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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Changes of Plastics Used in EVs Compared to ICVs & Why
Ashok Adur, Ph.D., March 2023

Electric vehicles have garnered a lot of interest and sales of these EVs are growing with many companies around the world producing them and entering the market besides Tesla. This presentation will cover changes in polymer usage in EVs compared to conventional internal combustion engine vehicles (ICVs). It will include: • Very interesting and unbelievable history of electric vehicles, • Plastics, elastomers, composites and other materials for light-weighting, • Changes in polymer materials and design needed for the several differences between the requirements of ICVs and battery electric vehicles (BEVs) and what factors led to these changes, • Use of recycled materials and sustainability, • Challenges BEVs faced, and how innovation overcame those challenges, and • Other challenges that remain and need more innovative approaches.

BlowView Simulation Tools for Design and Optimization of Thermoplastic Liner in Hyperbaric On-Board Hydrogen Storage Tanks for Mobility
Zohir Benrabah, Ph.D., March 2023

A key challenge to the widespread commercialization of fuel cell electrical vehicle, is to design compact and cost effective on-board Compressed Gaseous Hydrogen tanks which store sufficient quantities of H2 without sacrificing passenger and cargo space. The first generation of FCEVs use 700 bar Type IV pressure vessels to store hydrogen. These vessels have a cylindrical BMPL, overwrapped by carbon-fiber composite material to maintain the internal pressure, which serves as a hydrogen gas permeation layer. However, due to its small molecular size, H2 permeates through the plastic liner wall. This represents a serious issue that should be addressed early in the design stage in order to minimize H2 emissions from the liner and conform to legal safety requirements and standards. Meanwhile, automotive OEMs and their suppliers are being challenged to design longer and thinner liners with very consistent wall thickness. One way to meet the hydrogen permeation rate requires a judicious choice of liner material. In the thermoplastic forming industry, it is still common practice to rely on trial and error to find the appropriate barrier layer configuration/thickness required to meet the permeation rate limit requirement. A tool offering a more efficient alternative, based on reliable predictive/virtual analysis of the H2 diffusion through the BMPL wall, could significantly shorten the design/development cycle by allowing product prototypes to be analyzed and tested virtually. A finite element based model that could help a designer better understand barrier layer properties was integrated in the latest version of NRC’s BlowView software. The mathematical diffusion model adopted is based on Fick’s diffusion law to predict H2 diffusion through a polymeric wall. Promising results, in terms of H2 permeation rate on an industrial BMPL, will presented during the presentation.

Recycling of Polyvinyl Butyral From Automotive Windshield
Manoj Nerkar, Ph.D., March 2023

Polyvinyl butyral (PVB) is used in laminated glass to bind multiple glass layers. Key applications of laminated glass include safety glasses in architectural and automotive. Even if glass breaks, adhesive nature of PVB keep pieces of glasses together preventing human injury and damage to the surrounding. Because of this aspect of PVB, its used in automotive windshield applications. Each car windshield contains ~ 1kg of PVB. At the end of car life, glass in windshield is separated from PVB and recycled. In this study the PVB removed from glass was evaluated for its feasibility to recycle. Specifically, rigidity and indentation properties of PVB were studied. Substantial improvement in these properties was achieved by adding acrylic additives to PVB, making it suitable for applications such flooring. It was found that hardness of PVB was increased by addition of acrylic additives, resulting in improved indentation and rigidity. Glass transition temperature of PVB was increased by > 10°C. Significant increase in storage modulus was also observed. Effect of acrylic additives on tensile and impact properties are also presented. Being adhesive in nature, PVB tends to stick to metal surfaces making it difficult to melt process, addition of acrylic additive improved handling of PVB during melt processing preventing it from sticking to metal surfaces. Modification of PVB with acrylic enabled recycling of PVB in various applications, specifically flooring. With improved indentation and rigidity performance, use of PVB in flooring can be increased significantly. PVB modification can diverge >100,000 lbs. of PVB from land fill and can be used in value added applications. Acrylic modification showed potential to recycle PVB into useful applications making complete recycling of windshield possible, leading to overall improvement in automotive recycling.

