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.

Reducing Resin Waste by Optimizing Polymer Process and Machine Design

Natti S.Rao, Ranganath Shastri, May 2006

Polymer processing and converting operations, whether they relate to extrusion coating, blown film extrusion, producing sheets for thermoforming or manufacturing finished articles by injection molding, generally involve some amount of resin waste. A total conversion of the resin into an article of desired quality is an exception rather than a rule.As material costs constitute the bulk of the total costs associated with any product, the aim should be to keep the resin waste as low as possible. With the quality of the product depending largely on the machine and processing parameters, one of the easiest and most effective methods of reducing polymer waste is to optimize the design of the converting machinery at the design stage before they are built as well as optimization of processing conditions.With the illustration of several examples representative of blown film extrusion, flat film extrusion, extrusion coating, blow molding and pelletization process, this paper demonstrates how by applying this strategy resin waste could be reduced.

Residence Time and Deformation Characteristics of the Real Screw Extruder

Myung-Ho Kim, Hyun-Chil Kim, Chong-Ku Keum, See-Jo Kim, Wook-Ryol Hwang, May 2006

We consider distributive mixing in the single-screw extrusion process. Several mixing measures in the extrusion process were proposed in the literature to quantify the mixing performance. In our previous research, we proposed the “Deformation Characteristics” (DC) as a new deformation measure of the screw extrusion process using the Cauchy-Green deformation tensor.In this work, the fourth-order Runge-Kutta method has been employed for numerical integrations to obtain the residence time and the deformation characteristics, using the three-dimensional velocity fields obtained by the finite element analysis with the periodic boundary conditions along the down-channel direction in the real screw geometry.

Sacrificial Mold Embossing for High Density, High Aspect Ratio Micro/Nano Structures

Chunmeng Lu, David Grewell, Avraham Benatar, L. James Lee, May 2006

An unconventional embossing method is evaluated in which de-embossing is avoided to prevent the deformation or damage of the polymer microstructure on the substrate due to one or more of the following issues involved in hot embossing process: higher feature density, higher aspect ratio, bad surface quality and under-cuts. In this study, a PDMS mold is used to transfer a SU-8 structure to a water-soluble polymeric stamp under low pressure and low temperature, which is used as the rigid tool in the following hot embossing and can be reused by being dissolved in water, an environmentally benign solvent. This method has potential uses in the replication of high aspect ratio microstructure on polymeric materials that cannot be easily achieved using other methods.

The Effect of Addition of PCL on the Mechanical Properties and Thermal Transitions of PLA

Laxmi K. Sahu, Katy Britten, Nandika Anne D’Souza, May 2006

Biodegradation of polymers is becoming an increasingly important consideration for packaging and biomedical applications. The availability of biodegradable materials would allow the invention and continuation of many polymer applications without any hazardous effects on the environment. Material scientists are focusing more intently on making environmentally-friendly polymers by developing biodegradable polymeric materials. Polylactic acid (PLA) and polycaprolactone (PCL) are two systems of application of this interest.Polylactic acid (PLA) is a frequently investigated, readily biodegradable polymer made from renewable agricultural products. It’s mechanical properties, and biocompatibility allow PLA to be used in a wide range of applications, such as biomedical implants and food packaging. However, despite it’s good tensile strength and high melting point, PLA is too brittle to be used in many of these applications. Polycaprolactone (PCL), on the other hand, is a very flexible and biodegradable polymer. In general the degradation of a polymer depends on various factors such as molecular weight, amorphous phase content, moisture level, temperature and pH. The main disadvantage of PCL is that the overall tensile strength of PCL is low. In addition, the low melting point of approximately 60 °C limits its use in many applications. We investigated the benefits of blending these systems and optimized one blend composition. Nanocomposites of this blended system are studied in detail.

Thermal Analysis and Nano-Mechanical Properties of Natural Fiber or Cornstarch-Reinforced Biodegradable Biocomposite

Seung-Hwan Lee, Siqun Wang, May 2006

Thermal analysis and nano-mechanical properties of natural fiber or corn starch-reinforced biodegradable composite were conducted by using a differential scanning calorimeter (DSC) and nano-indenter, respectively. Thermal flow properties of composites were also investigated by using capillary rheometer. The effect of coupling agent and filler on isothermal and non-isothermal crystallization was investigated by Avrami equation and its modified equations. Analysis of kinetic data according to nucleation theories was also performed. Nano-mechanical properties of the reinforcing materials used in this study were also investigated by continuous nanoindentation technique.

