SPE Library
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
THE EFFECT OF COOLING RATES ON GAS PENETRATION AND FINGERING OF GAS-ASSISTED PLASTIC AND POWDER INJECTION MOLDING
Kevin Lee, Rajiv Nambiar, Donghan Kim, Hyung-Pil Park, Baeg-Soon Cha, Byung-Ohk Rhee, Seokyoung Ahn, May 2012
The effects of cooling rate on gas penetration depth and residual wall thickness (RWT) of gas-assisted injection molding (GAIM) parts was investigated for polypropylene (PP) and for stainless steel powder feedstock (SSPF). Gas penetration depth and RWT of PP in SLA and in Al cavities did not show any significant difference. However, gas penetration and fingering of SSPF in SLA and in Al cavities were found to be different.
POLYETHYLENE BLENDS CONTAINING POLYMERIC MICROSPHERES FOR MILITARY PACKAGING APPLICATIONS
Sarah Schirmer Cheney, Matthew Burke, , Gregory Pigeon, Jo Ann Ratto, Jeanne Lucciarini, May 2012
A low density/ linear low density polyethylene (LDPE/LLDPE) blend was compounded with expandable polymeric microspheres at 1, 3 and 5% loading levels. Multilayer blown films, comprising of a microsphere loaded core with neat blend skins; were processed and characterized for mechanical properties, tear strength, oxygen and water vapor barrier, density, optical microscopy, and thermal conductivity. Significant reductions in thermal conductivity and effusivity, as well as reductions in density were observed at increasing microsphere loading levels.
RENDERING WATERPROOF AND MULTIFUNCTIONAL FIBROUS SHEETS OF CELLULOSE: FROM PACKAGING AND ANTICOUNTERFEIT TO CONSTRUCTION APPLICATIONS
Despina Fragouli, Ilker S. Bayer, Anese Attanasio, May 2012
We present a scalable, inexpensive and green process to render cellulosic sheets waterproof with additional functional properties (magnetic, photoluminescent, antibacterial, etc.). The fibrous cellulose-based sheets are treated in their final, dry phase, with a huge potential economic impact in the manufacturing industry. Our method is based on the impregnation of cellulose sheets with acrylate monomers and micro or nano-scale functional fillers solutions, which polymerize as soon as they come in contact with the fibers. The formed polymeric nanocomposite creates a cladding around each individual fiber and not an overall coating onto the cellulose sheets. The treated cellulose fibers can be still recycled due to biodegradability of the used polymer.
MORPHOLOGICAL ZONES IN MICRO INJECTION MOLDING OF POLYOXYMETHYLENE
Rabie El Otmani, Musa R. Kamal, Abdesalem Derdouri, May 2012
A Battenfeld System 50 micro injection molding machine was used to produce micro moldings of polyoxymethylene (POM), using a stepwise reduced thickness (0.8 mm, 0.45 mm, 0.2 mm) mold. Polarized light microscopy (PLM) was employed to investigate the morphology of the POM micro moldings. Morphology was examined in both the flow and transverse planes. A variety of morphological zones (oriented skin, shish kebab, cylindrulite, twisted lamellae, oblate, spherulite, etc.) are obtained, depending on the location. The morphology depends strongly on the thickness of the molding and thickness changes. The oriented skin layer tends to diminish away from the gate and near the vent end.
A NEW POLYPROPYLENE/CLAY NANOCOMPOSITE FOR REPLACEMENT OF ENGINEERING PLASTICS IN AUTOMOTIVE APPLICATION
Saeid Zokaei, Pouyan Motamedi, Reza Bagheri, May 2012
Polypropylene matrix nanocomposites reinforced with organoclay are investigated and their ability to replace some polyamide automotive parts is evaluated. This is so interesting from industrial point of view because of cost saving and ease of processing and recycling. This work is focused on different nanocomposite systems, which are PP/nanoclay, and PP/PA/nanoclay. Also the effect of compatibilizer is presented here. Structures of these systems are studied by using WAXD, TEM and SEM. Mechanical properties of specimens are studied using uniaxial tensile test. As it will be demonstrated, nanoclay sheets tend to disperse in PA particles. On the other hand, introducing nanoclay into PP/PA blends is proven to have a significant effect on the shape and size of PA particles. In addition, incorporation of nanoclay and compatibilizer into PP matrix directly affected the elastic modulus and yield strength, respectively. Finally, it is observed that among different formulations, PP/PA/nanoclay with PP-g-MA shows the most similar mechanical properties in comparison to neat PA. Based on these results, an automotive part (hubcap which is usually made from PA) was manufactured and its performance investigated in service situations as a case study. Automotive manufacturers' standards were considered and all results were satisfactory.
