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.

The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?

Not an SPE member? Join today!

Use % to separate multiple keywords.

Search SPE Library

Recycling

Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.

Influence of High-Speed Extrusion on Structure and Properties of Bioplastics Blends

Margaret Sobkowicz, JeongIn Gug, May 2017

This work describes a novel, high-speed twin-screw extrusion process applied to blends of bioplastics. The blends were chosen for their ability to combine synergistic polymers to produce more robust bioplastics with diverse properties. The influence of interfacial reaction was also studied, both from the perspective of morphology development and final properties improvements. Immiscible PLA/PA11 blends were successfully compatibilized by in-situ reactive twin-screw extrusion. During processing, the molecular weight of PLA sharply decreased due to chain scission. Mechanical property improvement was realized through processing parameter optimization and addition of a chain extender.

Keratin Bio-Composites with Polysiloxane Thermoplastic Polyurethane

Firoozeh Pourjavaheri, Oliver A.H. Jones, Isaac Martinez Pardo, Frank Sherkat, Arun Gupta, Robert A. Shanks, May 2017

A sustainable resource in the form of chicken feather derived keratin was used to enhance the thermo-mechanical properties of polysiloxane-polyurethane bio-composites. Two methods, solvent–casting–evaporation–compression molding, and solvent–precipitation–evaporation–compression molding were used to create new bio-composites incorporating 20 %·w/w of chicken feather fibers into a polysiloxane-polyurethane matrix and the results were compared. A molecular modeling visualization indicated the possible existence of hydrogen bonding between fibers and polyurethane molecules. The thermo-mechanical properties of both the polysiloxane polymer and feather reinforced bio-composites were assessed using thermogravimetry, dynamic mechanical analysis and stress–strain measurements with hysteresis loops. The dispersion uniformity of the keratin fibers in the plastic matrix was investigated via macro photography. Addition of chicken feather fibers to the polysiloxane matrix was found to decrease the recovery strain and mass loss of the composites (at lower temperatures) but increase the elastic modulus, storage modulus, and char level (at higher temperatures). The results demonstrate that keratin derived from what is currently a waste product from the poultry industry (with significant economic and environmental disposal costs) can improve the thermo-mechanical properties of the tested bio-composites simply and cheaply, with potentially large cost savings and environmental benefits.

Latest Developments in TPO Stabilization for Automotive Applications

Emilie Meddah, May 2017

In the past few years started a race for performances in TPO compounds for Automotive applications. Lighter, stronger, more durable, better aesthetics, more sustainable, less smell, a large amount of requirements for a given part in vehicles is making new developments more and more demanding and challenging. Clariant Business Line Polymer additives, specialized in polymer stabilization, is introducing new solutions which provide most of the current performances requested by the OEMs and beyond. Heat and light stabilization, low odor, surface appearance, low/no blooming are some of the qualities provided by this new range of products dedicated to Automotive TPOs under the AddWorks terminology. Specific AddWorks have been developed for Interior, Exterior and Under-the-Hood applications, and will be presented here.

Long Fiber Orientation and Structural Analysis Using Moldex3D, Digimat and ABAQUS Simulations

Jessica Lin, Huan-Chang Tseng, Chia-Hsiang Hsu, Rong-Yeu Chang, May 2017

Long fiber-reinforced thermoplastic composites open up exciting new possibilities for the green automotive industry, owing to excellent mechanical properties, advantageous weight reduction, and economical fuel consumption. However, fiber microstructure including fiber orientation and fiber length, is a very critical issue to cause anisotropy in mechanical properties and warps. For an injection-molded, long-glass fiber composite part, we use Moldex3D to obtain an accurate fiber orientation prediction. Thus, mechanical properties depending on the predicted orientation is calculated via Digimat. It is ultimate to explore changes in stress with respect to strain in the ABAQUS structural analysis. All of the predictions are compared with experiments herein.

