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
Keynote: Structural Characterization of Hybrid Composites with Graphene to Increase the Use of Light Weight
Nathaniel Blackman, May 2020
Injection molded composites have been used effectively in automobiles, but there is still a need for the development of lighter and greener materials. Hybrid composites, composites with multiple kinds and length scales of fillers, present the opportunity for exciting new material breakthroughs and the opportunity for finely engineer the performance of the manufactured materials. This study presents the structural testing results for a hybrid composite composed of a blend of glass fibers with graphene nano-platelets within a PA6 matrix. This blend is chosen to meet the high demands of the automotive industry for select under the hood applications. The results presented in this work demonstrate that the addition of less than 1% by mass of graphene nanoparticles can allow the reduction of glass fillers by nearly 25% with only a minimal reduction in performance while reducing the density increase relative to the neat polymer by nearly 20%.
Long- and Short-Term Tensile Strength and Morphology of Joined Beta-Nucleated Polypropylene Parts
Andrea Wübbeke, May 2020
This paper presents the results of static short-term and long-term tensile tests for beta-nucleated joined polypropylene samples by the hot plate welding process. In the present study different dimensionless joining displacements are accounted for. The results show that high short-term tensile strength does not directly transfer to high long-term tensile strength. The morphology of the weld seam in the joined samples is examined by means of transmitted and reflected light microscopy. For the dimensionless joining displacements of 0.75 and 0.95, stretched spherulites are obtained. X-Ray diffraction can be used as a tool for qualitative and quantitative analysis and eventually for differentiation of samples of various joining displacements.
Low- and High-Pressure Foam Injection Molding of Polypropelene/Talc Through Chemical and Physical Foaming Agents
Gethin Llewelyn, May 2020
Recent research in the area of advanced polymer processing has demonstrated the potential of foaming agents to introduce additional functionality within injection molded components. In this research, Talc filled Copolymer Polypropylene (PP) ISO standard tensile bars were produced through low- and high-pressure foam injection molding (FIM). Two chemical blowing agents (CBA), Microcell® 548 and TecoCell® H1, in addition to N2, a physical blowing agent (PBA), were processed at both low-pressure and high-pressure configurations. The 2 foaming configurations were used to create parts with weight reductions of 12.6% and 8.8%, respectively. The samples foamed through CBAs produced stronger mechanical parts in both tensile and flexural modulus. Also, low-pressure foaming through CBA produced parts that had near-perfect surface finishes, matching that of conventional molding. High-pressure foaming through PBA showed an improved surface finish compared to low-pressure (through PBA) but was still inferior to that of the CBA foamed parts.
Machine Calibration Effect on the Optimization through Design of experiments (DOE) in Injection Mold
Rui-Ting Xu, May 2020
Quality issue is one of the most important concerns in injection molding. However, before executing mass production, how to retain good quality is one of the crucial factors in injection molding. To retain good quality, it is commonly using CAE to assist from original design to revision and to fabrication. However, even using CAE, it doesn’t guarantee the quality factors obtained from CAE can be applied to real experiments. Moreover, the design of experiment (DOE) method has been utilized into injection molding product development. Today, there are still some challenges when people using DOE in injection molding. In this study, we have designed one injection molding system to define quality factor based on a circle plate. Then, we have tried to perform a series virtual DOE testing for injection molding using CAE to optimize the process condition. Furthermore, we also performed real DOE experiment to verify the virtual DOE concept. Finally, we will discuss about the machine calibration effect on the accuracy of quality comparison. Results shows that before machine calibrated, both virtual CAE-DOE and real DOE optimization can provide better quality for injection parts. However, there is some difference between the virtual and real DOE results. To find out why the difference between the virtual and real DOE results happened, we have investigated the machine feature and tried to calibrate it. After machine calibrated, the difference between the virtual and real DOE results has been improved by 58%.
Machine Learning and Multi-Objective Optimization of Industrial Extrusion
David Kazmer, May 2020
A three-level multivariate control system is described that transforms a vector of machine inputs to a vector of virtual process states, and then these virtual process states to key performance objectives. The multivariate system is implemented on a 150 mm (6 inch) screw diameter producing approximately 500 kg/hr of polyvinyl chloride (PVC) film having a nominal width around 1 m (37 inch) and a nominal thickness of 0.38 mm (0.149 inch). Validation is performed with respect to modeling and optimization of three performance objectives including production rate, energy efficiency, and process capability. The results suggest significant gains with respect to the Pareto optimality (efficient frontier) of energy efficiency and process capability.
