nadimpalli, May 2017

The quality of fused deposition modeling (FDM) 3D printed parts are primarily influenced by the process conditions and mesostructural features. This study aims to establish the relationships between the process parameters/mesostructural features and the fracture resistance of printed parts. Double cantilever beam specimens of ABS were printed at different nozzle and bed temperatures, and with different layer height and layer width and then fracture-tested to measure the fracture resistance using J-integral in a finite element model. The result indicated that nozzle temperature and layer height had the most significant effects on the fracture resistance. The fracture resistance increased by ~30% with 20°C increase in the nozzle temperature. The bed temperature and the layer width appeared to be less significant factors, compare to the nozzle temperature. The results of this work establish insight and guidance in the design of printed materials for structural and functional applications.

Method to Evaluate Biaxial Stretch Ratios in Stretch Blow Molding
Masoud Allahkarami, Sudheer Bandla, Jay C. Hanan, May 2017

The structural performance of poly (ethylene terephthalate) (PET) films depends on material distribution and microstructural changes in PET from stretching. Biaxial stretching during processes such as blow molding creates a specific thermomechanical history of the film, which determines material properties. The dependence of PET film crystallinity and the resulting mechanical properties on stretch ratios makes them a critical parameter in designing an efficient lightweight design. Therefore, it is important to have a method which can provide accurate material distribution information along with local stretch ratios. Such material efficiency can be applied to container design. In this work, we introduce a method to track material distribution from a “preform” to a “bottle” during a two-step injection stretch blow molding process and evaluate the stretch ratios.

Numerical and Experimental Analysis of Infill Rate on the Mechanical Properties of Fused Deposition Modelling Polylactic Acid Parts
Atakan Altinkaynak, Övgü Yagiz Çiçek, Efe Can Balta, May 2017

Material characterization of 3D printed PLA parts with different infill rates was performed by standard tensile tests. Three-dimensional finite element simulations of the tensile tests were also performed. For the simulations, a method for reconstructing the CAD model of the printed parts with different infill rates was proposed and numerical simulations were conducted on the reconstructed models. A reasonable prediction of the experiments in terms of material behavior and the stress-strain characteristics for infill rate of 100% is obtained from the numerical analysis. Discrepancies between the numerical predictions and experimental results especially in the plastic deformation region for other infill rates are discussed in the paper.

Polycarbonate Filled with Hybrid Conductive Fillers for Bipolar Plate Application
Amir Ameli, A. Naji, Petra Pötschke, May 2017

Conductive polymer composites (CPCs) of polycarbonate (PC) filled with carbon fiber (CF), carbon nanotube (CNT), graphite (Gr), and their double and triple hybrids were prepared using solution casting method followed by compression molding. The through-plane electrical conductivity of CPCs filled with single and hybrid fillers were investigated. The results showed that the percolation thresholds for the PC-CNT and PC-CF was ~1 wt.% and ~10 wt. %, respectively, while no clear threshold was found for PC-Gr composites. Addition of 3-5 wt.% CNT improved the conductivity of PC-CF and PC-Gr systems up to 6 orders of magnitude. The results of hybrid CPCs filled with all three fillers (with constant total loading of 63 wt.%) indicated that the best conductivity result is achieved when the CF and CNT loadings were near their percolation thresholds. Therefore, a triple filler system of 3 wt.% CNT, 10 wt.% CF and 50 wt.% Gr resulted in a composite with the highest through-plane conductivity (12.81 S.cm-1), surpassing the reported values in the literature, and a step forward toward meeting the US Department of Energy criterion for the electrical conductivity required for bipolar plates of fuel cells.

A Composition-Morphology Mapping of Particle-Filled Polymer Blends up to High Fill Fraction
Derrick Amoabeng, David Roell, Kendal Klouse, Brian A. Young, Sachin S. Velankar, May 2017

This study explores the effects of particulate filler on the morphology of two immiscible high-molecular-weight thermoplastic polymers across a wide range of composition. Blends of polyisobutylene (PIB) and polyethylene oxide (PEO) with silica particle loadings of up to 30 vol% were studied. The silica particles have a strong affinity for PEO, and hence the effects of particles on the morphology depend on whether or not there is sufficient PEO to engulf the particles. We observe two morphologies that are qualitatively different from those seen in particle-free polymer blends: one in which particles are bonded together by small menisci of PEO, and the other in which a highly-filled particles-in-PEO phase percolates throughout the sample. Other morphologies in filled blends resemble droplet-matrix or cocontinuous morphologies in corresponding unfilled blends. Overall, particles have major effects on the morphology when the polymer preferred by the particles (PEO) is in a minority, but only modest effects when the preferred polymer is in a majority.

