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.
MODELING OF COUPLING BETWEEN SPECIFIC ENERGY AND VISCOSITY DURING TWIN SCREW EXTRUSION OF STARCHY PRODUCTS
Starchy products are commonly transformed by twin screw extrusion, either for the manufacturing of food products (extrusion cooking of snacks or breakfast cereals, for example) or for the production of bio-based materials (bioplastics). During the extrusion process, starch is submitted to high shear rates and stresses which lead to a modification of its basic structure. As many properties of the extruded starch are directly connected to the molecular weight and its distribution, it is very important to be able to predict the changes experienced during the extrusion process. In order to model the transformation of starch during twin screw extrusion process, it is thus necessary to take into account the strong coupling between viscosity and thermomechanical treatment. It is the purpose of thepresent work. We have used the software Ludovic was developed ten years ago to calculate the flow of a polymer along a twin screw extruder. We have assumed that the degradation reaction (viscosity decrease) was linked to the specific energy received during the flow. We have compared extrusion cases with and without viscosity/energy coupling and we show that it is important to take it into account in order to correctly predict the parameters of the extrusion process (torque, energy, product temperature') and the starch transformation.??, which
MORPHOLOGY DEVELOPMENT IN THE PELLET DURING COMPOUNDING OF RECYCLED POLY(ETHYLENE TEREPHTHALATE) (RPET)/POLYPROPYLENE (PP) BLENDS
The morphology of RPET and PP pellets has been shown to have a profound effect on the properties of injection moldings. The size of PP dispersed phase is critical as it dictates the ductility of the blend. It has been shown that the size of a dispersed phase could grow by either coalescence or relaxation during and immediately after extrusion where temperatures are high. This study focuses on the chronological development of PP dispersed phase throughout the extrusion line during RPET/PP blending prior to pelletizing. The effect of compatibilizer content will be correlated to the growth rate of PP phase and also on the mechanical properties of subsequent injection moldings.
NEXT GENERATION HDPE FOR BLOW MOLDING APPLICATIONS
High density polyethylene (HDPE) is widely used to fabricate blow molded articles for rigid packaging as well as for other market segments such as industrial and chemical containers automotive home and recreation. The drive to reduce packaging cost as well as minimize impact on the environment has increased the emphasis on light weight packaging. A next generation (NG) of HDPE resins was developed through selective molecular architecture modification to offer a unique combination of easy resin processing on existing extrusion blow molding equipment and a superior balance of physical properties which allow blow molded articles to be light weighted. A higher percentage of post consumer recycle can also be incorporated while meeting the blow molded article performance requirements.
NOVEL BIO-BASED THERMOSET RESINS FROM EPOXIDIZED VEGETABLE OILS FOR STRUCTURAL APPLICATIONS
Bio-derived thermosets were cured from inexpensive, low-toxicity precursors. Epoxidized linseed oil (ELO) and epoxidized soybean oil (ESO) were crosslinked with a range of crosslinking agents: branched polyethyleneimine (PEI) and triethylenetetramine (TETA). Curing conditions were optimized through solvent uptake and soluble fraction analysis. Properties may be varied from elastomeric to rigid. Rigid bioepoxies, while not as stiff as conventional materials, are expected to display better toughness and may be promising for coatings and as binders in engineered wood products.
NOVEL ECO-FR" STYRENIC POLYMERS"
Flame retardants (FRs) additives are commonly usedin polymeric materials, with non-halogenated flameretardants being preferred for environmental, health andsafety reasons. However, developing non-halogenated FRsis a challenge for styrenic polymers such as acrylonitrilebutadiene-styrene (ABS) since they burn very easily anddo not produce any char. Here, we have developed ahalogen-free flame retardant system for ABS using woodor cellulose as a charring material and ammoniumpolyphosphate (APP) as a catalyst. The use of theseadditives permits compounding and molding of ABS atlow temperatures. The resulting materials can achieve a V-0 or V-1 rating on UL-94 type tests.
