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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Biocomposites Based on Poly(L-lactic Acid) and a Functional Synthetic Filler
This work is a continuation of an earlier study on poly(Llactic acid)/hydrotalcite composites prepared by solution mixing. Two types of these synthetic magnesium/aluminum carbonate/hydroxide minerals, at 30wt% filler level, were used; surface coated and uncoated. Differential scanning calorimetric and thermogravimetric analysis of the unfilled polymer and its composites showed significant differences in structure and morphology through the addition of the filler. The composites were exposed to a phosphate buffer saline solution, at 37°C, to study the “in vitro” degradation of the polymer, and also to simulated physiological solution to detect bioactivity by the formation of an apatite type structure layer. The composites were analyzed before and after immersion for predetermined time periods in both solutions, by weight changes, SEM, EDX and RAMAN microscopy. Preliminary results suggest that these novel composites could have a potential use in tissue engineering applications.
Effect of the Mixing on the Mechanical and Thermal Behavior of HDPE/Hydroxyapatite Composites
In composite materials is important an adequate dispersion of the filler on the polymer due to the effect exerted on the material's behavior and as a consequence in its biomedical application. For this reason the objective of the present work is to analyze the thermal and tensil properties of HDPE composites with different hydroxyapatite compositions (10-30 wt.%) prepared by two different methods, extrusion and solution in decaline. The results showed that a better dispersion was reached and as a consequence, resistance at break and Young modulus increased for the composites prepared through solution.
Process Development for Molding a Medical Grade Silicone Elastomer via Rheological and Thermal Analysis Approach
Both thermal analysis and rheological approaches were employed to study the cure behavior of a medical grade silicone elastomer. Isothermal cure experiments were conducted calorimetrically at temperatures from 80 to 100 °C and rheometrically at higher temperatures from 100 to 180 °C. Non-isothermal cure experiments were also performed at different heating rates from 5 to 50 °C/min. It has been observed that the glass transition temperatures for uncured and cured materials remain almost unchanged and that the rheometric measurements are more suitable for characterizing the process of curing, especially for the prolonged, later stages of cure. Based on the changes in dynamic viscoelastic properties measured under isothermal conditions, the characteristic times of cure, including the gelation and peak cure time were determined, and presented as functions of cure temperature. These results were used in an attempt to develop a robust and viable molding process. It has been found that the post-molding cure is essential for stabilizing and optimizing mechanical properties of molded silicone elastomers.
The Study of the Novolac Type Phenolic Resins: Cure Characteristics and Mechanical Properties
The phenolic resin system widely used, such as fiber reinforced composites, honeycomb panelling, electrical laminates, acid resistant coatings and wood panels and so on. phenolic resins like other thermoset resins demand analysis about cure behavior to enhance property of final products. Therefore, investigation of cure kinetics is very important to achieve the full cure state for the proper properties, not to pass vitrification states. The optimum contents of hardener, HMTA(Hexamethylenetetramine), were determined by measuring the heat of cure and mechanical property. And then we conducted the isothermal cure kinetics of novolac type phenolic resin by performing differential scanning calorimeter.
Effects of Free Phenol Contents and Cure Temperature upon the Cure of Phenolic Novolac Resins
The cure conditions as well as resin structure is the most important factors for coming up to possibilities of the hidden strength of the thermoset polymers like phenolic resin which are widely used for the industrial binder due to their excellent thermal and chemical properties. And it is very difficult to eliminate or minimize the unreacted phenol contents below ppm levels in the phenolic resins whereas the containing of phenol is definitely undesirable things especially for the electric/electronic applications and highly thermal resisted applications. In this work we studied the cure temperature effects on their cured properties, also quantitatively investigated the unreacted free phenol effects upon the cure behavior and cured properties of phenolic resins by performing the differential scanning calorimeter, dynamic mechanical analyzer, and izod impact tester. Thus we could figure out the higher temperature above 140? can not be recommended to reach the full cure state, and cure acceleration effects rather than the plasticizer effects of free phenol components on their thermal and mechanical properties when the resins were cured at high temperature which it could be easily reach the vitrified state.
Dimensional Analysis and Scaling Approach for Thin-Wall Injection Molding
In thin - wall injection molding processes, parts thinner than 1 mm are produced using high injection pressures and velocities. Modeling has not been successful in predicting process physics during molding. A dimensional analysis is performed, considering the most relevant variables of the process, the geometry and the non – linear material properties. Using similarity analysis with the material and process related dimensionless groups, the process is scaled by reducing the thickness. The scaled dimensionless groups are used to find relations between process conditions, material properties and other physical parameters, which lead to reasonable conclusions.
