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.
Effect of Multiple Shear Histories on Rheological Behavior and Devolatilization of Poly(Ether Ether Ketone)
The effect of shear history on the properties of poly(ether ether ketone) (PEEK) was investigated by processing it through a twin screw extruder 20 times. Samples were taken at various stages in the recycling sequence for testing. The melt rheological behavior, solid mechanical properties, and total outgassing performance were monitored to evaluate the degradation of the PEEK as a function of processing history.The results of rheological testing suggest that degradation is initially dominated by chain scission with cross-linking becoming more significant with more reprocessing cycles. The rheological and mechanical behavior shows similarities to liquid crystalline polymers and filled polymer systems. The results of outgassing testing showed that the total amount of volatiles decreased with increasing processing cycles.
Rheological and Degradation Properties of Renewable Resource Polymer Blends
Over the past decade, considerable interest has emerged in replacing conventional fossil fuel-based polymers with bio-derived polymers. Two bio-derived polymers that have garnered significant interest are PHA and PLA. In this study, shear and extensional rheology, coupled with degradation studies using GPC, are used to investigate the flow properties of blends of these two polymers. The development of blends with tailored flow and thermal/mechanical properties is pursued.
Sharkskin and Melt Fracture of Some Biodegradable Polymers
Sharkskin and melt fracture phenomena have been investigated in two commercial biodegradable polyesters– aliphatic-aromatic co-polyester (AAC), poly(lactic acid) (PLA) and their blends. The study was conducted in a two bore capillary rheometer. It was observed that at high shear rates and stresses PLA exhibits sharkskin and gross melt fracture, while AAC exhibits only gross melt fracture. Experiments indicate that the blends exhibit both phenomena and that blending is beneficial for postponing the onset of flow instabilities to higher shear stresses.
Structural, Thermal, and Mechanical Properties of Miscanthusderived Biocomposites
Miscanthus, a high yield, fast growing perennial grass with low mineral content, was put under a microscope to explore its potential as a source of natural and environmentally friendly fibers and polymers for composite manufacturing. The manipulation of miscanthus’ structural and thermal properties at 25°C < T < 550°C, as probed by SEM, DSC, TGA, and in situ diffuse reflectance-FTIR, suggested that composites with flexural strength as high as ~ 65 MPa could be formulated without the addition of external polymers.
Environmental Stress Cracking in Polycarbonate – Prediction of the Long Term Behavior by the Use of Short Time Tests
The environmental stress cracking is the most common failure reason of polymer parts during their use. There are already many tests to verify the stress crack resistance. Most methods use combinations of an external strain and aggressive liquids to achieve a quick test result. The extrapolation to longer time periods is only successful with the help of the expert knowledge of the raw material producers. The development of a new testing method enables a simulation of the material long-term behavior on the basis of a short time test of plastics under the influence of a medium.
Environmental Stress Crazing in Polystyrene: The Roles of Chain Length and Architecture in Craze Initiation
This work aims to assist in optimising the solid state performance of polymer products, by developing an understanding of the molecular factors involved in initiation of environmental stress crazing. Experiments measuring craze initiation stress in miniature rectangular beam samples saturated in diethylene glycol were performed on 26 isotropic atactic polystyrenes with molar mass from 66 kD to 1148 kD, including a wide range of monodisperse linear and branched materials. Results indicate that both solid-state molecular disentanglement and chain scission play roles, depending on the chain architecture and length of the polymer. A simple rule is suggested for predicting ESC raze initiation in polydisperse polymers.
Failure Analysis and Prevention – A New European SIG
The new European Failure Analysis and Prevention Special Interest Group (FAPSIG) is creating a database with failure cases. The members share this database and contribute with their own failure investigations. The two main groups are Failure Causes and Failure Mechanisms. Failure Causes are subdivided in: Stress concentrations, low mass and/or mould temperature, highly stressed weld lines, faulty ribbing; too high stiffness of construction elements, incorrect joining, and incorrect material selection.Failure Mechanisms are subdivided in: Creep and stress relaxation, wear, fatigue, UV degradation, chemical attack, environmental stress cracking.The paper will present some examples for designers of plastic products.
