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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Conference Proceedings
Potential Of Five-Axis Kinematic Systems For Additive Manufacturing Using Fused Deposition Modelling (FDM)
Fused Deposition Modelling (FDM) technology is a widely used additive manufacturing processes. In this process, a plastic filament is fed to a nozzle, melted there and deposited in the X, Y direction based on an imported geometry. Afterwards the print bed moves one layer in the Z direction and starts depositing the plastic again in the X, Y-direction. These steps are repeated until the component is completely built up. In a recently developed system by one of the authors, the degrees of freedom in movement of the print head are extended to five axes: X, Y, Z-movement in translational direction plus an additional degree of rotation of the print bed and the possibility to tilt the print head with respect to the printed surface. Thereby, the surface quality and the geometric accuracy for rotationally symmetrical parts are intended to be improved. This paper investigates the potential of the additional motion axes with respect to part quality. To determine the accuracy, surface quality and the ability to print overhangs, tests have been carried out and compared to conventional manufactured FDM parts (X, Y, Z-kinematics). In a further step, the printing of the parts after model preparation in polar coordinates is compared to printing in Cartesian coordinates. To investigate the influence of the print head adjustment on part quality, namely surface roughness, test runs were performed with print head adjusted at different angles to the surface. Suitable demonstrators were developed for this purpose and evaluated in comparison with manufactured FDM parts using commercially available printers limited to X, Y, Z-movement only. The tests show that the recently developed 5-axis printer has a lot of potential. It’s comparable in performance to a commercially available FDM printer from the mid-price segment. The possibility of tilting the print head is the biggest advantage of the system. This has significantly improved part quality when printing overhangs and angled surfaces. The comparison between polar and Cartesian coordinates showed an improvement in surface quality for cylindrical parts printed by polar coordinates.
Investigating The Optical And Mechanical Properties Of Stimuli Responsive Electrosterically Stabilized Nanocellulose Crystals In Thermoplastic Polyurethane
A new type of nano-cellulose crystal (CNC) has been gaining interest for its unique morphology combined with its as-produced carboxylate functionality: electrosterically stabilized nano-crystalline cellulose (ENCC). When ENCCs are added to thermoplastic polyurethane (TPU) composites and submerged in water they display a unique increase in opacity. Using UV-VIS and DMA, the optical and mechanical properties of these composites can be studied at differing ENCC concentrations.
Fabrication Of Expandable Filaments Towards In-Situ Foam 3D Printing Of Microcellular Poly(Lactic Acid)
The purpose of this study was to investigate the feasibility of in-situ foaming in fused filament fabrication (FFF) process. Development of unexpanded filaments loaded with thermally expandable microspheres, TEM is reported as a feedstock for in-situ foam printing. Four different material compositions, i.e., two grades of polylactic acid, PLA, and two plasticizers (polyethylene glycol, PEG, and triethyl citrate, TEC) were examined. PLA, TEM and plasticizer were dry blended and fed into the extruder. The filaments were then extruded at the lowest possible barrel temperatures, collected by a filament winder, and used for FFF printing process. The results showed that PLA Ingeo 4043D (MFR=6 g/10min) provides a more favorable temperature window for the suppression of TEM expansion during extrusion process, compared to PLA Ingeo 3052D (MFR=14 g/10min). TEC plasticizer was also found to effectively lower the process temperatures without adversely interacting with the TEM particles. Consequently, unexpanded filaments of PLA4043D/TEM5%/TEC2% was successfully fabricated with a density value of 1.16 g/cm3, which is only ~4.5% lower than the theoretical density value. The in-situ foaming in FFF process was then successfully demonstrated. The printed foams revealed a uniform cellular structure, reproducible dimensions, as well as less print marks on the surface, compared to the solid counterparts.
Production Of Flexible Thermally Conductive Thermoplastic Pipes By Orientation Of Filler Particles
Pipes for heat exchanger systems are usually made of metals to achieve a high level of energy transfer. Polymers, in comparison, save weight and costs and are suitable for use in corrosive and chemically aggressive environments. However, for many applications the comparatively low thermal conductivity of polymers is a disadvantage. To overcome this, polymers are usually mixed with high amounts of fillers, which transport the heat through the pipe wall. But the use of high filler ratios influences the mechanical properties of the pipe significantly. The aim of this paper is to develop a concept for a pipe extrusion die which aligns the filler particles in radial direction, so that the anisotropic material properties of the compound can be utilized and thus the amount of filler can be reduced. Consequently, the flexible material properties can be maintained as far as possible. Several die concepts are presented and their influence on the thermal and mechanical properties of the pipe are compared.
