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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

Accelerated Aging And Viscoelastic Effects Of Medical-Grade Resins
Rob Klein, March 2019

Accelerated aging is used throughout the Medical Device sector and other sectors to evaluate materials and devices in an accelerated fashion. Accelerated aging has several typical modes, depending on the type of materials and functional mechanisms involved. One mode is related to stress relaxation and creep, which impacts the function of parts under sustained strain or stress as well as influencing time to develop cracks. This paper explores viscoelastic behavior of moderate melt flow medical grade polycarbonate as related to accelerated aging. The relationships between stress relaxation, creep, and complex modulus (as a function of time and temperature) are discussed. An example demonstrating the correlations between stress relaxation, creep, and Dynamic Mechanical Analysis (DMA) master curve data for a medical-grade polycarbonate is provided. Additionally, Q10 factors as intended for accelerated aging are estimated for stress relaxation of medical-grade polycarbonate using DMA master curve results. Accelerated aging is used throughout the Medical Device sector and other sectors to evaluate materials and devices in an accelerated fashion. Accelerated aging has several typical modes, depending on the type of materials and functional mechanisms involved. One mode is related to stress relaxation and creep, which impacts the function of parts under sustained strain or stress as well as influencing time to develop cracks. This paper explores viscoelastic behavior of moderate melt flow medical grade polycarbonate as related to accelerated aging. The relationships between stress relaxation, creep, and complex modulus (as a function of time and temperature) are discussed. An example demonstrating the correlations between stress relaxation, creep, and Dynamic Mechanical Analysis (DMA) master curve data for a medical-grade polycarbonate is provided. Additionally, Q10 factors as intended for accelerated aging are estimated for stress relaxation of medical-grade polycarbonate using DMA master curve results. Accelerated aging is used throughout the Medical Device sector and other sectors to evaluate materials and devices in an accelerated fashion. Accelerated aging has several typical modes, depending on the type of materials and functional mechanisms involved. One mode is related to stress relaxation and creep, which impacts the function of parts under sustained strain or stress as well as influencing time to develop cracks. This paper explores viscoelastic behavior of moderate melt flow medical grade polycarbonate as related to accelerated aging. The relationships between stress relaxation, creep, and complex modulus (as a function of time and temperature) are discussed. An example demonstrating the correlations between stress relaxation, creep, and Dynamic Mechanical Analysis (DMA) master curve data for a medical-grade polycarbonate is provided. Additionally, Q10 factors as intended for accelerated aging are estimated for stress relaxation of medical-grade polycarbonate using DMA master curve results.

Fabrication And Characterization Of 3-D Porous Hydroxyapatite (Ha)-Modified Polyurethane (Pu) Scaffold For Tissue Engineering
Qianting Wang, March 2019

In this work, the 3-D porous hydroxyapatite (HA)-modified polyurethane (PU) scaffold successfully fabricated by using simple ultrasonic assisted method. The hydrophilcity, water absorption and mechanical properties of HA-modified PU scaffold were significant higher than those of PU scaffolds. Compared with PU scaffold, the addition of HA nanoparticles could effectively improve the attachment and growth of human umbilical vein endothelial cells (HUVECs) cultured on the HA-modified PU scaffold. These results suggest that HA-modified PU scaffold possesses a great potential to be used as tissue engineering scaffold and the ultrasonic assisted technique could be a simple, effective and universal method to decorate the tissue engineering scaffold.

The Effects Of Material Propertis On Microcellualr Injection Molding Simulation
Sejin Han | Syed Rehmathullah, March 2019

This paper presents a study about the effects of material properties on the modeling of the microcellular injection molding process. In particular, the effects of gas solubility and diffusivity data on the simulation results were examined. Often, actual measured data are not available for these properties. The effectiveness of using a generic equation to estimate these values has been evaluated by comparing the simulation results from this to a simulation that uses the actual measured data. The study indicates that by properly using these estimated material properties data, meaningful simulation results can be obtained.

Medical Plastics: Review Of Material Models Required For Simulation Through Case Studies
Hossam Metwally, March 2019

Computer simulation to model the manufacturing as well as the performance of plastic part requires a good understanding of the material properties at the representative conditions. The same material behaves differently during different processes, e.g. extrusion is a shear dominated process, while thermoforming is elongation dominated. Additionally, viscoelastic effects may be relevant to capture since they control the amount of die swell depending on the geometry and process conditions. Additionally, plastics are also non-linear materials and exhibit non-linear stress-strain behavior that can possibly be rate dependent as well. This paper is a review highlighting the different processes that have been modeled before and the different material models that are required for a successful simulation will be discussed. The following case studies will be used to highlight the material models; catheter extrusion, tray thermoforming, and catheter kinking.