Mechanical Properties of Electrospun Fibers from Ozone-treated Lignin
Jiawei Chen, May 2020
Ligninis a viableprecursor alternative for electrospun carbon fiber. Purification of lignin typically involves chemicals. Ozone treatment is an environmentally-friendly approach to purify lignin. In this study, electrospinning of untreated and ozone-treated lignin was conducted with polyethylene oxide (PEO) as an aid-polymerto form submicron fibrous mats. Morphology and mechanical properties of the electrospun fibers were investigated. Electrospun ozone-treated lignin fibers showedspherical shapes attached to smooth fibers, characterized as beads-on-a-string (BOAS) morphology. It was found that longer duration of ozone treatment resulted in decreased average fiber diameter while increasing bead density, changing spindle-like beads into spherical beads. Ozone treatment did not have significant influence on the strain at failure of the electrospun lignin mats. Bead formation reduced the tensile strength and the elastic modulusof the electrospun fibers. Medium ozone consistency and short reaction duration were found to be the optimum conditions where highest tensile strength and elastic modulus were achieved.
Method for Determining Cooling Time in Injection Molding Using Infrared Thermography
Eric Boud, May 2020
Injection molders face confusion about the best way to determine cooling time. Many methods exist to estimate cooling time, but disagreement among results and fundamental flaws create error that leads to extra work, long cycle times, and a loss of profitability for molders. This paper proposes a new method for determining cooling time at the injection molding machine using infrared thermography and DMA data to relate part ejection temperature to dimensional stability. Experiments showed evidence that dimensional stability is linked to material modulus, which would allow molders to choose cooling times based on required dimensional stability by relating measured ejection temperatures to specific modulus values using DMA data.
Minimizing Interfacial Orientation During Processing of Immiscible Blends
Donggang Yao, May 2020
An interface between two immiscible polymer phases represents a material weakness due to reduced cohesive adhesion. For a co-continuous polymer blend, this interface can be viewed as an elastic membrane. From continuum mechanics, we show that the deformation of this interface during normal melt processing is largely affine, involving a slow relaxation process as compared with the relaxation process of the polymer chain. Accordingly we propose a processing strategy to minimize the development of the unwanted interfacial orientation and yet promote the development of molecular orientation so that a strong blend material can be fabricated. Some experimental results are provided and discussed.
Modeling of Heat Generation in Spin Welding
Miranda Marcus, May 2020
Spin welding is a common joining process for plastic parts with circular joints such as insulated cups and bowls, filter housings, and valves. In this process, heat is developed from surface friction as one part is revolved about the axis of the joint, resulting in a high linear speed. Finite element analysis (FEA) of the process can provide insight into potential mechanical deformation or failure under load that may compromise the weld, as well as aid in determining proper process parameters to achieve sufficient heating for a good weld. In this work, an approach to predict the weld temperature has been investigated and compared to measured results.
Modeling the Non-Isothermal Conveying Characteristics In Single-Screw Extrusion By Application of Network Analysis
Wolfgang Roland, May 2020
This paper deals with the modeling of the conveying behavior of polymer melts in single-screw extruders based on a network-analysis approach. The polymer-melt rheology is strongly temperature-dependent and hence the temperature profile affects the pumping capability. In this work, we propose an approach to predicting the non-isothermal, coupled axial pressure and temperature profiles. We present the fundamental background of the implemented pumping and dissipation models and the network theory for modeling the axial pressure and temperature profiles. The simulation procedure for calculating the non-isothermal conveying characteristics is shown and a few exemplary simulation results are presented. The novel algorithm provides fundamental insights into the non-isothermal extrusion characteristics and enables screw design and process optimization in single-screw extrusion.
