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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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Conference Proceedings
COMPARISON STUDY OF N2 AND CO2 AS PHYSICAL BLOWING AGENTS FOR INJECTION FOAM MOLDED WOOD-FIBER PLASTIC COMPOSITE
Peter U. Jung, Yongrak Moon, C.B. Park, May 2010
Due to rising environmental concerns, the plastic industry has been seeking bio-plastics that can replace current plastics. Efforts are continuously being made to reduce weight and cost without a major compromise to required properties. Foaming can offer a plastic with significant weight reduction. There has been research to evaluate the effects of chemical blowing agents (CBAs) on wood-fiber plastic composites (WPC). Although physical blowing agents (PBAs) have a number of advantages, their effects on WPC have not been fully investigated. Therefore, this research utilizes N2 and CO2 to analyze their effects on the foaming and mechanical properties of injection foam molded WPCs.
THE ROLE OF MOLECULAR PARAMETERS OF PP IN THE SENSITIVITY TO SPECIFIC NUCLEATION
Lenka Chvátalová , Jana Výchop ová , Roman Cermák , Martin Obadal, May 2010
The efficiency of -nucleating agent (NU 100) in commercial isotactic polypropylenes (PP) differing in melt flow indexes (MFI) was analyzed. Polymorphic composition of neat PP and PP containing 0.01 and 0.03 wt.% of NU 100 was analyzed using wide-angle X-ray scattering and differential scanning calorimetry.Morphology was observed by polarized-light microscopy.MFI influenced the -phase formation only with 0.01 wt.% of NU 100: The step change of -phase content between PP with MFI 1 and 12 was observed. A significant effect of final temperature of heating on -phase formation in the samples was detected. PP containing 0.03 wt.% of NU 100 crystallized into -phase.
MODELING OF COUPLING BETWEEN SPECIFIC ENERGY AND VISCOSITY DURING TWIN SCREW EXTRUSION OF STARCHY PRODUCTS
Françoise Berzin , Ahmed Tara , Bruno Vergnes , Chantal David, May 2010
Starchy products are commonly transformed by twin screw extrusion, either for the manufacturing of food products (extrusion cooking of snacks or breakfast cereals, for example) or for the production of bio-based materials (bioplastics). During the extrusion process, starch is submitted to high shear rates and stresses which lead to a modification of its basic structure. As many properties of the extruded starch are directly connected to the molecular weight and its distribution, it is very important to be able to predict the changes experienced during the extrusion process. In order to model the transformation of starch during twin screw extrusion process, it is thus necessary to take into account the strong coupling between viscosity and thermomechanical treatment. It is the purpose of thepresent work. We have used the software Ludovic was developed ten years ago to calculate the flow of a polymer along a twin screw extruder. We have assumed that the degradation reaction (viscosity decrease) was linked to the specific energy received during the flow. We have compared extrusion cases with and without viscosity/energy coupling and we show that it is important to take it into account in order to correctly predict the parameters of the extrusion process (torque, energy, product temperature') and the starch transformation.??, which
AN INVESTIGATION OF THE EFFECT OF SCREW GEOMETRY ON MELTING IN A SINGLE-SCREW EXTRUDER
S. Azcarate, A. Herrero, J. Esmoris, R. Oñate, A. Cervera,, May 2010
Screw-freezing experiments in a single-screw extruder were conducted with screws having different compression ratios and compression rates for an ABS resin. Three-dimensional finite element simulations of the melting process in the compression section of the extruder were also performed for the compression ratios and compression rates used in the experiments. Even though some discrepancies existed between the numerical predictions and experimental data, the melting profiles predicted by the finite element simulations were in good agreement with the corresponding experimental data.
DEVELOPMENT OF PLASTIC DENTAL BRACKETS BY MICROINJECTION: MECHANICAL AND RHEOLOGICAL SIMULATION, PROTOTYPES PRODUCTION BY MICROMILLING AND PRODUCTION BY MICROINJECTION
S. Azcarate , A. Herrero , J. Esmoris , R. Oñate , A. Cervera, May 2010
Although plastic dental brackets are available on the market, they are all made out of plastic materials with poor mechanical properties. This project sought to develop plastic dental brackets with better mechanical properties than the metallic ones in order to enlarge the aesthetic treatment market. The project started by selecting the material, PSU from BASF, and then focused on prototype production by direct micro milling in order to check the design and mechanical properties experimentally. Once the design was tuned, rheological simulation took place to be produced by microinjection. A first micro mould was produced to check microinjection feasibility. The remaining micro moulds were produced and the first production series obtained. The product was patented and launched on the market.
