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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Various topics related to sustainability in plastics, including bio-related, environmental issues, green, recycling, renewal, re-use and sustainability.
Effect of different fiber tex feeding on mechanical properties of glass fiber reinforced RPET composite by DFFIM process
Two different linear densities of Glass fiber (GF) consisting 1200 and 2400 tex, which were reinforced recycled PET (RPET) composites fabricated by DFFIM process. The results indicated that processing ability of GF/RPET composites with 180-rpm injection screw speed on fiber loading content were in range of 16 wt.% to 55.7 wt.% It was found that the incorporation of glass fiber into RPET composites improved tensile properties, bending properties and impact properties. However the improving tendency on mechanical properties of GF/RPET composites was constant, when fiber loading content was over 40 wt.% for impact strength and 50 wt.% for tensile and bending strength, respectively. At high fiber loading content, 2400 tex of glass fiber exhibited in higher agglomeration of glass fiber especially in core layer when compared with 1200 tex of glass fiber. In addition the fiber length was decreased with the increasing of fiber loading content. The decreasing of fiber length, fiber distribution, effectiveness coefficient and poor fiber orientation resulted in the declination of mechanical properties.
Reduced Post Crystallization of Polyhydroxybutyrate (PHB)
Polyhydroxybutyrate (PHB) belongs to the family of polyhydroxyalkanoates (PHA) and is both, biobased and biodegradable. Due to its linear chain structure, PHB is highly crystalline and has a melting temperature close to its decomposition temperature. Pure PHB crystallizes very slowly, so that the use for some technical applications is not commercially viable. This paper describes the crystallization of pure and nucleated PHB by means of differential scanning calorimetry (DSC). The cooling curve and the metabolic rate as a function of temperature are elaborated.
Environmental Stress Cracking of Medical Thermoplastics: Assessing Lifetime of High Performance Amorphous Resins in Presence of Hospital Cleaners
There is a critical need to quantify and predict the likelihood of Environmental Stress Cracking (ESC) in medical devices, due to the expanding use of medical cleaners in hospitals to prevent infection as well as increased FDA documentation requirements. This paper performs constant flexural strain ESC experiments on two high performance resins, Noryl 20%gf and Ultem 20%gf, using three common hospital cleaners (bleach, quaternary amine with isopropanol, and hydrogen peroxide). ESC testing was performed using a 7-day soak followed by tensile testing to assess residual stress-strain performance.
From strain-at-break results for this 7-day soak method, ratings were obtained for each resin-cleaner combination. These results can be fed into mechanical models of components to quantify likely failure locations and safety factors.
Using time-to-crack datasets, an initial estimate of the n exponent for the ESC dependence on stress was obtained. Also, it was found that the use of Hansen Solubility Parameters could, with reasonably accuracy, predict trends in ESC damage.
Environmental Stress Cracking Study of Alternative Welding Processes in Apparatus, Tank and Pipeline Construction
The infrared (IR) and vibration (VIB) welding processes are joining technologies established in series fabrication. They are characterized by their economically viable and efficient process management. These joining technologies are suitable for utilization in apparatus, tank and pipeline construction. However, they cannot be applied to this field. One reason for this is the lack of knowledge and proof in relation to the Environmental Stress Cracking (ESC). Within the framework of a research project promoted by AiF (Allianz industrieller Forschung), the vibration and infrared welding processes were investigated. Their potential for long-term applications was studied. The results show that minimum tensile creep welding factors of 0.8 are achieved by using the infrared (short-wave radiation emitter) and vibration welding processes. It was possible to obtain values which correspond to those of heated tool butt welding. Furthermore, the knowledge base of the mechanism of failure behavior of welded joints between plastics undergoing ESC was extended.
Evaluating the Effect of Nanoclay and Recycled HDPE on Stress Cracking in HDPE Using J-Integral Approach
This study employed the J-integral approach to investigate the effect of recycled HDPE and nanoclay contents on the long-term stress cracking behavior of pristine HDPE. This behavior was conventionally approached by using stress intensity factor K, which defined the stress cracking behavior as two failure mechanisms: creep and slow crack growth (SCG). Unlike the conventional approach, the J-integral method identified the short-term failure prior to the creep failure. By integrating the short-term and SCG failure behavior, this study derived a correlation between Jc and SCG. The SCG behavior of recycle-blended materials without nanoclay was governed by Jc which decreased as the recycled contents increased. The decrease of Jc led to a reduction in SCG failure time. In contrast, the addition of nanoclay (up to 6-wt%) reduced Jc and stress relaxation of the material, subsequently extending the SCG failure times.
