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 Influence of Stress on Peel Strength of Acid Copolymers to Foil
Barry A. Morris, May 1999
As an acid copolymer is converted in the extrusion coating process, it undergoes considerable stress and orientation. This stress arises from shear forces in the extruder and die, from extensional forces as the melt curtain is drawn down and from shrinkage forces during crystallization. It is hypothesized that these stresses may influence peel strength by impacting tensile properties and residual stress at the foil-polymer interface. Relationships are developed between stress and common processing parameters such as air gap, die gap, melt temperature and line speed. An experiment is described where processing parameters were changed in a systematic way to alter the stress imposed on the polymer. Data is presented which strongly supports the hypothesis, and provides an understanding as to the role and impact of various processing parameters.
Munsell Color Science Laboratory Industrial Color Difference Consortium - Current Initiatives and Future Directions
Roy S. Berns, May 1999
There is a continual need for automated approaches to defining color quality within the industrial community. It is well known that color vision is a most complex process with many variables affecting visual color tolerances. Although much progress has been made, as all professionals in this field are likely to agree, much remains to be done. One of the very few such efforts internationally is the RIT Munsell Color Science Laboratory's Industrial Color Difference Consortium, started in 1995. The Society of Plastics Engineers is one of ten members. This paper will summarize recent research and future initiatives.
Automation in Thermal-Analytical Instrumentation and SPC Helps in Supplier Quality
Vijay N. Reddy, May 1999
Defect prevention and reduction of variation are described as minimum expectations in the fundamental quality systems. There are strong relationships between reduction in variation, zero defects and ultimately the cost. Heavy reliance is placed on in-process inspection, testing and on-line monitoring of process parameters. Statistical process controls (SPC) and control charts are used to determine the process capability index (Cpk). Thermogravimetric analysis (TGA) is widely used to measure product quality. We will discuss the use of Robotics-TGA and SPC that has come to the aid of process engineers to improve Cpk in production of polymer based devices for automotive applications.
Snap Tie Cones Made from Recycled PET and HDPE
Bryan Failing, May 1999
To address the growing environmental concern, Santa Clara University's Plastics Recycling Laboratory chose a relatively inexpensive product with low structural demands to open a new market for 100% recycled material products. Snap tie cones, used in construction to space wall forms prior to pouring the concrete, were injection molded from recycled PET and HDPE and tested against the cones used in industry made from HIPS. Four tests- dimensional checks, compression, impact, and creep- were designed and conducted. The commercial cones along with ones made of recycled PET and HDPE were tested before and after ultraviolet (UV) exposure. The data analysis shows that the recycled PET cones outperform their industry counterpart, while recycled HDPE did not perform as well. This leads to the conclusion that recycled PET is a viable alternative to HIPS in this application.
Testing of Recycled PET Rebar Chair
Todd Jenkins, May 1999
Small chairs for supporting reinforcing steel in concrete slabs were molded from recycled PET. The performance of these chairs was tested relative to plastic chairs available on the market. Four tests were used to evaluate the chairs. The tests were designed to evaluate impact, compression, and UV degradation strengths of the chairs, as well as the adhesion between the PET and concrete. The recycled PET chairs performed better than commercial chairs under compression, but did not allow for flow of the concrete. The impact performance of recycled chairs was very comparable to the commercial chairs. UV results are embedded in the impact and compression tests.
Effects of Drying Parameters on Recycled PET
Scott Kennedy, May 1999
With the rising usage of plastic PET bottles and the rising need to recycle them, there is an increasing demand to refine the recycling process. It is very important to have the recycling process be cost and time efficient. The focus of this study is on the drying aspect of the recycling of PET. In this experiment, different parameters of the drying process were varied, specifically the time and the temperature. The strength was not significantly affected by time or temperature of drying. The melt index data showed that drying the PET at 177°C gave the best results. The overall best results seemed to be at 177°C, and a time around six hours. Longer or shorter drying times appear to degrade the material.
