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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Experimental and Numerical Study of Stamp Thermo-Hydroforming for Shaping Glass Mat Fiber Reinforced Thermoplastic Sheets into Hemispherical Cups
The goal of this study was to verify through experimentation and numerical modeling that the stamp thermo-hydroforming process provided a suitable alternative to conventional methods such as thermoforming and stamp forming as a means for processing thermoplastic materials. Hydroforming involved supporting the thermoplastic sheet with a bed of viscous fluid that applied a hydrostatic pressure across the part during forming. The external support provided a through-thickness compressive stress that delayed the onset of tensile instabilities as well as reduced the formation of wrinkles due to tensile frictional forces. Preliminary experiments were conducted using a procedure that was designed and built in-house. Initial experiments focused on a fluid pressure applied from one side of the draw blank material. Evaluation included pure stretch experiments experiments where the material was allowed to draw and experiments conducted under a combination of draw and stretch. Complications arose during the experimentation but the benefits of a localized hydrostatic pressure were demonstrated including a 7-10% increase in draw depth for the thermoplastic sheets. The numerical analysis conducted using MARC showed results that correlated with the experimental trends. Overall the experimental results coupled with the numerical modeling showed that the stamp thermo-hydroforming process was a viable processing method for thermoplastic materials that warrants additional attention based on the significant advantages in cost savings and part production accuracy.
Continuous Fiber Reinforced Thermoplastic Composites in The Automotive Industry
Composite materials continue to gain popularity in the automotive community primarily due their ability to reduce weight. Other key advantages include function integration corrosion resistance and low cost tooling. Although thermoplastic composite products have been commercially available for some time now new products specifically continuous fiber reinforced thermoplastics are spurring engineering activity in this growing segment of the composites industry. This paper serves to review materials technologies and applications of continuous fiber reinforced thermoplastics in the automotive industry. Specific application areas include underbody protection bumper beams and load floors.
Development of Low Density GMT Headliners with Improved Acoustical Performance
Low-density GMT (glass mat thermoplastics) materials are being used increasingly in automotive interior applications. These composites have found wide acceptance amongst various automotive OEMs for overhead systems. The superior mechanical properties availability in various basis weight grades ease of processing and ability to be molded to differing thickness makes the AZDEL SuperLite a versatile material for both structural and non-structural headliners. In this paper we have presented the acoustical performance of these low-density composites. Various combinations of this headliner substrate with face fabrics and covering materials were made and their normal incidence sound absorption coefficient was obtained according to ASTM E1050 test method. By varying the areal density molded thickness and the types of skins on the surface of the composite the porosity and the airflow resistance can be tailored to provide optimal sound absorption across a broad range of frequencies. The effect of these factors and their interactions are discussed.
3D FEM Simulation of Feed-Block Profiling for Flat Die Coextrusion
This paper presents the results of a 3D FEM analysis of some layer spreading experiments performed on flat die with a coextrusion feed-block. The complete feed-block and die assembly was simulated using a commercially available 3D FEM software package and a path-line analysis was used to determine the interface position and the degree the of layer spreading. The results obtained were in good agreement with the experimental data. The simulation also provided a better insight into the flow development within these types of systems.
Adhesive Bonding of Polymers and Composites with Microwave Mode-Switching Method
Microwaves provide rapid, selective and volumetric heating in processing polymers and polymer composites. A variable frequency mode-switching method was studied to uniformly bond two polymer composites with an epoxy-based adhesive. Results were compared with thermal process. For one substrate, microwave method reduced the bonding time and enhanced the bonding strength significantly. For the other substrate, microwaves reduced the bonding time and achieved equal bonding strength as that in thermal process.
Advances in the Stabilization of Flexible PVC Using a Liquid Calcium-Zinc Technology
The global market for liquid mixed metal stabilizers is migrating toward heavy-metal-free products. Historically, these systems have not been performance and cost competitive. High efficiency calcium-zinc stabilizers have the potential to replace heavy-metal-based products. The intrinsic value of non-phenolic lubricating calcium intermediates and calcium-zinc stabilizers are discussed within the following report.
AFM Study of Ultrathin Tri-Block Copolymer Films on Tailored Grafted Polymer Layer
AFM was used to study the morphology of ultrathin poly[styrene -b- butadiene -b-styrene] copolymer (SBS) films deposited on polystyrene brushes. The grafting density and molecular weight of the grafted polymer layers were varied to reveal the relationship between the parameters of the brush interface and the structure of the film. We found a strong effect of the underlying brushes on the formation of the SBS films.
Analysis of Large Diameter Polyethylene Piping Failures
Large diameter high density polyethylene (HDPE) pipe, typically with diameters greater than 300 mm (12 inches) often have very different failure modes than smaller diameter pipe of the same materials. Heavier wall thicknesses, sometimes greater than 50 mm (two inches), are more susceptible to oxidation during manufacture. The aqueous media transported in such pipes may also oxidize the pipe wall. Such pipes are also often more susceptible to excessive deformation by soil settlement. In this paper, failures in three different large diameter HDPE systems will be investigated.