Thermoplastic Semiconductive Power Cable Jacket
A new thermoplastic semiconductive power cable jacket compound is presented. The compound is designed by adding carbon blacks to a blend of linear low density polyethylene and elastomer to achieve overall excellent performance, including good electrical conductivity, excellent mechanical properties, superior environmental stress crack resistance, and low moisture vapor transmission rate as well as low temperature brittleness property. The compound meets wire and cable industrial specifications such as ICEA S-94-649-2013.
Fabrication and Characterization of Bio-based PCM Microcapsules for Thermal Energy Storage
Bio-based phase change microcapsules (MicroPCM) consist of polylactic acid (PLA) shell and butyl stearate core were fabricated by emulsion evaporation method. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimeter (DSC) were employed to characterize the morphology, the chemical structures, and the thermal properties of the fabricated MicroPCM. The results indicated that higher energy input during the emulsion step, utilized a sonicator, is critical to fabricate microPCM with smaller size (i.e., 10-12 ?m) and narrower size distribution. In short, the experimental results demonstrated the possibility to fabricate 100% bio-based MicroPCM with enhanced environmental sustainability for thermal energy storage applications.
Farmlands for Plastics, Textiles, Dyes or Food: Are Bio-Based Materials Really Sustainable?
This presentation aims to contribute to an honest dialog on sustainability of oil-based vs bio-based materials in a consumer context that often includes significant “greenwashing” based on misinformation. This consumer context has raised consumers’ expectations and has put undue burden on many industries and in particular on the plastic and textile industries. Textile companies have tried to find a niche or “green” appeal in this increasingly competitive market; therefore, some are using labels such as “Sustainable”, “Eco-friendly”, “Eco-fashions” etc. As a result of high competition and low margin of profit, some companies have adapted practices such as creative marking and creative reporting/labeling that makes the consumer feel good about a “sustainable” choice, while the carbon footprint, or overall environmental impact, of the products or their production processes on the environment is not significantly better, and in some cases is even worse, than the alternative. Therefore, consumers either have false assumptions about the products they purchase, or are receiving conflicting information and are confused. Consumers are not the only ones that are confused; some members of industry have a hard time sorting out information on sustainability and, in turn, making decisions about where to invest their resources to create more sustainable products. This presentation will attempt to shed some light on these issues and raise some serious questions.
Green Plastics: Utilizing Chicken Feather Keratin in Thermoplastic Polyurethane Composites to Enhance Thermo-Mechanical Properties
A 'green', sustainable resource, in the form of chicken feather derived keratin, was used to enhance the thermomechanical properties of polyurethane bio-composites. Solvent–casting–evaporation method was used to incorporate three levels of chicken feather fibers (0, 10 and 20 %·w/w) into a polyurethane matrix. The thermomechanical properties of the resulting composites were then assessed using differential scanning calorimetry, thermogravimetry, dynamic mechanical analysis and stress–strain measurements with hysteresis loops. The uniformity of the dispersion of the keratin fiber in the plastic matrix was investigated via macro photography and optical microscopy. Scanning electron microscopy of fracture surfaces was used to verify that the adhesion between fiber and polymer was effective. Addition of chicken feather fibers to the polyurethane matrix was found to decrease the glass transition temperature, recovery strain and mass loss of the composites but increase the elastic modulus, storage modulus, and char level. The results demonstrate that keratin derived from what is currently a waste product from the poultry industry (with significant disposal costs) can improve the thermo-mechanical properties of composites, simply and cheaply, with potentially large environmental benefits.
High Performance High Density Polyethylene (HDPE) for Hot Fill Closure Applications
High performance bimodal high density polyethylene (HDPE) was developed for the hot fill closure applications. Performance of the bimodal HDPE was benchmarked versus incumbent unimodal HDPE resins. The bimodal HDPE resin delivered better environmental stress cracking resistance (ESCR) than a conventional HDPE homopolymer while maintaining a good heat deflection temperature (HDT) and a good Vicat softening point. The high performance HDPE also exhibited greater shear thinning behavior, indicative of good processability under the high shear rates typically encountered in the injection molding process. In addition, the closures made from the new HDPE resin are advantaged with respect to the removal torque.
High Performance Inorganic Pigments: Complex Inorganic Colored Pigments
Color is as basic to people as emotions. When we are sad we feel blue, when we’re sick we look green and when we’re mad we are red under the collar. In fact, our use of color predates even modern humans.1 Scientists have discovered that humanities ancestors dispersed pigments with an abalone shell and quartz rock into natural resins to produce paints for body adornment and cave paintingsthe first DIY home improvement projects. Those earliest pigments were natural ochres. In the ongoing centuries we have expanded our palette of pigments to include synthetic pigments and organic chemistry based pigments. A special branch of this pigmentation are the Complex Inorganic Color Pigments (CICP)s.