Improving the Toughness of Poly(Lactic Acid)(PLA) through Co-Continuous, Immiscible, Biodegradable Blends with PHA
Poly(lactic acid) (PLA) and Polyhydroxy octanoate (PHO) were melt blended using a torque rheometer in the ratios of 80/20, 60/40, 50/50, 40/60, and 20/80. In this study, the rheological, thermal, and mechanical properties of the blends were investigated. Differential scanning calorimetry showed that the two components in these blends were found with two crystalline phases and two amorphous phases confirming the coexistence of two immiscible components. The addition of modified PHO in PLA increased the toughness of the PLA and increased the elongation to break more than 158%. Results obtained from rheological test indicated that the melt viscosities of PLA/modified PHO decreased as a function of modified PHO content.
Investigation of Fracture Mechanism of HDPE Subjected to Environmental Stress Cracking
Environmental stress crack resistance (ESCR) is a commonly used test to characterize cracking failure of high density polyethylene (HDPE) used in rigid packaging applications. From a resin design standpoint it is important to understand the mechanism of environmental stress cracking (ESC) especially in the case of materials with significantly different ESCR values. In this report, the morphology of ESC is studied by scanning electron microscopy (SEM). A model to predict polymer ESCR using tie chain concentration considering the permeability of IGEPAL® solution is proposed.
Ionic Liquids as Additives for Thermoplastics
In attempts to develop new process modifiers for thermoplastics, two ionic liquids with long chain hydrophobic cations and different anions were introduced in a biodegradable polymer. Methods of incorporation included melt blending, solvent casting and microencapsulation from w/o/w systems at concentrations up to 10 wt%. The modified polymers were characterized rheologically and by TGA to determine process and thermal stability, respectively, and by DSC to determine miscibility and types of the polymer-ionic liquid interactions. Potential applications in plasticization, lubrication and emulsification are discussed for selected polymer-ionic liquid combinations.
Manufacture and Mechanical Characterization of a Composite Material Made of Wasted Tires and Recycled Polyethylenetherephtalate (PET)
Solid residue was obtained by two processes to reduce discarded tires: pyrolysis and thermal shock. Techniques such as X-ray, FTIR, TGA and SEM were used to characterize the samples. Two types of polyethylenetherephtalate, PET (virgin and recycled) were analysed physicochemical and mechanically to be used as matrix. A composite material was manufactured by employing a Brabender mixing chamber in order to use the granules as filler on PET at different concentrations. The mixed material was laminated and tension test were undertaken in samples to acquire the mechanical properties. Studies of fractography were performed to understand the failure mechanics.
Micropatterning Poly(Acrylamide) on PLA Films Using Photolithography
Micropatterning is a robust tool to surface-modify bioplastics like poly(lactic acid) (PLA) for biomedical applications. We used a sequential two-step photografting and photomask approach to micropattern poly(acrylamide) (PAAm) on PLA film. In step one, a PLA specimen, dip coated in benzophenone solution in ethanol covered with the photomask, was sandwiched between two glass plates and exposed to UV in an inert atmosphere. In step two, benzophenone-micropatterned film was immersed in 10% v/v monomer solution in water and exposed to UV for 3 h to grow poly(acrylamide) (PAAm) from the film surface. The resultant film surfaces were examined by AFM and optical microscopy, which revealed the resolution and acuity of the micropatterns.
New Materials from Polylactide Bioplastics
Renewable resource based bioplastic are the next generation of materials, which will play a major role in building of a sustainable bioeconomy. Polylactide (PLA) is a renewable resource based bioplastic. The realm of PLA bioplastic is expanding through innovative research methodology, products and processes. There is pressing want to enhance the versatility of this bioplastic, so that it can compete with conventional polymers. Inclusion of nanostructures in polymeric matrices is looked upon as unique approach to create revolutionary material combinations. Harnessing the benefits of nanotechnology in generating new biobased material is considered as a benign approach. Biodegradable polymer-clay nanocomposites have already been explored extensively. The niche application of nanotechnology to bring breakthrough research in the field of biobased polymer is still elusive. Recently, polylactide (PLA) has been modified with a new technology based on nanoscopic hyperbranched polymers (HBP) at Michigan State University. The modified PLA has shown a unique balance of stiffness and toughness. Such modified PLA bioplastic will act as ideal matrix for nano-clay, talc as well as natural fiber reinforcements leading to the development of new materials from PLA bioplastics.
