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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
Radiation Grafting for Surface Modification of Nano-Fibers
Giuseppe R. Palmese, May 2004
The performance of polymeric materials in a particular application depends to a great extent on the properties of the interface or interphase between the polymer and the applied environment. Grafting is a useful technique for modifying polymer surface properties and for constructing materials whose bulk and surface properties are different. Radiation grafting provides significant advantages over chemical grafting methods. Radiation sources include electron beam (EB) ultraviolet light (UV) and plasma. The concept of using radiation grafting as a method for tailoring polymer surface properties has been applied to a wide variety of applications including bio-medical, textile, electrical, and membrane applications. In this work, we focus on applying radiation grafting technology to nanoscale polymer systems, specifically nanofibers produced by electrospinning polysulfone (PSF). Using EB, hydrophilic monomers such as acrylamide have been grafted on PSF fibers and the modified materials have been evaluated using surface analysis techniques including XPS, ATR-FTIR, ESEM, and contact angle measurements. Our results indicate that we have successfully grafted acrylamide onto polysulfone electrospun fibers while maintaining the fine fibrous structure in these systems.
The E-Beam Curing of Epoxy Resins
Leonid R. Vorobyev, Alexander N. Bykanov, Richard J. Moulton, May 2004
The electron beam curing of epoxies is actively explored for application in composites and adhesives. The dynamics of epoxy homopolymerization was studied at different doses of irradiation – from 0.05 to 17 Mrad. The results enabled estimation of the maximal uncured dose and minimal cured dose. These values are useful for repeatable electron beam processing, for example to ensure proper ply consolidation during Automated Tape Placement (ATP) with in-situ EB cure. DSC tests were used to study the dynamics of heat postcuring for preliminary irradiated resins and to estimate the values of residual exotherms of irradiated epoxies.
A Rapid, Nondestructive, In-Situ Analysis of Plastics for Heavy Metals with Portable X-Ray Flourescence Analyzer
Stanislaw Piorek, May 2004
Recently introduced regulations, such as European Community “Packaging Directive” - ECDirective 94/62/EEC (1), impose the maximum limit on total amount of metals such as Cd, Cr, Hg and Pb in plastic packaging materials to less than 100 mg/kg. Another EU Directive, 91/338/EC (2), sets the maximum allowable concentration of cadmium in plastics used for consumer goods at 100 mg/kg. In the US, the “Proposition 65” introduced in California banned cadmium from use.Effective enforcement of these regulations creates the need for analytical methods capable of rapid, accurate, nondestructive in-situ analysis of plastics. An X-ray Fluorescence Analysis (XRF for short) is very well suited for this task.In this paper we report on successful application of a small, portable X-ray fluorescence analyzer in analysis of plastic for metals. The analyzer can quantify heavy elements such as lead and cadmium in plastics down to 10 and 25 mg/kg, respectively, at a 120 sec. measurement time per sample.
Sustainable Polymers: From a Glorious Past to a Bright Future
Brian E. Ralston, Tim A. Osswald, May 2004
In the coming decades it will become increasingly difficult to cheaply satisfy society's thirst for petroleum-based polymers. Additionally, the problems associated with disposal of non-renewable, non-degradable petroleum based polymers will drive the search for agriculture based plastics that do not sacrifice cost or performance. Although agriculture based plastics have been around for over a century, they were largely forgotten after the advent of synthetic, petroleum based polymers. This paper revisits the literature left to us by early twentieth century engineers who made protein based plastics from casein and soy protein on an industrial scale. In recent years, there has been a resurgence of interest in this type of material. This paper reviews current research on biopolymers such as casein and soy protein based plastics as well as polylactide acid, or PLA.
Use of Natural Fibre as Reinforcing Agent in Biodegradable Foamed Packaging Materials Made from Wheat Flour
P.R. Hornsby, Y-G. Kang, J. Song, K. Tarverdi, J. Zhou, May 2004
The use of packaging materials is expected to increase annually on average by about 5 percent in the foreseeable future, but the technology for reusing and recycling of packaging waste is lagging behind. This paper considers the evaluation of an alternative packaging material, derived from renewable resources, which is economical to use, biodegradable and recyclable by composting. In this paper consideration will be given to the preparation, characterisation and properties of starch-based materials derived from wheat flour. A range of techniques, used to characterise these materials will be discussed, including image analysis, SEM, thermogravimetric analysis, compressive strength, impact and recovery measurements.