Material Characterization of CF-Nonwovens with Thermosetting Matrices

Jasmin Mankiewicz, Michael Heber, Ernst Cleve, Jochen S. Gutmann, May 2017

Regarding the need of robust and lightweight materials there is an increasing market for carbon fiber (CF). Therefore blending fabrics produce a huge amount of valuable process waste like prepregs which are out of specification and end-of-life products. The carbon fiber is regained from polymer matrix by new recycling methods. These fibers are chopped and can be reused for manufacturing isotropic fleece by wet-laid process. Created fleeces are impregnated with thermosets by resin transfer molding (RTM). At the beginning the isotropy of the fleece is verified by a circular disk and a 4-point bending test. After that the influence of different fiber surface weights and homogeneity, as well as no significant effect of various dispersing agents are identified. In addition to that the interrelation between fiber volume content, fiber length and specific values (tensile strength, flexural stiffness, Young's modulus) is analyzed. Referring to the results for thermosets with virgin fibers the process is transferred to recycled fibers.

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.

Methodology to Improve Injection Molding Energy Performance: Successful Case Studies

Iván D. López, Juan C. Ortiz, Alexander Hernández, Omar Estrada, May 2017

Energy efficiency of injection molding is critical to increase the sustainability indexes of this process and to reduce production cost. The Energy Gap Methodology (EGM) is presented as a valuable tool to prioritize the interventions to increase the energy efficiency in injection molding and other polymer processes. This methodology identifies four gaps: production, process, technological and R&D gaps. Three industrial successful case studies reducing energetic gaps in injection molding are presented, obtaining specific energy consumption (SEC) reductions between 9 and 15%.

Microcellular Foaming Behavior of Biodegradable Poly (3- Hydroxybutyrate-CO-3-Hydroxyvalerate)/Polylactic Acid Composites

Jiajun Ju, Zijian Li, Qinglin He, Xiangfang Peng, Tairong Kuang, May 2017

In this paper, Biodegradable poly (3-hydroxybutyrate-co- 3-hydroxyvalerate) (PHBV)/polylactic acid (PLA) biocomposites were prepared using the Hakker rheometer. We investigated the effect of various PLA content on the PHBV’s thermal properties and on its foaming behavior. The differential scanning calorimetry (DSC) results showed that the presence of PLA facilitate the cold crystallization of PHBV matrix. Along with the addition of PLA, the melt temperature of composites are lower than pure PHBV. SEM results of foamed samples presented that the addition of PLA led to the various foaming morphologies, and cell morphologies was changed from close cell to open cell as increasing the content of PLA in the PHBV matrix. The changed foaming morphology was attributed to the phase morphology and composites melt strength changed, and the resultant mechanism was also proposed.

Microencapsulation of Pamitic Acid with Polylactic Acid Shell for Thermal Energy Storage

Maryam Fashandi, Siu N. Leung, May 2017

Microencapsulation of vegetable-derived palmitic acid (PA) in bio-based polymer shell of polylactic acid (PLA) by solvent evaporation and oil-in-water emulsification was investigated. This study deals with the preparation and characterization of PLA-PA microcapsules. Chemical structures, morphology of microcapsules, and thermal properties were determined by Fourier transform inferred spectroscopy, scanning electron microscopy, and differential scanning calorimetry, respectively. In short, this work has demonstrated the possibility to fabricate 100% bio-based phase change material microcapsules for thermal energy storage applications.

Micro-Graphite Enhanced Extrusion Foaming of PET Resin

Feng Chen, Zhi-Yu Min, Eusebio Cabrera, Jose Castro, Ly James Lee, May 2017

Extrusion foaming of neat and recycled polyethylene terephthalate (PET) resins are difficult due to their high melting temperature and low melt strength. Chemical crosslinking modification of the PET resins is the most widely used method to solve this problem. However, the modified resins are expensive and difficult to be re-used. In this work, micro-graphite or nanoclay particulates were added to PET to adjust its melt viscosity and strength and to serve as a nucleation agent to facilitate cell growth during extrusion. Micro-graphite is an excellent infrared attenuation agent (IAA) that may provide enhanced thermal insulation to PET foams. Using our small lab extruder, the foamed micro-graphite/PET composite extrudates could reach a low density of 0.21 g/cm3, close to that achieved by chemical crosslinking modified PET resins, using injected hydrofluorocarbon (HFC) as a blowing agent in extrusion. Properties of the PET foam including density, cell size, and crystallinity depend on particulate type and processing conditions.

