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.

Bio-Composite Materials as Alternatives to Petroleum-Based Composites for Automotive Applications

L.T. Drzal, September 2001

Natural/Bio-fiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive applications. Natural fibers which traditionally were used as fillers for thermosets are now becoming one of the fastest growing performance additives for thermoplastics. Advantages of natural fibers over man-made glass fiber are: low cost low density competitive specific mechanical properties reduced energy consumption carbon dioxide sequesterization and biodegradability. Natural fibers offer a possibility to developing countries to use their own natural resources in their composite processing industries. The combination of bio-fibers like Kenaf Hemp Flax Jute Henequen Pineapple leaf fiber and Sisal with polymer matrices from both non-renewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention i.e. biofiber- matrix interface and novel processing. Natural fiber reinforced polypropylene (PP) composites have attained commercial attraction in automotive industries. Needle punching techniques as well as extrusion followed by injection molding for natural fiber–PP composites as presently adopted in the industry need a “greener” technology-- powder impregnation technology. Natural fiber–PP or natural fiber–polyester composites are not sufficiently eco-friendly due to the petro-based source as well as non-biodegradable nature of the polymer matrix. Sustainability industrial ecology eco-efficiency and green chemistry are forcing the automotive industry to seek alternative more Eco-friendly materials for automotive interior applications. Using natural fibers with polymers (plastics) based on renewable resources will allow many environmental issues to be solved. By embedding bio-fibers with renewable resource based bio-polymers such as cellulosic plastic corn-based plastic starch plastic and soy-based plastic are continuously being developed at Michigan S

Polyester Resin System Utilizing Renewable Sources - Soybean and Corn

T.D. Wade, September 2001

A resin that utilizes 25% grain-derived organics has been developed. Ethanol and soybean oil are reacted with other materials to produce a durable polyester resin capable of equal or better performance than current polyester resin systems. Utilizing the sheet molding compound (SMC) molding process this unique renewable-source polyester resin has successfully produced large combine parts for use in the agriculture industry. The transportation industry is investigating this resin for use on upcoming vehicles.

Development of Low Density GMT Composites for Automotive Applications

V. Raghavendran, September 2001

The development in the field of composites has been spurred by the need for lightweight fuel-efficient automobile that is environmentally friendly and affordable. A low density light weight GMT composite containing long chopped fiber strands was developed by AZDEL Inc. for use in headliner and other automotive applications. The low density GMT (LD-GMT) is available in grades ranging in basis weight of 600 to 2000 g/m2. This paper presents development of this LD-GMT material for automotive interior and structural applications. This thermoformable material has several advantages over other traditional materials like steel and thermoset composites. The LD-GMT offers design flexibility low weight high rigidity excellent energy absorption characteristics faster cycle times and an environmentally friendly manufacturing process. The design flexibility and application of these LD-GMT composites in automotives and the advantages of applying these composites over the other materials in interior structural and modular applications will be discussed.

A Rational Way to Reduce Number of Colorants Used

Joseph M. Cameron, S.T. Greer, May 2001

The number of colors or colorants used in your operation takes on a life of its own, ever growing in size and complexity. There are valid reasons for the growth; to better match colors, satisfy a key customer, gain more heat or light stability, improve cost or processing properties, more reliable supply or to provide a specialty product. At the time each one is introduced we are typically under some driving force to satisfy a tactical need, what the heck its just one more item, and we lack the time to take a more strategic view. Next thing you know the number has grown from 80 - 100 items to 300 or more! So, do you really need that many colors? If you had fewer colors, your operations would be much simpler and simplicity implies better, less costly more reliable operating. So why not do the job with 50 colors. Well why stop there, why not 20 or maybe 16, shucks the rainbow only has 7, ROYGBIV. You know, we see all the colors on a TV screen or CRT & they are made from just Red Green & Blue, why not 3 colors? This paper will deal with the issue of what is the right number of colors, how you can go about getting there (and maybe staying there) and finally some of the benefits you might expect.

Blends of Recycled Polyethylenes and Metallocene Impact Modifiers for Rotational Molding

E. Takács, M. Kontopoulou, J. Vlachopoulos, E. Voldner, K. Nichols, May 2001

This paper describes the development of blends of recycled polyethylenes suitable for rotational molding. The blends consist of recycled post-industrial polyethylene resins and polyolefin plastomer impact modifiers, produced by single-site (metallocene) catalysts. The rheological properties of the blends were found to be favorable for rotational molding. Rotomolded parts provided satisfactory low temperature impact strength and good tensile properties.