In-Depth Rheological Study Of Acrylic Processing Aids For Rigid Pvc Applications
Acrylic processing aids are used widely in rigid Polyvinyl Chloride (PVC) applications. Key functions of processing aids in terms of processing and performance are discussed in the paper. Effect of molecular weight of acrylic processing aids on their functions are studied. Additionally, effect of processing conditions, such as temperature and shear on fusion characteristics of PVC formulations, are investigated. Shear rate in the processing was varied by means of rotor speed in torque rheometer. Processing aids of wide molecular weight range are evaluated in the study. It was observed that relatively lower molecular weight processing aids have different response to change in shear and temperature than higher molecular weight processing aids. Depending upon fusion conditions PVC formulations can yield either single or double fusion peak. Generally, it was considered that ultra-high molecular weight processing aids yield double fusion peak, however, it was demonstrated in the studies that it is not true. Fusion conditions, temperature, and shear are the main driving forces of fusion dynamics, resulting in either single of double fusion peak. Melt viscosity and shear thinning properties are also examined. Relatively lower molecular weight processing aids showed higher shear thinning behavior.
Scale Up Optimization Of Optical Nanolayer Films: Improved Thickness & Compositional Control
A nanolayer coextruded optical film process was scaled up and optimized to show improvements in the thickness and compositional control at production level throughput rates. Adjustment of processing temperatures, implementation of online continuous gauging and automatic die lip adjusting equipment, and upgrades to the cast film pinning system led to improvements of film thickness control. A unique profile control scheme utilizing only the middle layer’s thickness instead of the total film thickness has been successfully utilized to control the critical layer’s thickness. Automation and optimization of the extruder’s feeding system provided compositional control capable of meeting tight quality specifications. With these improvements, production scale throughput rates of high-quality optical cast film capable for unique gradient refractive index (GRIN) optical applications were demonstrated.
Development Of A Micro-Capillary Rheometer For High Solids Content Rheology
Rheological testing of new material formulations can require significant quantities, specifically when considering development of new chemistries at the laboratory scale. In order to minimize the quantity of material required for evaluation, we are developing approaches suitable for characterization of high solids content formulations using micro-capillary rheometry. The goal of this investigation is to design and produce a micro-capillary rheometer capable of characterizing basic rheological properties, such as viscosity and shear-thinning behavior, while requiring the least amount of sample possible. In our current design, we implement a micro-dispensing approach combined with calibrated force transducers. With this approach we can further elucidate an understanding of the differences between typical capillary rheometry and behavior at reduced dimension flow fields. Issues such as pressure relaxation and free volume compaction can therefore be studied through readily modified geometries and testing rates. This design will lead to a better understanding of micro-capillary rheometer design and enable a unique approach for rheology measurements for new chemistries and formulations, including high solids content formulations (up to 60+ vol%). Additionally, this framework will facilitate the study of a variety of flow geometries applicable to a wide range of applications including precision dispensing of adhesives and sealants, and direct ink write additive manufacturing.
Evaluation Of Component Specifications Of Largeformat Plastic Products Through The Use Of Machine Learning Methods
This conference paper presents the investigations, results and findings from the research project "Tool-integrated assistance system for production control of highly complex and demanding component specifications" (acronym in German WASABI). The project investigates the possible use of sensor technology in combination with machine learning methods for the prediction of quality-determining component features on large-format plastic products. Furthermore, the information obtained will be used to propose target-oriented recommendations for action based on the predicted feature characteristics. An outer skin component (bumper) from the automotive sector was defined as the reference product for the investigations into the prediction possibilities of demanding component specifications. The injection molding tool required for production was designed as part of the project work and equipped with a variety of different sensor types (including pressure, melt contact, displacement measurement). The recording of the measurement signals is realized by a self-developed hardware system concept. The aim of the research is to predict various quality-determining characteristics from the fields of geometry (including total length) and surface (including sink marks). In the course of the project, extensive tests were carried out to generate a meaningful database. Through analysis and evaluation, it was possible to define the positions and number of sensors that provide a high level of information. Ultimately, three different approaches of machine learning methods could be learned for the prediction of component qualities and the prediction of corrective actions. These structures could be verified in laboratory environment by appropriate test data sets.
Recycled Carpet-Reinforced Composites From Polyester Carpet And Recycled Pet Resin
A method was developed for fabricating recycled composites from post-consumer polyethylene terephthalate (PET) carpets and recycled PET resins. Compression molding of the components under different pressures, temperatures, and compositions was performed. Preliminary molding conditions were arrived at based on analyzing the differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and melt viscosity data for different raw material combinations. Molding factors were screened to define applicable ranges for each parameter. The effects of configuration and composition of components, temperature, molding time, and pressure were considered in the screening process. Mechanical properties of composites were determined by 3-point flexural (according to ASTM D790) and creep tests. The molded materials showed acceptable mechanical strength and modulus values required for structural applications.