Modern Rheological Techniques for Polymer Analysis: Capillary Rheometer, Screw Rheometer, and Melt Strength Tester
Myung-Ho Kim, May 2020
As a result of measuring the shear viscosity on a capillary rheometer and the screw rheometer, a viscosity function corresponding to 6 decades of shear rate of 0.1 to 10,000 [1 / s] was obtained. We have identified a new method for identifying crossover point with a single temperature measurement without performing complex ‘Time-Temperature-Superposition’. Also shear viscosity and melt strength functions were compared for eight LDPE grades. It was found that the melt strength showed a completely different behavior for similar melt index materials.
Morphology and Mechanical Performance of Pipe Grade HDPE Exposed to Chlorinated Water
Andrew Hagen, May 2020
Thin samples of a pipe-grade polyethylene with a bimodal molecular weight distribution were exposed to 5ppm 70C chlorinated water for up to 3000 hours. The samples were characterized by tensile tests, size-exclusion chromatography, infrared spectroscopy, and differential scanning calorimetry. Throughout exposure, the molecular weight data showed evidence of degradation: weight-average molecular weight was reduced, and a shift in the molecular weight distribution from a bimodal to a unimodal distribution (decreased dispersity). After 2250 hours of exposure, brittle behavior was observed, in which the average elongation at break was 12%. At this level of degradation, the weight-average molecular weight was 9 % of its undegraded value, and the crystallinity had increased from 70% to 85%. Average tensile strength was reduced from 31.8 to 16.6 MPa. The data imply that the presence of short-chain branching may inhibit chemicrystallization and subsequently delay the onset of brittle behavior.
Multi-layer Co-extruded Annular Structures Burst Pressure Performance
Erik Steinmetz, May 2020
Recent developments in the area of multi-layer co-extrusion have led to the ability to produce annular structures with high numbers of very thin layers. The burst pressure of these pipe structures was investigated. It was observed that die head rotation can have significant impacts on the mechanical properties of these structures due to the elimination of weld lines as well as biaxially orientation effects in the annular structures. It was also observed that following the elimination of the weld lines, the burst strength increases, possibly due to the biaxial orientation effects at higher rotation speeds.
New Development in Adhesion Promotion Using Flame Plasma Surface Treatment - Tutorial
Joseph DiGiacomo, May 2020
Adhesion promotion technologies have wide application in the numerous industries for a wide range of plastic parts, such as those made of PE, PP, PET, etc. One method used to modify the surface of these and other polymer products to promote adhesion of coatings and adhesives is flame plasma. This paper describes the theory behind natural gas, propane or LPG fired flame plasma surface treatment to promote adhesion of water based inks, coatings, adhesives, labels and other substrate laminates to polyolefin based substrates. Critical parameters in flame treatment are, flame chemistry, flame geometry, plasma output and distance of the burner to the part. The interrelationship between these variables, and how to control them for optimum surface treatment, will be discussed. The use of Schliren imaging technology, high speed photographs of the flame geometry, used to develop new burner designs, as well as advances in equipment technology will be presented. A completely new patented process design has been developed and successfully implemented providing significantly improved control of the flame chemistry, while at the same time simplifying the process control and mechanical hardware required. In addition, the new design improves the overall efficiency of the flame treating process Troubleshooting & maintenance of flame plasma surface treating systems will be discussed.
Novel Method of Compounding Cellulose Nanocrystal Suspensions into Polylactic Acid and Polyvinyl Acetate Blends
Ronald Sabo, PhD, May 2020
Cellulose nanocrystal (CNC) suspensions were compounded into blends of poly(lactic acid)(PLA) and poly(vinyl acetate)(PVAc) using a novel wet compounding approach in which drying and compounding werecarried out simultaneously. The resulting CNC/PLA composites were compared with those produced using a more traditional method of freeze-drying CNC suspensions followed bymelt-blending into PLA. CNCs in wet compounded composites appeared to be well-dispersed in the PLA/PVAc blends, and films extruded from these compounds exhibited high transparency compared with melt-blended composites. Gel permeation chromatography indicated that molecular weight degradation due to wet compounding was comparable to that from melt blending. The formulation, including surfactant modified CNCsand PVAc processing aids, played a significant role in the dispersion and properties of the nanocomposites. The elimination of a stand-alone drying stepfor cellulose nanomaterials can potentially overcome some of the challenges associatedwith producing thermoplastic cellulose nanocomposites and help advance commercialization of these materials.
