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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Recycling

Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.

Clear Barrier at Atmospheric Pressure – the Second Phase

Rory A. Wolf, Rick E. Elwanger, May 2007

The barrier properties of transparent layers deposited on flexible plastic substrates are of interest to many in the packaging industry. Numerous methods have been used to manufacture transparent barrier coatings with varying degrees of success to address evolving environmental laws requiring the reduction or elimination of volatile organic compounds (VOCs), which are the byproduct of curing liquid topcoats. There is also a consumer preference to visually inspect packaged products through packaging prior to purchase. This paper will present new evidence since the 2006 SPE FlexPack Conference of the potential for clear barrier at atmospheric pressure through the use of plasma processing as integral steps in a composite, or several stage, process for deposition and polymerization of functional barrier coatings. XPS analysis of polymerized film showed presence of silicon, carbon and oxygen in ratios different from the monomer, and in fact approaching a Si:O atomic ratio of 1:2 confirming cross linking effects, and the plasma polymerized organo-silicon films displayed good functional barrier properties without the environmental concerns of VOCs.

Novel Polycarbonate Blends with Improved Environmental Stress Cracking Resistance (ESCR) to Hospital Cleaners and Household Disinfectants

Srinivas Siripurapu, Asima Chakravorty, Naveen Singh, May 2007

Impact modified Polycarbonate blends are preferred for medical housings due to their excellent balance of mechanical properties, flame resistance and processability. These housings are increasingly subject to aggressive cleaners and disinfectants to meet heightened sanitation requirements. New flame retardant polycarbonate blends using tailored silicone copolymers exhibit improved environmental stress cracking resistance (ESCR) to many classes of these cleaners.

Polymag Process; Separate & Recover Co-Molded Resins

W. John Collins, Eriez Magnetics, May 2007

The PolyMag Additive & Process enables the automated separation of mixed resin regrind. This innovative system reduces the cost of waste in multimaterial, co-molding operations. This paper will describe the process and applications for post-industrial resin recovery and recycling.

Crystalline Polymer Microgels with Surface Interactions

Gerald H. Ling, Montgomery T. Shaw, May 2007

We report one rheological and microstructural investigation of dispersions of polyethylene microgels in squalane. Emphasis in literature has mainly been limited to systems that depend largely on polymer-solvent interactions and little is known of systems that exhibit both intra- and inter-particle crystallinity. The majority of similar reported systems are prepared using a bottom-up approach while the described system is prepared from recycled bulk XLPE via mechanical grinding and fragmentation by sonic energy. Bulk rheological properties and particle surface interactions are explored using conventional rotational and oscillatory rheometry.

Polypropylene/Polysulfone Membranes

S. Lawal, V. Flaris, May 2007

Polypropylene (PP) and polysulfone (PSU) were successfully blended despite viscosity and processing temperature variations. These blends showed structure-property improvements with the addition of functional polyolefins. A series of membranes were made using an environmentally-friendly process.

Processing Conditions and Thermal Properties of Poly(Lactic Acid)

Langang Niu, Nick R. Schott, May 2007

Poly(lactic acid) (PLA) is an excellent biodegradable polymer that is widely used. The processing conditions of PLA were established by developing a Molding Area Diagram (MAD) on a Roboshot® injection molding machine with different mold temperatures. Isothermal bulk crystallization kinetics of the PLA with 1weight% of talc as a nucleating agent was studied on DSC.

Designing Injection Molded Bioplastics Products

Rolf Koster, Bregtje van Dijken, Lobke van Erve, May 2007

The ongoing need to keep reducing trial-and error in product design definitely applies to plastics products, and perhaps even more to bioplastics. It remains essential to optimize unavoidable weak spots in injection molded products, such as flow weld lines. Critical product properties were investigated for a poly-hydroxybutyrate, an experimental wood fiber-filled poly-hydroxybutyrate, and a general purpose polystyrene for comparison. Specimens from products molded with poly-hydroxybutyrate were found to have quite good impact strengths in weld line regions. Certain non-trivial injection molding settings, which reduce the impact strength in neat product regions, were found beneficial for weld line properties.