Micropelletization of Virgin and Recycled Thermoplastic Materials

Christian Schäfer, Jackson S. Bryant, Tim A. Osswald, Stefan P. Meyer, May 2017

Traditional polymer powder and micropellet based processes, such as powder bed fusion and rotational molding, have been in increased demand in modern processing industries. These processes require polymer powders and micropellets with a small particle size, narrow size distribution and defined geometry for a variety of polymer resins. Therefore, micropelletization technologies, where particles in the size range of 50 to 1000 µm are generated, have been attracting growing attention over the past decade. A new technique, developed at the Polymer Engineering Center, yields micropellets with a controlled morphology and narrow particle size distribution. In this process, a polymer melt is extruded through a capillary and is subsequently stretched with a hot air stream until flow instabilities cause it to break up into particles. Small changes in process conditions result in different size distributions and particle shapes, such as lentil-like pellets, fibers and thread segments. This work shows how material properties and processing parameters influence the produced micropellets. Besides the processing of virgin thermoplastic material, recycled high density polyethylene flakes are used as feedstock for the micropelletization process in order to show the capability of this process to contribute to current polymer recycling efforts.

Modified Polylactide with Improved Thermal and Rheological Properties for Foaming

Svenja Göttermann, Christian Bonten, Tobias Standau, Volker Altstädt, May 2017

Polylactide (PLA) is the most important bioplastic on the market due to its good mechanical properties and the permanent growth of the production capacity. One drawback of commercial polylactide is its too low melt strength and melt extensibility, which is disadvantageous in terms of foaming. To overcome these commercial grades need to be modified. Therefore, several chemical modifiers were used to induce crosslinking, chain extension or grafting by means of reactive extrusion on a twin-screw extruder. The best results were achieved with organic peroxide. With this modifier the melt strength and the crystallization rate were improved and lead to foams with a closed-cell structure and low density. Organic peroxide was found to be more efficient than the commercial multifunctional epoxide modifier.

Multilayer EVOH/HDPE Packaging in Processing and Performance of Recycled HDPE

Jon Mitchell, Didier Houssier, Geert Herremans, Edward Kosior, Kelvin Davies, May 2017

Kuraray, EVAL Europe N.V. (EE) produces Ethylene Vinyl Alcohol copolymers (EVAL™), which are used in multilayer structures in a combination with a wide range of materials such as High Density Polyethylene (HDPE) to produce multilayer bottles to provide superior barrier properties to gases, flavours or bring functional barriers against external contaminants such as mineral oils (MOSH,MOAH). Bottles are typically made by Co-Extrusion blow moulding (Co-EBM) technology and are used for beverage packaging such as dairy products and specialty milk and other packaging applications for sauces or dressings or for the packaging of medical products for which the Water Barrier of HDPE is of added value. The objective of the study was to investigate if multilayer EVOH/HDPE rigid packaging material, which is a percentage of the post-consumer recycling stream, can be effectively sorted with the HDPE stream and decontaminated back to food grade approved for use as Post-Consumer Recycled (PCR)-HDPE into food packaging applications. Multilayer rigid food packaging found in the post-consumer recycling stream has been represented in the design of materials guides and recycling guides as ‘may be suitable’ for recycling. The present work investigates the recyclability of EVOH barrier packaging due to the growing trends of multilayer rigid food packaging and more importantly, as recovery systems strive towards a better circular economy. The steps taken to produce food grade rHDPE with analysis included; Audits of the HDPE fraction at Viridor MRF, testing on automated NIR sorting equipment at Tomra (Titech), compounding in a low pressure, elevated temperature, food-grade decontamination process and overall migration testing conducted by Smithers-Pira. The evaluation showed that post-consumer HDPE (rHDPE) material containing at least 0.25% EVOH (equivalent to 5% multilayer EVOH/HDPE packaging) can be “super cleaned” to food grade quality without any significant impact on the process performance or physical properties compared to rHDPE only. The results showed that at the levels of multilayer EVOH packaging typically found in the recycled HDPE stream, the rHDPE can be processed and utilized in a full range of applications, without impact on migration characteristics or physical properties compared to rHDPE alone.

