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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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ANTEC®

The Influence of Laser Power Variation on SLS-printed PA6 Parts and their Long-term Properties
Tobias Heckner, May 2020

In the field of Additive Manufacturing (AM), Selective Laser Sintering (SLS) is well-known as anAM technique to produce partswith comparatively high load capacity. The usage of Polyamide 6 (PA6) materials allowshigher continuous operating temperatures than Polyamide 12 (PA12) materials, which aretypicallyused forSLS. For this work,PA6 SLS specimens were printed with a high temperature SLS industry printer. The samples were aged thermo-oxidatively at different temperatures, tested mechanically and investigated with different analytical methods. The SLS processing of PA6 materials has not beenstudied sufficiently yet. The aim of this study was to deliver first contributions:the laser power energy wasvaried to identify the influence on the mechanical properties of the printed specimens andtheirlong-term properties. In addition, the material structure of the specimens wasinvestigated and the viscosity number (VN) was determined.

The Influence of Recycling On Thermotropic Liquid Crystalline Polymer and Glass Fiber Composites
Tianran Chen, May 2020

In this paper, high-performance thermotropic liquid crystalline polymer (TLCP)/polypropylene (PP) and glass fiber (GF)/PP composites were prepared by the injection molding process. Mechanical recycling of TLCP/PP and GF/PP composites consisted of grinding of the injection molded specimens and further injection molding of the granules. The influence of mechanical recycling on mechanical and thermal properties was investigated. In situ TLCP/PP maintains tensile modulus and strength during the recycling process, indicating the regeneration of polymeric fibrils at each reprocessing stage. GF/PP composite exhibits deterioration of mechanical properties after recycling because of fiber breakage during processing, which is a very common issue on reusing glass or carbon fiber reinforced composites. The experimental results reveal that the TLCP/PP composite has better recyclability than GF/PP and significantly enhances the mechanical properties of the blend.

The Use of Novel Biomaterials For Affordable Packaging
Karnik Tarverdi, May 2020

The effects of the use of biomaterials for the development of novel packaging composites have been evaluated. An increase in the amount of treated fillers improved the dispersion of the particles and consequently led to an enhancement of the mechanical properties of the materials. The composites were melt-blended using co-rotating intermeshing twin screw extrusion technology and although there can be degradation of the organic additives during extrusion processing, it did not affect the dispersion of the novel biocomposites and the biofillers.A range of techniques used to characterise these materials will be discussed, including morphology, differential scanning calorimetry, (DSC), Scanning electron microscopy (SEM), including experimental techniques likemechanical property evaluations.

Thermal Derating Factors for Fused PVC
Tom Marti, May 2020

The use of PVC pipe has been expanded in the most recent edition of AWWA C900-16. Once solely for drinking water, the AWWA C900 standard now includes reclaimed water, irrigation water, wastewater, or any other fluid compatible with nonplasticized PVC. When limited to drinking water, there is relatively little use for PVC to operate at elevated temperatures. The scope increase including industrial, raw water, geothermal, and other opportunities now make the use of PVC pipe viable so long as the pipe can meet temperature and pressure requirements. The hypothesis tested is that the present set of thermal derating factors may contain room for adjustment with the present PVC pressure pipe extrusion formulations and technology. This presentation details out the test methods used to screen and then develop derating guidance for fused PVC pipe. Screening methodology and results to validate the hypothesis are discussed. With positive results from the screening, the long term testing done to develop an alternative set of derating factors is also included.

Thermoplastic Elastomer Blend Exhibiting Combined Shape Memory and Self-Healing Functionality
Christopher Lewis, May 2020

Here we report on a polymer blend consisting of a soft-thermoplastic polyurethane (TPU) elastomer and a low melting temperature thermoplastic healing agent (Polycaprolactone, PCL) capable of repairing highly deformed cracks without the need for an external load. In this study, a blend containing 30wt% PCL (30PCL) was shown to exhibit two well-separated melting transitions thus enabling shape memory behavior. Moreover, upon heating to above PCL’s melting temperature the flow of PCL into an undeformed crack was shown to fill the crack void thus promoting self-repair. A combined healing mechanism relying on both shape memory and self-healing action was demonstrated. Through the simple action of mild heating (90C/30 minutes), fracture surfaces are brought into intimate contact through the action of shape memory recovery and subsequently healed. Healing efficiency was evaluated by comparing the tensile force restoration after healing of a highly deformed, notched sample to its behavior prior to notching. Here it was shown that the polymer blend exhibited full restoration of its originally mechanical integrity whereas the mechanical performance of pure TPU was only minimally restored (about 5%). This blend is based on thermoplastic ingredients and thus able to be converted using conventional melt processing. Applications of such blends can be extended to products prone to damage such as liner materials, protective coatings, sporting goods and shoe soles.

