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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Failure Analysis of Copolyester Clamps
Cracking and subsequent failure of a clamp feature on a broken copolymer component occurred through brittle fracture as a result of environmental stress cracking. Environmental stress cracking (ESC) is a phenomenon whereby a particular plastic resin is affected by a specific chemical agent while under stress. ESC occurs commonly in polymeric components but the fractographic features of copolyester are similar in both ESC and creep. The analytical techniques employed in this article provide a guideline by which to properly determine the root cause of failure for copolyester components and describes characteristics typically observed in copolyester ESC failures.
Experimental Results of Melt Modulation Packing Parameters Control on Cold-Runner Injection Molding Final Product Quality
This paper details the experimental results performed on a clear polymer, STYRON? 685D (GPPS), to investigate the impact of varying the packing processing parameters on its final quality. Packing processing parameters, including packing pressure and packing time, have significant impact on the internal molecular orientations, mechanical properties and optical performance of injection molded polymeric products. Experimental results have been obtained from three melt modulation control methods to control the packing pressure, packing time and control valve angle during each cold-runner injection molding cycle.
Experimental Analysis of Fibers Orientation and Mechanical Properties in Injection Molding of Thermoplastic Reinforced Materials by Rapid Heat Cycle Molding
Injection molding of reinforced thermoplastic materials is increasingly used in order to obtain high specific mechanical properties and good surface finishing. In this work a rapid heat cycle molding (RHCM) technology was employed to study the influence of injection molding parameters on fibers orientation and mechanical properties of thermoplastic fiber reinforced injection molded parts. X-ray computed tomography (CT) was employed to allow a direct observation of the fibers orientation. The injection molding parameters investigated were mold temperature, injection speed and part thickness. The experiments show that the mechanical properties are maximized by high part thickness, low mold temperature and injection velocity. However, the variation of the investigated injection molding conditions had a negligible effect of fibers orientation.
Mechanistic Model Simulation of a Compression Molding Process: Fiber Orientation and Fiber-Matrix Separation
A mechanistic model was implemented in order to simulate the fiber motion in the SMC process (Sheet Molding Compound). In this model, each fiber is represented by a chain of segments interconnected by articulations. A balance of forces and torques is considered for each of these segments in order to determine the velocity and position of each of them during the simulation. This balance of forces and torques includes hydrodynamic effects (drag forces and torques), fiber-fiber contact forces and bending moments.
Regarding the fiber orientation, the results of the mechanistic model were compared with experimental results in the literature. It was found that the model is in good agreement with the experiments, but it slightly over predicted the orientation. The fiber matrix separation phenomenon was observed and it was concluded that it increases with the fiber content and with the fiber-fiber friction coefficient.
The Effect of Localized Heating on Polyethylene Tubing
Polyethylene (PE) tubing is used in a wide variety of industrial and residential applications, including as a means of transporting water for use with appliances and other equipment. Temperature limits are applied to PE tubing to prevent premature failure due to loss of mechanical properties from heat and oxidation effects, especially in pressure-carrying systems. Product lifetime will be shortened by oxidation and subsequent embrittlement, which allows crack initiation, propagation and ultimately a fluid path through the tubing wall. In this case study, we present an example of the effects of localized external heating on hot water carrying PE tubing.
On the Use of Self-Assembling Block Copolymers to Toughen an Aromatic Amine-Cured Epoxy
Block copolymers have received considerable attention in epoxy toughening due to the wide variety of nanostructures that can be produced. In this study, a series of self-assembling diblock and triblock copolymers were added to aromatic amine-cured epoxies. In most cases, spherical micelles formed and diameters as small as 20 nm were imaged. Increases in toughness were observed in all cases and the toughening mechanism involved the formation of a crack-tip plastic zone. It is important to note that the size of these plastic zones are relatively small when compared to those generated by more traditional toughening agents.
Rheological Behavoir and Structual Development of Thermoplastic Polyurethane Annealed at High Temperature
The changes in phase transition behavior and structure were investigated through varying hard-to-soft segment ratios of a model thermoplastic polyurethane (TPU) system. Dynamic rheological measurements showed a high temperature phase transition related directly to the hard segment content. Extensional viscosity also detected a relationship between the hard segment content and the material?s strain-hardening behavior. Annealing the samples near the phase transition temperature caused an increase in moduli as well as an inversion in extensional behavior. Understanding the material property changes associated with changes in composition and annealing could provide a route to further tailor these versatile materials.
