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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Modeling Of The Ultrasound-Assisted Ejection In Micro Injection Molding
In this paper, an ultrasound-aided ejection system was designed and tested for various polymers and mold topographies. The use of ultrasound vibration aims at decreasing the ejection friction by reducing its adhesion component, which is controlled by the real contact area developed in the filling phase of the injection molding process. The experiments indicate that the ultrasound vibration reduces the ejection friction up to a maximum of 16%. The effect depends on the polymer used and it increases for rougher mold surface. Moreover, the dependence of ejection friction on mold surface roughness, melt viscosity and elastic modulus at ejection was modeled using the experimental data.
Improving Accuracy Of Mold Filling Simulations With Experimental Data From Fast Scanning Chip Calorimetry
In this study, mold filling simulation crystallization data were compared with experimental data collected with a fast scanning chip calorimeter. This new technique gives the opportunity to collect data at higher cooling rates, which mimic the injection molding process. Experimental data showed that the crystallization temperature depends on the cooling rate, which is neglected in previous models implemented in the simulation software. It is suggested to modify the simulation software crystallization data in order to account for more realistic prediction of the crystallization process and, consequently, microstructure formation affecting properties.
Infrared Welding Of Continuous Glass Fiber-Reinforced Thermoplastics – Approaches To Use The Fibers In The Joint
Thermoplastic prepregs that are also known as organo sheets are processed in presses and formed to half shells. Larger components can be produced by joining the half shells, which results in hollow bodies. However, current manufacturing technologies allow only cap profile shaped joints, which cause fiber deflections in the joint plane. This paper shows that overlapping infrared welds in organo sheets enable weld strengths close to the interlaminar shear strengths of the unwelded materials and thus a fiber utilization across the joint plane. By using high welding pressures, a matrix depletion and a change of the fiber alignment in the weld plane may occur which causes low weld strengths. Therefore, criteria for the successful welding were defined various possibilities to the optimization of the weld strengths were investigated.
Stylight - New Material Solution For Lightweight Design
A newly developed material known as Stylight has been created for design flexibility and lightweighting solutions. Stylight incorporates carbon and glass fibers in an SAN (amorphous polymer) matrix. The SAN matrix allows for a smoother "Class A" finish than traditional thermoformable composite sheets that are normally used hidden structural applications. The glass and carbon fiber also help provide a rigid and tough backbone for structural applications as well. Stylight also provides design flexibility and is able to be painted or covered in decorative film or used with carbon weave pattern.
Infrared Welding Of Highly Filled Graphite Composites
Beside the economical production of bipolar and heat exchanger plates made from graphite composites, the stack assembly is of great importance for the further technological development of fuel cell, redox-flow battery and heat exchanger systems. In order to choose a suitable welding method, to evaluate the weldability of the composites and to produce a secure stack assembly, a comprehensive understanding of the welding behavior of the materials is required.This work focuses on the welding of graphite composites using the infrared welding method. To form a material-locking joint during the welding process, a defined melting of the material in the joining area is decisive. Due to the thermal properties of highly filled graphite composites, the welding process differs fundamentally from conventional welding of unfilled or low-filled thermoplastics.To perform a scientific examination of the material heating depending on the heating source, a surface and a contour-following infrared radiator were used. Independent of the radiator type, no high-quality joining connection could be achieved. Due to the high thermal conductivity and the low heat capacity of the graphite compounds, the joining area does not have a sufficiently high temperature after infrared heating. Furthermore, it is not possible to apply a sufficiently high joining force, as deep material heating takes place. As a result, the formation of a material-locking joint is significantly impaired with an increasing graphite content.
Development Of Molecular Diffusion Models For Ultrasonic Welding Of Pla
This research focuses on the characterization of bioplastics joined using ultrasonic welding and modeling of temperature distributions and interfacial healing. Polylactic acid (PLA), which is typically derived from starch-rich crops such as corn, was studied. While the measurement of activation energy for interfacial healing at weld interfaces of PLA films has been reported, here, this information is used to predict the weld strength of rigid PLA samples welded by ultrasonics. A characterization of the mechanical properties was completed with a tensile test to determine the effects of amplitude, weld velocity and collapse distance on weld strength. From previous interfacial healing activation energy measurements based on an impulse welding method, it was also possible to predict weld strength. It was found that the most influential parameters were weld time, collapse distance and weld velocity. In general, the model predicted weld strength reasonably well with r2 values between 0.77 and 0.78.