Recycling of Airbag Wastes
Sinja Pagel, March 2023

Multi-layer materials (e.g. in packaging or technical parts) are used to achieve certain properties of products. However, a major challenge of plastics recycling is the separation of the various polymer layers. One example for this are airbags. Airbags consist primarily of polyamide 6.6 fibers and an additional silicone coating. To prepare for recycling, the wastes are processed to easily dosable fabric particles. However, the fabric particles subsequently do not consist exclusively of PA66, but still contain the silicone coating. In principle, it is possible to process these PA66 silicone fabric particles into plastic granules by extrusion, though this results in a product of low quality. This is mainly due to the low adhesion between the PA66 matrix and the contained silicone particles. The low adhesion leads to increased interfacial delamination and thus to premature failure. Mechanical properties such as impact strength or elongation at break are therefore very poor and high-quality technical components cannot be manufactured from this recyclate. An alternative to the extrusion of silicone-contaminated PA66 waste is the chemical separation of the silicone from the polyamide. However, the disadvantages of this recycling alternative are the large amounts of solvents required as well as the high energy requirements. Up to now, there is no efficient process for the mechanical recycling of PA66 wastes which contain silicone. However, from an environmental point of view and due to the large available amount of this type of waste (e.g. airbags), it would be desirable to process it into a high-quality recyclate which can be applied in the production of technical plastic components. Therefore, the aim of this work was to investigate a new approach for the recycling of PA66/silicone wastes using the example of airbag wastes. Thereby, the silicone particles should not be regarded as impurities but as a functional additive/impact modifier. To this purpose, a coupling between the PA66 matrix and the silicone particles was formed through a reactive extrusion in a twin-screw extruder by means of a silane coupling agent. This type of modification intents to reduce the risk of interfacial detachment in the resulting recyclate. After the reactive extrusion, an in-depth material analysis was conducted to verify the achieved coupling reaction in the twin-screw extruder. Rheological tests confirmed the formation of a cross-linked structure through the addition of the coupling agent. However, it cannot be determined through the rheological analysis if a chemical bonding has taken place. It can be assumed that the silicone has become inert during the airbag production and therefore none or only few functional groups are available. However, silanes and silicones have a basic structural similarity. Therefore, physical bonding can be expected, which may well lead to improved mechanical performance. The improved integration of the silicone particles into the PA66 and the reduction of cavities in the compound could be demonstrated by using Nano-IR-AFM analyses. Additionally, mechanical tests showed the increase in notched impact strength and elongation at break and therefore the possible function of the silicone as an impact modifier. The reactive extrusion process was further investigated in a hinged twin-screw extruder. After stopping the process, it is possible to open the processing unit and to take samples at different positions along the processing zone. This further analysis of the process emphasized the need for an adjustment of the machine parameters as well as the screw concept in order to optimize the reaction conditions in the processing zone and to prevent post-reactions as well as degradation effects. Future experiments will concentrate on the detailed investigation of the exact nature of the formed bonds (physical and/or chemical). In this context, the formation with additional silane types should also be taken into account. Furthermore, the process parameters of the reactive extrusion will be optimized with the aim to increase the additive content in order to further increase the notch impact strength while avoiding process-related post reactions that could hinder the processing of the compounds.

Novel Polyamide Solutions to Dampen Structural Vibration
Bradley Sparks, Ph.D., March 2023

A portfolio of innovative solutions has been developed that affectively address NVH and weight challenges of the EV market space. Significant advancements made in modeling, testing and correlation of the material properties to the part performance across frequencies. Ascend offers a wide range of products that address these goals from standard automotive grades up to our AVS High Damping grades.