Towards Multi-Tiered Quality Control In Manufacturing of Plastics and Composites Using Industry 4.0
Saeed Farahani, May 2020

One of the most important topics in modern manufacturing, Industry 4.0 is quickly changing the way in which production lines in many industries operate. Industry 4.0 broadly refers to the connection of multiple manufacturing systems into a large system in which those individual systems communicate with one another. With systems connected in such a fashion, manufacturers can easily obtain actionable data from every aspect of their systems and use that data to improve their processes. Generally, Industry 4.0 technologies will vary significantly with application, and as a result, it can be difficult to develop an effective system from scratch. Given the increasing quality requirements demanded of the composites industry, particularly from automotive manufacturers, the development of an effective system to integrate data from the manufacturing process and apply it to advanced quality control methods is critical. Accordingly, we propose the concept of a multi-tiered system that combines machine data, in-mold sensors, external sensors, and a human component for use in plastics or composites manufacturing settings. Using this infrastructure, a multivariant analysis is first conducted to evaluate the advantages and limitations of each data sources in terms of determining process and part deviation. In the second study, the feasibility of developing a framework for monitoring quality of injected parts is investigated using a machine learning approach.

Transition From Ductile Failure To Brittle Fracture of High Density Polyethylene Under Creep Loading
Na Tan, May 2020

Uniaxial creep tests on notch-free specimens were conducted on unimodal high-density polyethylene (HDPE) over a wide range of stress and temperature. As expected, occurrence of ductile failure or brittle fracture was found to depend on the applied stress and temperature. In this work, a stress-time-temperature (StT) expression was established to construct the master curve of stress versus creep time to ductile failure (or brittle fracture) at a given temperature, which contains the transition between the two behaviors (commonly known as the DB transition). For the unimodal HDPE used in this study, critical stress for the DB transition was found to decrease significantly, from 11.43 to 6.50 MPa, by increasing test temperature from 296 K to 358.5 K. The corresponding time also reduced considerably, from over 560 hours at 296 K to about 6 hours at 358.5 K. In addition, critical stress for the DB transition shows a good correlation with one characteristic quasi-static stress that we reported before. Such a phenomenon sheds a light on the possibility of using a short-term test to characterize DB transition of PE pipe.

Transition Metal-Catalyzed Degradation of Polymers: Review and Future Perspectives
Andrew Worthen, May 2020

In many instances, failure of polymer-based articles is attributed to chemical interaction with metals or metallic compounds. Indeed, the stability of polymers is often modified by these species; however, their effects on the degradation of polymers are complex and influenced by many factors. This paper reviews known polymer degradation mechanisms and how metals may influence them, discusses deactivators and their role use as stabilizers in polymer formulations, provides literature-based vignettes describing example scenarios where metal-accelerated degradation of plastics may contribute to failures, and provides commentary regarding potential future areas of work in the field.

Understanding the Limitations of 3D Printed Polymers Through A Staged Screening Protocol
Jessica Hemond, May 2020

Direct printing of polymers has continued to advance with new printing technologies and engineering grade materials allowing actual additive manufacturing versus 3D printing of prototypes. Key developments include the adaptation of digital light processing (DLP) printers as well as improvements to and novel powder-based printing systems. These technologies offer the ability to bring new printed materials to the market. However, simply because a material can be printed does not mean that it will function well. With the number of printing and material advances, the need to understand possible failure modes and incorporate that knowledge into screening testing is critical. This work provides basic consideration and screening methodology to ensure that these possible material failure modes are accounted for.