Application of Chemo-Rheology to Establish a Process Window for a New Solventless System to Manufacture Pre-Pregs and Laminates for Electronic Applications

L.M. Dehnke, Permadi, Jose M. Castro, May 2001

The most common commercial processes for manufacturing pre-pregs for electronic applications use solvent-based epoxy systems. Solvents are environmentally unfriendly and contribute to voids in the pre-preg and laminate. Voids cause product variability, which is a major source of scrap in board shops. In this paper, we use chemo-rheological and kinetic measurements to identify a potential epoxy-based resin system for a solventless process, based on injection pultrusion. DSC and rheological data show that the candidate system does not react appreciably without catalyst to temperatures of 170°C or with catalyst at temperature below 110°C. The system solidifies below 105°C. It was found that the overall viscosity of the resin system is dependent upon the temperature, degree of cure, and filler content. Kinetic rate and viscosity rise expressions to be used in process modeling and optimization have been developed. A preliminary process window for the process has been established.

Biodegradable Plasticizers for Polylactic Acid

Stephen McCarthy, Xu Song, May 2001

Poly(lactic acid) [PLA] is a well known biodegradable polymer which has been used in drug delivery systems, surgical repair systems such as sutures and bone fracture fixation pins and screws. PLA is biocompatible, has a high tensile strength, and has a high elastic modulus[1,2]. However, one drawback of PLA is the low elongation at break due to a brittle fracture while under tensile and bending loads. The elongation at break of PLA is typically 3 - 5 percent[1]. The reason for this brittle behavior is due to physical aging which occurs during storage at room temperature and has been studied extensively.[3] Plasticization is a common technique used to increase the ductility of a brittle polymer. In the case of PLA a suitable plasticizer must be miscible with PLA so as to decrease the glass transition temperature, as well as be biodegradable and nontoxic so as to provide a useful biodegradable blend. The advantages of the plasticization are low cost, ease of processing, and the ability to alter the properties of the blends by varying the amount of plasticizer. Use of a functionalized plasticizer can be more desirable such that a chemical bond is formed with the PLA polymer thereby preventing loss of the plasticizer through migration.

Blends of Starch with Poly(Vinyl Alcohol)/Ethylene Copolymers for Use in Foam Containers

Geoffrey A.R. Nobes, William J. Orts, Gregory M. Glenn, Gregory M. Gray, Micahel V. Harper, May 2001

The use of foamed polymer packaging such as polystyrene (PS) cups, bowls and clamshells has decreased in recent years because of perceived environmental disadvantages. Blends of starch with poly(vinyl alcohol-co-ethylene), PVOH, a degradable, water-resistant polymer, were processed into viable alternatives to PS providing degradable polymers from renewable resources. Modulated DSC and X-ray crystallography were used to characterize the miscibility and morphology of extruded starch/PVOH blends that contained a series of plasticizers. These included combinations of water, glycerol, triacetin, citrate esters, and amino acids. The optimal blend formulation, based on miscibility, strength, aging characteristics, and capability to replace PS foam was--60-65% wheat starch, -25 -30% PVOH, and -5-10% plasticizer.

Blends of Various Proteins with Poly(Hydroxy Ester Ether)

C. Wang, C.J. Carriere, J.L. Willett, May 2001

Blends of poly (hydroxy ester ether) (PHEE), a recently developed bisphenol A ether-based synthetic biodegradable thermoplastic polymer, with a soybean protein isolate and two hydrolyzed wheat glutens were studied. Blends of the proteins with PHEE were produced from 20-70% by weight of protein content. The Young's moduli of the protein/PHEE blends falls in the range of 0.8 - 1.5 GPa with the tensile strengths ranging from 10-30 MPa. Fracture strengths of the blends ranged from 9-2 MPa-m1/2 depending on the amount of protein added. Morphological analysis indicated acceptable adhesion between the protein and PHEE phases in the blends. In general, as the protein content was increased the materials lost ductility and failed in a brittle manner; however, the mechanical properties of several compositions were comparable to current commercial thermoplastics such as polystyrene.