Extrusion and Thermoforming of Flame Retardant, Halogen-Free, Glass-Filled Thermoplastic Composite Material for EV Battery Pack Applications
Anil Tiwari, Carlos Pereira, March 2023

Thermoforming is a widely employed technology for large part manufacturing, in part because of lower initial tooling costs and the suitability of this process for medium to low production volumes. Currently, the industry manufactures electric vehicle (EV) battery components predominantly through sheet metal forming. Though these solutions are relatively heavy and present challenges with respect to thermal and electrical insulation, lack of alternate mature large-scale manufacturing processes has kept sheet metal forming as the industry’s leading choice. The challenges and limitations of using conventional metal solutions for battery pack components such as top covers and bottom trays may potentially be addressed through the development of thermoplastic-intensive solutions. The incumbent large metallic battery enclosure applications present immense scope for significant weight savings, range extension and enhanced thermal runaway protection through use of thermoplastics. Furthermore, thermoplastics can deliver added benefits, such as increased functional integration, and enhanced thermal and electrical insulation, among others. Developing such solutions requires a holistic approach combining optimal design, novel thermoplastic material formulations and creative approaches for manufacturability. It also requires developing methods for validation at sub-system level. This study highlights novel thermoplastic composite materials – 30% glass-filled, intumescent, halogen-free, flame-retardant (FR) polypropylenes (PP) – used to manufacture an EV battery pack’s top cover, through sheet extrusion and thermoforming. The composite material was first extruded successfully into flat sheets at both pilot scale and commercial scale to exhibit its manufacturability. Next, the sheets were tested under different fire scenarios to assess performance of the material against thermal runaway conditions. Finally, the extruded sheets were thermoformed into multiple prototype geometries, from small to large-scale – to validate formability of the material for the top cover and enclosure pats of a large EV battery pack. Study findings demonstrate the feasibility of extrusion and thermoforming of the thermoplastic composite material for large-scale components with complex geometric features. In addition, tests show the potential of the enclosure made using the FR glass-filled PP material to withstand the thermal runaway conditions encountered in battery packs so they can meet the respective GB standards.C21

Characterization Of Vibration Welded Pine, Maple, And Bamboo
Curtis Covelli, Dr. David Grewell, Shichen Yuan, Klaus Schmidt-Rohr, June 2022

This study investigates the factors affecting the welding of pine, maple, and bamboo pulp-board. This research used a Branson Mini II vibration welder traditionally used for welding plastics. The effects of weld pressure, amplitude, and weld time were varied to determine their effects on lap-shear weld strength. Strength testing was performed with a universal testing machine. The morphology of the weld zone was also analyzed to gain insight into the welding mechanics. The highest strength of pine samples was 8.4 MPa, while maple was approximately 35% stronger and had a smaller standard error. It was observed that bamboo pulp board weld strength was primarily dependent on weld pressure. Also, pulp-board seemed to weld in a similar fashion to wood.

Aqueously Degradable Pet Films Containing A Latent Metal Oxide Reagent
Natalie Duprez, Christopher Luettgen, Donggang Yao, June 2022

In this study, PET was combined with a latent metal oxide reagent, CaO, which allowed the PET to hydrolyze when submerged in water, breaking down the polymer chain and forming calcium terephthalate as a nontoxic byproduct. PET/CaO composites were mixed at 10, 20, and 30 wt% CaO, and 0.001” thick films were prepared by compression molding. These films were degraded in water at 90°C for varying amounts of time. Puncture testing, optical microscopy, FTIR, and TGA were performed to probe the degradation of the material and verify that it was producing the products that were expected from the reaction. The PET/CaO composites were shown to be degradable in water, with a significant loss in mechanical properties after only an hour. The rate of degradation was strongly dependent on the concentration of CaO, with significantly faster degradation at higher concentrations.

Impact Modification Of Pla (Poly Lactic Acid) By Blending Small Amounts Of Amorphous Pha (Polyhydroxyalkanoate) Copolymers
John Licata, Raj Krishnaswamy, Michael Andrews, Allen Padwa, Zhiguan Yang, June 2022

This work demonstrates the efficacy of amorphous polyhydroxyalkanoate (a-PHA) copolymers in enhancing the impact strength of PLA without compromising the compostability and bio-based carbon content of the final product. The influence of PHA polymer composition on the performance of PLA will be highlighted for applications including thermoforming, film and injection molding. Finally, the morphology of the blend will be used to explain the impact modification mechanism. Blends of 100% bio-based and fully biodegradable a-PHA and PLA exhibit good toughness and clarity in injection molding, extruded sheet and blown film. It will be shown that the level of toughness increase and modulus reduction can be tuned by blend composition.

