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.
In recent years, the increasing concerns on the widespread use of petro-based polymers and the pollution problems associated with their inadequate disposal and handling are driving the development of new and more sustainable polymers, especially biodegradable plastics obtained from renewable resources. The biodegradability of biopolymers depends on their physical and chemical properties, but also on the environmental conditions of the biodegradation media, on which depends the type and availability of microorganisms involved directly in the biodegradation process. Biopolymers showed biodegradability in compost, soil and marine conditions, however, presents different biodegradation rates when compared between these environments. For example, polylactic acid (PLA) showed an excellent biodegradation in compost. Conversely, in marine environment, PLA presented low mineralization rates, while polyhydroxyalkanoates (PHAs) presented an excellent biodegradation in marine conditions. In this sense, a biopolymer with a biodegradation rate around 10% may not be considered as biodegradable in any condition and their accumulation in ecosystems can result harmful. In this study, biodegradation of bioplastics under different environmental conditions are discussed.
Nanocellulose is a unique and promising natural material which is extracted from natural cellulose. The nanocellulose is gaining attention for its use in biomedical applications because of its remarkable physical property, special surface chemistry, excellent biocompatibility and low toxicity. In this study Polybutylene Succinate (PBS) with 5 levels of cellulose nanofibril (NFC) is being developed. The results demonstrate that the addition of NFC has modest effect on the thermal properties but improved the mechanical properties of PBS. The complex viscosity n* of NFC/PBS presents the shear thinning behavior. Furthermore, the water contact angle defines the hydrophilic nature of NFC/PBS composite.
The issue of plastic waste recycling and the idea of establishing a circular economy of plastics is receiving considerable interest from society, policymakers, and industry alike. A truly sustainable development in this field, however, can only be achieved when finding proper solutions to recycling challenges in world regions where formal waste management systems are lacking. In this work, polyolefin recyclates sourced from an informal waste picker community in Nairobi, Kenya were characterized in terms of material composition and basic mechanical properties. It was found that despite the absence of formal waste management systems in developing and emerging economies it is possible to produce technically useful recyclates that may compete with today’s commercially available recyclate grades.
Finding biobased fillers is growing more important as the need to use less petroleum-based plastics increases. Natural fillers provide advantages over non-natural fillers, such as glass and talc, in that they are typically lighter, biodegradable and renewable. These experiments were focused on increasing the interfacial bond in agave fiber (AF) - polypropylene (PP) biocomposites. Processing parameters, such as number of wash cycles the AF underwent, drying time prior to injection molding, and AF loading level were studied in order to characterize the mechanical properties of the composite formulations. It was found increasing the fiber loading level increased stiffness however reduced elongation as well as tensile strength. There were insignificant differences in tensile strength between the fibers that underwent no wash, one or, three wash cycles. In addition, the specific strengths were inversely proportional to the addition of AF into the composites. There was not observed a significant effect of drying time prior to injection molding on the mechanical properties.
The aim of this paper is to study the influence of combining two fillers on the coefficient of linear thermal expansion (CLTE) of polyamide 6 (PA6) hybrid nanobiocomposites. The influence of a new environmentally friendly filler (biocarbon) on the CLTE of PA6 biocomposites was examined and compared to its hybrid additionally containing nanoclay. The results were supported by morphological and thermal characterization showing that the CLTE of the nanobiocomposites were enhanced with the inclusion of a small amount of nanoclay. Accordingly, properties and potential applications of PA6-biocomposites were discussed.
With increasing interest towards biobased and/or biodegradable polymers that generate high performance composites, instead of petroleum based products, creates new opportunities and research challenges. Polylactide (PLA) is supposed to be one of the most promising biodegradable polyesters because of its high mechanical strength, high modulus and good biodegradability. However, the low melt strength of PLA has greatly limited its melt processing such as casting or blowing film, and finally limit its application as packaging. Therefore, firstly the mechanical properties of the PLA were modified by blending with PBS and PBAT; then the melt rheological properties of PLA ternary blends were modified by peroxide in reactive extrusion, and the enhancement effects were evaluated by rheological studies here. Rheological properties revealed that peroxide can greatly enhance the melt strength of PLA ternary blends. A PLA ternary blends/peroxide system can be a good candidate to fabricate biodegradable films with high toughness via stretching shaping process such as casting or blown film.
Hybrid composites are made by incorporating two or more different types of fillers in a single tailorable matrix. This paper investigates a direct injection molding technique applied to hybrid composites made of conventional carbon fiber (CF), glass fiber (GF), and environmentally friendly wood fiber (WF). The favorable combination of these fibers would lead to enhanced mechanical properties and reduced cost. The target markets for the developed hybrid composites could be construction, auto industry, aerospace industry, etc. To meet the strict requirements for these applications, the burning behavior and water absorption behaviors of these hybrid composites were also investigated. Coupling agents (CA), normally used in polymer composites to enhance mechanical properties, were also investigated on their effects on burning and water absorption behaviors.