Numerical Analysis of Polymer Micro-foaming Process in Extrusion Flow
Lixia Wang, May 2020
In this paper, effects of microviscosity and wall slip were considered, and a mathematical model of isothermal extrusion micro-foaming process was adopted based on classical nucleation theory and cell model. A simulation scheme of the extrusion micro-foaming process was conducted combining with the cross-section/imaginary area method and the Runge-Kutta method. The simulation program of the extrusion micro-foaming process was realized on MATLAB. The effects of inlet pressure on evolution of cell morphology and cell size distribution during the extrusion micro-foaming process were analyzed by the numerical examples. The results indicate that the higher the inlet pressure, the higher the maximum nucleation rate, and the closer to the die outlet the nucleation spot, the shorter the growth distance of the bubble, which is more conducive to formatting smaller cell radius and higher cell density.
Optical 3D Metrology the Ultimate Biomechanics Tool
Justin Bucienski, May 2020
3D Digital Image Correlation (DIC) provides the ability to measure non-contact 3D coordinates, displacements and strains of materials and structures. Although widely accepted in mechanical engineering and materials engineering, this tool as yet to prove its capability within the biomechanics industry with soft tissues, bones and most medical-specific materials. Known for its unique capability to be used for rapid full-field measurements from material characterization to full component testing, providing the equivalent of the results of over 10,000 contiguous strain gauges or displacement sensors, this technique is now recognized and certified (NIST, Boeing...) as equivalent to standard mechanical testing tools in the aerospace and automotive industries. 3D DIC is used across industries for improving the quality and the accuracy of the data collected to best understand mechanical behaviors of components or validate FEA models. This work focuses on the integration of the DIC technology with load frame such as Instron, MTS and Zwick for simple coupon testing of soft tissues, implants and prostheses. It was shown that DIC could in fact provide a more flexible measurement platform with capabilities for any coupon size, very small to large strains with a single instrument as well as multi-axial data in every direction for each and every one of the biomechanics applications evaluated.
Optimization of Processing Properties of Co2 Rubber Compounds
Michael Drach, May 2020
In order to reduce the carbon footprint, carbon dioxide (CO2) can be used as a raw material for synthesizing innovative rubber materials. In the following, the process of testing and improving CO2-based rubber compounds is described. The substitution of parts of the polymer chain by CO2 contributes to a sustainable rubber industry. A wide range of different raw materials is provided by the manufacturer, compounded and then tested. In order to improve processability, compound recipes are modified and improved. The investigations focus on static and dynamical mechanical properties and caloric properties. After the ability to be processed in an internal mixer is proven and improved by the use of processing aids, the compounds are tested for extrusion and vulcanization. It is shown, that CO2-rubber compounds can be processed on a rubber extruder and can be vulcanized by using hot air and infrared radiation.
Overmolding of Thermoplastic Elastomers Onto Hard Substrate Materials
Ernest Kumeh, May 2020
Historically, soft thermoplastic elastomer (TPE) materials have been applied onto the hard substrate materials via an overmolding process in order to enhance the performance of the molded articles. In this process, it is important that the soft TPE adheres well enough to the substrate materials to maintain the desired performance. Depending on the characteristics of the substrate material, a TPE must be formulated to facilitate the adhesion of a TPE onto the substrate during an overmolding process. KRAIBURG TPE has engineered and marketed TPEs that can bond to a variety of hard substrates including metals. The adhesion characteristics of these TPEs are presented in this paper.
Polyethylene/Graphene/Carbon Fiber Waste Hybrid Nanocomposites
Fahed Albreiki, May 2020
With growing applications of polymer nanocomposites, the need to manufacture cost-effective nanocomposites is increasing. In this work, we report economical nanocomposites from polyethylene (PE) using graphene (GnP) and carbon fiber (CF) waste. The nanocomposites were prepared by simultaneously mixing PE, GnP and CF in a melt blender where CF appeared to be randomly dispersed along with GnP in PE matrix. A delayed crystallization was observed when nanocomposites were crystallized from the melts non-isothermally. The crystallization data was well explained using Avrami model. Moreover, the hybrid filler (CF and GnP together) showed better mechanical performance with increasing CF/GnP ratio.

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