Combined Process Variables and Process Energy Monitoring for Injection Moulding

A.J. Dawson, P.D. Coates, A.L.Kelly, M. Woodhead, R. Collis, L. Owen, D. Owen, May 2001

Good injection moulding machine control is a necessary requirement for control of the process, however there is an acknowledged lack of process understanding, related in turn to a lack of understanding of the polymer under process conditions which inhibits the development of standardised route to process control. In our laboratory, specific pressure indices in an identified low noise region of the primary injection stage of injection moulding have been found to provide a sensitive indicator of changes in a polymer, including batch to batch changes and process-induced changes, which in turn allows meaningful Statistical Process Control to be undertaken. Growing concern for environmental issues, including international standards agreements such as ISO14001, demonstrate a clear requirement to conserve energy for both environmental and cost issues. Detailed energy measurements on injection moulding machines both in the laboratory and in industry demonstrate the potential of process energy measurements as an aid to the development of a systematic management approach to the environmental concerns of an organization. Laboratory DOE studies allow a further insight into the influence of a variety of machine variable settings on the total energy consumption. We are currently in the process of combining both process variable and process energy measurements, to provide processors with the richest level of process information.

Conductive TPO for Electrostatic Painting

Susan Babinec, Ray Lewis, Robert Cieslinski, May 2001

The TPO (Polypropylene/Elastomer) market for injection molded automotive bumper fascia is driven by cost reduction, a balance of physical properties, ease of processability, and desirable aesthetics. Global volume for this application was approximately 740 MM lbs. in 1999, nearly half of which is electrostatically painted. Decreased application costs, increased productivity, and reduced environmental emissions can be realized through system optimization. This report describes the rheological and morphological phenomena governing the development of a conductive TPO (CTPO) for enhanced electrostatic painting.

Degradation Mechanisms of Thermoplastic Polyurethane Resins

Philip H. Patterson, James M. Sloan, Alex J. Hsieh, May 2001

The use of polymeric materials for transparent, lightweight armor has been of great interest to the U.S. Army for a number of years. Field items such as goggles, lens, face and windshields are currently manufactured using advanced polymeric plastics. These items are designed with polymers that provide excellent optical clarity, rugged abrasion resistance, and high ballistic impact strength. However, as with any organic polymer system, these materials are susceptible to degradation over time when exposed to various environmental (i.e. sunlight, moisture, temperature) conditions. This structural degradation (1-4) will eventually comprise the original integrity of the materials' desired properties. In this study, the impact of accelerated weathering upon newly developed polyurethane based thermoplastic materials was investigated. A fluorescent ultraviolet (UV)/condensation weathering tester was selected for the exposure study. The materials were characterized by UV/VIS spectroscopy and FT-IR spectroscopy. The results reveal that the urethane linkages undergo a scission reaction upon UV exposure drastically affecting the mechanical properties of the material. Furthermore, these urethane scissions produce a yellowing of the polyurethane which can inhibit its use where optical clarity in important.

Development of High Quality Recycled Polyethylene Resins for the Replacement of Virgin Resins

Violet Stefanovski, Edward Kosior, Syed Masood, Pio Iovenitti, Igor Sbarski, May 2001

Dairy and fruit juice bottles are a major source of post consumer recycled high density polyethylene (PCR HDPE). The recycled HDPE has limited post-consumer applications due to its poor stress crack resistance (SCR). This paper presents a review of a test method for SCR and some preliminary results of the development of recycled HDPE blends with improved SCR. The improvement has been achieved with the addition of a modifier, and results indicate that there is a potential to incorporate the use of recycled HDPE in non-pressure pipe applications. These customised blends have been tested for SCR according to the Notched Constant Ligament Stress (NCLS) test. The NCLS test is a new test method (ASTM F17.40) which is currently under development. The NCLS test will be used to determine the susceptibility of HDPE resins to slow crack growth (SCG) under a constant ligament stress in an accelerated environment. The results from the test will subsequently be correlated with field performance results.

The Effect of Blending on the Viscosity Reduction of Recycled Milk Bottle Grade HDPE

Natalia Kukaleva, George Simon, Edward Kosior, May 2001

Post-consumer plastic waste in Australia contains over 50,000 tonnes p.a. of HDPE blow moulded bottles, with half still ending up in landfill. Recycled milk-bottle grade HDPE is known to be too high in molecular weight for processing by injection molding. In this study, the target was to make injection-molded compositions with a content of the recycled material of 75% or higher by blending with commodity plastics. The results of rheological, thermal and mechanical studies of the blends are presented.

