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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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Effects of Supercritical Carbon Dioxide Processing on the Crystallization of Polyvinylidene Fluoride
Polyvinylidene fluoride (PVDF) is an environmentally friendly, durable and low-cost alternative to traditional piezoelectric materials in sensors and actuators. PVDF is a semi-crystalline polymer with different crystal phases. Among them, the polar ß-phase is the crystalline structure that is responsible for its piezoelectric property. Conventional technology for promoting ß-phase crystals in PVDF is mechanical stretching. In this paper, processing of PVDF with supercritical carbon dioxide (ScCO2) was investigated to examine its effect on PVDF’s crystallization behavior. In the long-run, elucidation of potential strategies to tailor PVDF’s crystal structures would help to identify feasible route to tailor PVDF’s crystalline structure for emerging applications including sensing and energy harvesting. The foam morphology of PVDF was analyzed by scanning electronic microscopy while its crystallization behavior was studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. Experimental results reveal that PVDF samples foamed at 120°C and 160°C under 2000 psi showed the highest crystallinity (54%) and volume expansion ratio (15.4 times), respectively. The crystallinity increase in ScCO2 processed PVDF represents a 16% increase over that of its compression-molded samples.
Sustainability of PVC (Vinyl) Pipe: A Comprehensive Environmental Review
• Thorough review of LCA data • Transparently report the findings to the water, sanitary sewer, and storm drainage industries • Support the goals and vision of the 2010 USEPA Clean Water and Safe Drinking Water Infrastructure Sustainability Policy and the 2015 USEPA National Water Program on Climate Change • Ensures the long-term sustainability of water and sewer infrastructure • Comparative review of competing pipe products
Environmentally Benign Processing of Poly(2,6-Dimethyl-1,4-Phenylene Oxide) (PPO) with Superheated Liquids
the expanding industry of polymer processing, a prominent area of current research is to process polymers efficiently without creating any environmental hazards. Processing of intractable polymers like PPO requires high processing temperature and toxic plasticizers. Very few research works have reported the use of superheated liquids to process intractable polymers. This research work presents a systematic study to explore the advantages of processing PPO with superheated liquids composed of ethanol and water. Microcellular foams of PPO having a density range from 0.13 to 0.56 g/cm3 can be produced with the aid of superheated ethanol, water and ethanol/water mixtures. Such foams also exhibit high specific strength. In addition, PPO can also be extruded with superheated ethanol or ethanol/water mixtures at a temperature which is 150 to 180 °C below the conventional extrusion temperature for PPO.
Evaluation of the Mechanical and Morphological Characteristics of PLA-Lignin, PLA-Tannin and PLA-CNF Composites
PLA has now attained significant utility in the plastics and manufacturing sector. It high stiffness, strength and bio-degradability has made it an attractive option for in many applications including additive manufacturing. This paper presents the modification in properties of neat PLA with the addition of Lignin, Tannin and Carbon Nanofibers fabricated via high shear twin screw compounding. Lignin and Tannin were chosen as completely bio-based fillers and Carbon Nanofibers were chosen for their high performance and modest expense as compared with other carbon based nano-materials. Detailed morphological evaluation of the composites is also presented.
Fabrication of High Strength and Toughened Biodegradable Electrospun Fibers: Poly(Lactic Acid)/Biomax Blends
The objective of this study is to prepare a toughened and strengthened electrospun fibrous biodegradable poly(lactic acid) (PLA) mat blended with Biomax, an ethylene copolymer designed to modify PLA to improve toughness properties, using electrospinning. Morphological, thermal, mechanical, and thermomechanical properties of PLA/Biomax blends were investigated. Morphological findings indicated that the electrospun PLA/Biomax fibers were uniform and smooth with an average diameter of 1.4-1.5 µm when Biomax contents below 2 % (w/v). The addition of 1 % of Biomax improved both thermal stability and mechanical properties of PLA/Biomax fibrous mats. PLA/Biomax mats with 1 % (w/v) of Biomax exhibited the maximum tensile strength of 4.6 MPa and tensile modulus of 103 MPa showing 64.3 % and 101 % improvement; as compared to neat PLA values of 2.83 MPa and 51 MPa, respectively. Furthermore, the presence of 1 % Biomax into electrospun PLA fiber mats improved the storage modulus by 107.5 % compared to PLA fiber mat (41.5 MPa). Strong and toughened PLA/Biomax biodegradable fibrous mat might be potentially suitable to be used in packaging, filtration, reinforcement of composite, etc.
Fabrication of Polypropylene Bio-Composites Utilizing Camelina Press Cake
Camelina (Camelina sativa (L.) Crantz, family Brassicaceae) is an emerging oilseed crop which produces high oil content but has a press cake that contains glycosinolates which are potential health risks if employed as an animal feed. As an alternative to a dietaric use Camelina press cake (CAM) was employed as a filler material to fabricate lignocellulosic plastic composites (LPC). LPCs were generated by blending polypropylene (PP) with 25% or 40% CAM with 0% or 5% by weight of maleated PP (MAPP) via a twin screw compounding and injection molding. Injection molded test specimens had mechanical and flexural properties comparable to neat PP.
High Performance Polymers for Medical Device Applications
EVONIK is a technology leader for high-performance polyamides, EVONIK’s current portfolio of specialty polyamides include PA12, PEBA (flexible polyamide), bio-based polyamides, transparent polyamides, and polyphthalamide materials for the medical sector. From catheters and balloons to diagnostic equipment and surgical instrumentation, VESTAMID® Care and TROGAMID® Care are well established. EVONIK offers flexibility in the design and manufacturing through our new Bonding VESTAMID® Care and TROGAMID® Care grade polymers. EVONIK’s VESTAKEEP® Care PEEK materials are used in temporary contact and instrument applications, while VESTAKEEP® PEEK i-Grades are used for permanent implant applications. From spine and sports medicine, to drug delivery devices and heart valve applications, new compounds of VESTAKEEP® PEEK are designed to meet the specific application needs and performance demands of medical sector.
High Speed Twin Screw Extrusion for Biodegradable Polymer Blends: Analysis of Compatibility and Rheology Prediction
This work examines the effects of high shear on the degradation and compatibility of blends of poly(propylene carbonate) and poly(butylene succinate) (PPC/PBS) in twin screw extrusion. Also, since solid PPC has poor flowing capabilities, different feeding methods for the TSE trials were compared for their ability to produce consistent results. The blends were compounded at 200, 500, 1000 and 2000 rpm. Viscosity measurements were used to estimate degradation, and it was found that the Maron - Pierce model for viscosity of composites accurately predicted blend viscosity at low shear. The viscosity change was inversely proportional to the screw speed, indicating matrix degradation. Moreover, the blend was more sensitive to thermomechanical degradation than the neat PBS. However, the molecular weight loss did not exceed 22% even at the highest screw speed of 2000 rpm. Finally, morphology investigation showed that the TSE blends had smaller droplet size with a broader shape distribution than the batch mixed blends. All results supported the idea that the high levels of shear stress are the governing factor in the morphology and the degradation of blends in twin screw extrusion.
Influence of High-Speed Extrusion on Structure and Properties of Bioplastics Blends
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
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
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
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
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
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
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
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
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
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
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
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.
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