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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DESIGN ASPECTS OF DISCONTINUOUS MOLD COOLING TECHNIQUES
The use of pulsed cold water instead of tempered coolant is suggested to be a versatile and cost-efficient technique for the cooling of injection molds. But the advantages and limitations of such discontinuous cooling strategies are still a controversial issue. In this paper the behavior of a discontinuous temperature control system is analyzed. The heat balance of a test mold is monitored and the inter?ªaction of adjacent cooling circuits is identified. It is demonstrated that the appropriate placement of the sensor whose signal is used as an input variable for the temperature control system is of crucial importance.
DEVELOPMENT OF A REACTIVE EXTRUSION PROCESS FOR THE CONTINUOUS SYNTHESIS OF POLYESTERAMIDES
Polyesteramides are among degradable polymers, which are of great interest for a wide variety of applications. In this paper we report a novel reactive extrusion process for the continuous synthesis of polyesteramides. It is based on anionic ring-opening polymerization of e-caprolactam in the melt of commercially available polyester - polycaprolactone. By this means polyesteramides of different chemical compositions were successfully prepared with high yield. Process simulation was carried out using obtained process and material data.
BIAXIALLY ORIENTED MULTILAYERED POLYMER FILMS FOR ENERGY STORAGE APPLICATIONS
Polymer films with enhanced dielectric properties are essential for the production of high energy density polymer film capacitors. By capitalizing on the synergistic effects of microlayering and biaxial orientation, polymer films using PET and a PVDF copolymer were produced which exhibit breakdown fields as high as 1000 kV/mm and energy densities as high as 16.2 J cc-1. Using needle/plane electrodes the fracture zones were investigated and it was evident that the layered films possessed a different fracture mechanism when compared to the single component films.
LASER SINTERING PROCESSES: PRACTICAL VERIFICATION OF PARTICLE COALESCENCE FOR POLYAMIDES AND THERMOPLASTIC ELASTOMERS
Polymer laser sintering is an Additive Manufacturing technology that has been implemented in a variety of industries from automotive and aerospace to the sports and leisure sector. This paper will explore the use of hot stage microscopy (HSM) and differential scanning calorimetry (DSC) to measure and observe powder polymer behavior with respect to the requirements for laser sintering. By observing this behaviour in a range of polyamides and thermoplastic elastomers, the results can be used as a tool for improved development of future materials, and potentially for process optimization, allowing laser sintering to compete in high volume manufacturing environments.
INVESTIGATION OF THE EXPANSION BEHAVIOR OF PE-LD FOAMED WITH CO2
The combination of PE-LD and CO2 to extrude foamed semi-finished products is widely spread. Especially for the extrusion of foamed sheets the decrease in density and cell size leads to an effect, which reveals a wavy pattern transverse to the machine direction and is known as corrugation. Since this effect has not been investigated yet, it is systematically investigated in a research project at the IKV. The aim of the project is to determine the foaming, process and foam parameters which lead to corrugation and thereafter develop strategies to minimize the corrugation in foamed sheet extrusion.
EXPERIMENTAL STUDY ON INJECTION MOLDING OF WHEAT-STRAW/HDPE COMPOSITES
Filling polymers with wheat straw can be environmentally responsible and reduce cost. Nowadays most composites with natural fibers are processed by compression molding. This study examined the feasibility of manufacturing wheat-straw and high-density polyethylene composites by injection molding. MFI and thermal analysis of composites with different wheat straw contents were characterized. Mechanical properties of injection molded composites were measured. It has been found the melt points of all composites were about 135C. The fluidity, tensile and impact strengthes of the composites decreased while the wheat straw content increased. However, the flexural strength increased slightly with the increase in wheat-straw content.
BOSS DESIGN AND OPTIMIZATION FOR MICROCELLULAR FOAM INJECTION MOLDED PARTS
There are two basic models companies following when implementing the MuCell microcellular foam injection molding process. The first and most common implementation is to apply the technology to a part designed for solid. The second implementation involves parts designed specifically to optimize performance with the microcellular foam process. In either case, the customer needs to understand the expected performance of the fastening mechanism. This study identifies the achieveable fastening performance with screws when using boss designs for standard solid injection molding and also identifies the optimum design geometry for microcellular foam molded boss design.