An Analysis of the Fiber-Fiber Interactions Using the Fragmentation Test and Optical Coherence Tomography
Multi-fiber model composites are being used in studies into the nucleation of failure in composites. Results have revealed that the nucleation of critical flaws in unidirectional fibrous composites may rely on the time-dependent redistribution of stress by the viscoelastic matrix. Although their role in flaw nucleation is not clearly understood, shear deformation bands have been detected between fiber breaks. Furthermore, interfacial phenomena have been detected in the matrix by Optical Coherence Tomography.
Analysis of the Polymer-Pellet-Flow into the First Section of a Single Screw
The flow of plastics pellets between the first flights of a single screw can lead to conveying problems. As a result, the throughput varies or not enough material reaches the following screw sections. In order to gain a better insight in the correlations that exist between pellet properties, barrel and screw geometry, a physico-analytical model is worked out. On the basis of this model, the pellet flow behavior can be analyzed relatively accurately.
Analysis of Tiger Striping in Injection Molded TPO
Tiger striping in injection molded bars made of thermoplastic olefin (TPO) blends has been examined by a detailed analysis of the disperse phase morphology. This is evaluated in flow mark regions and out of flow mark regions on the part surface and near the wall, and also just behind the flow front but away from the wall. The results point to a way to control the rheology of the components for avoiding or delaying the onset of flow lines.
Annealing of a Co-Continuous Polystyrene/Polylactide Blend and its Influence on the Morphology
In this paper, polystyrene and polylactide were blended at a composition of 50/50 to form a co-continuous morphology. The influence of annealing on the final morphologies of the blend is investigated using SEM and Mercury Intrusion Porosimetry. It is demonstrated that a series of co-continuous networks with pore sizes ranging from 1 to 80 microns and higher have been achieved by varying the annealing conditions. A mechanism of coalescence is discussed in order to account for the said morphologies.
Application of Ultrasound in the Determination of Fundamental Extrusion Performance: Barrel and Screw Wear Measurement
Ultrasonic stand-alone and film-type high temperature sensors and system have been used to measure in-line the barrel and screw wear during low-density polyethylene extrusion. These sensors are nonintrusive and non-destructive. For the screw wear measurement the system is equipped with fast data acquisition. Measurement accuracy of better than 50 ?m can be achieved.
Application of a Single Screw Extruder Simulation towards Design
This paper provides an overview of the application of extrusion simulation towards process analysis and screw design. The paper discusses some of what is possible today with computer aided screw design; what can be obtained from simulation results, what the limitations are, and shows a couple of examples of how to apply simulation towards design.
Application of an Online Rheometer to Evaluate the Melt Properties of PVC
A portable online rheometer has been developed for characterizing plastic melts that can be used for different measurement applications. The rheometer is intended particularly for use in rigid PVC processing. An adapter mounted between the screw tip and the die implies that it is possible to conduct measurements on virtually all the different types of extrusion lines. During the development of the rheometer, particular value was set on having an instrument that is compact and universally deployable. Apart from viscosity curves, the rheometer can also be used to reveal wall slip effects.
Application of Small-Angle X-Ray Scattering to the Lamellar Thickness Analysis in Semicrystalline Polymers
The determination of the crystalline lamellar thickness in semicrystalline polymers is a tricky issue. In this paper, three methods have been employed to analyze the lamellar thickness in semicrystalline polymers. The three methods are small-angle X-ray scattering correlation function method, Fast Fourier Transformation and transmission electron microscopy. Based on this study, the larger value of the two correlation length values should be assigned as the lamellar thickness.
Application of Thermoplastic Elastomer Material Testing Data for Automotive Body Seal Analysis
Material recycling requirement gradually opens the automotive body sealing market to thermoplastic elastomers (TPE), which is primarily dominated by EPDM thermosetting elastomers. Due to special material behaviors of elastomers, careful attentions should be taken when analyzing the body seal performance using material testing data, especially for TPE materials. This paper will address some of the issues by analyzing body seal products using TPE materials. The general guidelines for body seal analysis and result evaluation will also be discussed.
Automated Plastication Setup for Injection Molding Machines
This paper presents a new algorithm for the automatic setting of the rotational speed, back pressure and barrel temperature profiles in a reciprocating screw injection molding machine. The algorithm is based on a computer simulation of polymer plastication. It achieves maximal throughput and good quality of melting and mixing within the limits provided by the injection molding machine.
Automated Set-Up for Gas Assisted Injection Moulding
A process initialisation and setup system for the gas assisted injection moulding process is developed. The initialisation routine uses settings taken from the machine operator or machine controller to formulate the starting point for the process settings. A setup routine is required that automatically changes process settings on the machine controller to provide an acceptable product. Process variables are monitored along with feedback from the operator on the condition of the product. The process initialization routine is outlined here.
Avenues of Introducing Chaotic Mixing in Single-Screw Extruders
It is widely known that single screw extruders are poor mixers and improving mixing in single-screw extruders is a challenging task, especially under low shear conditions. In this paper, a methodology based on chaotic mixing sections, spread over almost half of the screw length, is described to improve mixing characteristics of immiscible and miscible polymer systems under low shear conditions.
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