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.
Morphology and Mechanical Properties of Polylactic Acid/Cellulose Nanofiber Composite Foams
This paper investigates the foaming behaviors of polylactic acid (PLA)/cellulose nanofiber composites and the mechanical properties of the composites and their foams. The composites were fabricated by mixing PLA and nanofibers in a solvent with different fiber contents, followed by drying and hot pressing into test specimens. The composites were then foamed via a batch foaming process with CO2 as a blowing agent at different foaming conditions. The effect of nanofiber content on the cell morphology of PLA was studied. The impact strength and thermo-mechanical properties of PLA composites and their foams were also investigated.
Morphology and Physical Properties of Biodegradable Multicomponent Blends with Polylactic Acid
Poly(lactic acid) (PLA) is one of the most promising biodegradable aliphatic polyesters derived from renewable resources and has received significant attention over the last decade. The blending of PLA with poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) is employed to overcome its inherent drawbacks. All prepared fully biodegradable blends show a thermodynamically stable complete wetting behavior which was in good agreement with the thermodynamic analysis. The results for the ternary blends demonstrate a viable route towards the achievement of biodegradable polymers systems with a highly balanced property set.
Notes on Characterization of Natural Fiber Polypropylene Composites
Injection molding simulation of natural fiber thermoplastic composites NFTC requires material full characterization of the following parameter: density, thermal expansion, viscosity, (Pressure- Volume- Temperature) PVT-behavior, thermal conductivity, thermal degradation, polymer structure, specific heat and dynamic mechanical properties. The effect of fiber type (regenerated cellulose, sisal, hemp, wood fiber, wheat straw and kenaf), fiber content (10 and 30 wt.-%) and fiber length (0.5 and 1.5 mm for cellulose) on the mentioned material parameter as well as on their processing behavior during injection in a spiral mold was characterized. Compound viscosity and fiber type/ size were correlated. Other auxiliary results are found in this study concerning the constancy of fiber content along the injected products and the pore formation due to the inevitable gas evolution from the natural fibers.
Novel Development Flame Retardant Additive for Environmentally Friendly Flame Retardant PVC Compounds
Historically phthalates have been used as plasticizers in PVC to provide flexibility over a wide temperature range. In applications where higher flame retardancy is needed along with flexibility, brominated phthalates have been used to meet the requirements. DynaSil™ is a novel flame retardant synergist that has properties of flexibilizing PVC while allowing for the replacement for antimony trioxide (ATO), brominated phthalate plasticizer, and/or ammonium octamolybdate (AOM) in PVC formulations. The results show that by using the DynaSil™, brominated phthalates, ATO and AOM can be replaced without loss of flame retardant properties, sacrificing flexibility, and negatively affecting smoke properties. In addition, DynaSil™ can preserve or improve performance properties such as tensile and elongation while providing a very eco-friendly solution at reduced costs.
Novel Melt Filtration Technology for Challenging Recyclate
The American market for recycled plastic offers both enormous economic potential and strategic challenges. Especially in light of the domestic shale oil boom, recyclers must find ways to maintain competitive advantage in the market. Tackling increasingly contaminated, wet and hard-to-process materials offers a path to this end. Co-rotating twin screw extruders are well suited for accepting plastic regrind of different shapes, bulk densities and contamination levels. Energy extensive drying steps after the washing process can be eliminated, when steam and moisture is removed in special venting barrels. In this paper, process experiences with a novel continuous melt filter are presented, which offers superior processing and flexibility for recyclers to capture untapped value. The functionality and processing potential of this filter in combination with the twin screw extruder is explained by using examples from the post- industrial recycling market, the automotive recycling effort and as well as the post-consumer recycling sources.
Paper Plastic Composites from Recycled Disposable Cups
The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs which has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). Samples were characterised using mechanical analysis and thermogravimetric analysis (TGA). The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.
Poly(Lactic Acid) with Improved Melt Strength and Gardner Impact Strength
Poly(lactic acid) or PLA is a commercial biopolymer made from lactic acid derived from sugar fermentation. “Greenbased”  PLA is desired as a biodegradable film, sheet and food packaging alternative to oil-based polymers. PLA has a Tm melting point range of 150-162°C . Unfortunately, PLA has poor melt strength and impact strength. High melt strength and impact strength are important properties when manufacturing sheet, film, fibers and molded goods. In this paper we explored several ideas to improve the performance of PLA while maintaining its “green” characteristics. We found that an acrylic based core-shell polymer used at a low concentration significantly increased the Gardner impact strength of 15mil extruded sheet. Also, a high molecular weight acrylic copolymer used at low levels doubled the PLA melt strength. Lastly, reacting PLA with organic peroxides increased the shear modulus, molecular weight and melt strength based on rheometer, multi-angle light scattering and Rheotens analysis.