PHA and PLA Biodegradable Plastics with Rice Straw Filler to Create Biobased Structural Insulating Panels (BSIPs)

Joseph Greene, May 2017

Biobased composites were produced with PHA and PLA biodegradble plastics with rice straw and walnut shells as fillers. Rice straw laminate bio-composite boards were produced with PHA and PLA biodegradable plastic pellets with rice straw in a Leitritz twin screw extruder. Rice straw and walnut shells were added to PHA/PLA plastic to form a rice straw composite with 40% filler and 60% plastic. The pellets were compression molded to form the skins of the BSIP. PLA foam was used to produce the biobased foam core. The PHA, PLA, rice straw, and walnut shell mixtures were injection molded and different concentrations of rice straw and walnut shell filler. Tensile testing results show that PHA/PLA blend had 16% lower modulus and 33% less load than PLA by itself. Walnut shells and rice straw reduced the tensile strength and elongation of the plastic composite but increased the tensile modulus. Walnut shells and rice straw also decreased the impact strength of the plastic biocomposite. The biocomposite panels can be combined with a PLA foam core to form the biobased structural insulating panels.

Plastic Packaging Recycling Using Intelligent Separation Technologies for Materials (PRISM)

Edward Kosior, Jon Mitchell, Kelvin Davies, Martin Kay, Rafi Ahmad, Edwin Billiet, Jack Silver, May 2017

A new way of rapidly sorting packaging into high purity streams (> 99%) has been developed based on intelligent labels with invisible markers that can be detected and sorted using existing high-speed optical sorting systems used in MRFs with minor modifications. The principles have been proven using a range of commercially available UV responsive fluorescent markers with high emission yields. A full-scale commercial optical sorting trial was conducted at the MRF facilities of Tomra in Germany. Sorting of used plastic packaging for closed loop recycling back into food packaging requires positive identification and sorting of the recycled materials to a higher standard. The operators of commercial food grade recycling processes are required to demonstrate the recycled materials meet relevant European Food Safety Authority (EFSA) criteria; these require at least 95% (PET) and 99% (HDPE) of the feed material must have been used for food contact in their first life. The initiation of closed loop food grade recycling of PP packaging is awaiting a viable technical solution to differentiate the food grade packaging. From previous sorting trials, it can be estimated that of the 143,000 tons of PP food packaging used annually [1], 77,077 tons could be recovered each year in the UK. The objective of this project was to further develop the fluorescent marker technology investigated in earlier projects that has the potential to meet EFSA requirements and to extend the scope to different applications, enabling and facilitating the sorting of different polymers to a high degree of purity. The scope of the project included the optimisation of fluorescent compounds, evaluation of their stability in the supply chain and the ability of the compounds to be effectively removed during the cleaning and decontamination process. The project investigated the viability of the technology and its capacity to be implemented in the UK and elsewhere. Unlike existing NIR sorting systems [2], this technology uses commercial labeling and decoration methods to sort targeted streams potentially including food-contact plastics, bioplastics, chemical packaging, automotive plastics, black plastics and different grades of one plastic. This technique has the potential to create new recycling loops for food grade PP, milk bottle sorting and PET products. The project demonstrated that the use of commercial labels incorporating fluorescent markers can be used to sort plastic bottles and packaging with high yields and purity.

Processing of In-Plant Mechanically Recycled PA-12

Tino Meyer, Paul Sherratt, Andy Harland, Barry Haworth, Chris Holmes, Tim Lucas, May 2017

The increasing public awareness and demand for a more sustainable handling of the earth’s resources has led to the idea/ concept of a circular economy. Within this concept materials will be re-used in a closed loop system rather than being down-cycled or inappropriately managed (disposed via landfill) at the end of their life-cycle. Based on previous research, Polyamide 12 (PA-12) is a promising material candidate in the sports and leisure sector and its ability for being reprocessed via injection molding has been investigated. While other PAs tend to show a decrease in impact properties on mechanical recycling, PA-12 is shown to be able to overcome these problems when reprocessed at a higher melt temperature, yielding samples with improved impact properties compared to the primary material.