Complex Inorganic Color Pigments provide highperformance color for the most demanding applications for plastics and polymers. CICPs can stand up to the most challenging and aggressive processing and applications. Recent advances have found that these pigments have properties that give them the ability to address regulatory requirements and give not only color, but also functional properties.
Injection Molding and Mechanical Characterizion of Carbon Fiber-Woodfiber/Polyproplene Hybrid Composites
Hybrid composites are made by incorporating two or more different types of fillers in a single matrix, which is highly tailorable. Carbon fiber (CF) reinforced composites have been well developed for certain industries such as aerospace and sporting goods. However, the high cost of carbon fiber, as well as lack of cost effective processing technologies for mass production, prevents its penetration to many different markets. Wood fiber (WF), an environmentally sustainable bio-fiber, has been used widely in making wood/plastic composites (WPCs) for building products and automotive applications, due to its low cost and lightweight. Nevertheless, WPCs have very limited structural applications where strong mechanical properties are required. Incorporating CF and WF into a polymer matrix to make hybrid composites through injection molding, would be a path to expanded applications for both. This paper investigated the injection molding of CF-WF/polypropylene hybrid composites and their mechanical properties. The effects of fiber content and hybridization on the mechanical properties were studied.
Melt Devolatilization Extruson Process for Brominated Polymeric Flame Retardant
A brominated polymeric flame retardant has a significantly advantaged environmental, health and safety profile compared to small molecule halogenated flame retardants due to reduced molecular mobility and thus no bio-availability. The brominated polymeric flame retardant can be prepared using an innovative indirect bromination reaction, which requires the use of a halogenated solvent. A devolatilization extrusion process has been identified as an economically favorable and technically simplest isolation process among many other isolation technologies assessed. The development of a devolatilization extrusion process for the brominated polymeric flame retardant is presented.
Open Cell Microcellular Foams of Poly(Lactic Acid) Blend with Poly(Butylenes Succinate)
Biodegradable poly(lactic acid) (PLA)-based PLA/Poly(butylenes succinate) (PBS) foams with open cell structure were prepared via batch foaming method using supercritical carbon dioxide as blowing agent. It was found that PLA was immiscible with PBS, and PBS phase was dispersed as tiny spheres or large domains at various concentrations. The addition of PBS reduced the viscosity of the blends. During foaming process, the PLA/PBS interfaces acted as cell nucleation sites and the low melt strength PBS contributed to the formation of cell connection channels, which resulted in open cell structure. The investigation of PBS content found that PLA/PBS (80/20) foamed at 100 °C obtained the highest cell opening rate (96.2%).
Polystyrene Foam Insulation: Implementation of Alternate Sustainable Flame Retardant
Sustainable solutions are being increasingly demanded in the construction product market place. Polystyrene insulation is an increasingly important component of green construction. The benefits of insulation in residential and commercial buildings include lower energy consumptions, improved thermal comfort, reductions in the first costs of the heating and cooling equipment and reductions in CO2 emissions from the burning of fossil fuels across the United States.
As with all foam insulations, polystyrene foam insulation is combustible and must comply with stringent building and fire codes, which have been in place since 1976. The basic requirement in codes is a flame spread index of 75 or less and a smoke developed index of 450 or less when tested in accordance with ASTM E84, in addition to separation of the foam insulation from building occupants through use of a thermal barrier, typically ½” gypsum board. Additional requirements are in place depending upon the particular application.
Like many other building products – from electrical wires to structural and decorative wood products to paint – foam insulation uses flame retardants to protect people and property from the hazards of fire. Flame retardants used in foam insulation meet current regulations and their history of safe use is supported by scientific research.1 Manufacturers are committed to product safety and the effectiveness of flame retardants, and support research and development efforts to continually advance and improve these materials.