Opening the Pandora's Box to Find Elastic Breakup as the Origin of Various Nonlinear Flow Behavior of Entangled Polymers
Chain entanglement is an essential concept in polymer science. It has been explored for six decades since the 1946 transient network theory of Green and Tobolsky. Another three decades after the 1971 de Gennes' reptation idea have passed before a method has been devised in computer simulation to depict chain entanglement [1]. More recently, the time-resolved determination of velocity profiles during and after shear of entangled polymers [2] have led to a specific molecular mechanism for chain disentanglement [3]. This work describes the latest understanding on the subject of polymer flow.
Phosphate Esters as Stress Crack Agents – Case Studies in Failure Analysis
With a recent push toward non-brominated flame retardants, phosphorus-based alternatives, such as phosphate esters, are used more frequently for various applications. Their use as plasticizers is also well known. However, their function as environmental stress crack agents of various thermoplastics is less well recognized. Two case studies, one - in which a triaryl phosphate was a component of the formulation, the other – in which it was migrating from an adjacent component illustrate some of the problems with their use. Fractographic analysis and various analytical techniques were used to determine a root cause of each of the two failures.
Potential Ultrasonic Compaction of Zein and Distiller's Dry Grain (DDGS)
As the demand for ethanol as fuel additive increases, a consequent rise in the production of distiller's dry grain with solubles (DDGS) and commercial zein is expected. Corn dry milling processing produces two major coproducts; ethanol and DDGS. In wet-milling, pure zein is a high value by-product of corn processing. This study evaluates the potential of ultrasonic compaction of zein and DDGS composites to produce biodegradable biorenewable plastics. Various amplitudes, compaction times and compositions were characterized in terms of tensile strength. It was found that samples could be formed within a few seconds with tensile strengths as high 12 MPa.
Product Design Support for Nanocomposite Materials Application
Biopolymers offer sustainability advantages over oilbased polymers as well as unique new property profiles, in addition to the ones of oil-based polymers. Advantages of polymer nanocomposites include high reinforcing effectiveness at low additive concentrations, and greatly improved recyclability as compared with fiber-filled polymers. A project was initiated to address both practical nanocomposite behavior in products and product design with bio-based nanocomposites. Such design support is useful to facilitate conversion of new materials and technologies into design opportunities. Additionally, new and surprising opportunities may be very inspiring in early design stages.
Production of a Tractor Cab Roof Module Using Direct In-Line Compounding of Long Glass Fiber Thermoplastics
Composite Products, Inc. continually adapts their Advantage In-Line Compounding Process to produce products that use novel composite molding tools and methods. In a recent agricultural application, a tractor cab roof combined long glass fiber thermoplastics with innovative tooling and molding methods to simultaneously maximize structure and aesthetic appearance. Additionally, significant cost and performance advantages were realized through part consolidation, material waste reduction, reduction in manufacturing steps at the OEM, and corrosion resistance. The launch of this product was achieved through the successful combination of materials, tooling and process.
Recycled Poly (Ethylene Terephthalate) (PET) Blends for Hot - Fill Bottles
Injection stretch blow moulded PET bottles offer glass like clarity, excellent gas barrier properties and good overall mechanical strength. However, PET bottles required for hot-fill (85 oC ) applications have encountered limitations due to its relatively low glass transition temperature.In this study, two virgin PET grade materials are blended with post consumer recycled PET. The heat-setting technique is used for the manufacturing of injection stretch blow moulded bottles for ‘hot-fill’ applications. The process parameters (the preform temperature, the heat-setting timing and blow mould temperature) and the blend ratios for PET bottles are optimised based on thermal and mechanical characterisation.
Recycled Vinyl Wallpaper- A New Composite
Mechanical recycling of waste polymeric based composites allows production of same or similar products, but in the case of vinyl wallpaper the quality of recovered material combines the cellulose component with the vinyl PVC resulting in a new composite which can have completely different applications compared with the original vinyl wallpaper.Vinyl wallpaper is generally composed of Polyvinyl chloride combined with cellulose fibre and with certain formulations a small percentage of different polymer based additives.It has been demonstrated and described in a previous presentation that this post industrial waste material can be recycled, the present paper will demonstrate that this recyclate can be claimed to be a new vinyl based composite. The present paper will also demonstrate advantages of using modified extrusion technology to recycle wallpaper continuously without degradation of base components. With properties characterisation and evaluation it will be demonstrated that this material can have different applications compared with vinyl wallpaper.
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