Polyvinyl Alcohol Foaming with CO2 and Water as Co-Blowing Agents
This paper investigated the continuous extrusion foaming of a biodegradable polymer, polyvinyl alcohol (PVOH), using supercritical carbon dioxide (scCO2) as the blowing agent. As-received PVOH pellets were first compounded with water to decrease the melting point of PVOH. In addition, the water can help to reduce the potential for thermal degradation during the extrusion foaming process. Furthermore, water also served as a co-blowing agent together with scCO2 to achieve high expansion and high cell density biodegradable polymer foams. The effect of scCO2 content and die temperature variations on the expansion ratio and cellular morphology of the PVOH foam were examined systematically.
Post-Consumer Recycle (PCR) Solution for PC/ABS Blends
To meet the continued commitment on environmental sustainability, SABICTM has developed and commercialized PCR PC/ABS blends portfolio, which provide more options for customer to choose Cycoloy product. PCR Cycoloy grades are all PC/ABS blends containing 30~35% recycled polycarbonate from post-consumer CD and/or water bottle. RCM6123 and RCM6134 are filled grades, while RCY6214, RCY6113, RCY6013 and RCY6713 are non-filled. These grades were developed for various applications with additional value on environmental sustainability. At the same time, in most applications they showed comparable properties to corresponding virgin grade.
Processing of Biomass Fillers and Reinforcements at Entitled Capacity on Co-Rotating Twin Screw Extruders
Polymers are increasingly being combined with renewable biomass fillers and reinforcements to improve product performance, reduce cost, reduce product density, improve aesthetics and/or reduce the carbon footprint typically associated with plastics. The use of renewable materials for fillers and reinforcements in plastics has existed for several decades, however, their acceptance is rapidly expanding due to increasing plastics costs and environmental concerns. Unfortunately, a common property most of these materials share - sensitivity to heat and shear, limits their availability to be mass produced in an efficient manner in order to be cost competitive with commodity plastics and thermoplastic composites. However, a better understanding of the physical mechanisms that contribute to the onset of thermal degradation and of the technologies available to prevent such can enable significant capacity enhancements when processing biocomposites using co-rotating twin screw extruders. Another characteristic of many of these materials is that they possess a low bulk density, making them difficult to transport into the extruder at a high throughput. Technologies have recently emerged that can effectively improve the conveying efficiency of “difficult-to-feed” fillers and reinforcements.
Processing Research and Development of ‘Green’ Polymer Clay Nanocomposites Containing Polyhydroxybutyrate, Vinyl Acetates, and Modified Montmorillonite Clay
The purpose of this research was to determine the feasibility of direct melt-blending (intercalation) montmorillonite nanoclay to polyhydroxybutyrate along with vinyl acetate, at different weight percentages, to enhance plasticization using typical plastic processing equipment and typical processing methodology. Single screw and twin screw extrusion, Banbury mixer compounding, and compression molding were used to intercalate montmorillonite, and for sample preparation purposes, to test tensile and flexural strength of the resultant polymer clay nanocomposites (PCN) developed. Dynamic mechanical analysis of tensile strength and flexural strength was compared as a result of this processing. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and melt flow analysis (MFI) were used to determine the thermal and flow properties of the PCN materials produced during the research.
Properties and Foaming Behavior of Biodegradable Poly(Lactic Acid)/Poly(Butylene Succinate) Blend
Biodegradable poly(lactic acid)/poly(butylene succinate) (PLA/PBS) blends with various blending ratios were prepared by melt mixing for properties and foaming studies. The phase morphology and thermal properties were investigated using scanning electron microscopy and differential scanning calorimetry, respectively. The studies show that PLA/PBS is immiscible blend, and PBS has an effect of plasticizer on PLA, promotes PLA crystallinity with the addition of PBS, meanwhile, decrease the thermal stability of PLA. Supercritical carbon dioxide foaming study shows that the composites foams exhibit larger cell size and smaller cell density compared with neat PLA foam due to lower melt strength of PBS.
Recent Advances in Glass Bubble Polymer Compounds
Glass Bubbles (Hollow Glass Microspheres), due to their unique spherical geometry and low density, provide several benefits in thermoplastic composites. They help produce lighter weight parts in order to achieve stringent fuel economy targets for automotive and aerospace manufacturers. They also provide productivity benefits through shorter cooling times, enhanced dimensional stability and less warpage – helping to reduce waste and improve throughput. In this paper, we provide solutions to achieve high impact strength in glass bubble polyolefin composites through the combination of impact modifiers and compatibilizers as well as demonstrate how GBs can be combined with supercritical foaming technology to achieve double digit weight savings with well maintained properties primarily for glass fiber filled composites.