Designing Sustainable Products Using Bio-Based Nanocomposites

Emre Tufekcioglu, Rolf Koster, Daniël Vlasveld, Remy Jongboom, May 2007

Environmental materials-related factors can be best addressed in the design stage. Conversion of materials to products is critically important in dealing with new and partly unknown challenges and opportunities. Experiments to explore bio-based nanocomposites included investigating injection molding processability and product properties. Several nanocompounds with modified poly(lactic acid) were prepared and geometries were molded with typical product characteristics, including flow weld lines. Further molding optimization is needed, preferably in conjunction with new mold design principles and dedicated molding machines.

Reinforcing Virgin, Reprocessed or Recycled Polypropylene with Agave Fiber and a Polymeric Coupling Agent

Carlos F. Jasso-Gastinel, Reyes J. Sanjuan-Raygoza, May 2007

The capability of using residual agave fibers from the tequila production process, to reinforce virgin, reprocessed or recycled polypropylene, is studied. Polypropylene composites were prepared with milled (65 mesh) agave fibers and Epolene E-43 in a twin screw extruder, varying the amount of fiber. Tensile, impact and dynamic tests, along with scanning electron microscopy observations were carried out. The importance of polymer-fiber interaction through the presence of the coupling agent is clearly shown.

Rheological and Degradation Properties of Renewable Resource Polymer Blends

Jason D. Conrad, James P. Eickhoff, Graham M. Harrison, May 2007

Over the past decade, considerable interest has emerged in replacing conventional fossil fuel-based polymers with bio-derived polymers. Two bio-derived polymers that have garnered significant interest are PHA and PLA. In this study, shear and extensional rheology, coupled with degradation studies using GPC, are used to investigate the flow properties of blends of these two polymers. The development of blends with tailored flow and thermal/mechanical properties is pursued.

Sharkskin and Melt Fracture of Some Biodegradable Polymers

D. Kanev, E. Takacs, J. Vlachopoulos, May 2007

Sharkskin and melt fracture phenomena have been investigated in two commercial biodegradable polyesters– aliphatic-aromatic co-polyester (AAC), poly(lactic acid) (PLA) and their blends. The study was conducted in a two bore capillary rheometer. It was observed that at high shear rates and stresses PLA exhibits sharkskin and gross melt fracture, while AAC exhibits only gross melt fracture. Experiments indicate that the blends exhibit both phenomena and that blending is beneficial for postponing the onset of flow instabilities to higher shear stresses.

Structural, Thermal, and Mechanical Properties of Miscanthusderived Biocomposites

Gediminas Markevicius, Sean C. Jones, Vivak M. Malhotra, May 2007

Miscanthus, a high yield, fast growing perennial grass with low mineral content, was put under a microscope to explore its potential as a source of natural and environmentally friendly fibers and polymers for composite manufacturing. The manipulation of miscanthus’ structural and thermal properties at 25°C < T < 550°C, as probed by SEM, DSC, TGA, and in situ diffuse reflectance-FTIR, suggested that composites with flexural strength as high as ~ 65 MPa could be formulated without the addition of external polymers.

Development of Renewable Polymers from 1,3-Propane Diol and Malonic Acid

Mathew D. Rowe, Erin M. Smith, Keisha B. Walters, May 2007

The goal of this research is to develop biodegradable copolymers from biomass-derived starting materials. The monomers, 1,3-propane diol and malonic acid, were selected based on the presence of reactive functional groups and availability of these materials in biomass. The effects of varying catalyst and temperature on polymer yield were determined. FTIR spectroscopy and nuclear magnetic resonance (NMR) were used to confirm polyester synthesis. The polymerization yields, using aluminum chloride, tin(II) chloride, and iron(III) chloride as the catalyst, ranged from 18-58%, 20- 43%, and 32-47%, respectively, over the 125-175 ºC reaction temperature range.

Effect of Molding Conditions on Morphology and Structure of Recycled-PET

T. Ohta, Y.W. Leong, K. Yamada, H. Hamada, May 2007

Mechanical and morphological properties of injection moldings are known to be highly dependant on molding conditions, e.g. barrel and mold temperatures, injection speed, and injection pressure. However, the not all conditions impart the same degree of influence on the final properties of the moldings. Here, the properties of recycled poly(ethylene terephthalate) (RPET) were gauged based on accurately measured injection molding conditions, i.e. transducers embedded in the mold cavity were used to measure the resin pressure and speed. Initial investigations have shown that injection speed exerts more influence on the properties of RPET than injection pressure.