Fundamentals of Twin-Screw Compounding: Kneading Block Performance Characteristics
Paul Andersen, May 2017

The co-rotating fully intermeshing twin-screw extruder has evolved significantly in the 60 years since it was commercialized in 1957. While this equipment might be considered a “mature” technology, it has not experienced a decline in new developments as might be expected, but rather a significant number of advancements. The technology continues to evolve. For example in the last 20 years several significant developments have been introduced. These include a) the implementation of high torque (power) designs, b) the use of increased screw rpm in conjunction with high torque for improved operating flexibility and productivity, and c) a breakthrough technology for feeding difficult to handle low bulk density materials. However, one area of twinscrew technology that has not evolved as much is screw elements geometry. Conveying elements and kneading blocks have remained essentially the same since the original Erdmenger design patents filed in the late 1940’s and early 1950’s. In spite of their longevity in the market, there are still unknown qualitative as well as quantitative operational characteristics. This paper will focus on kneading blocks, specifically looking at some significant aspects related to performance. These include pressure generation as a function of 1) absolute pressure, 2) disc profile (2-lobe vs, 3-lobe), 3) disc width, 4) disc stagger angle, and 5) material viscosity.

Knowledge-Based Support for the Designer regarding Injection-molded Part Design
René Andrae, Alexander Porsch, Peter Köhler, Johannes Wortberg, May 2017

CAD-Systems have become a standard tool for the development process. Due to the extensive possibilities of modern CAD-software, the classic approach turns into a more dynamic one. This opens up the possibility to take into consideration influences from the production and computation at an early stage of the design process. This paper presents a methodological approach to ensure a design for injection-molded parts. An important goal is the realization of a knowledge based assessment of manufacturing possibilities and the preselection of materials for a safe and objective product planning. Furthermore, the project objectives for the acceleration of the design of molded parts through the reduction of unnecessary optimization steps according to the usage of knowledge based systems.

Mechanical Characterization and Fractography of PC, ABS and PMMA – A Comparison of Tensile, Impact and ESC Fracture Surfaces
Farzana Ansari, Christopher Lyons, Ryan Siskey, Suresh Donthu, Steven MacLean, May 2017

This work presents an effort to document and describe fracture surfaces for three commercially available amorphous polymers (PC, PMMA and ABS) each subjected to tension, impact and environmental stress cracking (ESC). We present mechanical properties as well as microscopic characterization at low and high magnification to distinguish between slow tensile loading, fast impact loading, and environmentally assisted creep failure mechanisms. Chemical surface analysis of select fracture surfaces was also performed to evaluate its utility as a failure analysis technique for identifying ESC failure. The fractographic atlas presented herein serves to assist others in identifying topographical fracture surface features and crack growth mechanisms of failed plastic components, and more accurately distinguish between pure mechanical failure and ESC-generated fracture, where possible.

Optimizing 3D Printed Components: A Methodological Approach to Assessing Print Parameters on Tensile Properties
Farzana Ansari, Chris Page, Steven Kreuzer, David Eason, Elham Hamed, Heather Watson, May 2017

Additive manufacturing provides the designer with more freedom, but at the cost of higher complexity when optimizing the design for additive manufacturing. Any 3D printing process or machine has easily over 100 unique variables and settings, and understanding their effects on the performance of the produced part is equally unique to the specific process. To achieve optimal design for additive manufacturing (DFAM), one must explore the trends and interactions present in these processes. Here we demonstrate an empirical method utilizing a statistical design of experiment technique and standardized mechanical testing which ultimately exposes trends and variable interactions specific to our selected additive manufacturing process.