Time Scales of Coalescence in Processing Flows: Investigation of Flow through Runners and Strip Molds
The time scales of coalescence in several processing flows were determined from a mechanistic model based on ballistic aproximation and drainage of partially mobile interfaces and compared with the characteristic times of flow through runners and filling of strip molds. It was found that coalescence takes place in a zone between the centerline and the walls of runner of circular cross-section and far away from the injection point in the filling of the strip mold. Qualitative agreement was found between model predictions and experiments carried out in a capillary die and in an injection mold.
Residual Orientation in Injection Molding: A SANS study
The orientation of polymer chains after Injection Molding is usually studied using techniques that measure the average orientation of a polymer segment. Small-angle neutron scattering (SANS) is a technique for measuring orientation at molecular scales and is very sensitive to molecular anisotropy. The residual orientation and conformation of polyethylene and polystyrene chains after injection micro-molding has been measured using SANS. We have found that, for micro-moldings, the residual orientation decreases with increasing injection speed and that the residual chain orientation at the molecular scale is not necessarily related to the average orientation of short chain segments.
New Method of Designing Runner System for Injection Mold using CAO Technique
Today it is popular to evaluate injection molding process using computational analysis in advance. Designing runner system is important to control flow balance and weld positions for molds of large parts with multi gates. If designers use conventional injection molding analysis, they need to evaluate many runner systems by trial and error for obtaining solution, which is optimum only within the tried runner systems.In this paper, we propose an automatic method of designing runner system using Computer Aided Optimization (CAO) technique in order to control weld positions, and show an example of this method with Variable Complexity Model (VCM) approach to reduce optimization time maintaining accuracy of analysis.
Grafting of 12-Aminododecanamide to EAA Copolymer Film to Reduce COF
The effect of covalently bound 12- aminododecanamide on the surface coefficient of friction (COF) of ethylene-acrylic acid copolymer (EAA) films was investigated. The reaction involved grafting 12- aminododecanoic acid to the inherent carboxylic acid groups on the film, followed by amidation of the grafted amino acid. Conversion of film carboxylic acid groups to primary amide groups was also conducted to compare the impact of direct surface amidation. Subsequent measurements showed that both surface amidation schemes reduced the kinetic COF from 0.30 to 0.15~0.18. Repetitive COF testing revealed that amide-modified EAA films maintained low COF values that were independent of the number of COF test runs. However, control experiments showed that COF values also depended greatly on simply exposing film to the various reaction solvents, which increased surface roughness.
Selection of Process and Design Variable Settings under Multiple Performance Measures in Injection Molding
Injection molding (IM) is one of the most prominent processes for mass-producing plastic products. Selecting the proper settings for an IM process is crucial because the behavior of the polymeric material during shaping is highly influenced by the process variables. Consequently, the process variables govern the quality of the part produced. In order to obtain the variable settings that result in the best balances between key quality performance measures, Data Envelopment Analysis (DEA) was used to solve the respective multiple objective criteria problem using empirical models as surrogates. In addition, a DEA modification is explained here with the objective to further screen efficient solutions. Finally, practical cases containing only a subset of performance measures were analyzed to illustrate customized analysis and to illustrate how to identify robust process settings.
Thermal Stability Characterization of Plasticized PVC Compounds Using Calcium and Zinc Stearates
Thermal stability of plasticized PVC compounds (50 phr di(2-ethyl hexyl) phthalate and 0 or 5 phr of epoxidized soybean oil) was studied. The effect of Ca/Zn stearate ratio (0.0/1.0, 0.2/0.8, 0.4/0.6, 0.6/0.4, 0.2/0.8 and 1.0/0.0) and total amount of stearates (0.25, 0.5, 1.0 and 2.0 phr) was considered. The effect of presence of epoxidized soybean oil was evaluated only in formulations containing 2.0 phr of stearates. Degradation behavior was followed by color evolution (yellow index and L a b color coordinates), measurement of gel content, total amount of HCl and polyene produced and mass loss rate.
Added Value for Long-Fiber Reinforced Thermoplastic Components by In-Line-Compounding in the LFT-D-ILC Process
The relevance of long fiber reinforced thermoplastics in the automotive sector has grown significantly during the last years. State of the art technologies are processing of semi-finished products like glass mat reinforced thermoplastics (GMT) and long fiber granulates (LFTG). However, the so called long fiber direct process technologies (LFT-D) are about to gain growing market shares. These technologies enable manufacturers to produce components based on the raw materials glass fibers, thermoplastic resin and additives by using a compression molding technique.An important characteristic of long-fiber reinforced composites is the effect of fiber-orientation and thus anisotropic material properties within the components. The implementation of a new characterization procedure, the analysis of circular tensile specimen (so called “Zugronden”) to obtain the integral fiber-orientation will be introduced.The second focus of this paper is the presentation of some selected results of the material development related to the LFT-D-ILC process technology. The interaction between the different material components polymer, fibers and additives were well-investigated to achieve fundamental understanding of the LFT-D-ILC-Process. This enables optimised material compositions for specific applications.