A High Performance Phosphite Stabilizer
Daryl Stein, Don Stevenson, May 1999
Organophosphites are an important class of stabilizers for polymers. They retard polymer degradation during melt processing by reaction with the reactive peroxidic intermediates that arise from oxidation of the polymer at high temperature. Moreover, phosphites can be used synergistically with hindered phenol stabilizers to provide a superior stabilization package that will allow the processor to expand the range of processing conditions without losing desired physical properties due to polymer degradation. As can be seen in table 1, phosphites have a wide variety of physical properties. One important property is resistance towards hydrolysis in the bulk state, because if a phosphite is sensitive to hydrolysis, difficulties in storage and handling can occur, especially in warm, humid climates. Recently we developed a phosphite (phosphite 7) that showed excellent hydrolysis resistance, but a question that quickly arose was, Does a phosphite with good resistance to hydrolysis have good activity as a polymer process stabilizer?" In order to answer this question we studied a key property of phosphites: their ability to react with peroxide intermediates in the oxidation cycle. The phosphites were oxidized in two hydrocarbon solvents which could serve as models for HDPE and PP: a C14-17 paraffin and poly-1-decene oligomer respectively. Then we compared the reactivity of the phosphite during oxidation with hydrolysis resistance to see if there is any direct correlation between the two properties. In addition we examined the activity of phosphites in multiple pass extrusions in order to compare the oxidations rates in a model system with processing activity during extrusion."
A High Performance Phosphite Stabilizer
Daryl Stein, Don Stevenson, May 1999
Organophosphites are an important class of stabilizers for polymers. They retard polymer degradation during melt processing by reaction with the reactive peroxidic intermediates that arise from oxidation of the polymer at high temperature. Moreover, phosphites can be used synergistically with hindered phenol stabilizers to provide a superior stabilization package that will allow the processor to expand the range of processing conditions without losing desired physical properties due to polymer degradation. As can be seen in table 1, phosphites have a wide variety of physical properties. One important property is resistance towards hydrolysis in the bulk state, because if a phosphite is sensitive to hydrolysis, difficulties in storage and handling can occur, especially in warm, humid climates. Recently we developed a phosphite (phosphite 7) that showed excellent hydrolysis resistance, but a question that quickly arose was, Does a phosphite with good resistance to hydrolysis have good activity as a polymer process stabilizer?" In order to answer this question we studied a key property of phosphites: their ability to react with peroxide intermediates in the oxidation cycle. The phosphites were oxidized in two hydrocarbon solvents which could serve as models for HDPE and PP: a C14-17 paraffin and poly-1-decene oligomer respectively. Then we compared the reactivity of the phosphite during oxidation with hydrolysis resistance to see if there is any direct correlation between the two properties. In addition we examined the activity of phosphites in multiple pass extrusions in order to compare the oxidations rates in a model system with processing activity during extrusion."
Blends of Flexible Polypropylene and High Density Polyethylene
Nupur Patel, May 1999
This study focused on the melt blending of flexible polypropylene (FPP), a polyolefin with controlled levels of propylene comonomer, with high-density polyethylene (HDPE). Specifically, FPP of melt flow 2.8 g/10 min and melt temperature of 146 °C was combined with a HDPE of melt flow 4.0 g/10 min via single screw extrusion. Blends were prepared at 20, 50 and 80 % FPP in the HDPE material, and properties were evaluated as compared to the pure resins. The blends were subjected to injection molding and mechanical properties were determined, including modulus, tensile strength, and impact resistance values, along with an examination of the ability of the FPP to modify the softness and flexibility of the HDPE material.
Polymer-Layered Silicate Nanocomposites: Emerging Scientific and Commercial Opportunities
Emmanuel P. Giannelis, May 1999
Polymer nanocomposites represent a radical alternative to conventionally (macroscopically) filled polymers. Because of their nanometer-size dispersion the nanocomposites exhibit markedly improved properties when compared to the pure polymers or conventional composites. These include increased modulus and strength, outstanding barrier properties, increased solvent and heat resistance and decreased flammability. In my presentation I will review the physical and mechanical properties of nanocomposites and discuss them in terms of their static (neutron scattering and computer simulations) and dynamic (including NMR and dielectric relaxation) properties.
