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

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.

DEPENDENCE ON MELT VISCOSITY OF FOAM PC/ABS INJECTION MOLDING AND MECHANICAL PROPERTY

Takahiro Kunimune, Tsugio Nagasawa, Noriaki Kunimune, Kazushi Yamada, Masuo Murakami, Hiroyuki Hamada, May 2012

This research has developed a novel PC/ABS blend foam injection moldings by focusing on the relationship between foaming agent, PC/ABS ratio, melt viscosity and mechanical properties in foaming PC/ABS materials. Higher melt viscosity exhibited high notched impact strength and smaller microcellular foam internal structure. Moreover, ABS could act as foam nucleating site so that the increment of ABS contents would increase foam internal structure, which benefit for light weight materials with high impact performance.

THE EFFECT OF MACHINE DIRECTION ORIENTATION ON MULTILAYER HIGH BARRIER FILMS

Danielle Froio, Sarah Schirmer, Jo Ann Ratto, Matthew Burke, Gregory Pigeon, May 2012

The effect of machine direction orientation (MDO) on high barrier packaging films was investigated. Multilayer films incorporated an ethylene co-vinyl alcohol (EVOH) core and polyolefin skin layers. Total film thickness and layer configuration were varied to determine the effect on film performance and compatibility with the orientation process. Films underwent a 4:1 stretch ratio, and displayed a 33% reduction in oxygen permeability, a 75% increase in modulus, and a five time increase in tensile strength.

FRICRIVETING OF CIVIL ENGINEERING COMPOSITE LAMINATES FOR BRIDGE CONSTRUCTION

Lucian Blaga, Sergio T. Amancio-Filho, Jorge dos Santos, Radu Bancila, May 2012

This article presents a feasibility-study of the new joining technology Friction Riveting (FricRiveting) on glass fiber reinforced thermoplastic composites and lightweight alloys. Glass fiber reinforced polyetherimide and titanium grade 2 were selected as an alternative solution for truss girder connections in composite bridge construction. Joints without extensive damaging of the fiber network were selected for mechanical testing based on their heat input generation. Fairly strong joints with tensile strengths within 1900 to 4000 N were achieved in this preliminary study. Tensile strength could be directly associated with the anchoring performance of the deformed tip of the rivet. The higher the Aspect Ratio (the penetration of the rivet divided by the width of the deformed rivet tip) the stronger were the joints. Fracture analysis of the tensile specimens revealed a new failure type (full rivet pullout) not observed in previous works. Further process optimization is required to achieve the levels observed for non-reinforced thermoplastic polyetherimide.

IMPROVED MANGEMENT OF PRODUCTION AND CAPACITY THROUGH APPLICATION OF MOLD BASED DATA COLLECTION

Alan Hickok, May 2012

There are multiple methods of tracking and monitoring mold performance and production output using on-board machine data count or discrete network-based systems within a production facility. However, these techniques miss the complete history of the mold from first trials through its life in production and including maintenance intervals and component design changes. Using on-board mold monitoring allows transparency and control of capacity, modifications and maintenance of the mold to deliver better overall performance and cost.

FLOW INSTABILITY IN MULTI-LAYER CABLE COATING DIES

Birane Toure, Jiri Vlcek, May 2012

The paper describes the study of a flow instability defect in a coextursion, cable coating process. The problem was first analyzed using a 2D Finite Element flow simulation. It was determine that the outer layer was experience very high deformation (velocity changes) when merging with the next inner layer. The problem was solved by modifying the coextruson die to reduce the velocity differences that the material experienced in the merge region. This modification stabilized the coextrusion process and removed the instabilities so that acceptable product could be made

FOAMING OF POLY(ETHYLENE-CO-OCTENE) WITH SUPERCRITICAL CARBON DIOXIDE ACROSS ITS MELTING RANGE

Raymond Chu, Yanting Guo, Jin Ho Zong, Nanqiao Zhou, Chul Park, May 2012

The objective of this work is to devise a strategy to produce high quality poly(ethylene-co-octene) foams through the study of the crystallization behaviors of foams attained across the melting range of the material. Experiments were conducted in a batch-foaming apparatus at different saturation temperatures and pressures. Through proper control of processing parameters, and thereby crystallization behavior and melt strength of the polymer matrix, POE foams with a micro-cellular morphology of 1.3x109cell/cm3 were achieved.

MOLECULAR NETWORK CONNECTIVITY IN EPOXY-AMINE THERMOSETS

Christopher M. Sahagun, Sarah E. Morgan, May 2012

Nanoscale interrogation of the fracture surfaces of cured epoxy systems has revealed the presence of non- homogenous network structures. This complicated network structure contains areas with varying levels of crosslink density. The connectivity of the network drives important material parameters such as mechanical properties and solvent and water permeation. This work presents an analysis of the network development of a typical aerospace- grade epoxy system with special attention paid to the influence of network connectivity on the fracture toughness.