MICRO INJECTION MOLDING: CHARACTERIZATION OF CAVITY FILLING PROCESS
Based on reciprocating micro injection molding machine, this paper characterizes the influence of machine process parameters and its transition response from velocity control to pressure control (V-P transition) on the micro cavity filling process. The method of Design of Experiment was employed to systematically and statistically investigate the effect of machine parameters on actual cavity filling process, which was described by the defined process characteristic values (PCVs). The statistical analysis indicated that injection speed was dominated factor affecting all PCVs in cavity filling process. It was also found that the machine V-P transition have significant effects on cavity filling.
EVALUATION OF BIODEGRADABLE COPOLYESTER RESINS WITH INCREASED GREEN CONTENT
Three different biodegradable copolyesters with increased green content (starting from 31 %) made from recycled post consumer poly(ethylene terephthalate) (PET) were evaluated in comparison to commercial poly(butylene terephthalate-co-adipate) (PBAT) in terms of thermal, rheology, and physical properties. The melting temperature of the resins is lower compared to commercial PBAT due to the presence of isophthalate and traces of diethylene glycol (DEG) linkages from PET. The melt flow values are 2.5 times higher than those of commercial PBAT, which has extensive branching. New resins show low crystallinity, high flexibility, and no break at maximum elongation compared to commercial PBAT.
THE INJECTION COMPRESSION EFFECTS ON THE OPTICAL PROPERTY BEHAVIOR FOR INJECTION PARTS
Injection compression molding (ICM) has been utilized in the manufacturing of optical parts since this molding process can improve optical property with reduced flow-induced residual stress and warpage. In this study, a true 3D simulation technology has been employed to predict flow-induced residual stress in ICM process by considering viscoelastic behavior of plastic materials. The optical behaviors of products are simulated according to photoelasticity theory. The simulations are performed with a two-cavity model of spherical lens. The process condition effects, including compression gap, compression speed compression time and delay time, on birefringence, residual stress and warpage results are investigated.
OPTIMIZATION OF MOLDING CONDITIONS OF A PLUG-ASSISTED THERMOFORMED THIN CONTAINERS IN A HIGH SPEED AND VOLUME PRODUCTION CONTEXT.
For an industrial thermoformer, thermoforming plastic thin containers using a plug involved technological knowledge on material behavior, plug material and process variables. Technical papers on the subject exist but not with reference to the optimization of process conditions on high speed and high volume lines. Design of Experiments (DOE) approach like the Taguchi method can be used to refine the process and to minimize rejects. In this paper, a case study on thermoforming PET thin containers on a high output industrial machine using a single criteria based on the Taguchi method for optimization of wall thickness distribution is discussed.
THE LIQUID-LIQUID SEPARATION AND RHEOLOGY OF BINARY STRONG INTERACTION SYSTEM
It is important to discern the liquid-liquid phase separation (LLPS) and crystallization from UHMWPE- liquid paraffin solution in order to control the membrane forming process. Since the UHMWPE- liquid paraffin solution belongs to a binary strong interaction system, accustomed methods such as DSC, light scattering, and optical microscopy (OM) are not so suitable. By adopting an inversing quenching rheological method we successfully obtained LLPS temperature of the polymer solution. The results show that viscoelastic properties are more sensitive to concentration fluctuation of L-L phase separation at the early stages than other methods.
PRECISION POLYMER NANO-MOLDING WITH ANODIC ALUMINUM TEMPLATE
Nano-patterning was achieved by application of nano-porous anodic aluminum oxide (AAO) template as mold inserts in injection molding and thermal nano-imprinting. Depending on the AAO template used, the nano-holes have a diameter of 30 200 nm and a depth that varies from a few hundred nanometers to 60 micro meter. Effects of structure size on polystyrene surface properties were investigated. The replication accuracy was improved using a heat insulator and a high-flow-grade polymer. Results showed high replication of surface nano-features, 30nm rod features, using the injection molding process.
