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Computational Modeling Of Impedance Tube And Validation For Tuning The Acoustic Transmission Loss Of Polymeric Materials
The need for lightweight solutions has increased the use of polymeric materials in many applications, with an aim of replacing multiple components with integrated multi-material and multi-functional polymeric parts. Apart from structural and thermal requirements, acoustic performance is an important functional requirement in many applications such as automotive, transportation, equipment enclosures and consumer electronics. The frequency-dependent acoustic transmission loss (henceforth referred to as TL) is one of the standard measures to understand the acoustic performance and is experimentally measured using an impedance tube setup. The process involves molding and preparing circular samples with two different diameters (for low frequency and high frequency impedance tube testing) and performing repeated tests. The tests are generally repeated for multiple samples of each material and averaged in order to compensate for uncertainties such as sound leakage from boundaries, fitment issues, sample variation, etc. Hence, experimentally determining the TL is expensive due to the labor-intensive and time-intensive sample preparation and testing. TL is a complex function of material composition, morphology, physical and mechanical properties, all of which can be modified for polymers (by using fillers) to achieve the desired TL values in the desired frequency range. As tuning the TL experimentally is a time and cost intensive affair, we have developed a computational model that has been validated with experimental measurements. It is a fully coupled structural-acoustic finite element model simulating the impedance tube. This model can be used to perform virtual design of experiments to arrive at the most likely properties of the polymeric material that will result in the required TL at the frequency range dictated by the application. Only this material configuration can then be prepared and the TL experimentally measured, enabling more quickly identifying a candidate material solution to meet the customer’s needs. In this study, we have experimentally validated the model using test data of TL from five samples of varying composition. This computational tool can be extended to estimate the TL from multi-layered laminates and sandwich panels with various core morphologies.
Bumper To Bumper - Removing Contaminants From Molded Plastic Parts With Dry Ice
It is not uncommon for many automotive plastic parts to be painted. Unwanted material, either left from the molding of the part itself, or the picking up of contaminants from the transporting of the part to the paint booth, must be removed prior to painting. Many of these parts are cleaned utilizing aqueous methods requiring that the parts be dried prior to painting. Reclaiming the water, fueling the oven (and dealing with its footprint), and the fact that sometimes the parts don’t get dried, are all problems can be alleviated by utilizing dry ice. Dry ice is a non-abrasive media that does not alter the dimensional characteristics of the part nor damage the surface of the parts to be painted. It is also dry, eliminating the need to have or operate a drying oven. Dry ice also sublimates, leaving nothing to be reclaimed behind and no possible water entrapped in part geometries of complex parts that may not get thoroughly dried. This paper will discuss the distinct advantages of utilizing dry ice as a blast media for the surface preparation of plastic parts prior to painting. The process itself will be explored as well as the common results.
Improving Long Term Corrosion Resistance In Electronic Applications
Improving long term corrosion resistance in electronic applications Electronic components have invaded the automotive environment with increasingly complex designs and functionality. In addition, the location and environment of these components continues to drive the requirements to higher performance materials. The combination of exposure to electrical potential, moisture, elevated temperature and environmental salt can affect the performance of electronic components. DuPont has developed a line of “EF” Electrically Friendly resins which will help reduce the risk of long term corrosion or performance degradation in aggressive environments.
Advances In Hydrolysis Resistance Pbt Resins For Electronic Applications Including Connectors And Hev Components
Advances in Hydrolysis resistance PBT resins for electronic applications including connectors and HEV components DuPont has developed a new PBT hydrolysis resistance technology to offer outstanding melt stability during molding. The process flexibility of this family of resins allows for more stable manufacturing processes and improvements in quality versus existing PBT HR grades on the market. This unique combination allows a wider processing window, including the use of hot-runners and regrind, without sacrificing the hydrolysis resistance as well as additional benefits for high voltage connectors and electronic applications
Polycaprolactone Nanofibers Containing Vascular Endothelial Growth Factor-Encapsulated Gelatin Particles Enhance Mesenchymal Stem Cell Differentiation To Endothelial Cells And Angiogenesis Of Endothelial Cells
During the regeneration of tissues and organs, growth factors (GFs) play a vital role by affecting cell behavior. However, because of low half-life time and quick degradation of GFs, their stimulations on cells are relatively short and discontinuous. In our study, a releasing scaffold platform, consisting of polycaprolactone (PCL) nanofibers and vascular endothelial growth factor (VEGF)-encapsulated gelatin particles, has been developed to extend the influence of GFs on mesenchymal stem cells (MSCs) and endothelial cells (ECs). The results showed that this kind of scaffold could direct the differentiation of MSCs to ECs and maintain the stability of its tubular structure for an extended period of time, thus suggesting its potential application in vascular tissue engineering.
