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.
This paper examines the tensile strength and Izod impact behavior of natural fibers and wood particles in recycled polypropylene composites for injection molding. The initial round of testing compares the performance of the straight recycled polypropylene resin versus non-compatibilized natural fiber or particle composites, and then the different composite performance was indicated through the addition of a compatibilizer. The mechanical properties of natural fiber or wood particle and recycled PP composites without a compatibilizer were firstly compared with those of only recycled PP. Then, some natural fiber or wood particle and recycled PP composites using various compatibilizers were investigated. It was found that the elongation at break and the Izod impact strength of some natural fiber or wood particle and recycled PP composites using specific compatibilizer were indicated for high flexibility and adhesive formation as compared with some natural fiber or wood particle and recycled PP composites without a compatibilizer. The difference between natural fibers and wood particle was also discussed.
Traditionally, setting of process parameters is significant for quality of molded parts and is a highly skilled job on the plant floor in plastic injection molding. The process window is especially instructive for this job. However, it is difficult to be depicted and obtained since it is an irregular region in a multi-dimensional space of process parameters. In this study, the process window is implicitly defined by a fitting of sample data from simulation results. Design of experiment, simulation and support vector machines classifier are combined to simultaneously fulfill the requirements of computational efficiency and prediction accuracy.
This research was carried out to improve mechanical properties of PBS by melt blending with recycled PET flakes from drinking bottles. Content of PET adding was 1, 2 and 5% by weight. Properties of polymer blends were evaluated by tensile test, impact test, SEM, DSC, and TGA. It is found that blending PET into PBS yielded stronger mechanical properties compared to neat PBS. However, melt blending between them required high temperature enough to melt PET flakes, so it caused thermal scission in PBS molecules as evidenced in TGA analysis. PBS/PET blends had higher tensile modulus but reduced flexibility with higher PET content. For DSC analysis, it is found that blending PBS with PET increased crystallinity of PBS matrix due to nucleating effect of PET dispersed spheres.
Semicrystalline thermoplastics generally have a smaller processing range for thermoforming compared to amorphous thermoplastics, due to their narrow temperature window for the transition from viscoelastic to viscous material behavior. Otherwise they offer superior properties for applications like ductility or chemical resistance. Previous research showed that cross linking of semicrystalline thermoplastics by high energy irradiation holds the potential to significantly improve their thermoformability. Within this article the effects of different degrees of cross linking and their interaction with processing conditions during thermoforming shall be discussed.
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.
The present investigation describes a facile and rapid approach of production of conductive nano-composites, and assessment of the opportunity for using them as electro-mechanical sensors. The new synthesis procedure includes an in-situ inverse emulsion polymerization method of aniline in the presence of CNT and dissolved thermoplastic elastomer, followed by a precipitation-filtration step. Incorporation of CNT/PANI in the SIS elastomeric matrix improves the thermal, mechanical and electrical properties of the nano-composites. Formation of the continuous three-dimensional CNT/PANI network, is responsible for enhancement of the resulting nano-composite properties, such as the relatively high electrical conductivity levels. The described novel approach provides an opportunity for developing tunable structures of remarkably distinctive architecture. The rapid electrical resistance response to the applied strain makes the developed nano-composites useful as sensitive strain sensors.
Carbon nanotubes (CNT) have drawn much attention in recent years. CNT have remarkable properties i.e. mechanical properties, electrical and thermal conductivity, thus offering opportunities for development of new nanocomposites. An homogeneous dispersion of nanoparticles in polymers using conventional processing techniques is difficult to produce since nanoparticles tend to agglomerate, thus efficient methods for agglomerate breakdown have been sought in recent years. The combination of CNT with intrinsically conductive polymers may lead to new and improved properties of the resulting materials. This work describes an in-situ inverse emulsion polymerization method of aniline in the presence of multiwalled carbon nanotubes (MWNT) in organic solvents using ultrasonication. PANI dispersion, as a reference, and the PANI/MWNT dispersions were stable for long periods of time without visible precipitation. Highresolution scanning electron microscopy (HRSEM) has shown that MWNT are coated with PANI, leading to a remarkably improved dispersability of the nanotubes, thus PANI coating reduces the tendency of MWNT to reagglomerate. The neat MWNT have a diameter of ~10nm, while the core-shell MWNT/PANI nanofibers exhibit a diameter of ~40nm. The dispersions obtained may have important potential applications in the fields of sensors, acoustic actuators, semi-conductors, solar cells and more. CNT containing materials suitable for the manufacture of thin, transparent, electrically conductive films have poor mechanical properties and are expensive. Our work on hybrid conducting nanocomposites has led to a remarkable combination of high conductivity and transparency along with low haze and good mechanical properties, aiming at competing with the existing ceramic materials, such as Indium Tin Oxide, (ITO).