A STUDY ON EFFECT OF SMALL PERTURBATIONS IN COLOUR FORMULATION ON OUTPUT COLOUR OF A PLASTIC GRADE COMPOUNDED WITH A SINGLE POLYCABONATE RESIN
Shahid Ahmed, Jamal AlSadi, Usman Saeed, Ghaus Rizvi, Daniel Ross, May 2012
Effect on output colour coordinates, of percent variation in pigments standard formulation is studied through statistical analysis of historical data of a compounded plastic grade manufactured at Sabic IP Cobourg Plant. Aim was to investigate sensitivity of output colour data to small adjustments made during production in pigments standard formulation to reach target colour of the plastic grade, which was a blend of polycarbonate resin, four fillers and four solid colour pigments including one organic – the black, and three inorganic - white, red and yellow. Analysis of the colour deviation caused by these adjustments reveals that output colour values are pretty much sensitive to perturbations made in white, black and yellow pigments amount compared with red. Results of optimization carried out to minimize colour deviation, are also presented for the plastic grade
INFLUENCE OF FIBER LENGTH ON THE FATIGUE BEHAVIOR OF GLASS FIBER REINFORCED POLYAMIDE
Melanie Rohde, Hannes Welz, Felipe Wolff-Fabris, Volker Altstaedt, May 2012
Injection molding of long fiber reinforced thermoplastics is a well-established method in automotive industry to mass-produce high quality structural parts without finishing. However, the process generally results in a reduction in fiber length and therefore the maximum fiber length in the parts is limited. Shorter fibers consequently result in reduced mechanical performance. Tensile properties, being static or fatigue, are mainly influenced by fiber length distribution or average fiber length respectively. When applying direct processes, which combine the compounding and the processing of the compound to a finished part, fiber length degradation is widely avoidable during processing. The aim of the present work is to study and compare the fatigue properties of standard injection molded fiber-reinforced polyamide and LFT-compounds processed by injection molding compounder technology. Effort is made to correlate the fiber length to the long-term behavior of dynamically loaded thermoplastic composites. Results of static tensile tests showed considerable improvements in Young’s modulus and tensile strength of composites with longer fibers. Furthermore, high temperature fatigue tests clearly showed that increasing the fiber length in the compound reduces the dynamic creep and improves the dynamic modulus. As a consequence, it is possible to tailor the composite performance by fiber length, and to draw correlations between the structure and the properties of fiber-reinforced compounds.
PLUG ASSIST MATERIALS FOR IMPROVED TRANSPARENCY WHEN FORMING POLYPROPYLENE
Kathleen Boivin, Noel Tessier, Corey Williams, Hubert Kittebmann, May 2012
To avoid scratching issues associated with syntactic foam, solid engineered polymers have been used as plug assist materials for forming transparent polypropylene. A new class of syntactic foam with a copolymer epoxy base has been designed to minimize scratching and improve clarity when forming transparent materials. The performance of copolymer syntactic foams for forming transparent polypropylene was evaluated and compared to the performance of engineered solid polymer and a traditional grade of thermoplastic syntactic foam.
THE EFFECT OF POLYHYDROXYBUTYRATE-CO-VALERATE (PHBV) CONTENT ON THERMAL, RHEOLOGICAL, MECHANICAL PROPERTIES AND FOAMING BEHAVIOR OF POLYLACTIC ACID (PLA)
Qi Guan, Reza Rizvi, Hani E. Naguib, May 2012
This paper examines the effect of PHBV content on the properties of PLA-PHBV blends and their foams. PLA and PHBV blends were manufactured in various compositions via compounding, and their tensile, thermal and rheological properties and their foam morphologies were characterized. The results indicated that although PLA and PHBV are immiscible, the addition of small quantities of PHBV (up to 30 wt%) lead to a finer and more homogenous cellular morphology.