Melt Processing of Traditionally Solution-Processed Polymers with CO2
Matthew D. Wilding, Quang T. Nguyen, Michael J. Bortner, Donald G. Baird, May 2004
The effects of using near critical and supercritical carbon dioxide (CO2) to plasticize polymers that are difficult to melt process are studied, in particular acrylonitrile (AN) and methyl acrylate (MA) copolymers. Previous work with PAN/MA copolymers included differential scanning calorimetry (DSC), used to evaluate the resulting shift in the glass transition temperature (Tg) following plasticization, and pressurized capillary rheometry to evaluate the melt rheology and entry pressure effects prior to and after plasticization. A slit-die rheometer has been designed to allow the attachment of various nozzles to the exit to maintain high pressure and single-phase flow, suitable for measuring viscosity reduction with CO2 in a continuous process. Comparisons are made between capillary and slit die rheometry for quantifying the effect of CO2 plasticization on a model 65% AN, 25% MA, and 10% rubber copolymer.
The Effect of Composition on Properties of Blends from Recylced Rubber and Polypropylene
N. Jain, C. Barry, J. Mead, D. Robertson, May 2004
Incorporation of waste (ethylene propylene diene rubber) EPDM into polyolefins has emerged as a new recycling technique that is eco-friendly and cost effective. The purpose of this study was to recycle EPDM, as well as to develop new impact modified blends. This study, which involved reactive blending of waste EPDM and polypropylene (PP) in a co-rotating twin screw extruder in the ratio range of 10/90 to 60/40, determined the effect of t-butyl hydroperoxide compatibilizer, low and high MFI grade of PP and ethylene-propylene impact copolymer on the mechanical properties of the blends. Formulations were injection molded and subsequently tested for tensile, flexural and impact properties. It was noted that the peroxide and the impact copolymer significantly improved the tensile elongation at break and impact resistance, but resulted in a decrease in the modulus. The approach of this investigation was to determine the optimum blending ratio of the components to achieve a balance in the flexural modulus and impact strength.
Polymer/Clay Nanocomposites with Halogenated Polymers
Younghoon Kim, James L. White, May 2004
To investigate the possible formation of polymer/clay nanocomposites halogenated polymers were melt compounded with montmorillonite clays. Natural and organic-treated montmorillonite clays were melt compounded with chlorinated and fluorinated polymers. The formation of polymer nanocomposites was confirmed by X-ray diffraction (WAXS) and transmission electron microscopy (TEM) characterizations. All chlorinated polymers studied including polyvinyl chloride (PVC), chlorinated polyethylene (CPE), polychloroprene (CR), polyvinylidene chloride (PVDC), chlorinated PVC (CPVC), and VDF containing fluoropolymers, polyvinylidene fluoride (PVDF), poly(vinylidene fluoride – hexafluoropropylene) P(VDF-HFP), poly(vinylidene fluoride – hexafluoropropylene – tetrafluoroethylene) P(VDF-HFP-TFE), poly(vinylidene fluoride – tetrafluoroethylene – perfluoromethyl vinyl ether – curesitemonomer) P(VDF-TFE-MVE-CSM) produced polymer/clay nanocomposites with organic-treated montmorillonite clay. Either polyolefin or natural montmorillonite clay did not form nanocomposites. The organophilicity of organoclays and polarity of halogenated polymers seems to contribute to the creation of polymer nanocomposites. The polarity of polymers could be estimated by Debye equation which shows the relationship between dipole moment and dielectric constant. The dielectric constant of polymers could be conveniently used to predict the successful formation of polymer/clay nanocomposites by melt intercalation.
Polyampholytes as Aqueous Viscosifiers: An Investigation of Stimuli-Responsive Rheology
Christopher A. Lange, May 2004
Solution rheological analyses of polyampholyte terpolymers composed of acrylamide (AM), sodium 3- acrylamido-3-methylbutanoate (NaAMB), 3- acrylamidopropyltrimethylammonium chloride (APTAC) were performed at varying polymer concentrations, solution pHs, NaCl concentrations, and molecular weights (MW). Steady-state shear sweeps and dynamic frequency sweeps of semi-dilute solutions were used to measure solution viscosity and viscoelasticity. Results are interpreted in terms of how experimental variables affect the solutions’ electrostatic charges and polymer/solvent interactions, which ultimately affect rheological properties.