Upcycling Ocean Bound PET Waste Into Durable Materials
Peter Vollenberg, May 2020

Dealing with plastics waste is a major issue confronted by the society. Single use items from water bottles to plastic packaging are major contributors to the generation of plastics waste globally. Innovative upcycling technology can transform a plastic with limited applications and a brief useful life into a different, more-durable resin with expanded potential uses and an extended lifetime. In this way, upcycling can help strengthen the circular economy and can help reduce the impact of single-use plastic applications on the environment. Using propritary de-polymerization of recycled polyester, SABIC has introduced a more sustainable polyester products family containing up to 60% recycled materials. This new PBT and its compounds have similar purity and properties as virgin resin. Hence they are drop in for many virgin PBT or compounded products. Chemistry, properties, and application for these sustainable polyester materials will be discussed. In particular, the application of ocean bound based resin in Dell computer fan housing will be highlighted.

Use of Gradually Changing Profile Shape in Extrudate Sizers for Simplification of Die Design
Mahesh Gupta, May 2020

Simulation of the flow and extrudate deformation in two extrusion dies with gradually changing profile shape in successive sizers is presented. The change in the profile shape in sizers is used to employ a simpler die geometry and then deform the extrudate in sizers to the required final product shape. Effect of non-uniform exit velocity, cooling shrinkage and shape of sizer profiles on extrudate deformation is included in the simulation. The predicted extrudate shape and layer structure is found to match accurately with those in a coextruded product.

Validation of the Virtual Lifetime Prediction Method for Elastomer Components
Simon Rocker, May 2020

In the field of mechanical engineering technical elastomers are indispensable due to their material properties. They are often used to avoid load peaks and to influence the vibration behavior of dynamically loaded systems, because of their damping characteristics. Therefore, one field of research constitutes the damage accumulation and lifetime prediction. This paper presents the validation of the virtual lifetime prediction model method, which was developed at the institute of product engineering at the University of Duisburg-Essen. The lifetime is defined as the number of load cycles till the global damage reaches the value 1. This damage is calculated by a failure criterion based on the change of a characteristic value like the dynamic stiffness degradation from a finite-element (FE) simulation. The virtual lifetime prediction method uses a combination of a damage-dependent material model (Yeoh-Model) and a nonlinear damage accumulation model (nlSAM). Both models are calibrated by means of experimental data from dynamically loaded elastomer components. The nlSAM computes the local damage for each finite element depending on material stresses and pre-damage. The dynamic stiffness degradation is a result of locally changed material properties in the FE simulation due to the damage of each element. Finally, the lifetime prediction for unknown loads and different component geometries of the elastomer is carried out, which shows good agreement with the experimental data of the same material batch.

Viscosity Considerations In Multilayer Coextrusion
Deepak Langhe, May 2020

Due to complex viscoelastic nature of the polymers, it is challenging to process multicomponent structures with uniform layer thicknesses. Although multilayered structures have been processed in a broad array of polymer materials and formulated to service a wide range of applications, a clear understanding of the effects of viscosity matching on the uniformity of the layer periodicity is not well understood. Significant work on viscous encapsulation and secondary flow patterns in the die channels affecting the layer structures has been previously reported. However, further evaluation of these effects on wide range of materials in commercial coextrusion lines has been limited. In this paper, we look to extend the initial studies of rheology in multilayered materials via layer multiplication coextrusion approaches and demonstrate preliminary results on model systems that illustrate the effect of mismatched viscosity on coextrusion multilayered polymer materials systems.

Workflow for Enhanced Fiber Orientation Prediction of Short Fiber-reinforced Thermoplastics
Susanne Kugler, May 2020

In this paper a workflow is proposed for an enhanced fiber orientation prediction in injection molding of short fiber-reinforced thermoplastics. The workflow is easy-to-use, as the final fiber orientation prediction is integrated into the commercial software Moldflow®. For a given material with polymer matrix P and a volume fraction x of fibers, four steps have to be performed: 1) Generating a representative volume element (in the following, referred to as cell) with volume fraction x and mean fiber length, 2) Shearing of the cell using a mechanistic fiber simulation, 3) Calculating the transient fiber orientation tensor and fitting macroscopic parameters and 4) Performing the fiber orientation analysis with the optimized macroscopic parameters in Moldflow®. Based on experimental data, the pARD-RSC model was selected as macroscopic simulation model. It was implemented in Moldflow® via the Solver API feature. The enhanced workflow is validated at the example of two industrial applications with different polymer matrices and different fiber volume fractions. With the proposed workflow, we observe equal or higher accuracy of fiber orientation estimation in comparison to Moldflow® fiber orientation models RSC and MRD.