Triboelectric nanogenerator is a promising technology that is capable of harvesting wasted mechanical energy. It is possible to modify the friction layers of triboelectric nanogenerators to improve their levels of triboelectrification and thereby their efficiencies. This paper aims to investigate the effects of electroactive crystal phases and foam morphology of polyvinylidene fluoride (PVDF), which can be used as the negative side of friction layers, on the performance of a triboelectric nanogenerator. Non-isothermal crystallization and supercritical carbon dioxide foaming were used to fabricate PVDF foams with high electroactive crystal phase contents. Under this approach, PVDF foams with pore size of ~15 μm and electroactive crystal phase content of ~62% were fabricated. Experimental results revealed that the maximum output voltage and current density achieved by using PVDF foams with high electroactive phase contents as the negative friction layers were 53.9 V and 5.1 mA/m2, respectively. This represents threefold increases in performance when compared to the case of solid PVDF friction layers with low electroactive phase contents.
Screw blind riveting combines plastic direct screwing with blind riveting. The new joining element can be integrated in the injection molding process of any injection-molded component. To qualify the element for industrial application, reduction factors for different sizes, geometries, environmental influences and long-term strength are determined. This paper focuses on the shear tensile strength of the screw blind rivet to allow engineers to design products and make this technology, comparable to conventional riveting in appropriate applications.
The Internet of Things (IoT) has been rapidly growing in recent years and is seen as a key enabler in a wide variety of applications such as manufacturing, transportation and healthcare. Home automation, in fact, has been a major market for both hobbyists and early adopters of IoT technology. Even a wave of smart kitchen appliances has been released such as a refrigerator with a built-in screen on its door or internet-enabled coffee maker. While green activists may applaud the appearance of tiny cameras inside our refrigerators to avoid the power loss of opening the door, displaying such images on a brilliant, 200W LCD monitor is not the “killer app” that many of us believe has the power to re-shape our every-day lives.
Plastics injection molding machines require an extensive amount of energy, and energy costs typically represent one of the major line items in a company’s operating budget. A typical injection molding operation spends almost as much on energy expenditures as it does on direct labor. As operators look to reduce costs and enhance sustainability, they typically turn to the more obvious levers – such as new equipment, lighting retrofits, and more. But, one of the easiest and most frequently overlooked opportunities to improve energy efficiency is lubrication. This paper outlines how lubrication influences energy efficiency, key lubrication-related energy saving opportunities, and how operators can implement the right lubrication strategy to reduce energy costs, improve their bottom line, and enhance sustainability.
Environmental stress cracking (ESC) is a common failure mechanism in a variety of polymeric materials. Despite this, the relationship between ESC agent concentration, applied stress, temperature, and polymer composition has not been thoroughly established for many commodity plastics. In this study, three common thermoplastic polymers (PC, ABS, and PMMA) were exposed to an environmental stress agent under different conditions (variable strain, temperature, or concentration). A process for acquiring critical strain curves for materials under these conditions is presented, providing a methodology for systematically assessing factors governing ESC failure of polymers. Additionally, fractographic and chemical analysis of polymer samples exposed to an environmental stress agent are reported.
In injection molding of thermally sensitive materials, the reduction of thermal stress often contradicts with the flow properties. Especially when processing small melt volumes, as often occurs in micro injection molding, long residence times lower the range of applicable materials. New processing strategies need to be developed to reduce the thermal load or improve flow behavior to open up new applications in medical technology. In this paper, the processing of blowing agent loaded bioplastics is investigated focusing on flow behavior in thin walled parts. In this feasibility study, a micro injection molding machine is modified to process plastics in a pressurized gas atmosphere in order to analyze flow behavior using a flow spiral and varying processing parameters.
Colour is essential to human experience. From pre-history, through ancient civilization into the modern era, cultures have strived to create colour in the objects around them. Early peoples exploited natural resources to create images from their surroundings, such as red earth, black soot and white chalk. With time people developed more sophisticated techniques to refine minerals to generate a wider palette with blue, green, bright red and yellow. Often toxic in nature, these early inorganic pigments formed the skeleton of the pigment manufacturing industry. With the discovery of coal tar in the 1800s, and the ensuing rapid industrialization of synthetic chemistry, an explosion of colour transpired, leading to the modern chemical industry. The historic generation of plastics followed a parallel path, beginning with use of natural materials such as ivory and tortoiseshell. Progression to processing of natural materials such as rubber, cellulose and shellac to generate more functional plastics, evolved to a place where coal tar chemistry provided a natural next step. This culminated in the discovery of Bakelite, the first fully synthetic plastic in 1907, which ignited the imagination for plastic materials, and the widespread production of consumer and industrial items accelerated. Colour and plastic developments went hand in hand, as by the 1950s the desire for brightly coloured, functional items sky-rocketed. Pigment chemistries were re-imagined with this new era in mind and from this point colour effects were generated specifically for plastic functionality. Textile fibers, automotive parts, plastic bottles, packaging and film; all un-thinkable now, without the effect of colour.