Physical Properties of Clay-Polymer Nanocomposite Coatings
D. Majumdar, S. Melpolder, T.N. Blanton, May 1999
Clay-polymer nanocomposites have recently received significant attention from the industrial community because of their wide range of novel physical properties. The dispersion of clay particles in a polymer matrix can result in the formation of three general types of composite structure: (1) Conventional composites that contain clay layers unintercalated in a face-to-face aggregation with macroscopic segregation of the clay and the polymeric phases. (2) Intercalated clay composites that are formed by the insertion of one or more molecular layers of polymer into the clay host galleries. (3) Exfoliated clay composites where singular clay platelets are dispersed in a continuous polymer matrix. It is the presence of clay as described in (2) and (3) that is of interest in coatings for practical applications. Intercalation and exfoliation of clay can be conveniently monitored by measuring the (001) basal plane spacing of the clay platelets using X-ray diffraction (XRD). In this work, XRD revealed significant information about the morphology of the clay-polymer nanocomposites which, in turn, determined the physical performance of the coatings. Commercially available synthetic smectite clay, identified as a transparent, environmentally benign nanoparticulate material, has been studied in various polymeric matrices. Depending on the polymeric species, the basal plane spacing of the clay platelets ranged from 13.5 to 40 Angstroms. Details about the XRD results and the corresponding changes in the physical performance of the clay-polymer nanocomposite coatings will be presented.
A New Family of Intercalated Clays for Clay/Polymer Nanocomposites
Gary W. Beall, Karl Kamena, May 1999
Over the past decade a new family of materials called nanocomposites have emerged as potentially important commercial composites for engineering and packaging applications. These materials have normally contained a smectite clay as the nanosize component of the composite. These materials are naturally occurring minerals that exhibit large aspect ratios and one dimension in the nanometer range. These minerals however, are normally very hydrophilic and, therefore must be surface modified in order to render them compatible with most polymers or monomers. This paper reports a series of new surface modified clays for use in nanocomposites and some application to nanocomposites. In recent years a family of surface modified clays has been developed that do not involve the use of onium ions. This paper will describe these new methods of surface modifications and examples of how they can be applied to polymer nanocomposites.
Property Retention Index of Thermoplastic Composites
William P. Landsman, May 1999
The use of thermoplastic polymers, reinforced with a variety of man made products, including fibrous glass, Kevlar*, polyester, and nylon fabrics, has been growing aggressively in recent years. Combining dissimilar polymer matrices as the impregnating skins allows for unusual combinations of functional properties. One major problem, unlike their sister thermosetting composites, is the lack of crosslinking, which ensures functional integrity, especially at elevated temperatures. This is offset, however, by enhanced impact toughness which most thermosetting composites cannot offer. The scope of this study was to investigate the property retention index (PRI) of a range of thermoplastic mat composites (TMC) and to evaluate the PRI for selected physical properties, including torsional modulus and flexural behavior. The role of the impregnating resin, the reinforcement type/physical form, and fabrication/assembly scheme shall be reported.
Comparison of Blow Molding Software Results to Actual Wall Thicknesses
Christopher Yochim, Jason Gilbert, May 1999
This paper will compare and contrast output from blow molding software to actual molded parts. The software being studied is a 3D shell element blow molding simulation package. With the rapid growth of blow molding today there is a need for simulation software, which will help processors, mold builders, and part designers. This software may help to reduce the time to market by eliminating design guesswork based on past experience. This study will examine one oval bottle and compare actual wall thicknesses to the software. A mold and a laser mic will be used to determine actual volumes, diameters and thicknesses along the parison.
Correlation of Experimental Data Using Simple and Complex Bottle Shapes with Blow Molding Simulation Software
Anthony R. Miller, John Woodward, May 1999
The purpose of this paper is to reduce design iterations in blow molding design by producing better products and reducing the time to market. The software being used can provide a good starting point for the design and initial process. This paper will provide published data on thickness predictions from the software and the actual values obtained from molded parts. Both simple and complex geometry will be tested. The geometry used at the start is a cylindrical bottle, followed by an oval bottle. The oval bottle will provide a good opportunity to see the thickness variations at the further extremes. The software predicts the thickness by using 3D shell elements.