PIEZORESISTIVE BEHAVIOR OF POLY (HYDROXYBUTYRATE VALERATE)/MULTI-WALLED CARBON NANOTUBES CONDUCTIVE COMPOSITE
In this study, piezoresistive behavior of poly(hydroxybutyrate valerate) (PHBV)/multi-walled carbon nanotoubes (MWCNTs) composite has been discussed. Melt mixing technique was used to achieve maximum possible dispersion of CNTs in polymer matrix, as this process involves very high shear forces during mixing. The prepared composite shows gauge factor value of three which is very close to gauge factor value of conductive metals like copper and aluminum. Quasi-static and time dependent piezoresistance was investigated for the prepared composite. Environmental scanning electron microscopy was performed to observe dispersion of CNT in PHBV matrix.
PLA PROPERTY IMPROVEMENT: IMPROVING THE PRACTICAL HEAT RESISTANCE OF POLYLACTIC ACID (PLA)
Polylactic Acid (PLA) is a renewable polymer with many unique features including compostability. However, PLA suffers from several performance deficiencies which limit its market potential. A key deficiency is its ability to withstand elevated use temperatures above 55 ?§C. PolyOneƒ??s objective was to explore a range of approaches to identify a practical path to improved heat performance while seeking to maximize renewable content and processability. This paper addresses the industry need for a high renewable content polymer with practical heat resistance without relying on any additional thermal treatments such as annealing. Various PLA-based compounds were prepared and screened using DMA in an effort to correlate results to the heat distortion temperature (HDT) exhibited by injection molded PLA. It was concluded that polymer blends offered the greatest commercial viability of all the approaches considered under normal injection molding conditions. Multi-phase compatible polymer blends were found to have the most significant impact on blend properties. All components of the preferred blend composition are commercially available today. Heat performance can be tailored based upon performance requirements and bio-content objectives. The PLA content of the blends studied varied from 72% to 35%, while the corresponding HDT (under 0.455 MPa load) ranges from 57 ?§C to 101 ?§C. Potential increased bio-derived contents are also considered.
PLA PROPERTY IMPROVEMENT: IMPROVING THE PRACTICAL HEAT RESISTANCE OF POLYLACTIC ACID (PLA)
Polylactic Acid (PLA) is a renewable polymer with many unique features including compostability. However PLA suffers from several performance deficiencies which limit its market potential. A key deficiency is its ability to withstand elevated use temperatures above 55C. PolyOne’s objective was to explore a range of approaches to identify a practical path to improved heat performance while seeking to maximize renewable content and processability. This paper addresses the industry need for a high renewable content polymer with practical heat resistance without relying on any additional thermal treatments such as annealing. Various PLA-based compounds were prepared and screened using DMA in an effort to correlate results to the heat distortion temperature (HDT) exhibited by injection molded PLA. It was concluded that polymer blends offered the greatest commercial viability of all the approaches considered under normal injection molding conditions. Multi-phase compatible polymer blends were found to have the most significant impact on blend properties. All components of the preferred blend composition are commercially available today. Heat performance can be tailored based upon performance requirements and bio-content objectives. The PLA content of the blends studied varied from 72% to 35% while the corresponding HDT (under 0.455 MPa load) ranges from 57 ºC to 101 ºC. Potential increased bio-derived contents are also considered.
POLYANILINE MODIFIED CLAY IMPACT ON POLYSTYRENE FOAMING ULTILIZING CARBON DIOXIDE BLOWING AGENT
Polyaniline-clay (PANI-MMT) nanocomposites were synthesized through in-situ polymerization of polyaniline with various dopants. Those nanocomposites were used to blend with polystyrene (PS) to form an expandable composite resin, which will significantly impact the foaming process using a CO2 blowing agent. The material composition and foam morphologies were characterized through various analytical techniques, such as, X-Ray diffraction (XRD), SEM, dielectric measurement, UV/vis, and FTIR. Based on our experimental results, we are proposing that the de-doped base form" of Pani-MMT nanocomposites and both "inorganic and organic salt-form" Pani-MMT nanocomposites will act as a "molecular CO2 reservoir" to control the CO2 releasing during the foaming. The selection and optimization on those compounds will be enormously important for developing a new inexpensive and environmental friendly blowing agent for the foam industry to achieve the final goal of replacing the existing CFCs /HCFCs /HFCs blowing agents!"
