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.

The SPE Library is just one of the great benefits of being an SPE member! Are you taking advantage of all of your SPE Benefits?

Not an SPE member? Join today!

Use % to separate multiple keywords.

Search SPE Library

Recycling

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

Composites Derived from Post-Consumer Nylon 6 Carpet

John Muzzy, Youjiang Wang, Melinda Satcher, Bryan Shaw, Andrew McNamara, Josh Norton, May 2004

Over 2 million tons of post-consumer carpet is landfilled each year. This waste carpet is a potential resource for composites. Since waste carpets can be rapidly identified and sorted by face fiber, this paper focuses on the processing and properties of nylon 6 post-consumer carpet. The carpet is cleaned, shredded and extrusion pelletized. This feedstock is compounded with glass fibers and compatibilizers. Based on the properties achieved and the projected costs, applications are identified.

Continuous Process for Recycling of Polyurethane Foam

Sayata Ghose, A.I. Isayev, Ernst D. von Meerwall, May 2004

A continuous process for decrosslinking high resiliency polyurethane foam in an extruder with ultrasonic devices was developed. Rheological, structural and NMR relaxation and diffusion characterizations of decrosslinked foam were performed. The decrosslinked foam was blended with the virgin polyurethane rubber (PUR) and cured and the blend properties were investigated.

Crystallization and Chemi-Crystallization of Recycled Photodegraded Polymers

J.R. White, I.H. Craig, C.K. Phua, May 2004

Injection molded bars have been made from blends containing recycled photodegraded polymers, then subjected to further ultraviolet (UV) exposure. Crystallinity measurements have been made at different depths from the exposed surface using X-ray diffraction and differential scanning calorimetry. Complementary information in the form of molecular mass distributions has been obtained using gel permeation chromatography, and the crystallinity results are interpreted in terms of molecular scission and photo-initiated molecular defects.

Applications of Large Volume Processors in Polymer Processing

Andrew Ingram, Rainer Naef, Hans Peters, May 2004

In recent years, pressure from economic and environmental requirements has been experienced in the field of polymer production. This trend towards single stage operational units, in processes such as low shear devolatilization of elastomer solutions, radical polymerization and polycondensation reactions, phase changing processes and the conversion from batch to continuous operation continues and has lead to the development of large volume, twin shaft horizontal processors (LVPs).These processors have been designed for applications requiring medium to long residence times (20-120 minutes).As an example of this new family of processors, the multi-purpose Reasol®, a new counter-rotating twin shaft processor, is introduced. Trials with model polymers have been performed in a 60L unit at the developer's test center. Its performance is described here by power consumption, RTD (residence time distribution) and self-cleaning and devolatilization efficiency.Trials show that product transport through the new LVP is characterized by a narrow RTD with a high degree of self-cleaning. Typically, the RTD exhibits a Peclet number in the region of 25-35. It is also shown that, unlike typical twin-screw extruders, the shape of the RTD curve is largely unaffected by the rotor speed or mass rate. Furthermore, rotor speed has a relatively small effect on mean residence time thus allowing the freedom to optimize rotor speed with respect to other processing objectives such as heat transfer, surface renewal or shear rate.The indications are that the characteristics of the RTD, power consumption and devolatilization are analogous to more traditional equipment such as twin screw extruders in spite of the larger free volume and residence time and the lower shear.The new LVP is commercially available up to sizes of 12,500 litres net processing volumes.

Devulcanization of Recycled Tire Rubber Using Supercritical Carbon Dioxide

Qiao Zhang, Costas Tzoganakis, May 2004

In this work, an extrusion process has been developed for the devulcanization of rubber crumb from recycled tires employing supercritical CO2. For that purpose supercritical CO2 has been injected in a twin screw extruder to swell the rubber crumb and to facilitate the otherwise impossible rubber extrusion process. As a consequence, waste rubber can be processed under mechanical shear and extensional forces at various operating conditions that may lead to different degrees of devulcanization.

Effects of Incorporating Recycled HDPE to Virgin HDPE and LDPE to Produce Tubular Film

José B. Sánchez, Erika Galvis, Rosalina Grimaud, Rosestela Perera, May 2004

This work presents the effects of incorporating post-consumer and post-industrial recycled HDPE to their virgin counterparts and to LDPE in different contents to produce tubular film for packaging. Tensile, surface and optical properties for each blend were measured.A reduction in the HDPEs blends physical properties and an increment in those of the LDPE/recycled HDPE blends were obtained as the recycled HDPE component was increased.