SYTHESIS AND FOAMING OF WATER EXPANDABLE POLYSTYRENE-ACTIVATED CARBON COMPOSITES
Jintao Yang , Shu-Kai Yeh , Zhihua Guo , Zhiqi Cai , L. James Lee, May 2010
Water can act as a co-blowing agent for carbon dioxide (CO2) based polystyrene foaming. With the introduction of water into the foaming process it is possible to produce foams with ultra-lower density. Herein we report a modified method to prepare water expandable polystyrene (PS)ƒ??activated carbon (AC) composites using suspension polymerization of inverse emulsion. PS is hydrophobic and does not absorb any water. Thus a good water absorbent carrier such as activated carbon can be used to carry water in the foaming process. Activated carbon pre-saturated with water is introduced into the styrene monomer resulting in the formation of water-inoil inverse emulsion. Via suspension polymerization spherical water/activated carbon PS beads could be subsequently obtained. By the extrusion foaming process a PS/AC composite foam with ultra-low density (~0.03g/cc) is successfully produced.
EXTRUSION FOAMING OF CANCELLOUS POLYSTYRENE STRUCTURES
Raymond K.M. Chu, S. Lee, W. Ishaque, B. Zaman, P. Jung, Chul B. Park, May 2010
Foams of cancellous structures are versatile. They can be utilized as particulate filters, spill absorbent linens, tissue engineering scaffolds, and selective extraction membranes. This paper presents an investigation on the fabrication of cancellous polymeric structures with a foam extrusion process. Experiments were conducted on styrenic polymers with supercritical carbon dioxide as the foaming agent. To promote cell wall opening, the strategy of inhomogeneous domain was incorporated in the foaming process. Results showed that a higher foam porosity and more cancellous morphological structure were achieved through the finely dispersed secondary phase in high-impact polystyrene.
A STUDY OF EXTRUSION FOAMING BEHAVIOR OF RANDOM AND BLOCK POLYPROPYLENE COPOLYMER/CLAY NANOCOMPOSITES WITH USING CO2 AS A PHYSICAL BLOWING AGENT
Wentao Zhai, Richard E. K. Lee, T. Kuboki, Chul B. Park, May 2010
Due to the excellent mechanical properties and low material cost, polypropylene (PP) has obtained an increasing market share, up to 26.5% in 2015 according to the expectation, in the world. However, the usage of PP in polymeric foaming field is limited owe to its poor melt strength. Several kinds of commercial high-melt strength PP have been developed for foaming, but high material cost, about 1.8 times compared to the regular one, tends to increase the price of final foam products. How to offer an effective and economical attractive way in fabricating PP foam have attracted a wide attention nowadays. In this study, two linear PP resins, i.e., random copolymer (RPP) and block copolymer (BPP), with similar melt flow rate were selected. Their foaming behavior was investigated by using continuous extrusion foaming with CO2 as the physical blowing agent. The nanoclay was introduced with the aim to show its potential effect in preparation polymeric foams with high expansion ratio and well defined cell structure. The difference in foaming behavior between RPP and BPP was also investigated.
A STUDY OF EXTRUSION FOAMING BEHAVIOR OF RANDOM AND BLOCK POLYPROPYLENE COPOLYMER/CLAY NANOCOMPOSITES WITH USING CO2 AS A PHYSICAL BLOWING AGENT
Wentao Zhai , Richard E. K. Lee , T. Kuboki , Chul B. Park, May 2010
Due to the excellent mechanical properties and low material cost polypropylene (PP) has obtained an increasing market share up to 26.5% in 2015 according to the expectation in the world. However the usage of PP in polymeric foaming field is limited owe to its poor melt strength. Several kinds of commercial high-melt strength PP have been developed for foaming but high material cost about 1.8 times compared to the regular one tends to increase the price of final foam products. How to offer an effective and economical attractive way in fabricating PP foam have attracted a wide attention nowadays. In this study two linear PP resins i.e. random copolymer (RPP) and block copolymer (BPP) with similar melt flow rate were selected. Their foaming behavior was investigated by using continuous extrusion foaming with CO2 as the physical blowing agent. The nanoclay was introduced with the aim to show its potential effect in preparation polymeric foams with high expansion ratio and welldefined cell structure. The difference in foaming behavior between RPP and BPP was also investigated.