Shape-Memory Polymers Based On Castor Oil And Lignin Sulphonate Synthesized From Waterborne Dispersion
Samy A. Madbouly, June 2022

Aqueous polyurethane dispersions based on castor oil and lignin sulphonate (LS) were successfully synthesized in homogenous solution with no organic volatile compounds and excellent dispersion stability. Transparent thin films of PU-LS with different LS contents were obtained via solution (dispersion) cast technique. The glass transition temperatures (Tgs) of the PU-LS films were evaluated from the dynamic mechanical analysis (DMA) at 1 Hz and 2 oC/min heating rate. The Tg was found to be strongly influenced by the incorporation of the small LS content. The Tg (temperature of tand peak maximum) for PU-LS film with LS content lower than or equal 3 wt.% increases considerable with increasing the concentration of LS. For higher concentrations, no significant additional increase in the Tg was observed. The crosslink density was also calculated from the elastic modulus at a temperature of 40 oC higher than the Tg based on the rubber elasticity theory. The crosslink density increases with increasing the LS content of the thin films. The thermal-induced shape-memory effect was investigated using DMA according to cyclic thermomechanical tensile tests. The PU-LS thin film was found to have an excellent shape-memory effect and the recovery was strongly dependent on the LS content. Fast recovery (17 sec) to the permeant shape was observed once the temporary shape sample was immersed in water bath at the programming temperature.

Biobased And Recyclable Polysulfones Using Imine Chemistry
Vitasta Jain, James Sternberg, Mark Johnson, Srikanth Pilla, June 2022

An alternative to bisphenol A was used to synthesize polysulfones (PSs) that are chemically recyclable. Vanillin was reacted with 4-aminophenol to generate a diphenol with an imine. The synthesis of PSs is done by means of polycondensation of dibasic phenols with sulfur-containing aryl halides by the mechanism of nucleophilic substitution. The lignin based diphenol replaces traditionally used bisphenols (a xenoestrogen) and is the site for recycling the polymer. The polymerization is studied under various conditions (temperature, time, monomer ratio) for best properties and product purity. The polymer structure was confirmed via NMR and its thermal properties studied using DSC and TGA (Tg~122°C, Td5~270°C, Td10~400°C, Tprocess~180). The stability of the imine bond was studied under the reaction conditions for reactant stability.

Evaluation of Polyamide Copper Hybrids for Automotive Battery Systems
Niclas Emrich | Stefan P. Meyer | Rüdiger Daub | Reinhard Schiffers, May 2021

Applications for automotive battery systems require hybrid joints of copper and polymer with high demands towards helium seal tightness and long-term durability. This work examines hybrid bonds, using indeterministic laser-nanostructures as pretreatment and variotherm injection molding as a joining method. Laser nanostructures are produced with two different laser setups; one having a mean power output of 20 W (state of the art) and one system with 200 W, promising faster processing rates by one order of magnitude. The spot distance and the number of laser pretreatment repetitions are varied systematically for both laser systems. All treatment variations are joined by variotherm injection molding using inductive heating of the metal specimen. A polyamide 12 compound with 10% glass fiber content is used. Bonds are tested for shear strength and helium seal tightness and the degradation of these properties due to ageing. For root cause analysis, the boundary layer is analyzed using ion beam cross-sectioning and SEM-imaging.

Effective Antimicrobial Protection for Automotive Composite Applications
F. Deans | H. Khan, May 2021

Abstract Submission Effective Antimicrobial Protection for Automotive Composite Applications by F. Deans & Dr. H. Khan A growing concern that OEM’s, suppliers, and dealers have is how to protect their customers from exposure and transmission of harmful pathogens. The market has been flooded with a number of products for direct human use. However, there remains unanswered data and details on how to effectively utilize antimicrobial agents for automotive components that could come into contact by human occupants. Specific information on types of antimicrobial performance, manufacturing techniques on protecting plastic and composite applications, and prolonging the antimicrobial effectiveness will be discussed.