Applications for Recycled Pots, Tubs and Trays
With pots, tubs and trays being a recent addition to recyclables collections, end markets and values are yet to develop in the same way as plastic bottles. The value of pots, tubs and trays depends primarily on the level of contamination and polyolefin content (polypropylene (PP) and polyethylene (PE) plastics). An assessment was undertaken to review markets conditions affecting the recycling of polyethylene terephthalate (PET) pots, tubs and trays (PTTs). This considered the supply of clear PET, potential available markets, and alternative technologies to provide a comparative assessment of market values (e.g. EFW, landfill, export markets). The actual cost of disposal of PTTs is somewhere between œ44.9m and œ55.5m. The business case for collecting pots, tubs and trays develops further when actual values are gained per tonne, and with new sorting facilities for pots, tubs and trays being commissioned, once end markets have developed the financial benefits to local authorities in the UK will increase. This work focuses on finding markets for recycled PTTs with a number of trials at major manufactures across Europe.
Functionalization of Soy Fatty Acid Alkyl Esters as Bioplasticizers
The combination of various functional groups such as epoxy, acetoxy, methoxy, thiirane, aziridine on the acyl chain of soy fatty acid alkyl esters have been synthesized and evaluated as plasticizers in poly vinyl chloride (PVC) applications. Numerous synthetic procedures such as epoxidation, methoxylation, acetylation, thiiration, and aziridination were used for synthesizing multifunctional soy fatty acid alkyl esters. Epoxidized soybean oil fatty acid alkyl ester served as the key intermediate to incorporate most of the functional groups on the fatty acid backbone. The physical and analytical properties of bioplasticizers such as acid and saponification values are acceptable for plasticizer applications. The high viscosity and darker color of aziridine and thiirane derivatives limit their usefulness, whereas the physical properties of the other derivatives were acceptable. The plasticizer evaluation of methoxy, acetoxy soy fatty acid esters (methyl and n-butyl) demonstrated good compatibility with PVC, high efficiency (Shore Hardness) and gelling properties and were comparable to commercial plasticizer, diisononylphthalate (DINP).
Reinforcement Effects in Amorphous Copolyester Nanocomposites
Decades after their initial discovery, polymer nanocomposites find use in a wide range of commercial applications. BCC Research indicates that the global nanocomposite market is worth ~$1.4 billion, with clay nanocomposites accounting for ~60%, and will grow to ~$4.2 billion by 2019. Novel nanocomposites are therefore both scientifically interesting and industrially relevant. Jafferji, Schmidt and Reynaud have previously described the mechanical properties of copolyester / clay nanocomposites based on Eastman?s Tritan TX1000 copolyester in combination with commercial nanoclay. These materials represent the first melt-blended polymer nanocomposites based on a commercial high-Tg amorphous thermoplastic that give increases in modulus, strength, and elongation at break with no loss in impact properties or clarity. In addition, IR imaging during tensile testing enabled us to identify a change change in the deformation mechanism of these materials (as measured by their ability to convert work to heat) with increasing nanoclay content.
Here, we report on analogous nanocomposites of Eastman?s Tritan TX2000 copolyester. Our previous results were unexpected for amorphous nanocomposites ? but x-ray diffraction (XRD) identified local ordering in the TX1000 systems which was enhanced through clay addition. In contrast, TX2000 is entirely amorphous and possesses a higher glass transition temperature. Otherwise, these systems are highly comparable. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) both confirm the lack of crystallinity in the TX2000 based materials. XRD further indicates that TX2000 is at least as clay-compatible as TX1000. While thermal stability is reduced on clay addition and hardness measurements are inconclusive, clarity is retained with little or no change in color. These results, in combination with ongoing mechanical characterization, will provide a better appreciation for structure-properties relations in this class of copol
Mechanical Response of Ageing and Annealing on Injection Molded High Density Polyethylene
Short term stress relaxation tests were performed to observe mechanical effects of ageing and annealing on injection molded High Density Polyethylene (HDPE). The investigation revealed no definite relationship between ageing time and relaxed stress. Two different annealing parameters were used to investigate the effect of annealing on injection molded samples. Samples annealed for longer time showed more consistency and higher relaxation modulus than the samples annealed for shorter time and the control samples. The effect of ageing on annealed samples was also studied in this work.