A STUDY OF EXTRUSION FOAMING BEHAVIOR OF RANDOM AND BLOCK POLYPROPYLENE COPOLYMER/CLAY NANOCOMPOSITES WITH USING CO2 AS A PHYSICAL BLOWING AGENT
Wentao Zhai , Richard E. K. Lee , T. Kuboki , Chul B. Park, May 2010
Due to the excellent mechanical properties and low material cost, polypropylene (PP) has obtained an increasing market share, up to 26.5% in 2015 according to the expectation, in the world. However, the usage of PP in polymeric foaming field is limited owe to its poor melt strength. Several kinds of commercial high-melt strength PP have been developed for foaming, but high material cost, about 1.8 times compared to the regular one, tends to increase the price of final foam products. How to offer an effective and economical attractive way in fabricating PP foam have attracted a wide attention nowadays. In this study, two linear PP resins, i.e., random copolymer (RPP) and block copolymer (BPP), with similar melt flow rate were selected. Their foaming behavior was investigated by using continuous extrusion foaming with CO2 as the physical blowing agent. The nanoclay was introduced with the aim to show its potential effect in preparation polymeric foams with high expansion ratio and welldefined cell structure. The difference in foaming behavior between RPP and BPP was also investigated.
BLISTERING IN POLYESTER SWIMMING POOL GELCOATS
Jan Spoormaker, May 2010
Blistering of polyester boats and swimming pools is a serious problem and this is mainly due to voids after the so-called gelcoat. Water diffuses through the gelcoat and fills the voids with water. The water can react with the polyester or with remainders of the components that react to obtain unsaturated polyester. The water soluble reaction products cause osmosis and the blister grows till it ruptures. Results from literature searches about the degradation reactions are presented. A court case about blistering of a swimming pool after 2.5 years will be used as an example. During this court case it was learned that an alleged party can try to use allegations that are not in line with laws from nature.
ON-LINE MONITORING OF POLYMER BLEND COMPOSITION BY EMISSION FT-IR SPECTROSCOPY
Jan Spoormaker, H. Schouenberg, May 2010
A FT-IR spectrometer is modified to collect the infrared radiation from the molten extrudate in a polymer blend compounding operation and the IR spectra are analyzed to quantify the blend composition on-line. PLS models are calibrated and validated using the spectra from a set of known blends and blend compositions are predicted via the PLS model from the emission IR spectroscopy acquired instantaneously on the extrudate strands. The chemical compositions of three types of polymer blends during compounding on a twin-screw extruder are measured and monitored in this way. This information can be used for on-line process monitoring and fault diagnosis as well as verification of extrusion models.
MOLD COST PRICE CALCULATIONS
Jan Spoormaker , H. Schouenberg, May 2010
The calculation of the cost price of injection moulds is based on experience with costs of previous molds. The widely used system of Maillard attributes 'points' to the complexity of the cavities, mould base and the number of cavities. A suitable computer program is CALCMASTER and it accounts for: Manufacturing hours for the cavities Manufacturing hours for the mould base Total number of toolmaker hours Total costs for hot runners Costs for injection trials, follow-up, price at mould acceptance. It also calculates: Injection time, Injection pressure and clamping force requirement. Theoretical cooling time, actual cooling time, cycle time, maximum holding time.
QUASI-SIMULTANEOUS LASER BEAM WELDING OF POLYMERS IN CLOSED LOOP
Wolfgang Horn, May 2010
Polymer welding with lasers is getting a state-of-the-art tool in medical device manufacturing and automotive production. Most commonly used are contour welding and quasi-simultaneous welding. An advantage of contour welding is the availability of closed-loop pyrometercontrolled processing optics. On-axis sensors are used for measuring the part's temperature. The pyrometer controller allows the storage of process data for documentation and quality analysis. The new optics developed combine the benefit of contour welding with the speed and addressability of quasi-simultaneous welding. Possibilities and limits of quasi-simultaneous closed-loop welding will be discussed with examples of industrial applications.
FAILURE ANALYSIS OF A GLASS-FILLED POLYPROPYLENE COMPONENT
Mary K. Kosarzycki, May 2010
Chemical attack of a polymer can occur through several mechanisms including oxidation molecular degradation and hydrolysis to name a few. Any one of these mechanisms can then be accelerated though service conditions of elevated temperature and mechanical stress over time (1). One particular failure which occurred for a glass-filled polypropylene part involved the synergistic effects of several factors including service conditions of chemical exposure at elevated temperature while under mechanical stress. Material issues of part design and resinfiller interaction were also identified as potential contributing factors. This paper will summarize the testing involved in determining the mode and potential source of the part failure.