Direct-Friction Riveting Of Metal-Cfrp Overlap Joints
Friction Riveting is an innovative and promising joining technology, which can potentially fulfill the industry requirements for sustainable and efficient systems. The objective of this work is to prove the feasibility of Direct-FricRiveting by inserting a metallic rivet through metal-composite overlapped plates and subsequent anchoring in the composite part, which is a challenging configuration with limited knowledge available. The case-study joint configuration used in this work comprised a Ti6Al4V rivet, which joined an overlapped AA2024-T3 upper plate with a 30% short-carbon-fiber-reinforced poly-ether-ether-ketone lower plate, material combination of high interest for the aircraft industry. Evaluation of joint formation, temperature development, microstructural and physicochemical changes in the composite, and mechanical properties were carried out for joints produced under low and high energy input. The feasibility was proved, showing satisfactory mechanical performance under lap shear testing (up to 7 ± 1 kN). Changes of polymer crystallinity and thermo-mechanical decomposition in the composite were shown not to affect the joint mechanical performance and failure behavior, while the plastic deformation at the rivet tip played the major hole. The knowledge gathered in this preliminary work will be further applied to optimize the process, contributing to the development of the Friction Riveting technology and improvement of its industrial applicability.
Experimental Investigation Of Amplitude Transmission In Ultrasonic Welding Of Thermoplastic Composites
Ultrasonic welding is an efficient technique for rivetless assembly of thermoplastic composites. To further improve this process, it is necessary to develop numerical simulations. A phenomenon often misevaluated but crucial for accurate process simulations is hammering. It is the loss of contact between sonotrode and upper adherend during the vibration phase. The goal of this paper is twofold: present an experimental procedure to measure the displacement of the sonotrode and upper adherend during welding, and discuss two strategies to quantify amplitude transmission to the upper adherend. This will lead to improvement of predictive models for ultrasonic welding and closer agreement with experimental data.
Research On Temperature Field Of Laser Transmission Welding Polycarbonate Based On 3D Real Surface Topography
Laser transmission welding is a complicated process with the coupling effect among the unsteady and uneven temperature field, mechanical force, stress and strain and plastic forming flow. The theory based on the ideal contact surface has not satisfied the requirement of practical production. In this paper, the mathematical model of surface roughness profile was built based on Weierstrass-Mandelbrot (W-M) fractal function, the contour welding process for polycarbonate (PC) was simulated with the idea taking real 3-D topography of contact area into account and the effect of laser scan power on the surface topography with different surface roughness was discussed, a combination of a rotary Gaussian volumetric heat source with a Gaussian distribution of surface heat source was proposed. Finally, finite element simulated results agree well with the experiments in contour welding with PC. The experimental study indicates that the laser absorption rate, the welding temperature and the variation of temperature gradients of rough surface are lower than the smooth one.
Temperature Field And Fluid Field Simulation Of Laser Transmission Welding Polycarbonate
According to the theory of laser transmission welding (LTW), a 3D transient finite element temperature field and fluid field coupling model based on volumetric heat source and melting and solidification model were built. The moving volumetric heat source of laser transmission welding and boundary conditions were implemented by programming user-define function file written by C language. The temperature filed and fluid field were obtained considering the influence of clamping force. Then distributions of temperature and fluid in heat affected zone were analyzed. The results show that the heat affected zone of opaque part is bigger than that of transparent part. The node of peak temperature is under the weld bead and lags behind the center of laser beam. In the molten pool, the higher the temperature is, the faster the fluid flows. In the Y-Z and X-Z plane, fluid flows to the solid liquid interface and forms two vortexes. Temperature field and velocity field simulation will help to guide and study on laser transmission welding process.