Cure And Mechanical Properties Of Filled, Zno-Free, Sulfur-Cured Isoprene Rubber
Barbara DeButts, March 2019

In this study, agricultural proteins were compounded into synthetic isoprene rubber (IR) and sulfur-cured. A constant filler loading of 8 parts per hundred rubber (phr) was used to evaluate the reinforcing capabilities of two full proteins, i.e., corn zein (Zein) and gliadin from wheat (Gd), a hydrolyzed protein, i.e., trypsin hydrolyzed gliadin (THGd), and a neat amino acid, i.e., arginine (Arg). Cure meter testing, tensile testing, and swelling experiments were performed to assess the curing kinetics, Young’s moduli (E), hysteresis, and crosslink densities of the vulcanizates. The filled vulcanizates exhibited comparable or higher E and [X] than an unfilled IR Control, but slower curing kinetics. The hysteresis, or unrecoverable mechanical energy, decreased with increasing elongation in the filled vulcanizates, which was opposite the behavior of the IR Control.

Development Of A Plastic Frame Mounted Bumper That Meets The Requirements For Pedestrian Safety Performance
David Job, March 2019

This paper presents the design and development of a chassis mounted pick-up truck front bumper for the 2018 Ranger Raptor which meets pedestrian safety performance. Truck bumpers are traditionally made of steel to meet customer expectations of a durable vehicle capable of suitable crash protection performance, firmness of feel and rugged styling. Pedestrian safety performance is increasingly becoming a regulation for the sale of vehicles in selected markets around the world.A traditionally mounted steel bumper does not have suitable energy absorption to meet this regulatory requirement. The bumper developed by Ford of Australia uses sandwich plastic bumper fascia with a steel support structure to meet the conflicting requirements of a soft front for pedestrian protection and a solid substructure to meet low speed crash requirements including static and dynamic stiffness for durability.

Challenge To Prepare For Flame-Retardant Polypropylene Foam Boards
Wenli Zhu, March 2019

In this work, neat polypropylene (PP) foam boards was produced under different saturation pressure and foaming temperature by using supercritical CO2 as a blowing agent in an industrial-scale batch foaming system. In addition, the effort was made to prepare for flame-retardant PP foam samples by introducing a basic magnesium sulfate whisker (MSW). The preliminary results showed that with addition of MSW, PP composite samples have increased Limiting Oxygen Index (LOI) and increased tensile property. As the increase of amount of MSW, the average cell sizes of PP foams have little change but the cell densities were decreased thus the volume expansion ratios were decreased as result. To obtain low-density flame-retardant PP foam products, systemic study on the foaming condition on cell morphology need be conducted.

Development Of Polypropylene Nanocomposites Reinforced With Cellulose Filaments
Julie GENOYER, March 2019

In this work, polypropylene (PP) reinforced with cellulose filaments (CF) nanocomposites were studied. Nanocomposites with CF loadings ranging from 0 to 30 wt% were produced by melt extrusion and characterized. Rheology using Carreau-Yasuda with yield stress model was used to estimate the dispersion state of CFs and showed that a suitable dispersion was achieved. Tensile tests were conducted to study the mechanical behavior of the materials. Results showed that nanocomposites with a higher rigidity can be obtained when a suitable dispersion is achieved, however, those nanocomposites are consequently more brittle.

Influence Of Injection Molding Parameters And Fiber Content On Product Roundness Accuracy
Pi-Lin Tsai, March 2019

In recent years, injection molding has become a common polymer molding process in the plastics industry. Injection molding can produce products which have complicated shapes, and offers high efficiency and productivity with low cost. However, uneven volume shrinkage during the injection molding process will cause deformation after demolding and poor product roundness. To find the best approach, this study focused on round products under different molding conditions, including melt temperature, mold temperature, and injection speed. CAE simulation was used to identify the effect of different fiber content and molding conditions on product roundness. Results showed that the roundness of PC material products without fibers was better than those with fibers. Moreover, those which contained more fibers exhibited lower dimensional stability. The uneven shrinkage and variations in roundness were caused by the different fiber orientations in the product. Changing the position of the gate improved the uneven shrinkage caused by fiber orientation. Furthermore, raising the mold temperature also improved the roundness of the product.