Biodegradation Of Biodegradable And Compostable Plastics Under Industrial Compost, Marine, And Anaerobic Digestion
Biodegradation was measured for biodegradable, compostable, and oxodegradable plastics while exposed to aerobic composting, marine, and anaerobic digestion environments. Biodegradable plastics included, corn-starch based biobag, PHA bag, Ecoflex bag, and PLA lids. Positive and negative controls included, Kraft paper and polyethylene. Other plastics included, and oxodegradable plastic bags. For industrial composting environment, compostable plastic products, along with oxodegradable, cellulose paper, Kraft paper, and polyethylene plastic wrap, were placed in an environment consistent with ASTM 5338 conditions. For marine environment, the plastic samples were placed in a test environment consistent with ASTM 6691. For anaerobic digestion, plastic samples were placed in an environment consistent with ASTM 5511. The degradation was evaluated by measuring CO2 gas, which evolves from the degrading plastic samples. For industrial compost conditions, the compostable plastics, namely, PLA, sugar cane, PHA, Ecoflex, and starched-based biobag, degraded at least 90% and met the degradation time requirement in the ASTM D-6400 standard. The oxodegradable, UV-degradable plastics, and LDPE plastic bag had negligible degradation. After 180 days placed in a commercial food-waste composting operation, PLA, PHA, Ecoflex, and corn starch plastics completely degraded. Small fragments of sugar cane lids and Kraft paper were visible. The oxo-biodegradable plastic bags, LDPE plastic bags and UV-degradable plastic bag did not fragment nor degrade. The samples were also exposed to a simulated marine environment. Under marine conditions, PHA experienced significant biodegradation. Alternatively, corn-starch based trash bag, PLA cup, Ecoflex bag, sugar cane lids, UV-degradable plastic ring, and Kraft paper did not exhibit biodegradation under marine conditions. Under anaerobic conditions PHA experienced biodegradation, but PLA, paper, and polyethylene did not.
Wheat Protein As A Participant In The Sulfur-Curing Of Isoprene Rubber
In this study, trypsin hydrolyzed gliadin (THGd) from wheat was used as a curative and reinforcing filler in synthetic isoprene rubber (IR). Curing kinetics of the THGd compounds demonstrated that THGd was most effective when utilized as an activator in place of zinc oxide and stearic acid (ZnO/STE). The THGd vulcanizates exhibited comparable or higher moduli to the control, but lower crosslink densities and slower curing kinetics. THGd was able to facilitate crosslinking, as shown by swelling experiments, but further study is needed to match/exceed the kinetic properties of the control. Interestingly, THGd was very effective as a reinforcing filler and reinforcement increased as a function of molding time. Thus, rubber processing was favorable to the self-assembly of hydrolyzed protein into a reinforcing phase.
Study Of Biocompatibilizer For New Renewable Blends Of Polypropylene Carbonate And Polybutylene Succinate
The lack of commercially relevant compatibilizers from renewable sources is limiting the usage of biopolymer blends and composites in today’s market. This work studies potential new compatibilizers that can be used in applications involving blends of sustainable polycarbonates and polyesters. Poly(propylene carbonate) (PPC) and poly(butylene succinate) (PBS) were functionalized separately using maleic anhydride (MAH) and an initiator to trigger free radical grafting. Different amounts of MAH were used during the melt compounding to study the effect of the MAH amount on the extent of the reaction. The resulting compounds were examined by means of titration, proton NMR and parallel plate rheometry. Formulations using both PPC and PBS successfully reacted with MAH, as evidenced by the appearance of new chemical shifts in their proton NMR spectra associated with midchain grafting and end groups reactions. The PPC compounds showed an increase of the grafting efficiency with addition of more MAH. The PBS formulations had maximum grafting efficiency value at 2% MAH. Rheometry showed that incorporation of 2% of MAH and DCP produced an increase in the viscosity of both PPC and PBS in comparison to their neat counterparts. Evaluating all these results together, it can be concluded that the PPC with 2% MAH and DCP is the most reactive compound and the one that could perform more efficiently as a compatibilizer. In addition, melt compounding presents an economic method to produce biocompatibilizers of high reactivity and high molecular weight.
Transamidation Of Corn Oil Side-Steam Product From Bioethanol Industry As Strategy To Develop Sustainable Polyesteramides
The valorization of side-steam products from bio-refinery is of crucial interest to develop further the viability of a bioeconomical system. The corn oil is one of the important co-products from the bioethanol industry with a production of more than 2.7 billion pounds in 2015 in USA.  In this investigation we propose to create new materials with higher added value by developing new monomers and polymers through transamidation and successive polyesterification. The resulted sustainable materials can be used as toughening agent for both thermoplastic and thermoset polymers.