Improvement On Fatigue Performance Of Metal-Composite Friction Spot Joints Based On The Weld-Bonding Concept
This work investigates the potential of the Weld-Bonding concept to improve the fatigue performance of friction spot joints. Therefore, friction spot joints of AA2024-T3/CF-PPS (carbon-fiber-reinforced polyphenylene sulfide) were produced with an additional thermoplastic film interlayer. Two joining conditions manufactured with low and high heat inputs were investigated. The fatigue performance of those joints was evaluated at 35%, 50% and 75% of their respective ultimate lap shear force (ULSF). It was observed that process-related microvoids decreased the fatigue strength of the joints in high cycle fatigue (HCF). Superior fatigue life of the joints with interlayer in comparison with those without interlayer was observed. At 105 cycles, typical qualification requirement of the aircraft industry, the interlayer joint showed fatigue strength of 51% of ULSF, whereas the fatigue strength of the joint without interlayer was 37% of ULSF. In the whole spectrum, the joint with interlayer showed a fatigue life approximately four times higher than the joint without interlayer.
Time-Dependent Vibration Welding Behavior Of Foam Injection Molded Parts In Consideration Of Various Fiber Reinforcements And Joint Types
Due to the rising demand of lightweight constructions as well as saving material, the density and weight of thermoplastic parts can be influenced significantly by using the thermoplastic foam injection molding process. The characteristic three-layer structure which is originated by the foam injection molding, a microcellular foamed core is surrounded by a non-cellular skin layer, results in a weight saving and leads to an increased specific bending stiffness with a simultaneous low tendency to warp. Whereas the established welding processes for solid parts have already achieved a high degree of perfection within the last decades, the joining of microcellular thermoplastics is a novel. The structure as well as the remaining foaming agent within the part represents a challenge for welding, which can cause great difficulties in the process. Unfortunately, there are no standards or experiences for welding such foamed parts yet.The present investigation researched the welding behavior of foam injection molded parts in comparison to their solid counterpart in dependence on fiber reinforcement and joint type. In contrast to solid parts, the welding behavior shows a significant time-dependence in case of foam injection molded parts for the various materials.
Effects Of Build Orientation And Fill-Level On Mechanical Properties Of Fused Deposition Modeling Pla
Fusion deposition modeling of PLA was studied to determine the effect of build orientation and fill-level on mechanical properties of tensile test samples. This was used to assist in the design and FDM manufacture of airless tires for the NASA rover competition. It was found that the failure and energy at break increased with increasing fill-level for flat built tensile samples, and there was evidence of crazing prior to failure. For the upright built tensile samples, the effect of fill-level on failure load and energy at break was small for fill-levels between 20% and 80%, with large increase for fill-level of 100%. However, for all fill-levels for the upright build samples, the failure load and energy at break were much lower than for the flat build samples. For tire types, the threaded tire in the upright build orientation has the highest failure load with the lowest deflection.
Benefits Of Vibration Welding With Ir Preheat
Many technologies exist for joining plastics, and each process has its advantages and compromises. Processes are selected based on the application and customer needs. This presentation examines vibration welding and compares it to Clean Vibration Welding (CVT), also known as vibration with infrared pre-heat. Vibration welding offers excellent strength, process speed, material compatibility, and the ability to weld large parts. However, vibration alone uses friction and high forces, resulting in particulate and unsightly “flash.” CVT adds an IR preheat step to create molten plastic prior to the vibration welding. The result is a cleaner joint with virtually no particulate, which allows more three-dimensional design flexibility and is ideal for applications with aesthetic requirements. Through material testing in a laboratory setup, engineers from Emerson demonstrate the results of CVT welding found on Branson products, and established a relationship between “changeover time” and weld appearance.
Establishing Polymer Equivalency Process For Medical Device Application
Polymer material selection for new medical device applications and also sustaining existing business presents challenge due to wide range of polymer manufacturer, grades available in the market. In addition, changing business climate results in acquisition of large corporations; causing consolidation of businesses and obsolescence of polymer grades.New methodology was presented to systematically analyze various factors for polymer equivalency. Besides engineering specifications, business factors with weighting/scoring approach were introduced to capture overall impact on business. Physical, mechanical, thermal property evaluation of polymers helps compare various resin grades available. Evaluation of Design and Process impact captures any potential risk to design, process or patient. As in many cases, changing polymer results in regulatory submission which may be lengthy process for medical device applications. In case of new product development, capturing overall impact assures new device development process can be completed in timely manner.