Flame Retarding Nylon 12 Elastomers Using Nanoclays as Char-Forming Flame Retardant
Lawrence A. Acquarulo Jr., Charles J. O’Neil, Amar S Nilajkar, May 2004
Our recent studies have shown that high levels of montmorillonite clay can be added to nylon 12 elastomers to achieve UL-94 rating in 1/8” thickness with minor detrimental effects on physical properties.In the past, in order to achieve this rating we had to use levels of flame retardant systems containing halogen and antimony oxide in excess of fifty percent by weight. This high level of flame retardant had detrimental effects on both the physical properties and the environment.Our goal was to reduce the use of this type of flame retardant system by twenty five percent and still maintain good physical properties. In fact our previous studies show that both impact and flexural modulus increase with increasing levels of nano clay with minimal reduction of elongation.
Surface Modification of Poly (Lactic Acid) Films via Grafting Hydrophilic Polymers
Amol V. Janorkar, Douglas E. Hirt, May 2004
The major objective of this research was to modify poly(lactic acid) (PLA) film surfaces with an ultimate aim of making a bioactive surface that will show selective protein adsorption and faster degradation. The PLA film was solvent cast and the film surfaces were activated by a plasma treatment procedure or UV irradiation. Poly(acrylic acid) (PAA) was then grafted to the PLA film surface using a UV induced photopolymerization process. The film surface resulting from each reaction step was analyzed using ATR-FTIR spectroscopy and contact angle measurements. The molecular weight of the grafted PAA film was estimated by measuring the molecular weight of the homopolymer formed in the solution during the reaction using GPC. Results showed that PAA (Mw ~ 2000) was grafted from PLA film surfaces in 2 or 3 h depending on the method of activation.
Solid Phase Graft Copolymerization of PE-g-MA
Patricia Roberts, Jignesh Shah, Sunggyu Lee, May 2004
The solid phase graft copolymerization method was used to graft maleic anhydride onto commercial polyethylenes. This process is environmentally friendly since it requires minimal recovery or no use of solvent and the process conditions are mild. NMR analysis confirms the successful grafting of maleic anhydride onto the backbones of both linear low-density polyethylene (LLDPE) and ultra high molecular weight polyethylene (UHMWPE). Graft levels for all the polymers were quantified by FTIR absorbance as well as wet-chemical titration. Significant processing parameters were identified based on statistical design of experiments.
Developments in the Use of Inorganic Tin Compounds as Fire Retardant Synergists for Hydrated Fillers
P.R. Hornsby, P.A. Cusack, M. Cross, May 2004
Consideration is given to ongoing developments in the fire performance of formulation variants of EVA copolymer containing zinc hydroxystannate (ZHS), alumina trihydrate (ATH), magnesium hydroxide (MH) and nanoclay mixtures. ZHS/MH combinations are shown to give the best performance in EVA, enabling significant reductions in overall filler levels to achieve an acceptable level of fire performance, however this is dependent on the grade of MH used. The fire resistance of these systems is further improved by small additions of silicate layer nanoclay. The ZHS is shown to function predominantly in the condensed (char) phase.
Chemically Tailored Polymeric Layers Grafted to and from a Copolymer Film Surface
Keisha B. Walters, Wenjin Wang, Ryan P. Harris, Douglas E. Hirt, May 2004
This work is part of a study aimed at creating tunable surface modifying layers. Polymer molecules were grafted at the polymer surface and the pendant groups of these grafted polymers were subsequently substituted. The polymer layer of interest in this study was poly(tert-butyl acrylate) (PtBuA) because it is relatively easy to substitute the tert-butyl ester groups with other functional groups to create a chemically tailored layer. The PtBuA was grown from the surface of ethylene-acrylic acid copolymer via atom transfer radical polymerization and was also grafted to the surface using end-functionalized PtBuA. The progression of the reactions and properties of the modified surfaces were studied using ATR-FTIR spectroscopy and static contact angle.
ColorWorks: Closing the Loop in Product Design
William Blasius, May 2004
A design is not finished until parts hit the store shelf. There are a number of steps between the first sketches on a napkin and commercial sales, any one of which could lead to delays and cost overruns. One of the most important design considerations is material selection. Plastic parts are unique in that the material is infinitely variable. Designers working off of raw material specifications can set themselves up for some counterproductive surprises. Colorants, flame retardants, mold releases, ultraviolet light stabilizers and regrind affect melt viscosity and physical properties. By looking at final resin formulations early in the design process, manufacturing and performance issues can be addressed when changes are least costly. ColorWorks is an integrated solutions tool to help designers get to the final material properties quickly.