Injection Molding Short Air Ducts Using TPVs
This paper presents comparisons between three primary process methods for the production of short air ducts for the automotive air induction market with a focus on thermoplastic vulcanizates (TPVs). Cost comparisons between rubber injection molding, extrusion blow molding and thermoplastic injection molding are presented. Injection molded short air ducts using TPVs offer recyclability and a lower air duct weight when compared to a thermoset rubber (TSR) air duct. Additionally, TPV injection molded short air ducts offer a lower cost alternative to blow molding by allowing simplified part consolidation and reduced finishing cost. Part design and process recommendations for injection molded TPV short air ducts are discussed.
In-Line Compounding and Molding of Long-Fiber Reinforced Thermoplastics (D-LFT) - Insight into a Rapid Growing Technology
Long-Fiber reinforced Thermoplastics (LFT) encounter an increasing success in the molding of structural parts, especially in the automotive industry where LFT applications are experiencing tremendous growth. The following paper discusses the different LFT processing technologies – GMT, LFT-pellets and D-LFT – and exposes their distinctive trend for the near future. It also discusses the average fiber-length inside the parts involved by each technology and shows its distinctive influence on stiffness, tensile strength and impact strength. The paper focuses particularly on the Direct-processing of LFT (D-LFT) and shows how this technology can improve the economics although involving technological risks and high investment costs. This paper provides an impartial understanding of the different LFT technologies and highlights the cases in which benefits could be got from the D-LFT processing. In covering both D-LFT injection and compression molding, it also provides information that help the reader to decide which of them could be the most appropriate.
A New Mass Production Process for Lightweight Structural Parts and their Application-Field
A new mass production process combining unidirectional endless and long fiber thermoplastic (E-LFT) has been developed. This one-shot production process is a combination of the well-established LFT process with the direct implementation of unidirectional endless fibers and enables low cost mass production of complex structural lightweight parts. The unidirectional endless fiber tapes (EF) provide excellent mechanical characteristics and can be inserted three-dimensionally, following exactly the paths of load, while the LFT provides high design freedom. First prototype parts have been produced and show that this process allows the substitution of components previously manufactured as metal structures only.
One Piece DLFT Automotive Running Boards
Decoma International has developed a one piece composite running board utilizing Composite Products’ patented Advantage™ inline compounding technology. Running boards are currently in production on the F250/350 Regular, Super and Crew cabs, Explorer and Mountaineer vehicles. The replacement of the 43 piece metal and plastic assembly translates into a running board that meets or exceeds performance requirements at a significant cost savings to the OEM at half the weight. Composite Products, Inc. has commercialized this in-line compounding technology to produce long fiber thermoplastic composite solutions for various automotive applications. Advantage™ systems continuously compound thermoplastic resin with fiber reinforcements such as chopped fiber glass, carbon or natural fibers to produce finished composites with outstanding toughness and excellent exterior appearance characteristics.
Static Charging Methods and Graphic Material Properties for Low Scrap In-Mold Decoration
The use of static charging techniques has been investigated to understand which methods produce the most highly repeatable results for in-mold decoration. The techniques studied were the direct and remote charging methods.In addition to charging methods, the study evaluated material properties, gate location and environmental conditions that contribute to the success and repeatability of in-mold decoration.The optimal method, environmental conditions and material properties were found that produce low scrap results. Conclusions were made regarding optimal charging methods and graphic label constructions.
Precision Printed Films & In-Mold Decorating Technologies
There are a multitude of definitions and processes associated with the decoration of plastic components within the injection molding cycle. In-mold decorating is otherwise known as IMD and either term can be used loosely to describe any process where a part is decorated in some manner “in-mold” or within an injection tool. There are many process names associated with IMD including; in-mold labeling (IML), in-mold priming, the injection of paints into a mold (In-Mold Paint), printing in-mold, et cetera. Many of these have variations between processes from one company to the next. Combining the various trade names and generic process names can form a veritable manufacturing and injection molding alphabet soup.
A Study on the Influence of Surface Roughness and Injection Moulding Parameters on the Gloss of ABS Parts
Plates from ABS, with surface texture varying from very smooth to very rough, were injection molded. They were used for studying the influence of the processing parameters on the morphology, topography and gloss of the surface. It was observed that the mold temperature is the more influent parameter on the final roughness of the moldings. The injection temperature and hold pressure follow next. Higher values of these parameters improve the replication accuracy that causes a decrease in roughness (and increase in gloss) of the very smooth surfaces and the opposite effect in the rougher surfaces.
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