Optimization of Polyamide Blends for Automotive Interior Applications Utilizing Mixture-Process Variable Experimental Designs
When developing complex compounded polymer blends, utilizing experimental design methods can aid in understanding the main effects of each component as well as higher order interactions between components. Even more intricate models allow the analysis of process variables and the complex interactions with the blend properties. This paper will review the fundamentals of mixture-process variable (MPV) experimental designs, ordinary least squares linear regression, and response surface methods as they apply to formulation of engineered polymer compounds. Response surfaces are generated for a multicomponent polyamide blend used in automotive interior applications including the effect of a single process variable where mechanical and appearance properties are all modeled and evaluated for optimal levels using desirability functions.
Intelligent Labels as a Basis for Auto-Sorting of Plastic Packaging
Polypropylene (PP) from packaging is a significant polymer in the mixed plastics waste stream and closed loop recycling of it back into packaging would enable considerable carbon savings to be realised and generate significant revenues. Recent estimates suggest that 143,000 tonnes of the total PP packaging is used for food-grade application. One of the remaining barriers to closing the loop on the recycling of PP food packaging waste back to food grade applications is the absence of an automated method for sorting PP packaging waste to separate a stream consisting of at least 99% PP packaging that has been previously used for food from other non-food PP packaging.
Machine readable inks (including fluorescent pigments) have shown great potential for the identification and separation of plastic packaging. Unlike existing NIR sorting practices, these technologies are not polymer specific and could be applied to targeted streams like food grade PP packaging and others, using commercial labelling and decoration methods and sorted using MRF infrastructure with only minor modification.
This report describes the work of an identification technique which is based on fluorescent pigments that can be applied to labels and packaging as a machine readable ink (MRI) to enable the automatic separation of target materials such as the sorting of food grade PP packaging for closed loop recycling.
Based on the audit of commercial of PP waste indicating that 55% detectability of existing packages together with potential yields of 98% from the sorting trials, it can be estimated that of the 143,000 tonne of PP food packaging, 77,077 tonnes could be recovered each year in the UK. This would increase dramatically if label design and application was modified to better accommodate identification and sorting requirements.
Thermally Conductive Polycarbonate for Electronics
The LED lighting market continues to grow rapidly as consumers recognize the benefits of this technology over incandescent and fluorescent fixtures. However, the relatively high price of LED bulbs has forced manufacturers to explore ways to reduce costs. Since the electronic component costs are usually fixed, other components such as the simple heat sink offer an opportunity to reduce costs and improve performance through unique assembly processes.
Developers at Bayer MaterialScience have created several polycarbonate grades aimed at LED applications, each with a potential to reduce cost, through the elimination of secondary operations and improved design freedom. This list includes thermally conductive polycarbonate.
Thermal management of electronics has traditionally been handled using highly conductive metal alloys. The unique properties of thermally conductive polycarbonate and the lower processing temperatures compared with die casting provide an integrated assembly opportunity that can reduce cost and eliminate thermal interface, potting materials and assembly steps.
Two polymer technologies, thermally conductive polycarbonate and polyurethane have been combined to allow in-mold electronic component assembly and encapsulation reducing the number of components while creating a finished part in a mold without additional manual assembly.
Compared to traditional manufacturing, this process reduces labor cost, increases supplier competition and improves thermal contact by elimination of relatively low conductivity thermal interface materials (TIM).
Enhanced Thermal Conductivity of Polybutylene Terephthalate Composites Using 2D and 3D Hybrid Fillers
Polymer composites filled with hexagonal boron nitride (hBN) are of great interests to researchers nowadays because they are considered to be potential candidates used for heat conduction and electrical encapsulation. In this paper, two grades of hBNs (AC6041 and PTX 60) of different sizes and structures were used as hybrid fillers in order to enhance the formation of thermally conductive networks. The effective thermal conductivity (keff) of the composites was tailored by varying the hybrid filler compositions. The keff reached a maximal value when the volume fraction of hBNAC6041 in the hBNs varied from 50% to 67% at a filler loading of 18.7 vol. %. In addition, an empirical model was proposed to explain the competing effect of using hybrid fillers on the PMC?s keff.