ELONGATIONAL RHEOLOGY AND MECHANICAL PROPERTIES OF BIODEGRADABLE PLA/PBSA BLENDS
Hassan Eslami, Musa R. Kamal, May 2012
Blends of poly(lactic acid) (PLA) and poly[(butylene succinate)-co-adipate] (PBSA) were prepared using a twin screw extruder. The morphology of the blends was examined using scanning electron microscopy (SEM). Elongational flow properties of the blends and pure components were studied. A strong strain hardening behavior was observed for PLA/PBSA blends, in which PBSA forms the continuous phase (PBSA wt% ? 50). The results of tensile test showed that even for blends containing only 10wt% PBSA, elongation at break increased significantly. By the addition of PBSA to PLA, a transition from brittle behavior (observed for pure PLA) to ductile behavior was observed.
VERIFYING AND IMPROVING THE PLASTIC DEFORMATION OF AUTOMOTIVE INTERIOR PARTS AT EARLY DESIGN STAGE
Kaushlendra Singh, Jeff Webb, Li Qi, May 2012
In the plastic injection molded product development and fabrication, warpage is one of the crucial problems to dominate product quality. In general, the integration of product design, mold design, material selection, and various operation conditions has been regarded as the major factor to warpage. However, the real major effects on the warpage are still not fully under control. In this study, two methods are adopted to systematically investigate warpage quality. One is based on manually flow domain modification under CAE simulation direction and the other is benefited from DOE suggestion of process condition revision. Following the flow behavior guideline, the warpage of original design was improved over 50%, due to suitable pressure compensation to the shrinkage. Meanwhile, according to DOE result, it shows mold temperature is one of the most sensitive parameter. After using the suggested parameters from DOE, the poor warpage problem was also be improved up to 50%.
PROCESSING WINDOW FOR SWIRL-FREE MICROCELLULAR INJECTION MOLDED POLYETHYLENE (LDPE) AND POLYPROPYLENE (PP) PARTS USING SUPERCRITICAL NITROGEN (N2) AS A BLOWING AGENT
Emily Yu, Lih-Sheng Turng, Patrick Gorton, Pankaj Nigam, Sezen Buell, May 2012
The surface swirl-marks on foamed plastic parts is an important issue with microcellular injection molding. Based on nucleation theories and experimental results, processing temperature windows for microcellular injection molded LDPE/N2 and PP/N2 parts were established. Comparisons of the predicted processing windows with the experimental results showed good agreement. Thus, based on these processing windows, the appropriate combination of gas dosage and processing temperature, which leads to swirl- free parts for microcellular injection molding, can be determined.
MODIFICATION OF MECHANICAL PROPERTIES OF POLYBUTYLENE SUCCINATE USING IN-SITU COMPATIBILIZATION BLEND WITH POLY(LACTIC ACID)
Benchamas Panyad, Nattakarn Hongsriphan, May 2012
PBS/PLA blends in various blend ratios added GMA to modify their compatibility were prepared using melt blending. Mechanical properties of polymer blends before and after in-situ compatibilization were investigated. Morphology and compatibility of modified blends was studied via SEM and DSC, respectively. PBS/PLA 50:50 wt% added 10 wt% GMA exhibited high percentage of elongation at break in a range of LDPE due to co-continuous structures. This phenomenon also benefited the impact strength of modified blends.
THE INFLUENCES OF PROCESSING TEMPERATURES AND NUCLEATING AGENT IN FOAMING OF A THIN-WALLED INJECTION MOLDED PART
Davoud Jahani, Peter Ungyeong Jung, Amir Ameli, Mehdi Saniei, Chul B. Park, H. Naquib, May 2012
The injection foam molding of a thin-walled polypropylene part of 1 mm thickness at low, moderate, and high melt temperatures using carbon dioxide, with and without talc, was conducted and the effect of process temperatures and nucleating agent on the cell morphology was thoroughly investigated. The results indicated that by using a modified gate geometry and proper control of the process parameters, a uniform microcellular fine-celled part could be successfully produced. Furthermore, the analysis of foams results produced at different temperatures, with and without talc, showed that in microcellular fine-cell foaming of thin-walled injection molded parts, temperature effect is more dominant.
ISOTHERMAL CRYSTALLIZATION-INDUCED FOAMING OF POLYPROPYLENE UNDER HIGH PRESSURE CARBON DIOXIDE
Anson Wong, Yanting Guo, Chul B. Park, Nan Q. Zhou, May 2012
Crystals can strongly influence plastic foaming behavior, final foam structure and properties. Using an improved visualization system, foaming process of polypropylene was captured and compared with differential scanning calorimetry analysis. It was observed that crystals nucleated and grew into spherulite. At low temperatures, cell nucleation occurred at crystals’ boundaries due to CO2 exclusion from crystal growth fronts and increase in tensile stresses in surrounding amorphous regions. At higher temperatures, these two mechanisms became less apparent.