POLYLACTIDE TOUGHENING USING IMPACT MODIFIERS
The major objective of this research was poly(lactide) (PLA) toughening using two impact modifiers (IMs). IM1 was derived from biodegradable resource and IM2 was non-degradable ethylene-acrylate copolymer. Blend films were prepared using a single screw extruder, and their mechanical properties were measured using tensile testing. Results showed that the Young's modulus did not change significantly with increasing concentration of IM1, but decreased with IM2 concentration. The maximum elongation at break was 240% for IM1 at 8 wt% loading and 255% for IM2 at 12 wt% loading. Clarity of the films decreased with higher additive concentrations for both IMs, but IM1 gave clearer film than IM2 for given composition. AFM images showed IM1 dispersed in PLA as isolated islands at lower compositions and transitioned to short threads at higher compositions; IM2 existed mostly as islands. Annealing of the films at 100 ?§C for 1 h increased the percent crystallinity, but did not affect the mechanical properties significantly.
PROCESSING COSTS AND ENVIRONMENTAL IMPACT OF BIO-PLASTICS
This work studied bio-plastics such as polylactic acid (PLA) and protein based plastics form corn and compared to petroleum based plastics such polyethylene (PE) and polystyrene in terms of their ecological as well as economical performance from a “Cradle to Grave” perspective. This study included energy input emissions output of green house gases and costs from their life cycle steps of raw material acquisition to the final product disposal. It was found that products manufactured from bio-based feedstocks were relatively higher in cost they resulted in less green house gas emissions.
RESEARCH ON DYNAMIC INJECTION MOLDING FOR METAL POWDER GREEN PART
A new injection molding for metal powder green part was put forward in detail in this paper. Vibration force field generated by electromagnetic field in the whole process of plasticization, injection and packing, implementing dynamical plasticization metering, injection and packing was introduced. An in-depth experiment study on the effect of vibration force field on metal powder 316L/binder under steady and dynamic injection conditions was carried out with an experiment equipment and dynamic injection machine. Experimental results show that the filling pressure will be reduced when the vibration is introduced, the flow of melts becomes more uniform and the distribution of different components is also more uniform in the green parts during the dynamic injection molding. The mixing dispersion and distribution effect are better and the density is also larger than the green part's with traditional injection molding. The existing of vibration can effectively promote not only the microcosmic structure and also quality of metal powder green part.
RESIN LIFE CYCLE ESTIMATION TO HELP GUIDE SUSTAINABILITY CHOICES
Life cycle analysis (LCA) is an accepted methodology to determine the environmental impact of a certain material or package at different stages in its product life. In some cases, however, LCAs can be complex and expensive to carry out. DuPont is looking at ways to internally estimate the LCA of its products by using a modular approach: building estimates of nonrenewable energy and green house gas emissions by summing proprietary information on our ingredients and unit operations. The output of this tool will be used to target our internal improvement efforts and potentially help our value chain partners make better multilayer flexible packaging design choices.
RESIN LIFE CYCLE ESTIMATION TO HELP GUIDE SUSTAINABILITY CHOICES
Life cycle analysis (LCA) is an accepted methodology to determine the environmental impact of a certain material or package at different stages in its product life. In some cases however LCAs can be complex and expensive to carry out. DuPont is looking at ways to internally estimate the LCA of its products by using a modular approach: building estimates of nonrenewable energy and green house gas emissions by summing proprietary information on our ingredients and unit operations. The output of this tool will be used to target our internal improvement efforts and potentially help our value chain partners make better multilayer flexible packaging design choices.