Reduction of Energy Consumption in Injection Molding of Polypropylene Parts through the Optimization of Mold Thermal Control

Giovanni Lucchetta, Davide Masato, Marco Sorgato, May 2017

The environmental impact of the injection molding process is mostly due to electricity consumption. This is particularly significant for packaging applications, which are the largest application sector for the plastics industry. In this work, electricity consumption measurements of the process were performed, considering a large packaging plant. In particular, the energy consumption related to mold thermal control were analyzed and minimized through a representative case study. The effects of alternative cooling channels configurations and different process parameters were experimentally investigated, considering also their influence on the quality of the molded parts. The results indicated that the common industrial practice for mold thermal control is highly inefficient. The implementation of electricity consumption measurements allowed the optimization of molds thermal control leading to considerable economic savings.

Relationships between Low Temperature Impact Performance and Structures of Rotationally Molded Crosslinked High Density Polyethylene

Yueqing Ren, Xia Dong, Xuelian Chen, Xiaojie Sun, Shuguang Wang, Yafei Li, Dujin Wang, Wenbin Liang, May 2017

The low temperature impact performance of rotationally molded specimen is of great importance for the final products. Crosslinked high density polyethylene (XL-HDPE) is a preferred material for large chemical and fuel tank due to its superior environmental stress crack resistance and high impact strength. In the present research the drop weight impact strength (defined as ARM impact strength) of rotationally molded XL-HDPE was carried out at -40°C and the relationships between impact strength and microstructures were investigated. The results confirmed that the microstructures of XLHDPE molecules in the innermost surface layer dominated the low temperature impact performance of rotationally molded XL-HDPE articles.

Research and Application of Gas Counter Pressure Technique to the Strength of Co-Injection Molding

Yan-Mao Huang, Wen-Ren Jong, Chi-Hung Kao, Chien-Chou Wu, De-Wei Liu, Shyh-Shin Hwang, May 2017

With people’s daily life full of various plastic products, many molding technologies are developed in order to reduce production cost, increase product strength, improve product appearance, and adhere to environmental protection. Co-injection molding is also known as sandwich molding, producing composite plastic products with a multilayer structure through one injection procedure. Most manufacturers use secondary recycled material or high strength plastics as the core material to reduce material cost and increase product strength or utilizes an appropriate proportion of materials to improve product strength and surface quality. This study employs the GCP(Gas Counter Pressure) technique in the co-injection molding process to increase product strength. As co-injection molding has two flow front behaviors of melt, the skin layer thickness distribution and core penetration length are difficult control, and the fountain flow effect results in an unstable injection of core melt. Therefore, the gas counter pressure technique in co-injection molding can inhibit the flow front behavior. This study discusses the effect of the gas counter pressure technique on core penetration and mechanical strength as well as the effect of penetration length and penetration section of core melt on mechanical strength under different gas counter pressure intensities. The experimental results show that the gas counter pressure mechanism enhances core material penetration stability, changes the penetration length and penetration section of core material, and effectively enhances the end product strength.

Rotational Molding of Polylactic Acid and Agave Fiber Biocomposites

Jorge R. Robledo-Ortiz, E.O. Cisneros-López, A.A. Pérez-Fonseca, D.E. Ramírez-Arreola, R. González-Núñez, Y. González-García, D. Rodrigue, May 2017

In this work, biocomposites of agave fibers (Agave tequilana Weber var. Azul) and polylactic acid (PLA) were produced by rotational molding. In particular, a simple dry-blending technique was used to disperse the agave fibers in the biodegradable polymer matrix. The effect of fiber content was studied (0, 10, 20, 30, and 40 wt.%) and the samples were characterized in terms of morphology, density and porosity to relate with mechanical properties (tensile, flexion, impact and hardness). The results showed that rotomolded biocomposites were successfully produced, but had high porosity leading to lower properties for fiber contents above 10%. It was possible to observe that low fiber contents produced the best morphology, indicating that there is an optimum fiber content to get well-distributed fibers in the matrix.

1
···
12
13
14
15
16
17
18
···
85