DISPERSION OF SINGLE-WALLED AND MULTI-WALLED CARBON NANOTUBES IN UNSATURATED POLYESTER RESIN
Esteban E. Ureña-Benavides, Matthew J. Kayatin, Virginia A. Davis, May 2012
Several strategies were explored for dispersing carbon nanotubes were dispersed in unsaturated polyester resin (UPR). CoMoCAT single-walled carbon nanotubes (SWNTs) were more difficult to disperse than HiPco SWNTs. Oxidation of nanotubes decreased the dispersion quality. Dodecylation via the Billups reaction also failed to improve dispersion quality. Polystyrene grafted from carbon nanotubes was found to be a promising strategy for dispersing both single-walled and multi-walled carbon nanotubes in UPR.
A STUDY ON RECYCLING OF POLYHYDROXYBUTYRATE (PHB) COPOLYMER AND ITS EFFECT ON MATERIAL PROPERTIES.
Bhavin Shah, Robert Whitehouse, Stephen McCarthy, May 2012
This study focuses on the ability of PHB copolymer to be processed a number of times and use of different virgin to regrind ratios. This work studied the effect of regrind levels and heat history on material properties of PHB Copolymer. The material was recycled for 10 regrind generations and also was studies for 7 regrind ratios with virgin material. 79% reduction in viscosity and 10% reduction in ultimate tensile strength were observed for 10 regrind generation. Also a drop of 5% was observed in the viscosity and ultimate tensile strength with a 50:50 virgin to regrind ratio.
INVESTIGATION OF SUPERCRITICAL FLUID-LADEN PELLET INJECTION MOLDING FOAMING TECHNOLOGY(SIFT)
Xaofei Sun, Lih-Sheng Turng, Patrick Gorton, Pankaj Nigam, Sezen Buell, Eugene Dougherty Jr., May 2012
A novel method of producing injection molded parts with a foamed structure has been developed. Compared with conventional microcellular foaming technologies, it lowers equipment costs without scarifying the production rate, making it a good candidate for mass producing foamed injection molded parts. In this study, further research on this method was conducted including: (1) comparison of different physical blowing agents, (2) shelf life of carbon dioxide laden pellets, and (3) optimization of the process conditions
EFFECTS OF UNSUPPORTED WALL HEIGHT ON LINEAR VIBRATION WELDING OF PMMA TO ABS
Abbass Mokhtarzadeh, Avraham Benatar, May 2012
Vibration welding is very popular in the automotive industry due to the short cycle time and high quality joints. It is frequently used in welding of PMMA lenses to ABS backing in automotive tail lights. The welding fixtures are designed to accommodate dimensional variations in the parts often resulting in welding of long and tall unsupported walls. Therefore, linear vibration welding of vertical PMMA plates to horizontal ABS plates in a T-joint with the vibration motion being transverse to the PMMA plate was studied. The effects of unsupported wall height of PMMA, amplitude of vibration, meltdown, and pressure on joint strength were evaluated. As expected, for short unsupported walls high quality welds with short weld times were produced. However, as the wall height increased, longer weld times were required to produce welds until the height was so large that the PMMA plate would bend rather than produce relative motion at the interface.
PACKING PARAMETERS EFFECT ON INJECTION MOLDING OF POLYPROPYLENE NANOSTRUCTURED SURFACES
Matteo Calaon, Guido Tosello, Hans Hansen, C. Ravn, A. Islam, May 2012
In today´s industry, applications involving surface patterning of sub-µm to nanometer scale structures have shown a high growth potential. To investigate the injection molding capability of replicating sub-µm surface texture on a large scale area, a 30x80 mm2 tool insert with surface structures having a diameter of 500 nm was employed. The tool insert surface was produced using chemical-based-batch techniques such aluminum anodization and nickel electroplating. During the injection molding process, polypropylene (PP) was employed as material and packing phase parameters (packing time, packing pressure) were investigated. The replicated surface topographies were quantitatively characterized by atomic force microscopy using specific three-dimensional surface parameters and qualitatively inspected by scanning electron microscopy. Results showed that the degree of replication from the toll to the polymer part was mainly influenced by packing pressure level and distance from the gate.
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