High Shear Viscosity Measurement Of A Natural Rubber And Synthetic Rubber Materials Using The Rubber Screw Rheometer
The shear rate-dependent viscosity of natural rubber and three types of synthetic rubber was measured using the Rubber Screw Rheometer. Viscosity values with Mooney viscometer, which has traditionally measured rubber viscosity, have a high correlation with the values of RSR shear rate 10 [1/s]. Thus the Mooney Viscosity value can be estimated using the RSR shear viscosity measurement. Also, in the case of virgin rubber, the accuracy of the measured value increases when it has a pre-shear history. It was confirmed that the viscosity measurement value was a measurement value having a deviation within +3% when comparing the three times repeated measurements. The measured value was correlated to Mooney Viscosity successfully with a first- order equation.
Development Of Modified Synthetic Fiber Reinforced Tpu Composites For Industrial Applications
There has been a common goal among various researchers across the globe to investigate sustainable and high-strength materials as a suitable replacement for metallic materials in many industrial sectors. Many products obtained through reinforcing steel can potentially be replaced with those synthetic fibers such as carbon and glass to overcome the critical issues pertaining to dimension stability along with the creep effect that could pose complications in applications such as belts driving heavy machinery. In the current study, Steel, Carbon and glass fibers were reinforced in TPU matrix and manufactured by compression molding. The resulting composite materials were then tested for tensile analysis. After comparing the mechanical properties of the fibers, it was observed that the carbon/TPU showed the highest load-bearing capacity, followed by steel and glass reinforced TPU composites. The results also opened up the possibilities for carbon fibers to be a suitable replacement candidate to the steel cords that are used in applications such as conveyor belts for providing the required tensile strength.
Aqueously Degradable Pet Films Containing A Latent Metal Oxide Reagent
In this study, PET was combined with a latent metal oxide reagent, CaO, which allowed the PET to hydrolyze when submerged in water, breaking down the polymer chain and forming calcium terephthalate as a nontoxic byproduct. PET/CaO composites were mixed at 10, 20, and 30 wt% CaO, and 0.001” thick films were prepared by compression molding. These films were degraded in water at 90°C for varying amounts of time. Puncture testing, optical microscopy, FTIR, and TGA were performed to probe the degradation of the material and verify that it was producing the products that were expected from the reaction. The PET/CaO composites were shown to be degradable in water, with a significant loss in mechanical properties after only an hour. The rate of degradation was strongly dependent on the concentration of CaO, with significantly faster degradation at higher concentrations.
Effect Of Seal Pressure On Leak Resistance Of Rigid Hot Tool Sealing Over Film Thickness Transitions In Multilaminate Films
In flexible packaging, film thickness transitions can be problematic regions to seal due to their propensity for leaking, as well as the high seal pressure required to create a continuous seal over the transition. A compliant anvil can be used to decrease the required seal pressure, as the hot tool will be able to contact both the thick and thin regions of the packaging, with compression of the compliant anvil. However, a compliant anvil cannot be used in a double-sided heating process. Therefore, in a double-sided heating process, high seal pressures must be utilized in order to reduce the film thickness in the thick region, to facilitate tool to film contact in the thin region. In this study, the required seal pressure needed to create continuous (non-leaking) seals over a 4-film to 8-film thickness transition was explored, with both a rigid and conformable anvil. With a rigid anvil 3.25 MPa was required to consistently create continuous seals. With a conformable anvil 0.87 MPa was required to consistently create continuous seals.
Reheat Injection Stretch Blow Molded Bottles Of High-Density Polyethylene Blended With Cyclc Olefin Copolymer To Improve Processing, Properties And Sustainability
Cyclic olefin copolymers (COC) provide manufacturers and converters with an opportunity to create thin, stiff, high performance polyolefin packaging products. COC provides an unexpected, but essential benefit that enables the manufacture of high-density polyethylene (HDPE) containers by reheat injection stretch blow molding. COC has good dimensional stability and excellent heat resistance, minimizes distortion of PE exposed to thermal and mechanical stresses.
Fibril-Flash Formation During Vibration Welding
Vibration welding flash occurs when molten polymer flows under pressure from the weld interface. This study examines the formation of small hair-like fibrils during vibration welding. Polypropylene and nylon 6 plates were butt-welded and the assemblies were assessed using a high-speed camera and digital microscopy. A mechanism has been proposed whereby initial asperities at the weld interface first melt to form a polymer pool. Thermal expansion of this pool allows polymer to be extruded laterally towards the edge of the weld interface. The extrudate is rolled up to form fibrils that can eventually grow to several millimeters in length.