Mechanical Properties of Plastics Used in Finite Element Method Calculations
Jan Spoormaker, Ihor Skrypnyk, Oleg Nikolaevich Stolyarov, Vladimir Gnenadevich Tiranov, A.J. Heidweiller, May 2004
Finite Element Method (FEM) calculations are suitable for predicting the mechanical behavior of plastic products with complex geometries. The problem is to obtain to the relevant material data in particular for thin walled sections. Results from laboratory tensile specimens are not very reliable, because they are relatively thick and have little orientation.To determine the influence of thickness and orientation, creep and recovery experiments have been carried out. The specimens had different thicknesses and different flow directions. The results from tests have been used for FEM-calculations to determine the influence of thickness and orientation on the mechanical behavior of a beam shaped product.
Reducing Paint Particle Size for Painted TPO Regrind
Shardul Ramolia, Jason Mello, Peter Zelic, May 2004
Many industries, such as the automotive industry, are faced with a high volume of plastics scrap associated with painted plastic parts. Ideally, the paint is removed prior to reuse of the painted regrind. Paint removal methods include differential thermal expansion, chemical attack and abrasion. If not removed, paint flakes in the regrind material influence the mechanical properties and aesthetics of the product molded from the painted regrind. The size of the paint flakes will likely have an influence on the mechanical properties of the molded part.A reground painted thermoplastic olefin (TPO) will be extruded using a general purpose and a “grater” screw being developed at UML. The grater section design will then be modified to implement a progressive grating technique. The effect of the design change on paint flake size, output, melt temperature and mechanical properties will be monitored.
An Investigation into the Gate Location and its Effects on Product Quality in Injection Molding
Jeremy Gokey, Tony Harris, May 2004
Gate location is an important aspect of thermoplastic part design, and injection mold design. A proper gate location will facilitate high quality parts, whereas poor gate location may cause the quality of the part to suffer. There are many different factors that affect the gate location. These factors that may affect gate location include: flow properties of the plastic, gating into the approximate center of the part, wall thickness, gating into an obstacle, style of the gate, separation of the runner system from the part, aesthetic properties, and ease of manufacturing. Computer simulations may help to facilitate the proper gate location and decrease the lead-time in producing a mold.The focus of this research project is to determine the ideal gate location given the previously mentioned factors for a single gated thermoplastic part, comparing both the experience of previous engineers through research of current materials, and the analysis of computer simulation software. The first portion of this project consists of research compiled from accredited individuals within the plastics industry; their perspectives and experiences have been combined to discuss the various possibilities in placing an ideal gate location. Following the research, these ideas were tested through the use of Mold Flow (Mold Flow Inc.) in various part designs. The last portion of this project compares and contrasts the industry experience to the results of the simulation software.
The Use of Sub-Micron Particle Size Calcium Carbonate Filler and Ester Modified Processing Lubricant Systems to Add Value or Performance to Rigid PVC Formulations
Robert A. Lindner, May 2004
Formulators are constantly being asked to lower cost, improve performance, or both. This paper addresses this problem by reporting on the evaluation of an old standard calcium stearate paraffin lube system and one micron filler, vs. sub-micron fillers with ester modified lube systems.In the past this approach has been successful in allowing the use of lower modifier levels, or higher filler levels, without loss of properties, with modifier levels lowered from 4.5 to 3.0phr. This paper answers the question, “Is there any merit to using this approach when the modifier ranges from 2 to 0phr?” with the goal of eliminating the modifier altogether.
Strength, Toughness, Lifetime and Reliability of Plastics in Engineering Applications
A. Chudnovsky, May 2004
Major factors affecting short term and longterm performance of plastics in engineering applications include a) chemical makeup and molecular architecture, additives etc; b) material and parts manufacturing conditions; c) installation and service conditions that include load, loading rate, temperature and other environmental conditions. Successful design of plastic components for intended application requires an understanding of the role of the above factors together with economic considerations that account for a cost of fabrication as well as for a price of failure. Material characterization and ranking with respect to strength, toughness and durability provide a basis for rational design with plastics. There are industrial standards and regulations develop to assist in product selection. Advantages and limitations of widely publicized standards and methods for durability and lifetime of engineering thermoplastics will be illustrated by examples of field failure analysis. Methodology of material durability and structural reliability assessment will be discussed.


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