Study Of Biodegradable Polybutylene Succinate/Poly(Butylene Adipate-Co-Terephthalate) Blends
With increasing interest towards biobased and/or biodegradable polymers that generate high performance composites, instead of petroleum based products, creates new opportunities and research challenges. Poly (butylene succinate) (PBS) is supposed to be one of the most promising biodegradable polyesters because of its good mechanical strength and high heat deflection temperature. However, the low impact strength of poly (butylene succinate) (PBS) has limited its application in some fields. Therefore, poly (butylene adipate-co-terephthalate) (PBAT) and poly (butylene succinate) (PBS) were melt-compounded to fabricate a novel PBS/PBAT blend to improve the impact strength of PBS. The effect of PBAT on the properties of the final binary blends, including mechanical properties, thermal properties and rheology properties, is studied in this research. Rheological properties revealed a strong shear-thinning tendency of the blend resulting from the high compatibility between PBAT and PBS. The partially compatibilized PBS/PBAT blends show high tensile strength (~50 MPa), high impact strength (~200 J/m) and a moderate tensile modulus (~500 MPa). A PBS/PBAT system can be a good candidate to fabricate high impact biodegradable products.
Tunable Degradation Of Poly(Butylene Succinate) By Copolymerization And Catalysts
In recent decades, poly(butylene succinate) (PBS) has been attracting attention as a promising and important polymer in the bio-based and biodegradable polymer family due to high thermal resistance and good mechanical properties. However, compared with other biodegradable polyesters (e.g., poly (lactic acid)), the high cost of PBS limits the widespread applications, especially for the packaging industry. In this paper, PBS-based copolyesters were prepared successfully by a two-stage melt synthesis, and degradability of the polyesters was investigated. It was found that the degradability of PBS could be tuned over a wide range by adjusting the degradation catalyst and lowering crystallinity by forming random copolymers. Based on our previous work on the tunable properties of PBS-based polyesters, the degradation results indicated that the enzymatic degradation mainly depends on the morphology and thermal properties, while the ratio of ester groups in polymer is the crucial factor for base-catalyzed hydrolysis.
Fully Biobased Degradable Plastic With Insecticide Functionality
Natural insecticide, pyrethrum, and insect repellent DEET were added to poly(lactic acid) (PLA) fibers via extrusion and spraying. GPC analysis showed that the addition of DEET caused an increase in depolymerization with the increase of DEET concentration. Contact Irritancy Assay (CIA) showed that DEET-treated PLA fabrics caused the lowest percentage escape response with an escape frequency of 33.3 ± 3.3%. This was followed by the extruded natural pyrethrum-treated PLA fabrics with an escape frequency of 80 ± 6.3%. PLA fabric spray-treated with natural pyrethrum caused an escape frequency of 98.3 ± 1.7%. All treated fabrics caused repellency.
Effect Of Shish Material On The Formation Of Self Induced Shish-Kebab Structure
The shish-kebab structure has been investigated for many years and it has been widely applied in many field, while the formation of the structure has still been found in limited materials. In this study, different electrospun poly(ε-caprolactone) (PCL) blended nanofibers with poly (ε-caprolactone-co-lactide) (PLCL), polylactic acid (PLA) and graphene (GO) were applied as shish materials in the self-induced crystallization and different crystalline structure were obtained. The PCL blended fibers with different internal crystalline structure led to different induced crystal lamellae morphology. By comparing with the surface crystalline structure, it seems that the formation of self-induced nanohybrid shish-kebab (SINSK) structure is regulated simultaneously by a lattice matching mechanism and a soft epitaxy effect in the crystallization process. This study might help people to explore the materials for creation of SINSK structure.
Effects Of Molding Conditions On Mechanical Behavior Of Direct Injection Molded Pla/Wood-Fiber Composites
Polylactic acid (PLA), derived from bio-resources, is an environmentally friendly plastic which has attracted tremendous interests in both academia and industry. This paper investigates the feasibility of direct injection molding of PLA/wood fiber composites and their mechanical behavior. Response surface methodology was adopted to study the effects of molding parameters, as well as their interacting effects, on the tensile strength of the composites. Melt temperature, hold pressure, injection speed were chosen as the molding parameters studied. Additionally, the analysis of variance was applied to identify the most significant factors. The statistical model would improve our understanding of the tensile strength behavior of PLA/wood fiber composite, and provide the guidance for selecting proper molding parameters to maximize the tensile strength.