Optimizing Mechanical Behavior of Basalt-Natural Fiber Hybrid Injection Molded Composites
Kyleigh Rhodes | Bharath Nagaraja | Raul Pelaez Samaniego | Vikram Yadama, May 2021

Environmental consciousness is driving modern research and development in the automotive sector to target the advancement of feasible green materials in automotive applications. Basalt fiber has shown to be a robust competitor against glass and carbon fiber and is more eco-friendly manufacturing processes. Reinforcing polypropylene with basalt fiber and hemp hurd using maleic anhydride-grafted polypropylene (MAPP) as a coupling agent, has shown to contain similar mechanical properties to its competitors. A mixture model was implemented to optimize the mechanical properties of a variation of fiber ratios and MAPP to compare against a controlled GF mixture. Scanning Electron Microscope (SEM) analysis of fracture surfaces show the variation in fiber–matrix adhesion based on addition of MAPP. This study concludes that the addition of MAPP improves the mechanical behaviors of hybrid composites made from basalt fiber and hemp hurd reinforced polypropylene.

Biocarbon Hybrid Composites for High-Temperature Automotive Applications
Amy Langhorst | Sabrina Peczonczyk | Hannah Sun | Alper Kiziltas | Debbie Mielewski, May 2021

Automotive manufacturers have been increasing use of natural fiber composites to reduce vehicle weight and respond to consumer demand for environmentally friendly products. However, the low thermal stability of natural fibers can limit their use to low-processing-temperature polymers and low-temperature automotive environments. Pyrolysis of biomass results in the formation of a porous substance called biocarbon, which can improve composite thermal performance, eliminate odor, and reduce hydrophilicity. The objective of this study was to investigate the effects of biocarbon on the performance of biocarbon-glass fiber hybrid composites for use in under-the-hood automotive applications. This study evaluated the macroscopic (mechanical performance, density) and microscopic (SEM) characteristics of biocarbon-hybrid composites with varying loading level and biocarbon type. Biocarbon-hybrid composites were approximately 10-13% lighter than currently used fan-and-shroud materials and the addition of biocarbon content improved composite flexural strength & modulus.

Water Absorption Behavior of Recycled PP and PA6 Composites with Fiber Reinforcement
Sandeep Tamrakar | Rachel Couvreur | Alper Kiziltas | Janice Tardiff | Debbie Mielewski, May 2021

The recyclability of natural fiber and glass fiber reinforced polypropylene composites and glass fiber reinforced nylon composites have been studied through injection molding and mechanical grinding. Mechanical properties of virgin and recycled composites were assessed through flexural, tensile, and impact tests. No significant degradation in the mechanical properties of natural fiber composites was observed after subjecting the composites through several rounds of recycling and water absorption at ambient temperature in tap water. However, severe degradation in the mechanical properties was observed for glass fiber composites. For instance, after five cycles of recycling, only 59% of flexural strength and 64% of flexural modulus was retained for glass fiber reinforced nylon composite. This is mainly due to severe attrition in glass fibers caused by recycling as evidenced by studies on fiber length distribution. Water absorption tests conducted at room temperature and subsequent environmental conditionings such as freeze-thaw cycling and extended freeze cycling only affected nylon composites. At saturation point, water absorption for nylon composites was 7.7% by wt. after 45 days of immersion, which significantly affected the mechanical properties. The tensile strength of the nylon composites reduced from 88.4 MPa to 36.2 MPa, and modulus reduced from 5.6 GPa to 1.8 GPa after saturation.