THREE DIMENSIONAL VISUALIZATION OF WATER PENETRATION AND MELT BEHAVIOR IN WATER ASSISTED INJECTION MOLDING
Water-assisted injection molding has some benefits over conventional injection molding such as shorter cycle time. The current study started from simulations of the flow behavior of various models. Theoretical methods and a numerical solver (Moldex3D R10) were used as the analysis tools. By using its three-dimensional visualization ability, water penetration behavior is easier to understand. Different processing condition effects related to water penetration length were investigated. The current research also focused on core out effects with different models. The results showed good agreement with experimental data and are helpful in understanding flow behavior in water-assisted injection molding.
BIOPOLYMER DATABASE EVALUATING QUANTITY, QUALITY AND COMPARABILITY OF BIOPOLYMER MATERIALS
The biopolymer database offers a knowledge platform about biopolymers with producer data and newly measured comparable properties. The database reflects the market situation and serves as connection between manufacturers, converters and end users. Many features allow search and compare possibilities to find the right material. In further working steps the database will be upgraded with processing properties, additives, examples of applications, etc. By using different methods like a questionnaire, interviews, etc the suggestions of the polymer industry will be integrated.
MOLECULAR WEIGHT EFFECT ON SCRATCH BEHAVIOR OF INJECTION-MOLDED POLYPROPYLENE
Polypropylene (PP) is increasingly utilized in various engineering applications because of its lightweight and good mechanical properties balance. Scratch resistance is crucial for various applications such as automotive interior parts. It's important to understand structure-property relationships in order to develop high performance PP. Molecular weight effect on scratch behavior is investigated in this paper. It was found that yielded zone size under scratched surface was correlated well with scratch visibility. Smaller yielded zone was formed in the case of higher molecular weight PP, leading to higher scratch resistance.
MECHANICAL AND MORPHOLOGICAL ANALYSIS OF HDPE / EVA / CACO3 TERNARY BLENDS
In this article, we report the mechanical and morphological analysis of HDPE, CaCO3 and EVA ternary blend. HDPE/EVA/CaCO3 ternary blends were prepared by melt blend technique. The mechanical properties of these blends were evaluated and found that, the incorporation of EVA modifies the toughness by inducing ductility in these composites. The morphology of these composites were investigated by Scanning Electron Microscopy (SEM). The phase structures of these composites were also investigated. We observed two main types of phase structures in these blends; separate dispersion of the EVA phase or encapsulation of the CaCO3 by EVA.
TEMPERATURE DIFFERENCES AND STRESSES IN THE GRP LINING IN CONDITIONS OF NON-STATIONARY HEAT CONDUCTIVITY
Functional layers of chemical resistant glass reinforced plastic linings (GRL) and load-carrying structure of acid baths, pools, chimney liners and other products, made from steel, concrete, or high filler plastic, have different physical properties. Change of the working environment temperature leads to occurrence in the productƒ??s wall of the temperature difference and the temperature stresses. The temperature difference time in functional layers and forecasting of the GRL crazing should be lead on the basis of a theory of non-stationary heat conductivity.
EFFECT OF MOLECULAR WEIGHT ON SCRATCH PROPERTY OF INJECTION MOLDED POLYCARBONATE (PC)
A standard scratch test ISO 19252 is performed to study the scratch behavior of injection molded PC. The effect of molecular weight (Mw) is investigated. A linearly increasing load scratch test provides critical normal loads for the onset of scratch visibility, abrasion, micro-cracking and material removal. Polarizing optical microscope (POM) was used to observe yielding behavior at the onset of scratch visibility and the earlier stage in scratch groove. Surface mechanical properties characterized by micro-cutting method are also discussed. The findings of this study suggest that scratch properties can be enhanced as Mw increased.
BENCHMARKING THE TECHNOLOGICAL COMPETENCE OF SMALL AND MEDIUM-SIZED INJECTION MOLDING COMPANIES
The economic environment for plastics processing companies has changed considerably in the last few decades through globalization and ever faster technological progress. The increasing complexity of organizations and processes is also leading to increasing complexity of the management tasks. In particular, the companies have to ensure taking or keeping a leading position in terms of the production technology. In order that these tasks can continue to be performed satisfactorily, a new key indicator-based assessment system is developed that allows a benchmarking of the technological competences of companies.
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