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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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.
DRAFT OF THE BASIC SYSTEMATIZATION OF INORGANIC AND ORGANIC MACROMOLECULAR COMPOUNDS
The word polymers is usually related to plastics and rubber. This definition narrows down the meaning of the word to a very significant group of materials, but leaves out numerous other substances and materials that are also polymers. The consequence is the difficulty in observing the interconnection or comparability of polymers among each other or with other non-polymeric substances and materials. Therefore, a draft of the basic systematization of inorganic and organic macromolecular compounds has been elaborated.
Changes in global markets and the recent financial crisis have prompted companies to re-examine their value chain and carefully review the demarcation line between internal and sourced development and manufacturing resources to determine which are still strategic to the business. This has caused captive molders to re-visit value propositions and seek new ways to remain financially viable and strategically relevant to their parent companies. One approach is migration to a hybrid model supporting both captive and custom molding. This paper explores the merits of a hybrid model and issues associated with transitioning to a combined model in a corporate environment.
DIRECT ISOLATION OF POLYPHENYLENE ETHER-POLYSILOXANE BLOCK COPOLYMER
A polyphenylene ether-polysiloxane block copolymer is produced by oxidative coupling polymerization of 2,6 xylenol and a eugenol-terminated polydimethylsiloxane. The reaction takes place in a solvent, such as toluene, which needs to be removed in an polymer isolation step. The isolation can be done by precipitation of the polymer with an anti-solvent such as methanol, or by direct" isolation in a devolatilizing extruder as described in this paper. Process conditions to control the desired residual solvent content in the product are reported as well as the effect of the process on key product properties.
DIRECT ISOLATION OF POLYPHENYLENE ETHER-POLYSILOXANE BLOCK COPOLYMER
A polyphenylene ether-polysiloxane block copolymer is produced by oxidative coupling polymerization of 2,6 xylenol and a eugenol-terminated polydimethylsiloxane. The reaction takes place in a solvent, such as toluene, which needs to be removed in an polymer isolation step. The isolation can be done by precipitation of the polymer with an anti-solvent such as methanol, or by direct" isolation in a devolatilizing extruder as described in this paper. Process conditions to control the desired residual solvent content in the product are reported as well as the effect of the process on key product properties."
GAS PERMEABILITY OF ORIENTED POLY(ETHER-B-AMIDE) (PEBAX) COPOLYMERS
Poly(ether-b-amide) (PEBAX) thermoplastic elastomers are used in high flux applications such as gas separation membranes. PEBAX grades with high polyether soft block content are favorable for gas separation applications due to a high permeability. Permeability measurements on uniaxially oriented PEBAX films in the stretched and recovered state showed a significant decrease between the unoriented films and 400% strained films. WAXS and DSC were used to identify strain-induced crystallization of the polyether blocks, resulting in a 3.5x permeability decrease for oriented PEBAX films.
FACILE THERMOPLASTIC OLEFIN (TPO) DISPERSION USING EXTENSIONAL MIXING
The mixing performance of a small-scale extensional mixer (Spiral Fluted Extensional Mixer, or SFEM) was benchmarked against a mixing bowl. TPO blends were chosen for this evaluation, with a broad range of elastomer melt indices. Various statistical metrics were evaluated to quantify the degree of dispersion of the blends. The conclusion is that due to stronger extensional flow, the SFEM batch mixer indeed has potential to offer better TPO dispersion than mixers with rotors in which shear dominates. A single-screw extruder equipped with SFEM mixing elements achieved even finer dispersion, usually achievable only with twin screw extruders.
EXPERIMENTAL INVESTIGATIONS ON THE IMPACT BEHAVIOR OF HYBRID STEEL-FRP STRUCTURES IN 3-POINT-BENDING TESTS
This paper presents an experimental investigation of the mechanical behavior of hybrid metal hat sections, reinforced with fiber reinforced plastics in 3-point-bending tests. The combination of FRP laminates with metal structures leads to an advanced hybrid material system evaluated for future automobile primary structures. A systematic high velocity impact testing program under 3-point-bending was conducted. To evaluate the impact performance and damage resistance, the load-displacement curves referred to the single steel hat section were used. Variations of fiber types (carbon, glass, aramid) and combinations of such fibers are discussed. Furthermore, the influence of laminate thicknesses and fiber orientations is considered.
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