A recent announcement by the Design for the Environment program of the U.S. EPA detailed a suitable polymeric flame retardant for use in polystyrene foam insulation. The chemistry is a brominated polymeric flame retardant to replace Hexabromocyclododecane (HBCD)2. HBCD has recently been listed as a persistent organic pollutant (POP) under the UNEP Stockholm convention and is on the Authorisation List (Annex XIV) under the European Union REACH (Regi
Preparation and Characterization of Biodegradable Polylactide/Ethylene Methyl Acrylate Copolymer Blends
The poly(lactic acid)/ethylene methyl acrylate copolymer (PLA/EMA) blends were melt blended with by a twin-screw extruder. The phase morphologies, mechanical, and rheological properties of the PLA/EMA blends with three weight ratios were investigated. The results showed that the addition of EMA improves the toughness of PLA at the expense of the tensile strength to a certain degree. All the PLA/EMA blends display typical droplet-matrix morphology, and different characteristic linear viscoelastic properties in the low frequency region, which were investigated in terms of their complex viscosity, storage modulus, and Cole-Cole plots. The interfacial tension between the PLA and EMA is calculated using the Palierne model conducted on the 80/20 PLA/EMA blend, and the calculated result is 3.3 mN/m.
Production of In Situ Microfibrillar Composites as a Novel Approach towards Improved Bio-Based Polymeric Products
In this work, we introduce the in situ microfibrillation of poly (lactic acid) (PLA)/polyamide-6 (PA6) blends as an effective approach in improving PLA’s properties as well as its foaming-ability. The in situ microfibrillation of the PLA/PA6 blends was performed using a facile and cost-effective extrusion process followed by hot stretching of the extrudates. The morphological studies proved the successful formation of fully stretched PA6 microfibrils with diameters as low as 200 nm. Inclusion of a small concentration of PA6 microfibrils (3 wt.%) was shown to lead to significant improvements in the crystallization kinetics and mechanical properties of PLA. In addition, formation of a physically entangled network of PA6 microfibrils improved the melt strength and elasticity of PLA which, in turn, improved the microstructure of PLA foams.
Properties of Melt Blended Chitin Nanowhisker-Polypropylene Composites
Chitin is a well-known biopolymer that can be extracted from crustacean shells and inherently has good mechanical properties. This paper focuses on using chitin nanowhiskers as a filler to improve the properties of neat polypropylene. Melt blended chitin nanowhisker polypropylene composites with chitin nanowhisker loadings ranging from 2 to 10 wt% was used for analysis. A combination of thermal, barrier, and mechanical properties were examined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), water vapor transmission test, and tensile test respectively. It was observed that the chitin nanowhisker helped improve thermal stability and crystallization. Additionally, an improvement of about 20% and 17% in elastic modulus and ultimate tensile strength respectively was observed at 5 wt% chitin nanowhisker loading. Lastly, a 258% improvement in water vapor resistance was displayed for the 2 wt% chitin nanowhisker loading. Results from the study showed that chitin nanowhisker is a suitable biodegradable filler material for polypropylene to strengthen its thermal, barrier, and mechanical properties.
Recycling of PP/LDPE Blend: Miscibility, Thermal Properties, Rheological Behavior and Crystal Structure
Blending of plastics used in packaging is an interesting approach for recycling or upcycling. Therefore, this study focused on the effects of processing on the properties of recycled PP and PP/LDPE blends. MFI measurements, Differential Scanning Calorimetry (DSC) and hot-stage polarized optical microscopy techniques were used to investigate the miscibility of PP/LDPE blends based on the thermal properties, degree of crystallinity, crystallization and morphology development in the blends. The MFI indicates, that PP and PP/LDPE blends are marginally sensitive to degradation at common processing conditions. The degree of crystallinity of the blends decreases with an increase of the LDPE content. Furthermore, the spherulite growth rate and crystal size of PP decrease with an increase of LDPE content.
The shifts of crystallization temperatures from the DSC measurement, in conjunction with the crystallization kinetics, indicate that PP/LDPE (25 wt% LDPE) is partially miscible.
Rubber Toughened Polylactide (PLA) via Catalyzed Epoxy-Acid Interfacial Reaction
Polylactide (PLA) is a promising material, with favorable modulus, renewable sources, and biodegradability. However, its low extension at break (4-7 %) and toughness (notched Izod, 26 J/m) limit its applications . PLA toughening has been the subject of recent reviews [1,2], and is the basis for several commercial products. This work aims to increase PLA toughness using rubbery linear low density polyethylene (LLDPE), glycidyl methacrylate functional PE compatibilizer (EGMA), and novel catalysts that promote copolymer formation at the interface of immiscible blends of PLA and EGMA/LLDPE. Droplet size was reduced from 2.7 ?m to 1.7 ?m with addition of 5 wt% EGMA, and further to 1.0 ?m with the addition of cobalt octoate catalyst. Extension at break of 200 % is achieved with only 5 wt% reactive compatibilizer, 15 wt% LLDPE, and 0.01 M cobalt octoate.
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