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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LFT-D-ILC - Innovative Process Technology Decreases the Costs of Large-Scale Production of Long-Fiber-Reinforced Thermoplastic Components
Long-fiber-reinforced thermoplastics (LFT) have gained an increasing market share in the European automotive industry. In some large-scale applications the processing of semi-finished products such as LFT-GMT (glass-mat reinforced thermoplastic sheets) and LFT-G (long-fiber-reinforced thermoplastic granulate) is already known. The LFT-D process in which continuous rovings are fed directly into the polymer melt differs fundamentally from the LFT-GMT and LFT-Pellet-Process. High economic efficiency is achieved when the cost intensive production of semi-finished products as well as the subsequent logistic costs are avoided. Thermal stress of the compound is minimized. Excellent flow properties as well as consistent glass fiber content are obtained. The degree of freedom regarding the use of new polymer blends and different types of fibers for example natural fibers enables an individual matching of the compound according to the specific needs of the application. In addition the glass fiber content can be adjusted as needed. The solution presented in this paper is based on the Dieffenbacher Direct Process (LFT-D-ILC). This development is responding to the technical requirements of automotive parts for large-scale production. As the leading manufacturer of presses and fully automated press lines for the production of components of fiber-reinforced materials such as SMC BMC LFT-GMT LFT-P and LFT-D-ILC Dieffenbacher offers complete technical solutions to suppliers and the automotive industry.
Characterization of Adhesive Failure and Modeling for Dynamic Analysis
One of the ways of increasing fuel efficiency of a typical automobile is to reduce its overall weight. To this extent plastics especially fiber reinforced plastics are finding an increasing role as automotive structural components. The automotive structural systems made up of these structural fiber reinforced plastic components should satisfy the needs in terms of safety strength NVH and durability in addition to being affordable manufacturable with desired fit and finish and recyclable. In general structural components made up of fiber reinforced plastics are adhesively bonded together to form structural systems capable of carrying automotive structural loads under static and dynamic conditions. Fiber reinforced plastics and the adhesive used to bond them to form a structure are inherently viscoelastic in behavior. It is imperative therefore to understand the behavior of these adhesively bonded fiber reinforced plastic components in terms of their load carrying capacity at different temperatures and different load or strain rates. One of the key factors in this understanding is to characterize the adhesive failure itself at different temperatures and different strain rates of loading. The present paper is an attempt to present some results from an ongoing research work on fiber reinforced adhesively bonded large injection molded thermoplastic automotive structural systems. In particular the paper presents the results from the test methodology and the mathematical models used to characterize the failure mechanics of adhesively bonded automotive body sections at different temperatures and different load or strain rates.
Development of Low Density GMT Composites for Automotive Applications
The development in the field of composites has been spurred by the need for lightweight fuel-efficient automobile that is environmentally friendly and affordable. A low density light weight GMT composite containing long chopped fiber strands was developed by AZDEL Inc. for use in headliner and other automotive applications. The low density GMT (LD-GMT) is available in grades ranging in basis weight of 600 to 2000 g/m2. This paper presents development of this LD-GMT material for automotive interior and structural applications. This thermoformable material has several advantages over other traditional materials like steel and thermoset composites. The LD-GMT offers design flexibility low weight high rigidity excellent energy absorption characteristics faster cycle times and an environmentally friendly manufacturing process. The design flexibility and application of these LD-GMT composites in automotives and the advantages of applying these composites over the other materials in interior structural and modular applications will be discussed.
The Effect of Sample Preparation on the Flexural Strength of Reinforced Nylon 66
Cutting flexural test specimens from molded plaques is commonly used in material testing. The mechanical properties of these cut specimens may be affected by the cutting process as it could introduce extrinsic flaws and thermal residual stress on the cut surfaces. The objective of this experimental research is to determine how band saw cutting affects the flexural strength of 33% short glass fiber reinforced nylon 66. The specimens for the flexural test were obtained by cutting molded plaques using different blade types blade speeds feed rates and levels of polishing. The results were compared with those from uncut specimens. Surface morphology of specimens’ cut edges was observed by using Scanning Electron Microscopy. The results indicate that lowest strength of cut specimens is achieved at the lowest blade speed and highest work piece feed rate.
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.
Structural Mechanics of Polymer Coated Optical Glass Fibers: Review
The paper contains a brief review of the state-of-the-art in the stress-strain analysis (Structural Mechanics) of polymer coated optical glass fibers, with an emphasis on the analytical modeling.
Kinetics of Isothermal Crystallization of Syndiotactic Polypropylene: Avrami and Urbanovici-Segal Analyses
In this paper, the Avrami and Urbanovici-Segal macrokinetic models were applied to describe the kinetics of isothermal crystallization from the melt state of syndiotactic polypropylene (sPP). Data analysis was carried out using a direct data-fitting procedure, in which the experimental data were directly fitted to each macrokinetic model using a non-linear multi-variable regression program. The results suggested that the Urbanovici-Segal model was the better of the two in describing the isothermal crystallization data of sPP.