Enhancing Emi Shielding Performance Of Thermoplastics With Long Steel Fibers And Carbon Fibers
Electromagnetic interference (EMI) is a common problem encountered by electronic devices, especially in electric vehicles. External electromagnetic (EM) waves affect the operation of an electronic device by interfering with the internal EM signals. To provide EMI shielding, various materials were studied, and the measured electromagnetic shielding effectiveness (SE) data are presented in this study. The main factors affecting EMI SE are quantified statistically – filler loading, shield thickness, and base polymer resin matrix. Long steel fiber thermoplastics provide the highest EMI SE, at over 60 dB at frequencies ranging from 30 MHz to 20 GHz, and at thickness as low as 1.6 mm. It is also demonstrated that carbon fiber filled thermoplastics can provide EMI shielding at levels greater than 50 dB.
Moisture Sensitivity Characterization In Pla/Pbs Parts During Ultrasonic Welding
Ultrasonic welding (USW) is a surface mating process where absorbed moisture in the surfaces of hydrophilic materials can negatively affect the weld joint quality and strength. USW is a secondary processing operation that is performed post-molding or extruding. Hence, during the storage time between primary processing and USW, the parts are susceptible to moisture absorption. Therefore, it is necessary to characterize the moisture sensitivity to meet the specified weld strength. Moisture sensitivity of Industrial standard test parts (ISTeP) made with PLA, PBS, and PLA/PBS 25/75 blend was characterized for USW in this study. ISTeP parts were moisture conditioned for one week at different relative humidity (RH) levels and then tested for weld strength. It was found that the weld strength decreased with increase in RH for 100% PLA ISTePs but it was not statistically significant. Above 65% RH, weld strength of 100% PBS was significantly decreased. Scanning electron microscopy of weld areas after the pull test revealed an increased amount of trapped porosity in the fractured surfaces of high relative humidity samples. It was also demonstrated that PBS and PLA/PBS composite can be ultrasonic welded.
Impact Modification Of Pla (Poly Lactic Acid) By Blending Small Amounts Of Amorphous Pha (Polyhydroxyalkanoate) Copolymers
This work demonstrates the efficacy of amorphous polyhydroxyalkanoate (a-PHA) copolymers in enhancing the impact strength of PLA without compromising the compostability and bio-based carbon content of the final product. The influence of PHA polymer composition on the performance of PLA will be highlighted for applications including thermoforming, film and injection molding. Finally, the morphology of the blend will be used to explain the impact modification mechanism. Blends of 100% bio-based and fully biodegradable a-PHA and PLA exhibit good toughness and clarity in injection molding, extruded sheet and blown film. It will be shown that the level of toughness increase and modulus reduction can be tuned by blend composition.
Mechanical, Thermal And Rheological Properties Of E-Beam Crosslinked Ethylene Octene Copolymer
Ethylene-octane copolymer (EOC) with high octane content (45 wt.%) was cross-linked via electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of cross-linking reflected in increased gel content, higher elastic modulus (G’), and lower tan obtained by rheology measurement at 150 °C. Cross-linking caused improvement in high temperature creep and also in elastic properties at room and elevated temperatures. Differential scanning calorimetry revealed that e-beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of cross-linking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break which could be aroused from the formation of crosslink networks. Radiation dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220 °C, slightly higher C=O peak for cross-linked sample was found by Fourier transform infrared spectroscopy while for room temperature samples no C=O peak was detected.
Long Term Aging Characteristics Of Post-Consumer Recycled (Pcr) Polycarbonates
In this paper, the tensile properties of indoor and outdoor post-consumer recycled (PCR) polycarbonates (PC) have been compared with virgin PC at various aging conditions. 50% recycled PCs showed comparable tensile strength at breakage (~70 MPa) and maximum strain (~190 - 200%) before aging, when compared to virgin PC of same MFR of ~10 g/10 min. Three different high temperature and high humidity aging conditions were investigated: 40oC 90% RH, 60oC 90% RH, and 85oC 85% RH for up to 500 hours. Strength at breakage was found to decrease as the aging stress or aging time (with the same aging condition) was increased. Both the indoor resins were comparable in strength up to 60oC 90% RH. But in 85oC 85% RH both showed significant drop in strength. On the other hand, outdoor PCR resin showed much better performance (only ~12% degradation) in 85oC 85% RH compared to other two indoor resins (25 - 40% degradation). Outdoor UV aging characteristics were also compared between 0%, 50% and 75% PCR and degradation up to 600 hours were found to be within 5%.
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