The Recycling of Thermoset Materials into Thermoplastic Composites

David D. Camlin, Matthew J. Heidecker, Sarah M. Reynolds, May 2001

Thermoset process scrap costs companies millions of dollars annually. Specific thermoplastics could benefit from the addition of recycled thermoset material. The incorporation of thermoset regrind into thermoplastic material would provide a viable alternative for the thermoset scrap that is currently sent to the landfills.

Environmental Lining Systems - Raising the Standards

Ian D. Froment, May 2001

Annually, the United Kingdom deposits around 20 million tonnes(1) and the United States around 2 billion tonnes(2) of waste into landfill. To protect the environment from the harmful effects of leachate from the waste, landfill sites are protected using a system of thermoplastic liners, typically made from polyethylene. Due to manufacturing limitations on the size of the lining sheets, welding is employed to join adjacent sheets at the landfill site. This paper reviews current welding practices, the industry approach to quality, and discusses the moves towards certification of welding personnel in order to raise standards across the industry.

Environmental Stress Cracking of PC in Contact with Aqueous Solutions

R. Berlich, E. Schmachtenberg, May 2001

The environmental stress cracking (ESC) behavior of some plastics is very well examined. Especially for polyethylene the mechanisms are nearly clear. For amorphous thermoplastics this mechanisms were examined in many researches, but are still not really clear. Especially for polycarbonat (PC) in contact with aqueous solutions systematic examinations of the ESC behavior are rare. In this paper examinations of the ESC behavior of PC in different aqueous solutions are presented. The tests were done by a medium-tensile-creep test. Different pH-values of water and a surfactant were examined about their influence on the ESC behavior. Also distinctive types of PC and their influence on the ESC behavior were examined. It is determined that the ESC of PC in contact with aqueous solutions is not only, like classical approach, controlled by physical effects. A large effect of chemical mechanism is also part of the failure mechanism.

Environmentally Friendly Plasticizers for Polyvinyl Chloride (PVC) Resins

Bhima R. Vijayendran, Herman Benecke, Joel D. Elhard, Vincent D. McGinniss, Kim F. Ferris, May 2001

There has been increased interest in developing alternatives to phthalate plasticizers used in the processing of polyvinyl chloride (PVC). This paper describes research on modifying the composition of vegetables oils such as soybean oil for use as primary plasticizers for PVC. Advanced computational chemistry and modeling studies have been conducted to correlate structures of modified soybean oil with their compatibilities in PVC resin. The new soy oil derived plasticizers have excellent plasticizing efficiency with significantly reduced migration and volatility. Properties and performance of the new modified soy oil compositions as primary plasticizers in typical PVC formulations are summarized and compared to those of a standard phthalate PVC plasticizer.

Extrusion/Compression of Long Fiber Thermoplastic Composites

Klaus Gleich, May 2001

It is becoming common for long fiber-reinforced thermo-plastics (LFT) to replace existing GMT-type applications as well as to capture new applications. This is especially true in the European automotive industry, where the market for parts made from LFT is experiencing tremendous growth. The following paper discusses the available materials, the mechanical and physical properties, machine techniques and processing details of the LFT process. It will also discuss potential applications for LFT. The paper will cover different process techniques such as direct processing and make comparisons with other processes. An explanation on the effects that LFT has on properties and economics will be made. It will show how the economics can be improved by adding recycled material to the process. This paper will provide a better understanding of the LFT-process and how you could get benefits from this process.

Failure Analysis of a Cracked Construction Vehicle Grille

Jeffrey A. Jansen, Mary K. Kosarzycki, May 2001

Cracking occurred within grilles used on heavy construction equipment, without apparent cause. The cracking was observed to be sporadic and had initiated while the parts were being stored in a warehouse, prior to installation on the vehicles. The cracking was found adjacent to holes used to secure a logo nameplate in conjunction with metal bolts. The focus of this investigation was a timely determination as to the nature and cause of the failures. Of particular interest was whether the failure was primarily associated with material, design, processing, or environmental factors. This paper will document some of the testing performed to characterize the failure mode and identify the root cause of the cracking, in order to illustrate the failure analysis process.