RISING TO THE HALOGEN CHALLENGE IN FLAME-RETARDANT ENGINEERING PLASTICS
Halogenated additives have long been used toenhance the flame-retardant properties of plastics.Recently, after many years of growing concern over theenvironmental and human impact of the disposal ofcertain halogen-containing products and theirincompatibility with recycling operations, leading globalelectronics manufacturers have begun moving to eliminateor sharply reduce the use of certain halogen-containingingredients in their products. DuPont is meeting the needsof these and other environmentally consciousmanufacturers with a growing range of engineeringpolymer grades using non-halogenated flame retardantsystems. This paper shows that they can fulfilldemanding requirements for strength, toughness, hightemperature resistance and processing efficiency.
ROOT CAUSE INVESTIGATION OF CRACKED POLYCARBONATE FOOD BLENDER JARS
Polycarbonates find applications in food industries due to their clarity and ductility. Sometimes failure of a polycarbonate part occurs. In food blender jars molded from polycarbonate, cracks were observed in the sealed joint only a few days after assembly. The root cause was investigated via microscopy, FTIR and GC-MS analyses. It was determined the cracks initiated and radially propagated from the bottom raised lip of the part. The root cause was a combination of a high stress in the lip region due to molding and design, and environmental chemical compounds, i.e., esters from a melt nut used in the assembly. The failure was typical environmental stress cracking (ESC) problem.
SENSITIVITY OF MECHANICAL PROPERTIES OF POLYAMIDE-IMIDE TO LOT-TO-LOT VARIABILITY
PAI (Torlon) is used in aerospace applications requiring excellent mechanical properties at high temperature, fluid resistance, and thermal stability. PAI is a delayed cure thermoset that reaches its ultimate properties and maximum Tg only with an extended postcure. This work examined the correlation of Tg and properties of four injection molded lots of PAI. Testing consisted of impact strength measurement, tensile and flexural strength and modulus testing at various temperatures and after different environmental conditioning. CTE in three orthogonal directions were measured and creep testing was run on samples after different environmental exposures, including long-term aging in turbine oil.
SHARKSKIN MELT FRACTURE CHARACTERISTICS OF POLY (HYDROXY BUTANOIC ACID) COPOLYMERS
Recent advances have rendered bio-based and biodegradable PHB (poly hydroxybutanoic acid) copolymers suitable for many extrusion applications. The high molecular weight and narrow distribution of melt relaxation times of these polymers can sometimes cause sharkskin melt fracture to occur during extrusion. This may be a limiting factor for their wide-spread applicability. This presentation will discuss the characterization of sharkskin melt fracture of these polymers using capillary rheometry including the identification, for the first time, a critical criterion for their occurrence.
SILICONE BASED FLAME RETARDANT FOR POLYCARBONATE
Kaneka Corporation has developed a silicone based flame retardant for Polycarbonate, Kane Ace MR-01. MR- 01 realizes non-bromine and non-phosphorus flame retardant PC compound and increases low-temperature impact strength. Kaneka's renowned graft polymerization technology makes it possible to disperse the cross-linked silicone particle into Polycarbonate matrix. MR-01 achieves V-0 in UL-94 protocol at 1.2 mm thickness (Kaneka's evaluation data) with a small amount of PTFE. MR-01 also has excellent thermal stability, which provides with superior impact strength retention after heat aging, and maintains the flame retardancy after recycling process.
SMC REPLACEMENT WITH ENGINEERING THERMOPLASTICS IN HEAVY COMMERCIAL VEHICLE BODY PANELS MARKET SPACE
Traditionally body panels of Heavy Commercial Vehicles (HCV) are built in Sheet Molding Compound (SMC) or metal. OEMs are looking for fuel-efficient, lightweight and greener technology solutions.The specific gravity of Engineering Thermoplastic (ETP) is much lower and offers significant weight reduction opportunity over SMC/metal. This paper presents limitations of SMC, key challenges in terms of aesthetics and high flow length to thickness ratio in processing HCV body panels with ETP.Show how these are solved through novel thickness distribution, feed system and process design.It is highly essential to design with plastic friendly concepts and to build the tool for balanced filling, no aesthetic defects, minimum pressure and tonnage. Predictive engineering is the best tool to use at the design phase to achieve first time right.
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