Effect of Multiple Shear Histories on Rheological Behavior and Devolatilization of Poly(Ether Ether Ketone)

Jeffrey Galloway, Richard Hoffman, Sanjiv Bhatt, May 2007

The effect of shear history on the properties of poly(ether ether ketone) (PEEK) was investigated by processing it through a twin screw extruder 20 times. Samples were taken at various stages in the recycling sequence for testing. The melt rheological behavior, solid mechanical properties, and total outgassing performance were monitored to evaluate the degradation of the PEEK as a function of processing history.The results of rheological testing suggest that degradation is initially dominated by chain scission with cross-linking becoming more significant with more reprocessing cycles. The rheological and mechanical behavior shows similarities to liquid crystalline polymers and filled polymer systems. The results of outgassing testing showed that the total amount of volatiles decreased with increasing processing cycles.

Environmental Stress Cracking in Polycarbonate – Prediction of the Long Term Behavior by the Use of Short Time Tests

Walter Michaeli, Jan Henseler, May 2007

The environmental stress cracking is the most common failure reason of polymer parts during their use. There are already many tests to verify the stress crack resistance. Most methods use combinations of an external strain and aggressive liquids to achieve a quick test result. The extrapolation to longer time periods is only successful with the help of the expert knowledge of the raw material producers. The development of a new testing method enables a simulation of the material long-term behavior on the basis of a short time test of plastics under the influence of a medium.

Environmental Stress Crazing in Polystyrene: The Roles of Chain Length and Architecture in Craze Initiation

Davide S.A. De Focatiis, C. Paul Buckley, Lian R. Hutchings, May 2007

This work aims to assist in optimising the solid state performance of polymer products, by developing an understanding of the molecular factors involved in initiation of environmental stress crazing. Experiments measuring craze initiation stress in miniature rectangular beam samples saturated in diethylene glycol were performed on 26 isotropic atactic polystyrenes with molar mass from 66 kD to 1148 kD, including a wide range of monodisperse linear and branched materials. Results indicate that both solid-state molecular disentanglement and chain scission play roles, depending on the chain architecture and length of the polymer. A simple rule is suggested for predicting ESC raze initiation in polydisperse polymers.

Failure Analysis and Prevention – A New European SIG

Jan Spoormaker, Erik Andreassen, Anton Heidweiller, May 2007

The new European Failure Analysis and Prevention Special Interest Group (FAPSIG) is creating a database with failure cases. The members share this database and contribute with their own failure investigations. The two main groups are Failure Causes and Failure Mechanisms. Failure Causes are subdivided in: Stress concentrations, low mass and/or mould temperature, highly stressed weld lines, faulty ribbing; too high stiffness of construction elements, incorrect joining, and incorrect material selection.Failure Mechanisms are subdivided in: Creep and stress relaxation, wear, fatigue, UV degradation, chemical attack, environmental stress cracking.The paper will present some examples for designers of plastic products.

Improving the Toughness of Poly(Lactic Acid)(PLA) through Co-Continuous, Immiscible, Biodegradable Blends with PHA

Jinkoo Lee, Stephen McCarthy, May 2007

Poly(lactic acid) (PLA) and Polyhydroxy octanoate (PHO) were melt blended using a torque rheometer in the ratios of 80/20, 60/40, 50/50, 40/60, and 20/80. In this study, the rheological, thermal, and mechanical properties of the blends were investigated. Differential scanning calorimetry showed that the two components in these blends were found with two crystalline phases and two amorphous phases confirming the coexistence of two immiscible components. The addition of modified PHO in PLA increased the toughness of the PLA and increased the elongation to break more than 158%. Results obtained from rheological test indicated that the melt viscosities of PLA/modified PHO decreased as a function of modified PHO content.

Investigation of Fracture Mechanism of HDPE Subjected to Environmental Stress Cracking

Byoung-Ho Choi, Jeffrey Weinhold, David Reuschle, Mridula Kapur, May 2007

Environmental stress crack resistance (ESCR) is a commonly used test to characterize cracking failure of high density polyethylene (HDPE) used in rigid packaging applications. From a resin design standpoint it is important to understand the mechanism of environmental stress cracking (ESC) especially in the case of materials with significantly different ESCR values. In this report, the morphology of ESC is studied by scanning electron microscopy (SEM). A model to predict polymer ESCR using tie chain concentration considering the permeability of IGEPAL® solution is proposed.