Weldability of Bio-Renewable Ultrasonic Exfoliated Nanocomposites

Maria Vlad, Greg Harmon, David Grewell, Avraham Benatar, May 2006

In this work the weldability of bio-renewable nanocomposites was studied. Soybean proteins were denatured in a glycerin solvent and plasticized with a screw extruder. The glycerin contained clay platelets that were exfoliated with high power ultarsonics (2.2 kW @ 20 kHz). Various levels of exposure to the ultrasonic energy were used to exfoliate the clay platelets resulting in nanocomposites with various levels of exfoliation. It was also seen that these materials were not effectively welded with hot plate welding; however, success was found with vibration welding where significant material pullout was seen at the faying surfaces after tensile testing.

Biobased Nanocomposites from Toughened Bacterial Bioplastic and Titanate Modified Layer Silicate: A Potential Replacement for Reinforced TPO

Amar K. Mohanty, September 2005

Biobased ‘green’ nanocomposites are the materials for the 21st century. Polyhydroxybutyrate (PHB) a bacterial bioplastic is recently highlighted because of its renewable resource based origin and its potential to replace/substitute petroleum derived non-biodegradable plastic like polypropylene (PP). The major drawback of PHB is its brittleness. This work investigates toughening mechanisms for PHB via incorporation of elastomeric components. Maleated polybutadiene with high grafting and low molecular weight was identified as the compatibilizer. The toughened PHB was characterized through their thermo-mechanical rheological and morphological analysis. The resulting toughened PHB showed ~440% improvement in impact strength over pure PHB with only 50% loss in modulus. The loss of modulus was recovered to permissible extent through incorporation of titanate modified montmorillonite clay. The hydrophilic clay was modified by titanate-based treatment to make it organophilic and compatible with the polymer matrix. The toughened PHB on reinforcement with 5 wt.% titanate based modified clay gave ~400% improvement in impact properties and 40% reduction in modulus over virgin PHB. The novel toughened bioplastic nanocomposites show potential as a green replacement/substitute of specific TPO for use in structural applications.

Feasibility of Continuous-Fiber Reinforced Blanks for Automotive Applications

Andrew Burkhart, September 2005

Recent developments in the rapid processing of continuous-fiber reinforced thermoplastics (CFRTP) offer a method for automakers and suppliers to manufacture high-performance structures that meet automotive cost performance and volume requirements. Benefits of thermoplastic composites include rapid processing high toughness ease of recycling long shelf life and multi-stage processing. CFRTP tailored blanks are flat net-shape preforms comprising aligned continuous reinforcing fibers in a thermoplastic matrix. These tailored blanks can vary in thickness fiber orientation material composition and shape based on part requirements. Main benefits include material efficiency low scrap and low weight. This paper investigates the feasibility of stamp forming CFRTP tailored blanks. Experimental results are presented showing effects of forming on consolidated tailored blanks and the potential for a high quality surface finish.

Hemp Fiber Reinforced Sheet Molding Compounds for Automotive Applications

Ellen Lee, September 2005

Natural fibers have been steadily gaining interest for use as a mechanical reinforcement material in place of fiberglass for thermoplastic and thermoset composites. In addition to their lower cost and lower density natural fibers are a renewable material and are less energy intensive to produce (grow) than glass fibers. In the current study hemp fiber reinforced SMCs (sheet molding compounds) were prepared and compared to conventionally reinforced glass SMC for cost density and mechanical properties. Continuous hemp fiber (in the form of twine) non-woven hemp mats fiberglass and hybrids (fiberglass/continuous hemp twine mixture) were examined. Severl commercial resins were screened for copatibility to the various fiber formulations and the effect of added compression during the compounding process was studied. In addition to mechanical performance moisture uptake measurements were performed for the hemp glass fiber reinforced materials. Selected SMC composites were evaluated against typical desired properties for automotive applications. Results show that certain formulations are currently close to target values. Next steps for additional optimization of composite formulation fiber dispersion fiber compatibility and moisture resistance will be discussed.