Development of an Apparatus to Measure Hoop Strength of Various Materials
Steven E. Horner, May 1999
Throughout the packaging industry decisions are often made concerning types of bottles to use for certain container applications. When deciding which type of bottle is suitable for a product one aspect is the hoop strength of the bottle. This hoop strength is measured by air pressure testing the bottles. Using the guidelines set forth in ASTM D 2561, an apparatus that consists of a pressure regulator and explosion chamber, an average hoop strengths were determined for each HDPE bottle. The results of the hoop strength testing will show the mechanical differences between the bottle types and material types. It will be shown that the apparatus can also be used to determine the increase in diameter of each bottle with pressure. It can also be used to determine long term creep properties. The specimen sizes provided variables to explore the hoop strengths of HDPE. Conclusions were made on the different hoop strengths of the different specimens.
Computer Simulation of Polymers with Intermediate Order: The Discovery of a Novel Helix-Kink" Architecture"
Peter J. Ludovice, Savant Ahmed, May 1999
X-ray diffraction patterns for polymers with splits in the classic Amorphous Halo" pattern are difficult to predict using molecular modeling. These polymers contain a level of order intermediate between that of a crystal and a truly amorphous polymer that is not simply a combination of the two (semicrystalline). We have accurately predicted the Wide Angle X-ray Diffraction (WAXD) pattern for 23 erythro di-isotactic poly(norbornene) (PNB)a polymer with promising application as an interlayer dielectric or a photoresist material in the microelectronics industry. Molecular modeling predicts this polymer exists in the glassy state in a helical conformation that is occasionally disrupted by kinks. Comparison to other modeling results on poly(t-butyl acetylene) (PTBA)suggests that both these polymers belong to a new class of polymers that contain this helix-kink conformation. This conformation is what is responsible for the viscosity behavior of PNB and it may be useful in understanding both viscosity and membrane barrier properties for this class of polymers."
Computer Simulation of Polymers with Intermediate Order: The Discovery of a Novel Helix-Kink" Architecture"
Peter J. Ludovice, Savant Ahmed, May 1999
X-ray diffraction patterns for polymers with splits in the classic Amorphous Halo" pattern are difficult to predict using molecular modeling. These polymers contain a level of order intermediate between that of a crystal and a truly amorphous polymer that is not simply a combination of the two (semicrystalline). We have accurately predicted the Wide Angle X-ray Diffraction (WAXD) pattern for 23 erythro di-isotactic poly(norbornene) (PNB) a polymer with promising application as an interlayer dielectric or a photoresist material in the microelectronics industry. Molecular modeling predicts this polymer exists in the glassy state in a helical conformation that is occasionally disrupted by kinks. Comparison to other modeling results on poly(t-butyl acetylene) (PTBA)suggests that both these polymers belong to a new class of polymers that contain this helix-kink conformation. This conformation is what is responsible for the viscosity behavior of PNB and it may be useful in understanding both viscosity and membrane barrier properties for this class of polymers."
Molecular Modeling of Elastic and Photoelastic Relationships for Crosslinked Polymer Networks: A Statistical Segment Approach
Hemant Nanavati, Prashant Desai, A.S. Abhiraman, May 1999
The polymer chain is considered to comprise of freely orienting statistical segments having a distribution of vector lengths and polarizabilities, which are utilized to develop stress-elongation and birefringence-elongation relationships for crosslinked polymer networks. This formulation provides an accurate fit of poly(cis-isoprene) and polyethylene stress-elongation data over a wide elongation range, using two physical parameters. These fitted parameters yield objective predictions of birefringence-elongation relationships. This approach incorporates primary molecular structural features in modeling mechanical and optical properties of rubbery polymer networks.
A Study of Polymer/Clay Nanocomposites for Biodegradable Applications
Jo Ann Ratto, Diane M. Steeves, Elizabeth A. Welsh, Bert E. Powell, May 1999
A series of biodegradable polymer/clay nanocomposites have been prepared using two techniques: in-situ polymerization and twin screw extrusion. These samples containing 5-25% clay and polycaprolatone (PCL) were characterized with regard to processability, biodegradability, morphology, thermal behavior and mechanical properties. The processing at different screw speeds (20, 40, 60 rpm) did not alter the polymer/clay interactions. Biodegradation results in soil showed 50% mineralization of PCL/clay in 50 days as compared to 10% for the pure PCL film. X-ray diffraction patterns demonstrated that the polymer had different degrees of intercalation in the silicate layers of the clay. Dynamic mechanical analysis showed no change in the PCL glass transition temperature with the addition of clay.


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