Biobased Composites Manufactured through a Reactive Extrusion of Maleated Wood Particles

K. Carlborn, L.M. Matuana, May 2004

Biocomposites such as particleboard and medium density fiberboard are currently made with formaldehyde-containing adhesives. Since the government is continuously developing and implementing very stringent regulations to eliminate formaldehyde emissions into the environment, alternative approaches must be developed to replace these adhesives. This study examined the concept of using a reactive extrusion process as a means of developing a new, formaldehyde-free binding system for wood composite products. The surfaces of wood particles were modified by grafting maleated polyethylene through a continuous reactive extrusion process. Chemical changes resulting from this treatment were followed by studying the FTIR and XPS spectra. The modified wood particles were compression-molded into panels, which were tested for bending properties. Both FTIR and XPS data revealed that the chemical reactions have taken place between the hydroxyl groups of wood particles and maleated polyethylene. The modulus of rupture (MOR) results showed that the composite panels compared favorably with current standard requirements for particleboard.

Failure of Plastic Plumbing Products

Paul Gramann, Antoine Rios, Bruce Davis, May 2004

Failures of plastic components are being seen more often in industrial, household and commercial settings. Many of these failures involve the transport of water and cause significant damage when they occur. These failures can be caused by improper material specification, bad design, over loading or incorrect molding conditions. Issues such as chemical resistance, environmental deterioration, geometric sensitivity, temperature dependence and aging are at times overlooked.

Green Composites from Biofibers and Poly(3-hydroxybutyrate)

Amar K. Mohanty, Lawrence T. Drzal, Prasad Mulukutla, Shrojal M. Desai, Manju Misra, May 2004

Eco-friendly green" composite materials are fabricated from inexpensive chopped natural fiber and poly(3-hydroxybutyrate) (PHB) through extrusion followed by injection molding processing. The incorporation of natural fiber in to the composite structure improved the modulus and impact strength of virgin bioplastic. Maleated PHB is synthesized by us and is also used as a compatibilizer in PHB based biocomposites."

Investigating Environmental Stress Cracking with In-Situ Contact Angle Measurements

Peter J. Walsh, Alan J. Lesser, May 2004

This paper probes a hypothesis for initiation of environmental stress cracking (ESCR) based on a thermodynamic criterion for localized swelling induced by stress on the polymer. The system chosen for study is polycarbonate with oleic acid. An experimental technique involving contact angle measurements of a sessile drop as a function of stress is presented. A novel technique for contact angle measurements using refraction is also introduced.

Cell Morphology and Impact Strength of Microcellular Foamed HDPE/PP Blends

P. Rachtanapun, L.M. Matuana, S.E.M. Selke, May 2004

Polymer blends such as result from recycling of postconsumer plastics often have poor mechanical properties. Microcellular foams have been shown to have the potential to improve properties, and permit higher value uses of mixed polymer streams. In this study, the effects of microcellular batch processing conditions (foaming time and temperature) and HDPE/PP blend compositions on the cell morphology (the average cell size and cell-population density) and impact strength were studied. Optical microscopy was used to investigate the miscibility and crystalline morphology of the HDPE/PP blends. Neat HDPE and PP did not foam well at any processing conditions. Blending facilitated the formation of microcellular structures in polyolefins due to the poorly bonded interfaces of immiscible HDPE/PP blends, which favored cell nucleation. The experimental results indicated that well-developed microcellular structures are produced in HDPE/PP blends at ratios of 50:50 and 30:70. Improvement in impact strength was associated with well-developed microcellular morphology.

Layout Design of a Platenless Molding Machine

Nirmal Doshi, David Kazmer, May 2004

A layout design of a platenless injection molding machine is developed. The machine design is motivated by economics, energy efficiency, compactness, ease of use, and environmental friendliness. The elimination of traditional platens allows for significant performance improvements as well as flexibility of new injection system and mold designs. This paper establishes theoretical feasibility, but also indicates that the design is most appropriate for clamp tonnages less than 150 tons due to actuator power and mold deflection limitations.

Low-Cost Composite Materials from Post-Consumer Plastics and Waste Paper

Aaron R. James, Igor Sbarski, Syed H. Masood, Edward Kosior, May 2004

Composites of post-consumer plastics and high volume fraction waste paper have been studied. Various production techniques have been tested, with an optimum processing method defined, allowing the manufacture of low-cost composites of up to 60% paper content. Results indicate increases in tensile, flexural and creep modulus and flexural strength compared to the matrix can be achieved without the requirement of additives, with only marginally lower tensile strength and brittle impact behavior.

Characterisation of Reactive Extruded Recycled Poly(Ethylene Terephthalate)

Fugen Daver, Firas Awaja, Edward Kosior, Rahul Gupta, Ferenc Cser, May 2004

Recycled poly(ethylene terephthalate) (R-PET) was chain extended with pyromellitic dianhydride (PMDA) in an industrial scale twin-screw reactive extrusion system. Reactive extruded recycled poly(ethylene terephthalate) (RER-PET) samples at different PMDA concentrations were characterised in terms of rheological properties; thermal transitions and crystallinity. The results confirm the increase in molecular weight with an increase of PMDA concentration, and the formation of branching at concentrations above 0.25 wt.% PMDA. Structural changes due to PMDA addition affect the Tm, Tc and the crystallinity; however, no significant change was observed for the Tg.