The Influence Of Fiber Length And Fiber Orientation On The Impact Behaviour Of Polypropylene
Maiko Ersch, March 2019

Discontinuous fiber reinforced thermoplastics materials combine the process related advantages of injection molding with the enhanced mechanical properties of fiber-reinforced plastics. Since the mechanical properties of FRPs are dependent on the fiber length, long fiber reinforced thermoplastics (LFT) offer a huge potential for lightweight design. In order to analyze the influence of the fiber length and orientation on the stiffness and strength of LFT under high strain rate loading, the authors conducted tensile impact tests as well as part impact tests. Thereby, polypropylene (PP) specimens with different fiber length were analyzed. It can be shown that the influence of the fiber length on the strain rate behavior can be neglected compared to the influence of the fiber orientation. Furthermore, a first implementation to describe the strain rate-dependent material behavior of LFT is presented.

Modelling Of The Mechanical Properties Of Medium Saturated Short Fiber-Reinforced Polycarbonate
Simon Koch, March 2019

There is an often ignored correlation between mechanical and chemical stress in plastics parts, which is very time- and cost-intensive to test. The model that was developed in this research allows the prediction of the mechanical properties of fiber-reinforced amorphous thermoplastics under media influence. The media influence is taken into account by the modulus of elasticity of the matrix, which is determined by a molecular dynamics simulation. The results correspond well with the tests for polycarbonate after storage in distilled water. An acoustic emission analysis shows an influence of the medium on the damage behavior of the fiber-reinforced samples during the test. The media storage results in significantly more acoustic emissions during the test. This indicates damage already during the test and not just shortly before the break.

Using Secondary Air Cooling In Blown Film Extrusion: Concept Design And Experimental Study
Christoph Dohm, March 2019

The characteristics and the quality of a blown film are strongly influenced by the stretching and simultaneous cooling of the molten polymer within the bubble formation zone. Moreover, the output rate of the process is generally limited by the cooling rates and the stability of the bubble. As a consequence, the design of cooling systems is highly relevant in terms of process optimization. Beside intensifying the heat removal, the concept of secondary air cooling aims at eliminating unsteady ambient influences during bubble formation and increasing bubble stability. Different concepts for cooling systems with integrated secondary air cooling are presented and experimentally tested. The results confirm that the implementation of secondary air cooling is feasible and generally supports bubble cooling regarding the aforementioned intention. Furthermore, the study reveals that an accurate design of such cooling systems is required.

Prefinished Metal Polymer Hybrid Parts
Ines Kuhnert, Matthieu Fischer, Michaela Gedan-Smolka, Peter Scholz, Didier Garray, March 2019

In this study, adhesive metal-polymer composites were investigated using pretreated aluminum substrates, each with an adhesion-promoting powder coat, a thermoplastic urethane elastomer (TPU) stress-compensation layer and a polyamide 6 top coat to allow further functionalization. One of the composite’s key features is the powder coating, which acts as a reactive adhesive agent and possesses a high-quality surface finish and very good formability. The composites were examined in terms of shaping and assembly behavior. The interfacial bonding was investigated using a peel test. Finally, a demonstrative part was manufactured for the automotive-interior sector.

Influence Of Chain Extender On Mechanical, Thermal Properties Of Pla/Poly(Methyl Methacrylate-Co-3-Trimethoxysilyl Propyl Methacrylate) Blend
Sung Wook Hwang, March 2019

Poly(methyl methacrylate- co- trimethoxysilyl)propyl methacrylate)(P(MMA-co-TMSPMA), and a chain extender, Joncryl ADR 4368 were used in this study. P(MMA-co- TMSPMA) copolymers were prepared by dispersion polymerization using a azo initiator with different TMSPMA content. The effect of the chain extender and/or P(MMA-co-TMSPMA) blends on the properties were investigated. The thermal and mechanical properties were analyzed with a differential scanning calorimeter, rheometer, and universal tensile machine. The crystallinity of the blends was found to be decreased while the complex viscosity increased. The results of the mechanical properties revealed that the addition of chain extender have an effect on increasing the tensile strength. Joncryl system increased molecular weight by forming a long chain branching structure for PLA blends. Also, it was found that the incorporation of the chain extender could enhance the degree of P(MMA-co-TMSPMA) dispersion.

Anomaly Detection In Injection Molding Process Data Using Cluster Analysis
Alexander Schulze Struchtrup, March 2019

Although modern injection molding machines allow operating processes resulting in high part quality and low reject rates, there are still external influences such as fluctuations in the material properties that may cause the production of reject parts. These are often detected with a time delay, which entails high costs. Hence, quality forecasting or control based on process data would be desirable. However, existing approaches did not yet prevail in industrial applications for several reasons. Therefore, supervised machine learning approaches may not always be applicable. Based on previous, univariate approaches aiming to overcome the limitations of the standard process monitoring with its fixed tolerance limits, this paper presents a procedure for multivariate anomaly detection in injection molding process data using cluster analysis as a means of unsupervised machine learning. The procedure allows detecting critical process states in real time and thus lays the foundation for root cause analysis and holistic process optimization.