Mechanical Behavior And Anaerobic Biodegradation Of A Poly(Lactic Acid) Blend Containing A Poly(Lactic Acid)-Co-Poly(Glycolic Acid) Copolymer
Poly(lactic acid) (PLA) is arguably the most well-known biodegradable plastic. However, its degradation behavior is far from ideal. The goal of this work is to prepare PLA blends that exhibit accelerated biodegradation performance whilst retaining adequate mechanical properties. To accomplish this a copolymer consisting of poly(L-lactic acid) and poly(glycolic acid) (PGA) structural units was synthesized and subsequently melt blended with a commercially available PLA homopolymer. The anaerobic degradation behavior of the polymer blend was greatly enhanced as a result of the incorporation of 20 wt% of the copolymer. A moderate change in mechanical properties including a 20% reduction in stiffness and strength and an 80% increase in elongation to break was also observed.
Hierarchical Micro/Nanostructures Of Poly (Lactic Acid) Scaffolds For Medical Applications
Although tissue engineering has shown great advances in recent years, creating proper mechanical properties and cell growth microenvironments is still challenging. In this study, electrospun poly (lactic acid), PLA, nanofibrous membranes were hot embossed to develop 3D hierarchical micro/ nanostructures. Human umbilical-vein endothelial cells (HUVECs) were then cultured on these structures. The hot-embossed membranes exhibited not only superior mechanical properties (the tensile strength was 7.01 ± 0.18 MPa and the tensile modulus was 166.91 ± 15.54 MPa), but also better cell viability as evaluated through a CCK-8 assay and fluorescent dye. The grating arrays of the micropatterned fiber mats encouraged the HUVECs to proliferate. The approach proposed here—combined electrospinning and hot embossing—has great potential for biomedical applications, including for use as polymer scaffolds in tissue engineering.
Physical Foaming Using High Pressure Gas Saturation For Biopolymer Applications.
Foaming technology is a useful way to optimize material consumption in plastic processing, increasing the material cost/benefit ratio and improving some properties such as the impact resistance, the insulation properties, and the dimension stability, among others. For compostable biopolymers, the foaming technology should not affect the biodegradation properties of the material.This work is oriented to analyze the effect of foaming parameters on the density and material hardness in a foamed poly lactide acid (PLA) part. In the foaming process, the PLA pellets are exposed at room temperature to a highly pressurized gas in order to saturate the pellets, then the material is processed in an injection molding machine. The effect of saturation and desorption time before the injection molding process is studied.A PLA from Nature Works is used. The most recommendable process window for the foaming of the material is proposed.
Development Of A Rapid Thermal Cycling Blow Molding Technology And Mold Heating System Optimization
More and more industrial plastics parts used in automobile are turning to be produced by extrusion blow molding (EBM). For directly obtaining high-gloss part in mold, a rapid thermal cycling extrusion blow molding (RTCEBM) technology was developed by integrating the dynamic mold temperature control strategy into the traditional EBM. The process principle was presented and process optimization by executing some molding operations in parallel was analyzed in detail. A typical automotive plastic part, i.e. spoiler, was taken as an example to illustrate the application of RTCEBM in actual production. The corresponding blow mold was designed and a two-step method was proposed and applied to optimizing the heating systems arranged in the mold cavity and core plates simultaneously. Finally, a prototype blow mold of spoiler was manufactured and used for molding the parts, it was found that the molded spoilers exhibit high-gloss surface appearance and could be directly used for the final assembly process without any secondary processing, as well as the molding cycle time was also in the accepted range.
Simulative Preform Optimization For Improved Topload Behavior Of Pet-Bottles Manufactured In The Two Stage Stretch Blow Molding Process
Biaxial stretch blow molding is a process for producing a plastic container from a preform or parison that is stretched in both circumferential and axial direction when the preform is blown into its desired container shape. It is well established for the large scale production of high quality PET bottles with excellent mechanical and optical properties.The concept of "virtual prototyping" is nowadays well established in the stretch blow molding industry in order to improve the containers properties during the design phase. Still, a virtual optimization is yet connected with much manual work. Therefore, a process simulation and a testing simulation for stacking strength was integrated into an optimization cycle to design a preform geometry for improved mechanical properties of the corresponding bottle. The optimization performed with Newton based algorithms however lead to suboptimal mechanical properties. The investigations show, that the objective function indicating the mechanical properties of the bottle has several local maximum values which prevent the determination of a global maximum. Further investigations will focus und different optimization algorithms.
PET Advancements In Extrusion Blow Molding
I would propose creating a summary of efforts to utilize PET in extrusion blow molding. The main processes for making PET bottles involve creating an expensive injection mold in combination with expensive blow mold tooling. This approach works for large volume production of 100million containers or more, but many potential packages for lower volume users are not well served. Resin suppliers have created grades of PET with increased melt strength that have begun to address this market need. These materials are imposing problems for recycling of PET which needs to be addressed. I think a summary paper of the activity that has taken place will be of interest to ANTEC attendees. I have not written the paper but will if the organizers wish a presentation.
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