Introduction of Corn By-Products to Composites for Use in In-Line Compounding

Darin Grinsteinner, September 2005

Composite Products Inc. has been developing their Advantage and Advantage Plus In-Line Compounding Processes to use alternative rein forcements and filler materials for automotive and non-automotive applications. While fiberglass remains the favorite when it comes to reinforcing thermoplastic composites natural reinforcements are beginning to gain renewed interest. Corn by-products when added to polypropylene can offer several advantages. Corn by-products offer low cost weight savings environmental friendliness and relatively good material properties.

Polyurethane Structural Composites: An Innovative Process using In-Mold Decorating Films for Exterior Vehicle Parts

Paul Farkas, September 2005

The Woodbridge Group continues to progress with innovative composite technologies for high performance applications encompassing its extensive expertise in the PU fields as well as its growing experience in composites. This paper presents a novel fabrication technology of PU Composites applicable for vehicles. The novel technology is based on an open mould pouring process that allows the usage of relatively low cost tooling low tonnage presses as well as a high level of component integration and process automation for the production of performance products. The process eliminates the need of in-mold or post-painting of the finished part by integrating in the composite structure a high performance film as a decorative exterior layer that provides a high quality surface resistant to environmental factors. The new process allows the fabrication of relatively thin lightweight structural composite with flexural modulus in the range known in other technologies as Polyurethane Structural Reaction Injection Moulding (PU-SRIM) and Sheet Moulding Compound (SMC) with Coefficient of Linear Thermal Expansion (CLTE) compatible with the In-Mould Decorating (IMD) films. The specific gravity of the part dependent on composition is lower than for similar strength products manufactured via PU-SRIM or SMC. End-product performance easily matches or exceeds the requirements of general transportation or other similar applications.

Wood Fiber Composites from Recycled Polyolefin

Minh-Tan Ton-That, September 2005

Wood composites based on recycled polypropylene (PP) were fabricated by melt processing. Different formulations involving two different types of coupling agents two different types of reactive additives and an impact modifier (IM) were used. The reinforcements were in the form of wood sawdust. The mechanical performance of the resulting composites was evaluated before and after conditioning in water for 1 and 7 days. The composites show superior mechanical properties when compared with the pristine matrix and resist humidity very well. The results also demonstrate the effect of formulations on the performance of the recycled composites.

Wood Fiber Reinforced Poly(lactic acid) Composites

M.S. Huda, September 2005

Natural fiber-reinforced composites are increasingly being used in applications in the automotive furniture or building industry. The processing and physical properties of these composite materials are the very important parameters in respect to the design layout and product guaranty. This paper presents the results of the study of processing and physical properties of environmentally friendly wood fiber reinforced poly(lactic acid) (PLA) composites that were produced by a micro-compounding molding system. Wood fiber-reinforced polypropylene (PP) composites were also processed and compared to PLA/wood fiber composites. The mechanical thermal-mechanical and morphological properties of these composites have been studied. PLA/wood fiber composites have mechanical properties of sufficient magnitude to compare with conventional thermoplastic composites. The tensile and flexural properties of the PLA/wood fiber composites were significantly higher when compared with the virgin resin. The addition of 20 wt % of wood fibers in PLA/wood fiber composite improved the flexural strength of PLA by 19 % the flexural modulus by 115 % and the tensile strength and tensile modulus by 5 wt % and 77 % respectively. The flexural modulus (8.9 GPa) of the PLA/wood fiber composite (30 wt % fiber content) was comparable to that of traditional (i.e. polypropylene/wood fiber) composites (3.4 GPa). Incorporation of the wood fibers in PLA resulted in a considerable increase of the storage modulus (stiffness) and a decrease in the tan delta values. The addition of the maleated polypropylene coupling agent (MAPP) improved the flexural and Izod impact properties of the wood fiber reinforced composites. The morphology as indicated by scanning electron microscopy (SEM) showed good dispersion of wood fiber in the PLA matrix. Microstructure studies also indicated a significant interfacial bonding between the matrix and the wood fibers. The specific performance evidenced by the wood fiber reinforced PL

Blends of Polylactide with Thermoplastic Starch

P. Sarazin, M.A. Huneault, W. Orts, B.D. Favis, May 2005

Blends of polylactide with thermoplastic starch are prepared using a one-step extrusion process. These materials, subsequently processed via injection molding, possess interesting properties. The tensile properties in these samples are related to the composition of the blends and also to the glycerol plasticizer content in the thermoplastic starch. These materials possess an advantage for the environment since they are fully biodegradable and are derived principally from renewable sources.