Modeling For Damage Accumulation Of Injection Molding Machine Components Using Production Planning Data For Predictive Maintenance
Chen-Liang Zhao, March 2019

In industry wear-prone components of injection molding machines are usually replaced by specified maintenance intervals. On the one hand, often these components are replaced too early, so the component service life is not utilized to full capacity. On the other hand a failure causes time-consuming and costly production downtimes. Thus, applications for predictive maintenance of wear-prone components are highly desired by injection molding machine manufacturers and users. Based on this, the present paper describes a procedure to use production planning data available in injection molding production to predict the service life of machine components, resulting in increased machine uptime while reducing storage and maintenance costs.

Air-Coupled Ultrasonic Inspection Of Thermoplastic Cfrp Tapes, A Probability Of Detection Analysis
Wolfgang Essig, March 2019

Besides the aerospace industry, endless carbon-fiber reinforced plastics have also spread towards many further applications such as automotive or civil engineering. Their superior strength and stiffness to mass ratio make them increasingly attractive high performance materials. In this work, we report on a Probability of Detection analysis (POD analysis) of an air-coupled ultrasound inspection of thermoplastic CFRP tapes. Several preliminary works were performed in order to optimize the data set being involved within the POD analysis. The influence of the tape temperature on the ultrasonic transducers and the behavior of the ultrasonic signal in thermoplastic tape at elevated temperature of up to 120 °C were examined in a specially developed testing rig. For maximizing the spatial resolution of ultrasonic transmission measurements, a cone design was developed. Special emphasis was given to both the achievable signalto-noise ratio (SNR) and the spatial resolution. The POD analysis was determined for artificial cuts through the thickness of the tapes and different fitting models were applied.

Effect Of Laser-Induced Periodic Surface Structures On The Self-Cleaning Properties Of Venting In Injection Molding
Marco Sorgato, March 2019

Clogging of venting slots in injection molds is a common maintenance problem related to the degradation of the resin and the accumulation of corrosive residues on cavity walls. In this work, the effect of laser-induced periodic surface structures on the self-cleaning properties of venting slots was investigated. The degradation of PET over different surfaces was characterized using a specifically designed experimental setup. The results indicate that the use of regular nano-structures aligned along the flow direction minimizes the deposition of gaseous residues on the venting slots.

Reduction Of Overmolding Of Thermoset In-Mold Produced Hybrid Components
Tim Deringer, March 2019

Thermoset In-Mold Forming (Duro-IMF) is a new hybrid process to combine the molding of fiber reinforced plastics (FRP) and injection molding of thermosets in one single step. In contrast to the conventional processes, the new molding technology enables the joint curing of both com-ponents in one mold, thus reducing the cycle time and in-crease efficiency. This study deals with the behavior of the Duro-IMF process for a high filled molding compound. One of the biggest challenges is the combination of the highly differentiated processing specifications of the two components. High injection pressures are required to fill the cavity with the highly filled thermoset molding com-pound, whereas only very low pressures are required when processing prepregs with low-viscosity resin. Accordingly, there is a risk that the injection molding component causes overmolding at the prepreg next to the interface. This paper investigates the reduction of overmolding by compression of the prepreg in the prerpeg cavity and the resulting dis-placement of the prepreg into the injection mold cavity. The results are correlated with the resulting component properties such as bond strength and residual strength of the prepreg.

Real-Time Characterization Of Microcellular Injection Molding Via Ultrasonic Technology
Peng Zhao, March 2019

Microcellular injection molding (MIM) has been extensively used for producing foamed plastic parts. It has the advantage of material, energy, and cost savings, as well as enhanced dimensional stability. However, the insitu characterization of MIM is still challenging. In this study, an ultrasonic method for the real-time characterization of MIM parts parameters—i.e., cell size, surface roughness, and skin layer thickness—during the MIM process is proposed. To the best of our knowledge, this is the first time that ultrasonic technology has been employed for the characterization of MIM. A series of experiments were performed to validate the proposed method. Experimental results showed that the duration process times of the ultrasonic signals and the change of the ultrasonic speed in the transducer path could be used to characterize the cell size and the skin layer thickness.The time delay of the first ultrasonic signal and the largest ultrasonic amplitude of the ultrasonic signals was employed to characterize the surface roughness. The proposed method has the advantages of being nondestructive, real-time, low-cost, and safe. As such, it has significant application prospects in MIM production.










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