EXPERIMENTAL STUDY OF FIBER-MATRIX SEPARATION AND FIBER DENSITY DISTRIBUTIONS IN FIBER SUSPENSIONS
Christoph Burgstaller, Wolfgang Stadlbauer, May 2010
Defects such as fiber density distributions and matrix separation are commonly encountered when molding polymer composites. Only in the last two decades this problem has been acknowledged by researchers. Such defects are an expensive source of inefficiency that has proved difficult to control and predict. This paper presents results obtained from an experimental setup using pressed samples of silicon oil containing carbon fibers. It is shown that increasing the closing velocity of the mold and the viscosity of the matrix leads to a lower chance of fiber-matrix separation, whereas a growing fiber weight content of the mixture causes a higher chance of separation. It is also shown that there is not only fiber-matrix separation in the flow front but also within the molded charge.
THE INFLUENCE OF MOISTURE CONTENT ON THE MECHANICAL PROPERTIES OF WOOD AND NATURAL FIBER REINFORCED COMPOSITES
Christoph Burgstaller , Wolfgang Stadlbauer, May 2010
The aim of this work was to investigate the influence of absorbed water on the mechanical properties of wood plastic as well as natural fiber reinforced composites. Different composites, with variations in wood content, wood type (and also with flax fibers) and polymer type were produced via twin screw extrusion and injection molding. Mechanical testing (tensile and impact properties) was carried out on samples in the initial state and after certain intervals of water storage. The results are discussed in terms of wood and fiber content and type as well as polymer type, to show the correlation between water uptake and formulation of the composites.
SIMPLE OPTIMIZATION OF PLASTIC PRODUCTS THE DESIGN STAGE
Jan Spoormaker, May 2010
Most designers of plastic products have little education in plastics and have not been trained in calculating plastic parts. The Strength of Materials textbooks derive equations for externally load beams, but many plastic parts, like snap-fit fingers, have prescribed deflections determined by the geometry of mating parts. In snap-fit design tapered beams are beneficial because less material is used and the occurring strain can be reduced up to 30 %. In most textbooks no useful formulas for tapered beam are presented. The threshold for engineering designers to use calculations is rather high and trial and error methods are widely used. Sometimes specialists are consulted to carry out FEM calculations. The problem with these methods is that the designer does not gain insight when others use these methods.
SOLID-STATE SHEAR PULVERIZATION: AN ALTERNATIVE TO NUCLEATING AGENTS FOR SOME SEMI-CRYSTALLINE POLYMERS
Cynthia Pierre , Amanda M. Walker , Katsuyuki Wakabayashi , John M. Torkelson, May 2010
The crystallization kinetics and physical properties of four semi-crystalline polymers polyethylene polypropylene (PP) -polycaprolactone (PCL) and poly(ethylene terephthalate) (PET) were enhanced using solid-state shear pulverization (SSSP) processing without the addition of nucleating agents. Solid-state shear pulverization processing resulted in enhanced isothermal crystallization rates of at least 27% for PP to as much as 85% for low density polyethylene (LDPE). The Youngƒ??s modulus of PCL increased by 65% after pulverization and moderate changes were observed for the other polymers.After SSSP the oxygen permeability of LDPE decreased by 17% PCL by 30% and PET by 55%. Changes in the shape and size of the spherulites during crystallization are attributed as the basis for the enhancements of the physical properties of the polymers.
SOLID-STATE SHEAR PULVERIZATION: AN ALTERNATIVE TO NUCLEATING AGENTS FOR SOME SEMI-CRYSTALLINE POLYMERS
Cynthia Pierre , Amanda M. Walker , Katsuyuki Wakabayashi , John M. Torkelson, May 2010
The crystallization kinetics and physical properties of four semi-crystalline polymers, polyethylene, polypropylene (PP), -polycaprolactone (PCL), and poly(ethylene terephthalate) (PET), were enhanced using solid-state shear pulverization (SSSP) processing without the addition of nucleating agents. Solid-state shear pulverization processing resulted in enhanced isothermal crystallization rates of at least 27% for PP to as much as 85% for low density polyethylene (LDPE). The Young’s modulus of PCL increased by 65% after pulverization, and moderate changes were observed for the other polymers. After SSSP, the oxygen permeability of LDPE decreased by 17%, PCL by 30% and PET by 55%. Changes in the shape and size of the spherulites during crystallization are attributed as the basis for the enhancements of the physical properties of the polymers.


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