Production of Structures from Thermoplastic Composite Towpregs
An efficient and cost effective way of producing continuous fibre-thermoplastic matrix composites relies on the use of towpregs. Equipments are being developed for the production of the towpregs and also to manufacture pultruded profiles and filament winding structures. The properties of the composite products are determined and compared with conventional alternatives. An assessment is made on the influence of the processing conditions on the output and mechanical properties of glass fibre/polypropylene (GF/PP) composites.
Friction Properties of Thermoplastics in Injection Molding
In the ejection stage of parts injection molded over cores the knowledge of the friction properties between the mould surface and the part are important to optimize the ejection system solution. The coefficient of friction depends strongly on the mould surface and the temperature at the moment of ejection. Prototype equipment was developed to measure the friction properties in as-molding conditions, and methods developed to perform the testing. Data will be presented for two thermoplastics (polycarbonate and polypropylene).
Prediction of Ejection Forces in Tubular Moldings in Amorphous Polymers
The prediction of ejection forces in tubular moldings (pipe fittings, cups, ..) is relevant for the optimization of the ejection systems in molds. An instrumented mold (pressure, temperature and force) for a tubular part was developed for measuring the actual ejection forces for two amorphous materials, polystyrene and polycarbonate. The ejection forces depend mostly on the holding pressure and the mould core temperature. The experimental data is used to validate a thermo-mechanical model that predicts the shrinkage and internal stresses.
Niche Marketing: High Temperature Nylons
As nylons 66 and 6 continue to grow in volume, they are beginning to take on the attributes of commodities, e.g., product interchangeability and price sensitivity. Producers are finding that high temperature nylons aimed at niche markets are sufficiently differentiated that they resist the trend toward commoditization while offering interesting volume potential in applications where value means more than price. This is an area where monomers make the difference and integrated producers have the field to themselves.
Fabrication of Quasi-Isotropic Laminated Films from Oriented LLDPE Film Using a Novel Supercritical CO2 Solvent Welding Technique
Supercritical Carbon Dioxide (SC CO2) is used as a reversible plasticizing agent to promote solvent welding in highly oriented LLDPE films. Films are stacked in a quasi-isotropic fashion to enhance film properties in all directions. It is shown that, after processing, the oriented morphology and crystallinity are unchanged. The strength of the laminate interface is tested. Tensile properties of the laminated film are evaluated and tear resistance is measured using a single specimen J1C.
Molecular Fortification of Crosslinked Networks
In this study, a small molecular phosphonate, dimethyl methyl phosphonate (DMMP), is investigated for its fortifier properties in addition to its diluent effects, using mechanical and thermal analysis techniques. This fortification is consistent with previously reported antiplasticization effects without the need for stiff, aromatic functionalities. Phosphonates are likewise known to enhance the flammability properties of polymers by reducing the heat release rate, resulting in a multi-functional additive.
Treatment of Hydronic Heating Hose with Additives in the Field
Radiant heating by circulation of fluid through hose in or beneath flooring has become popular because of cost efficiency, particularly in new construction. Many systems in the field have been operated above recommended temperatures or used poor choices of circulating fluid and, as a result, show degradative effects and crack initiation. An additive package was developed that largely reversed these effects as indicated by dynamic mechanical measurements of elastic modulus.
Melt Index from a Single Pellet
The melt index of a single pellet is measured by combining experimental viscosity determination and simple modeling of the flow in the melt indexer. Special parallel plates are used to quantify the shear rheology of a 5 mg sample, the viscosity data is fit to a Power Law model, and the melt index is calculated. Results from this technique are compared to the results from actual melt index measurements for polyethylenes with a range of melt index values.
Effect of Die Geometry on the Orientation of the Velocity Field during Bi-Layer Extrusion with a Conical Extruder
In this study, coextrusion flow in a new type of multi-layer extruder is analyzed by means of numerical simulation. This prototype extruder is based on a conical rotor-stator assembly. The extrusion of a range of polyethylenes and polypropylenes was investigated at various rotor speed regimes. The effect of die design and viscosity ratio between adjacent layers on the helicoidal flow is discussed.
The Secrets of Building Brand Loyalty and Customer Retention to Grow Profits by 10-15%
With it being widely recognized and accepted that by raising customer retention rates by as little as 5%, benefits far beyond the obvious can be gleaned from repeat customers. Learn how companies are making efforts to develop brand loyalty and prospering while those that aren't are missing out on growth and profit opportunities.
Optimized Mechanical Performance of Welded and Molded Butt Joints: Part I-Similarities and Differences
Recent developments were oriented on the analysis of the mechanical performance at local (knit lines and welds) and bulk (molded part) areas, with the influence of molding and welding conditions. It has been found that for non-reinforced and reinforced nylon, the mechanical performance in the knit planes and welded areas are approximately equal to the mechanical performance of a base resin (matrix). The observations on similarities and differences in the formation of knit and weld lines are presented in Part I of this paper.
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