Review of PE Pipe Lifetime Prediction Based on Pent Test
I. Sedat Gunes, Feina Cao, Sadhan C. Jana, May 2010

A new method of evaluating polyethylene (PE) pipe brittle failure time has been recently proposed. The method consists of an extrapolation of the failure time in standard PENT test to brittle failure time of PE pipes of arbitrary diameter and wall thickness at various loads and temperatures. The method is based on several assumptions that have not been adequately addressed in [1]. This paper presents a detailed review of the theoretical and experimental basis of the extrapolation proposed in [1] and reveals its limitations. A fracture mechanics analysis of the PENT test is presented. It requires evaluation of parameters in power law" equation of the slow crack growth (SCG). Thus a specimen whose stress intensity factor (SIF) is independent of crack length has been used to serve this purpose. Such specimen allows an accurate determination of crack growth rate vs. SIF relationship and thus predicts the duration of SCG stage of brittle fracture process at various temperatures. The study indicates that the formula proposed in [1] can be used for materials ranking with respect to SCG resistance within a limited temperature range but is inadequate for estimation of lifetime in brittle fracture."

Water Vapor Transport Properties of Shape Memory Polyurethane Nanocomposites
I. Sedat Gunes , Feina Cao , Sadhan C. Jana, May 2010

In this paper water vapor permeability (WVP) of thermoplastic polyurethane nanocomposites with crystalline soft segments was evaluated. Organoclay nano-size silicon carbide (SiC) and a high structure carbon black (CB) were mixed with shape memory polyurethane (SMPU) based on semi-crystalline soft segments. All nanocomposites were prepared by bulk polymerization using a Brabender internal mixer. Compression molded specimens were used in the determination of WVP. The results indicated that the presence of silicon carbide augmented WVP by reducing the soft segment crystallinity whereas that of organoclay reduced the WVP considerably due to excellent exfoliation.

Polymer Clay Nanocomposites of Linear Low Density Polyethylene (LLDPE) and Polyoxymethylene (POM)
M. Shahlari, P. L. Roberts and S. Lee, May 2008

Polymer-clay nanocomposites involving a blend of two otherwise incompatible thermoplastic polymers were prepared and investigated for the effects of adding organically modified clay. Linear low density polyethylene (LLDPE) and polyoxymethylene (POM) at several composition ratios (70/30, 50/50, 30/70) were melt mixed with 5% Cloisite 15A and 5% Cloisite 30B, respectively. Their blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The LLDPE/POM (70/30) blend nanocomposites incorporating Cloisite 15A showed co-continuous morphology according to the SEM images, while those with Cloisite 30B showed some limited levels of compatibility. Further, Cloisite 15A improved the melting temperature of LLDPE and POM while Cloisite 30B had no significant effect on the LLDPE melting temperature but increased the melting temperature of POM. As for the LLDPE/POM (30/70) blends, Cloisite 15A made the two originally incompatible phases indistinguishable, while the blends containing Cloisite 30B showed a significant decrease in the domain sizes. However, the blend samples without organoclay incorporation did not exhibit any compatibility and the dispersed phase was totally segregated. TGA results showed that addition of clay decreased POM degradation temperature but there was no significant changes detected in PE’s. The clay’s compatibility with one or both polymers is shown to make a significant difference in the blend morphology and compatibilization mechanisms of the polymer-clay nanocomposites, which are phenomenologically explained in this paper.

Evaluation of Shape Memory Properties of Polyurethane Nanocomposites with High Hard Segment Content
F. Cao | S. C. Jana, May 2008

Shape memory polyurethane (SMPU) with high hard segment content offers good shape recovery ratio and high recovery stress. This study considered further improvement of shape recovery stress with the introduction of nanoclay. Reactive nanoclay particles were tethered onto polyurethane chains via urethane groups and provided extra crosslink points. This led to increase of modulus and recovery stress, e.g., a recovery stress of 19 MPa with 5 wt% clay compared to 13.5 MPa for unfilled PU. The recovery ratio of SMPU was not influenced by the addition of clay. The influence of stretching rate, stretching ratio, and stretching temperature on shape recovery force was studied.








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