Macromolecular Structure-Property Relationship for Impact Strength and Hardness of Polydimethylsiloxane (PDMS) Blends
Ahmed Anwer, Hani Naguib, May 2017

In this study, Polydimethylsiloxane (PDMS) with varying crosslinking densities were fabricated by vacuum assisted bubble free casting of PDMS followed by heat treatment. Shore A hardness tests and impact tests were performed to evaluate the hardness and maximum impact strength of PDMS. PDMS with varying mix ratios of 5:1, 10:1, 15:1 wt/wt silicone resin to curing agent were fabricated for instrumented drop weight impact testing and hardness testing. Fourier transform infrared (FTIR) spectroscopic analysis revealed that there is a strong correlation between impact strength and hardness with respect to molecular dipole moments of Silicone-Oxygen-Silicone (Si-O-Si) bonds. It was also determined that there is an inverse correlation between dipole moments of Oxygen - Hydrogen (O-H) bonds with respect to impact strength and hardness of PDMS.

Evaluation of the Mechanical and Morphological Characteristics of PLA-Lignin, PLA-Tannin and PLA-CNF Composites
Muhammad Anwer, Hani Naguib, May 2017

PLA has now attained significant utility in the plastics and manufacturing sector. It high stiffness, strength and bio-degradability has made it an attractive option for in many applications including additive manufacturing. This paper presents the modification in properties of neat PLA with the addition of Lignin, Tannin and Carbon Nanofibers fabricated via high shear twin screw compounding. Lignin and Tannin were chosen as completely bio-based fillers and Carbon Nanofibers were chosen for their high performance and modest expense as compared with other carbon based nano-materials. Detailed morphological evaluation of the composites is also presented.

Bio-Inspired Textured Composite Surfaces with Increased Hydrophobicity
Ali Anwer, Reza Rizvi, Hani Naguib, May 2017

Texturing composite surfaces in the past employed techniques such as photolithography, laser sintering and plasma etching. However, these techniques pose to be very complex in nature. In this paper, we present a method to texture composite surface without the need for using such complex surface texturing methods. The textured samples were fabricated by taking advantage of the fiber de-bonding and pull out process. Varying fiber volume fractions of carbon fibers were melt blended with Thermoplastic Polyurethane matrix followed by cutting to expose the fibers from the matrix surface. The TPU composite had shown a 23% improvement in the contact angle.

Influence of Long-Term Annealing on Residual Stress Distribution and Quasi-Brittle Failure Properties of Talcum Reinforced Pipe Grade Polyproyplene
Florian J. Arbeiter, Gerald Pinter, May 2017

In this study a polypropylene material with talcum reinforcement used for sewer pipes has been subjected to an annealing procedure at 80°C, roughly 60°C above the actual application temperature, in air for a time period of 18 months. As expected, examination of the material showed no significant decrease in mechanical or fracture mechanical properties due to the temperature exposure. However, samples stored at higher temperature showed better resistance against quasi-brittle failure in fatigue tests compared to unconditioned samples. This could mainly be attributed to the decrease of residual stress in the pipe wall. Even though pipes have been annealed for very long times above Tg, residual stress could not be totally relaxed within 18 months.

Cocontinuous Conductive Polymer Composites with Interfacial Graphene
Lian Bai, Siyao He, John W. Fruehwirth, Andreas Stein, Christopher W. Macosko, Xiang Cheng, May 2017

Interfacial localization of graphene in the cocontinuous polymer blends is shown to be effective in stabilizing the cocontinuous morphology and increasing the conductivity with a lower electrical percolation threshold. We created polylactic acid (PLA) and polystyrene (PS) cocontinuous blends filled with thermally reduced graphene oxide (r-GO) jammed at the interface. The resulting conductive composites show dramatically improved conductivity at low filler loadings and an ultralow percolation threshold of 0.028 vol%. We found that r-GO transfers from the PLA phase to the interface during melt compounding and forms a spanning 3D network during annealing, which effective suppresses the coarsening of the cocontinuous structure. Our study demonstrated that the 3D r-GO network significantly increases the conductivity and the storage modulus of the melt blends.

Use of Decahydrodecaborate as Flame Retardants in Coatings
Austin Bailey, Charles J. Neef, Timothy Dawsey, May 2017

As the need to protect the environment continues to increase, there is a growing demand for non-halogenated flame retardants. Two different decaborate compounds were combined with triphenylphosphine oxide into polyurethane and characterized. The thermal stability and the potential flame retardancy of the new materials were tested via thermogravimetric analysis and cone calorimetry. The cone test provided heat release rates and smoke release rates. Per the results of these tests the combination of the new decaborate, and triphenylphosphine oxide showed potential for flame retardancy at minimal amounts of flame retardant.

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