Chain Extended/Branched PET-Organoclay Nanocomposites

Ulku Yilmazer, Ali Emrah Keyfoglu, May 2005

The effects of chain extension and branching on the properties of nanocomposites produced from recycled poly (ethylene-terephthalate) and organically modified clay were investigated. As the chain extension/branching agent, maleic anhydride (MA) and pyromellitic dianhydride (PMDA) were used. Both MA and PMDA improved the mechanical properties of the nanocomposite owing to the branching and chain extending effects that increase the molecular weight. However, PMDA gave better results at lower content.

Advanced Development of Molded Expanded Polypropylene and Polyethylene Bead Foam Technology for Energy Absorption

Steven R. Sopher, May 2005

Recent advancements in the field of polyolefin resins in the area of PP+PE copolymers, impact co-polymers, and homopolymers have allowed for the creation of a new class of thermoplastic foam products. These new products are capable of improved performance due to the advancements that have been made in the area of polyolefin resin catalyst systems. These new Metallocene catalysts are being used to create resins with improved mechanical properties that otherwise were not available using the traditional Ziegler- Natta catalyst systems currently being used to produce a majority of the thermoplastic materials available today.This paper describes these recent advancements and how they allow for improved properties in the area of moldable expanded bead foam used in the automotive, marine and recreational occupant safety and cushioning system designs. This technology allows for improvements in the mechanical properties of these thermoplastic foam components, while allowing them to be produced on existing processing equipment. This paper will also compare these advancements to those currently being used, and demonstrate how improvements in performance, system integration, and cost can be realized. Compliance to existing and new environmental substance regulations and restrictions are also addressed.

Characterization of Virgin/Recycled Nitrile Rubber Blends

M.A. García, M. Hernández, M. Ichazo, J. González, May 2005

Blends of Virgin and Recycled Nitrile Rubber within a blend ratio of 10-30 %wt recycled NBR were studied. Reference was made to mechanical and physical properties. Results obtained indicate that a maximum percentage of 20%wt recycled rubber can be added to a NBR formulation without diminishing considerably final properties, since higher percentages promote a premature vulcanization. Concerning chemical resistance, an excellent oil resistance and a very low resistance to polar solvents were obtained for all formulations.

Clay Nanocomposites Incorporated into Biodegradable Polymers

Matthew Jackson, May 2005

Nanocomposites based on biodegradable polycaprolactone (PCL) and mica clay organically modified with L-arginine were prepared through solvent blending. Their properties were analyzed with TGA, DSC, and tensile testing. The addition of the organically modified clay caused an increase in properties, but at large incorporation, properties began to decrease. Samples of 3%, 5% and 10% organically modified clay were compared to pure PCL.

Comparative Performance and Barrier Properties of Biodegradable Thermoplastics and Nanobiocomposites vs. PET for Food Packaging Applications

D. Cava, A. López- Rubio, L. Cabedo, E. Giménez, J.L. Feijoo, R. Gavara, J.M. Lagaron, May 2005

This paper reports about the comparative behaviour, regarding PET, of biodegradable biopolymers such as PCL, PLA and PHBcoV and their nanobiocomposites, in terms of thermal and retorting resistance (thermal humid processes) and oxygen, water vapour and aroma barrier by means of time-resolved synchrotron radiation, FT-IR and permeation methods.

An Investigation into the Reuse of Painted TPO Regrind

Adam Nadeau, Hardik Valia, Jeremy Perras, May 2005

Thermoplastic olefin (TPO) is currently the material of choice for automotive bumpers and fascias. The part is generally painted with thermoset paint after molding. Unless removed, this paint layer creates problems during recycling of rejected parts. It causes a change in the processing characteristics and properties. The techniques used for removing the paint layer from the TPO create additional steps in the process and adds extra costs. The concept studied is the possible reuse of painted regrind by reducing the paint particle size in an injection molding process; possibly eliminating the need for paint removal in some recycling applications.A modified progressive double row grater screw was used to reduce the particle size of the paint flakes. The physical properties of these material blends are compared to similar blends obtained using a general-purpose screw. It is shown that reducing the paint flake size has a marginal effect on mechanical properties. However, the surface finish is greatly enhanced when the paint flake size is reduced.