Sb2O3 Free FR PBT Product Development
Antimony trioxide (Sb2O3, ATO) is widely used as a flame retardant in combination with halogenated materials. The combination of the halides and the antimony is the key to the flame-retardant action for polymers, helping to form less flammable chars. The Objective of this work is to develop ATO free FR PBT products with equal robust FR properties. Many candidates were screened to replace ATO as the flame retardant synergist. Among them all, one FR combination package with no ATO was tried in a glass filled PBT system. Experimental results demonstrated that this ATO free FR PBT product shows good flame properties and passes UL 94 V0 rating @ 0.71 mm thickness. Meanwhile, the physical properties, mechanical properties, and processability were all well maintained. In addition, the ATO free FR PBT formulation is very robust against both extreme extrusion conditions and abusive molding conditions even when recycle materials are incorporated. The same ATO free FR package has the potential to work in other unfilled and filled PBT resins or blends too.
Solid Phosphorous Based Flame Retardants in Impact Modified Polycarbonate Blends for Superior Properties
Phosphorous based flame retardants have been widely employed as eco-friendly flame retardants for impact modified polycarbonate (PC) blends but some of the liquid phosphates cause significant deterioration in key physical properties like impact strength and heat deflection temperature. This work shows results from recent developments at SABIC in order to achieve superior physical properties while maintaining thin-wall UL94 V0 ratings by using solid phosphorous based flame retardants. Additionally, some of these blends also show significantly improved hydrolytic stability which could translate into a more sustainable solution enabled by longer service life for parts made out of such materials.
State-Of-The-Art Additive in Automotive Plastic Applications or How Performance and Aesthetics Can Meet Sustainability
Innovation in additives continuously enhances the offering to the plastic industry. Conversion processes of engineering thermoplastics compounds can be very demanding, especially when reinforced with fillers like glass fibers. Performance, quality, productivity and weight reduction are the automotive industry drivers for plastic applications, combining excellence and awareness. The answer to these needs is the development of specific additives or solutions which provide to the compounds, outstanding protection and process improvement ability, with a particular focus on sustainability.
Study of Mechanical Properties of Soy Flour Additives in Elastomer Composites
Bio-based polymers and biofiller polymers are becoming viable alternatives to petroleum-based plastics and offer increase bio-content at the end of service life compared to conventional plastics and rubbers. Advantages of soy flour include being lightweight, low cost, high strength and stiffness but interfacial adhesion poses to be an issue. In this project, soy flour as an additive to synthetic rubber matrix based composites were studied. Surface modification such as acetylation and grafting with PMMA were compared to untreated soy flour composites. In general, untreated as soy concentration increased, the mechanical properties of the composites decreased. In contrast, pretreated soy flour (acetylated soy flour and grafted soy flour) at 10wt% performed comparable to that of the neat rubber and resulted in an increase in tensile stress.
Sustainable Plastics: Life Cycle Assessment of Biobased and Recycled Plastics
Plastic materials and products produced today should not deplete resources or abilities of future generations to produce plastic materials or products. Sustainable plastics can be sustainable by producing products with reduced greenhouse gas emissions, reduced solid waste, and reduced pollution as compared to conventional plastics. Based on cradle-to-grave life-cycle assessments (LCA), PLA plastic containers had lower greenhouse gases, lower waste generation, and lower pollution than virgin and recycled PET containers. The PLA clamshells had 86% and 79% lower overall environmental impacts than recycled PET and virgin PET containers, respectively, as measured with a Greene Sustainability Index (GSI).
The Effect of Immiscibility on Biobased PLA/PHBV Foams
Biodegradable polymers are currently a critical global research topic as they may potentially serve as replacement to conventional petroleum based plastics. One key strategy to widen its range of application potential is by improving its physical and mechanical properties. Such characteristics can be engineered by blending two polymers of desirable properties together and by inducing a cellular morphology in the pure polymer or blend with the aid of a foaming agent. This paper examines the effect of blending PLA and PHBV on their overall miscibility as well as the effect of their miscibility on the resultant foam fabricated using carbon-dioxide as a blowing agent. PLA and PHBV blends were manufactured in various compositions via compounding and foamed, and their physical, mechanical and morphological properties were characterized. The results indicated that although PLA and PHBV are immiscible, the addition of small quantities of PHBV (at 15wt%) lead to a finer and more homogenous cellular morphology.
The Effect of Reprocessing on Mechanical Properties of Polypropylene
Polypropylene (PP) was injection molded up to 20 runs to study the effect of recycling procedures. The influence of the recycling was studied by observing changes in melt viscosity, tensile and impact resistance properties. The main effect of recycling was decrease in melt viscosity, which is attributed to molecular weight reduction. The observed degradation processes only slightly affected the small strain properties of the materials studied. However, break properties were affected apparently. All the tensile properties related to breaking as well as impact resistance of recycled polypropylene decreased with recycling.
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