High Temperature Air Channel Testing of Thermally Bonded PVC Geomembrane Seams
ABSTRACT: The objective of this paper is to present a procedure for high sheet temperature air channel testing of dual track thermal seams for 0.75 mm thick PVC geomembranes. This objective is accomplished by developing relationships between seam peel strength and seam burst pressure for sheet temperatures ranging from 46.7øC to 62.8øC during field air channel testing. This paper extends the original relationships presented by Thomas et al. (2003a) and Stark et al. (2004) that only extend to 46.7øC because a sheet temperature greater than 46.7øC is frequently encountered during hot summer months. The original relationship is extended to 62.8øC using the Arrhenius model and a polynomial equation is presented that can be used to convert the sheet temperature during field air channel testing to the air channel pressure required to ensure the specified seam peel strength of 2.6 N/mm (15 lb/in) is met or exceeded. Thus, the proposed relationship and equation allow the seam peel strength to be verified by field air channel testing without conducting destructive tests.
Thirty-Year Durability of a 20-Mil PVC Geomembrane
In 1971, twenty circular aquaculture ponds were constructed for the W. K. Kellogg
Biological Research Station in Hickory Corners, Michigan. The 30.5-m-diameter research ponds were lined using a 0.51-mm-thick fish-grade PVC geomembrane. Over the years the ponds became congested with dense, persistent stands of cattails, trees, and other vegetation, which required the ponds to be cleared and relined in September 2000 in order to allow the initiation of new experiments. The lack of holes in the exhumed geomembrane suggests that it resisted biological attack from microorganisms and also root penetration. Laboratory testing shows that the tensile behavior of the nearly 30-year-old PVC geomembrane is within current specifications for new 0.51-mm-thick PVC geomembranes. Test results also indicate that performing laboratory tests at in-situ moisture conditions provides a better estimate of the field properties of PVC geomembranes than desiccating the material prior to testing, as is required by ASTM Standard Test Methods.
Curing Kinetic and Viscosity Behavior of Liquid Silicone Rubber for Reaction Injection Molding Analysis
Computer-Aided Engineering (CAE) analysis for the Reaction Injection Molding (RIM) process is very useful to predict problems in design process. For the accurate prediction, the curing reaction of the materials during the process has to be estimated accurately. However, the curing reaction of the LSR is very difficult and restrictive to measure because it is a highly complicated behavior. Accordingly, it is desirable to analyze the curing reaction with finding interrelated components among various measurement methods. Isothermal and non-isothermal tests were carried out to study the curing kinetics behavior using Differential Scanning Calorimetry (DSC). The viscosity measurements were also carried out to study the viscosity behavior using rotational rheometer.
A New CMR-Free Polyamide Imide Resin
Polyamide imide [PAI] resin polymers are well-known thermally stable polymers that are used for many high performance coating applications due to their excellent adhesion, temperature resistance, and high strength.
For the various coating uses, PAI resins are used in solvent-based formulations. However, ever-evolving regulations dictate the need to find a solution and replace the traditionally used n-methyl- and ethyl-pyrrolidone [NMP/NEP] solvents. NMP is the most-commonly used solvent in a variety of coating applications. In the 1980?s and 1990?s NMP was used to produce ?environmentally friendly? coatings, replacing cresol as the predominant solvent at that time. Now NMP and NEP have been classified as reprotoxic chemicals, based on the EU REACH regulations and, once again, PAI users face a similar threat which will close entire segments in Europe unless an alternative solvent can be found.
As a key sustainability initiative, Fujifilm Hunt has successfully developed a proprietary alternative solvent solution to the REACH-classified CMR (carcinogenic, mutagenic, reprotoxic) chemicals currently available for PAI coating applications.
Epoxy Silicate Composite Dielectric Characterization by TSDC Techniques
Understanding the magnitude and mechanisms of charge release associated with the dielectric properties of materials has implications on the reliability assessment of microelectronics. Insulators protect devices from conductive currents. However, due to dipole-charge and interface trapping, a release current typically appears around the glass transition. The effect of fillers on the charge release is a critical parameter in investigating the reliability of dielectrics. In this paper, thermally stimulated depolarization current (TSDC) was done to analyze the prediction of material behavior. Parallel thermal measurements were done using DSC to analyze the uncharged material relaxations.
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