The aim of this work was to compare the effects of compatibilisation with a pre-fabricated additive and the in-situ generation of a similar additive in the melt for LDPE-PA6-blends and to investigate the effect of mixing protocol (i.e. compounding vs. dry-blending) of the prefabricated additive on the resulting properties of reprocessed LDPE-PA6 films. We found, that it is possible to compatibilize LDPEPA6-blends via the addition of maleic anhydride based compatibilizers, regardless of fabrication approach. This effect can be seen from the morphology of the samples as well as from mechanical properties. Also, the reprocessing of films from LDPE and PA6 with reasonable properties is possible when adding a compatibilizer. The best, i.e. the most balanced properties can be found when the compatibilizer is melt compounded, as this gives the best distribution. These results show that it is possible to reuse multilayer materials when considering the blend components and properly selecting a compatibilizer.
In order to increase added value of plastics in terms improved circular economy, an increased use of recycled polymers becomes more and more important, also for the plastic pipes industry. Unfortunately, compared to specially designed virgin pipe grades, recycled polymers show deteriorated long-term properties. The current paper investigates the influence of different polyolefin cross-contaminations on the slow crack growth (SCG) resistance of a polyethylene (PE) pipe grade. The investigation was conducted with the CRB test on blends of a virgin PE100 with different contents of polypropylene homopolymer (PP-H), blow molding PE-HD, and a recycled first generation PE-HD. The results demonstrate that 5% of cross-contamination content already results in a significant reduction of SCG resistance and that the highest reduction is caused by blending with PP-H.
Coatings on plastics is a very dynamic space driven both by the desire for more environmentally friendly coatings and by an ever increasing demand for improved performance and additional functionality. This presentation will discuss the reduction of the carbon footprint by use of waterborne coatings and UV coatings. In addition the importance of UV coatings to improve scratch and mar resistance, improve energy efficiencies and increase throughput will be discussed. Options for dual cure allowing for upgrade of conventional lines and coating formulations to meet customer needs will be covered. New innovations and future directions base on customer needs and expectations will be reviewed as well. The use of bright colors using Nano pigments and dyes, self-healing paint, easy to clean coatings for high gloss interiors, anti-glare coatings and UV reflective coatings to control interior temperature will be introduced.
Metal Injection Molding (MIM) is a manufacturing method combining injection molding with powder metallurgy. Since MIM involves numerous process characteristics, unstable product quality is a common problem. Defects such as warpage usually appear after debinding caused by the residual stress and non-uniform concentration during the injection molding process. MIM is a series of processes for producing small, complex, and precise metal parts. The metal product is processed through injection molding, de-binding, and sintering. The debinding process of MIM requires the longest time of these processes. If the volume of the product is large, de-binding time can double. This study used gas-assisted injection molding (GAIM) to form a hollow product. Several conventional MIM parameters and GAIM parameters were investigated. The purpose of the study was to reduce the de-binding process time by combining GAIM and MIM. The results show that using gas-assisted injection molding in metal injection molding can reduce the defects from powderbinder separation, and reduce the shrinkage of green parts. Because the product’s structure is hollow, the shrinkage from sintering may also be reduced. The de-binding time can be greatly reduced.
The global demand for epoxy is increasing at a fast pace, with projections of the industry having a worth of $11.5 billion by the year 2022. However, amidst growing concerns about eco-sustainability, the use of toxic and environmentally hazards chemicals in conventional epoxies has triggered efforts among researchers on developing epoxies from various bio-sources. Yet, such efforts have not been accompanied by a thorough analysis of the environmental performance of such bio-based epoxies vis-à-vis their conventionally derived counterparts. This work aims at understanding the environmental performance of two different bio-based epoxies and compare with petroleum derived epoxy. It also highlights the impact of petroleum-based epoxies on human health and human carcinogen toxic categories. Lignin based epoxy performed poor on all the impact categories mainly due to use of excessive amount of chemicals during molecular breakdown of lignin to Vanillin.
This study investigated the mechanical behaviors of injection molded polylactic acid (PLA) composites reinforced with carbon fiber (CF) at different fiber loading levels (5 wt%, 10 wt%, 15 wt% & 20 wt%). PLA, a biodegradable thermoplastic derived from renewable resources, has been replacing petroleum-based plastics in many applications due to its sustainability and low environmental impact. However, the low mechanical strength limits its wide structural applications. The addition of small amount of CF significantly increased the tensile strength and modulus while leading to reduced ductility. Compared to pure PLA, the composites with 5 wt% CF content had a 40% increase of tensile modulus and a 63% decrease of elongation-at-break. The effects of water absorption on the mechanical properties of PLA/CF composites were also studied.
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