Accelerated Aging Of Medical-Grade Resins: Q10 Factors And Material Aging Models
Accelerated aging is used throughout the Medical Device sector and other sectors to evaluate materials and devices in an accelerated fashion. If used properly, it can shave years off of validation efforts. If used improperly, it can generate misleading or completely incorrect data about the resins and products in question. This paper explores the fundamental principles and provides supporting data. It is critical to understand the four primary modes of aging for polymers: (1) physical aging (embrittlement and loss of free volume); (2) chemical aging, which includes oxidation, chemical damage, sterilization, etc.; (3) sustained strain cracking, creep rupture, and environmental stress cracking; and (4) fatigue. For sustained strain or sustained load environments, stress relaxation and creep are also key factors. A case study is presented for polycarbonate and copolyester resins that are undergoing physical aging, sustained strain cracking, and environmental stress cracking (ESC), and a model presented to account for the various factors.
Opportunities And Obstacles For Plastic Primary Packaging In Drug Delivery Devices
Drug delivery devices like multi-dose pens and auto-injectors help patients manage their conditions in the comfort of their own homes. The drug inside these devices is traditionally packaged in a glass cartridge or syringe. Polymer containers are available alternatives for drug delivery devices but their substitution for glass containers is complicated by regulatory, cost, and practical drug filling process considerations. This talk will highlight the current state of polymer drug container technology, identify situations when glass packaging issues are solved by polymer containers, and review the key selection, processing, and regulatory requirements polymers must meet in this demanding application.
Effects Of The Biological Environment On Thermoplastic Polyurethanes
Implantable thermoplastic polyurethanes (TPU) have been utilized in the medical industry for decades due to their combination of biocompatibility, abrasion resistance, and processability. Attempts to improve the biological stability of TPUs have been an area of intense activity and have resulted in a number of different formulations [1-5]. It has been observed that the nature of the soft segment in the TPUs is the primary factor in controlling the biostability of the final polyurethane. In many studies [5 – 9] it was seen that siloxane based soft segments presented the best performance in in vitro and in vivo tests and materials based on siloxane based soft segments are most suitable for long term implant applications. In this study, the results from various in vitro and in vivo tests are put together focusing on the performance of a siloxane based TPU (Optim) in cardiac lead insulation applications. The performance of Optim is compared with other materials, primarily polyether based TPUs.
Processing Of TPUs For Medical Applications
Thermoplastic polyurethanes (TPU) are a common choice as a biomaterial for many medical devices, especially devices requiring long term implantation. Many of the desirable properties of TPUs as biomaterials are directly related to their unique microstructure, containing both hard and soft polymer segments. However, this microstructure can be influenced by a number of factors present both before and during the device manufacturing process. Because components for medical device applications are held to a high quality standard that requires consistency between parts, changes to the polymer microstructure can have a significant impact on the completed part. Further complicating their processing, medical device parts are often smaller and require a lower throughput in production than non-medical device parts. In this study, the effects of storage conditions, drying conditions, and process settings were evaluated in order to understand how changes in these factors impact important material properties.
Chemical And Thermal Analysis Of The Surface Extractives Of Medical Tubing Of A Poly(Ether-B-Amide) Copolymer Using Ftir, Gpc, And Dsc Methods
Medical tubing extruded of a commercially-available PEBA (poly(ether-b-amide)) copolymer resin, namely Pebax® 4033 SA01 MED, was surface-extracted using a typical nonpolar solvent, n-hexane. After the completion of solvent evaporation, the obtained extractive solution was dried into waxy specimens, which were then chemically characterized using ATR-FTIR (attenuated total reflectance-Fourier transform infrared spectroscopy) and GPC (gel permeation chromatography) methods. It is determined that the surface extractives of medical tubing contain the oligomeric polyether reactant residual existing in the PEBA resin and various low MW (molecular weight) species rich in polyether segments. Thermal analysis on the as-received tubing and the PEBA resin was conducted using DSC (differential scanning calorimetry) technique. The relevant results suggest that the surface extractives, though they are loosely attached onto the surface of medical tubing, are fully miscible with the bulk PEBA material upon melting. The mechanism for the formation of the surface extractives during tubing extrusion and applicable effects on post-extrusion process development for making medical devices are discussed.
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