Characteristics and Performance of Starch-Poly- (Vinyl Alcohol) (PVA) Blends with Agricultural Waste Fiber

S.H. Imam, G.M. Glenn, J. Shey, A. Clamczynski, D. Wood, T. Nguyen, K. Cornish, W.J. Orts, May 2004

The renewable polymers are environmentally friendly and naturally biodegradable, and could serve as an inexpensive source of raw material for single-use engineered products. Efforts are underway to develop ecocompatible consumer plastics by incorporating renewable polymers as an alternative to petroleum-derived chemicals. Therefore, gaining fundamental understanding of biobased polymers is critical for the design and development of consumer products. The research efforts at the USDA laboratory pertaining to the development of biopolymer blends, polymer processing, characterization and lifetime evaluation are presented.

Characterization of BMI-Carbon Fiber Composite Microcrack Development under Thermal Cycling

Jaehyung Ju, Roger J. Morgan, May 2004

The objective of this research is to determine the effect of thermal cycling on the development of microcracks in BMI-carbon fiber composites (5250-4 RTM / IM7 6K 4-harness satin weave fabric). By clamping composite specimens on the radial sides of two half cylinders having two different diameters (127mm and 70mm), two different pre-stresses (-0.4 to 0.4 GP and -0.7 to 0.7GPa) are applied to the composites. Three different thermal cycling experiments, 1) –196°C to 250°C, 2) 23°C to i)150°C ii) 200°C iii) 250°C, and 3) -196°C to 250°C were performed as a function of pre-stress, number of thermal cycles, heating or cooling rate, and humidity conditions. An in-situ monitoring microscope is used to observe the microcrack development under synergistic stress, time, and temperature conditions. The experimental results suggest that there is a higher probability of microcracking with increasing number of thermo-cycles, higher pre-stress and humidity. A mathematical model considering residual stress and pre-stress is suggested to predict the microcracking under environmental conditions.

New Capillary Viscometers for the Compounding Industry

Giancarlo Locati, Enrico Corazza, May 2004

New Capillary Viscometers, beyond offering remarkable precision, may also broaden the characterisation of polymer compounds.After a short review of the features of recent equipment, some selected examples of applications will be shown. They range from improved quality control of incoming and outgoing products, to recycling management, masterbatches characterisation, and evaluation of dispersion effects on filled materials.

Controlled Epoxy Network Structure-Property Relationships: The Effect of Chain Termination

Nikhil Verghese, Maurice Marks, James Hrovat, Ha Pham, May 2004

While epoxy thermosets are commonly used and are best known for their high glass transition temperature (Tg), creep resistance, environmental resistance and high stiffness, they are extremely complicated and intractable to thorough investigation. This is in part due to the fact that these are curing systems and gelation marks a turning point in the system’s performance as well as ability to be probed for effective structure-property relationships. In addition, practical formulations often contain multiple components that have subtle but important interactions to the final performance.In this presentation we will cover work that was performed recently to quantitatively probe the effect of one such practical yet important effect, namely chain termination. The effect of the size as well as flexibility of the chain termination group will be examined via a controlled host matrix chemistry that comprises of DER™ 332 as the epoxy, bisphenol A (BA) as extender and tris(4- hydroxyphenyl)ethane (THPE) as a crosslinker. Data and trends pertaining to Tg, stiffness, yield strength, fracture toughness and thermal expansion coefficient will be discussed.

Controlling the Performance and Rate of Degradation of Polylactide Copolymers

D.M. Bigg, May 2004

An important factor in the commercial development of biodegradable polymers is the ability to control the rate of degradation. Ideally, the polymer should not degrade during functional use, but degrade quite rapidly when discarded. This paper discusses various aspects associated with the control of the rate of degradation of polylactide copolymers; both from the perspective of stabilizing the polymer during processing and product use, and subsequently accelerating the rate of degradation after disposal. Of particular interest are the influences of molecular weight, crystallinity, end-capping and plasticization.

Creep Prediction Using the Non-Linear Strain Energy Equivalence Theory

Jennifer K. Lynch, Kenneth Van Ness, Thomas J. Nosker, Richard W. Renfree, May 2004

The Non-Linear Strain Energy Equivalence Theory, a semi-empirical model, is utilized to predict long-term creep from short-term compressive stress-strain experiments conducted at different strain rates. Stress-strain experiments in uniaxial compression are performed at strain rates of 3 and 0.03 %/minute to predict creep behavior and stress-strain data at several strain rates for an immiscible polymer blend of recycled fractional melt flow high-density polyethylene and recycled polystyrene. The creep behavior is predicted up to 50 years at stress levels of 400 and 800 psi.