The Journey to Stabilization of Automotive Plastic Applications
Emilie Meddah, April 2021

This paper will treat to expose the complexity of stabilization of plastics in automotive applications. First, we will review some basics on stabilization, the use of phosphites and phenolic antioxidants. We will cover the different aspects of polymer stabilization: during processing and along the service life of the parts. This will involve discussion around light stabilization too. Along this paper, we will see some examples of outstanding chemistries than can lead to combine several benefits to achieve the performances required by OEMs.

Advanced Thermpolastic Material Solutions To Improve Fuel Economy and Emissions Performance
Rodrigo Orozco, May 2020

Fuel economy and emission regulations are challenging automotive manufacturers to meet global targets, which are becoming more stringent over time, in particular, for internal combustion engine powered vehicles. Internal combustion engines will likely remain dominant for a long time and will require system innovations or in many cases electrification solutions to meet the regulations. This document describes the thermoplastic material solutions to meet the application functional requirements of engine solutions, such as turbocharging, exhaust gas recirculation and gasoline direct injection that are the current trend for system innovations of light-duty vehicles.

Characterization of the Non-Uniform Compression Behavior and the Internal Morphology in Flexible Polyurethane Foams Using Digital Image Correlation and X-Ray Micro-Tomography
Hieu Truong McElroy, May 2020

In this work, digital image correlation was performed during compression testing of twodifferent flexible polyurethane foams to obtain full-field strain maps and understand the non-uniformdeformation the foams exhibit. In addition, X-ray micro-tomographywas performed on the foam samples at different locations through the thickness to obtain micro-tomographs of the foams’ microstructures. Measurements and statistical analysis from these micro-tomographs made it possible to quantify the cell size distribution and their variation through the thickness, as well as identify differences in the microstructures of different foams.It was found that observations from compression tests with digital image correlation are in good agreement with observations from X-ray micro-tomography analysis.

Compounding Technology (Techniques and Tips) For Improved Performance and Productivity of Automotive
Paul Andersen, May 2020

Ever since the first polymer applications were incorporated into the automobile in the 1960’s, OEM requirements for polyolefin based automotive compounds have pushed the performance envelope with respect to, for example, improved mechanical properties such as flex modulus, tensile strength, and heat distortion temperature; aesthetic properties such as surface quality; processing characteristics such as viscosity; and as always, cost. However, density was not a critical concern since the part being replaced was most probably made of metal. To attain required physical, esthetic and viscosity properties such as those listed above, compound formulations have become very complex. The main additives to the base polymer in early automotive applications such as a battery tray, were typically glass fiber and/or mineral filler for reinforcement. However, as manufacturers have continued to push vehicle weight reduction, they are re-evaluating specifications for current polymer-based applications/parts, i.e. bumpers, trim, etc., for future model years. In most instances, all the specified mechanical and flow properties remain the same, but density is reduced between 5 and 10%. Generally, this requires an extensive material reformulation to meet the new specifications. As part of most light-weighting reformulations, high bulk density filler content is decreased and replaced with multiple grades of polypropylene having a wide range of viscosities. These resins need to be melted and uniformly blended to provide, for example, strength from a high MW, high crystallinity component and good flow characteristics from a low MW grade. Additionally, any IM (impact modifier) needs to be dispersed and uniformly distributed. For reinforcement to be effective, fibers need to be unbundled as well as maintain a critical length during the compounding process. Minerals, depending on their structure, need to be distributed and/or distributed and dispersed. The co-rotating twin-screw compounder has long been the equipment of choice for such compounding functions. However, compounders still face processing challenges such as how to optimize the extruder set up to uniformly compound 1) diverse viscosity matrix polymers, 2) incorporate and disperse impact modifier, 3) unbundle and distribute fibers, and/or 4) feed, distribute and disperse a poor flowing, “sticky” mineral filler or possibly an easy to fluidize low bulk density talc while simultaneously maintaining an economically viable production rate. Additionally, the process can be challenged to maximize fiber length in high viscosity mineral filled formulations. This paper will review requirements for compounding automotive polyolefin compounds with an emphasis on recent innovations in Co-rotating Twin-screw technology that have enhanced product quality and productivity for these complex lightweighting material formulations.

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