This research presents a new fabrication method for tailoring polymer/carbon nanotubes (CNTs) nanostructures with controlled architecture and composition. The CNTs are finely dispersed in a polyacrylate latex, via ultrasonication, followed by a microfiltration process. This step allows preserving the uniform dispersion structure in the resulting solid nanocomposite. This original fabrication method is applied for supercapacitorc, biocatlytic membrane and low reflecting coatings. The combination of microfiltration and proper choice of the polymer latex allows the design of complex nanostructures with tunable properties e.g., porosity, mechanical properties. An important attribute of this methodology is the ability to tailor any desired composition of polymer-CNTs systems, i.e., nanotubes content can practically vary anywhere between 0 to 100 wt%. Thus, for the first time a given polymer/CNTs system is studied over the entire CNTs composition, resembling immiscible binary polymer blends. The polymer in these systems exhibits a structural transition from a continuous matrix (nanocomposite) to segregated domains dispersed within a porous CNTs network. An analogy of this structural transition to phase inversion phenomena in immiscible polymer blends is suggested.
Blends of polyaryletherketones (PAEK), such as polyetheretherketones (PEEK) and polyetherketone-ketones (PEKK), with polybenzimidazole (PBI) are of commercial interest due to their improved high-temperature stability and wear properties. Regarding the PBI component, the origins of the properties that are generally thought to be disadvantageous in thermally or chemically aggressive environments are not well understood. The same accounts for the specifics of the interactions between the PBI and PAEK components in melt or dry blend systems. In this presentation, we focus on the molecular changes of PEEK-PBI and PEKK-PBI blends and their pure components after treating them with liquid water and steam at elevated temperatures and pressures. The pure polymer components and the PAEK-PBI (50:50 wt%) blends are steam-treated at 150 °C (302 °F) and 315 °C (599 °F), also with deuterated water (D2O). The overall goal is to understand the chemical changes on the molecular scale that might take place upon high-temperature steam-treatment and to examine the extent and reversibility of moisture uptake. Changes of the materials, as well as interactions and reactions of the water with the functional groups of the polymer components have been studied by 15N and 13C CP/MAS, 2H MAS, and 1H wideline NMR spectroscopy, in combination with using deuterated water.
This paper investigates the effect of different cellulose fiber grades on the rheological properties and the foaming behavior of a linear polypropylene copolymer. Three cellulose fiber grades with different fiber lengths were used in this study. The average length of the fiber grades were 300 ?m, 500 ?m and 700 ?m. The preparation of the compounds were carried out on a co-rotating twin screw extruder and the foaming experiments were executed with a grooved feeded 45 mm single screw extruder. For the foaming experiments supercritical CO2 was used as blowing agent. All compounds were characterized with a cone plate rheometer to compare the influence of the fiber length and the amount on the rheological properties. The different formulations were compared, due to their effect on the maximum cell density, in terms of cell size and the foam density. It was shown that the effect on the materials viscosity increases with increasing fiber length. The foam morphology was not affected by the fiber length. However the volume expansion ratio depends on the fiber length.
Because of the exceptionally high modulus of multiwall carbon nanotubes (MWCNT), they can be used as reinforcing fillers in polymer and rubber nanocomposites. However, the commercial implementation of such nanocomposites has generally been met with very limited success owing to poor dispersion of the MWCNT in the polymer matrix. A strategy that overcomes many of these difficulties is described here with a view towards replacing a portion of the carbon black or silica with MWCNT for improved elastomer performance. Tire treads are very prone to experience micro-cracking at the edges, which eventually leads to overall failure. MWCNT can serve as good bridging elements to avoid the growth of micro-cracks if they are well dispersed and discreet in the rubber matrix. A concentrated, easy to process MWCNT-rubber masterbatch, with the freedom of diluting to various lower loadings, and feasibility of blending with different rubbers, would be of commercial benefit to the tire industry. Discreet oxidized MWCNTs were dispersed in an SBR matrix and the rheology, tube dispersion, dynamical mechanical, and electrical properties of these composites were examined. Morphology and mechanical properties of the cured nanocomposites were investigated and related to the effective aspect ratio of MWCNTs.
The accumulation of thermal energy in polymeric materials can pose a serious threat to service life as well as appearance of a finished product. The types and levels of pigments used in the fabrication of polymeric goods can have a profound effect on the impacts of thermal energy accumulation. In this paper we will provide a primer on the physics behind the effects of the terrestrial components of solar radiation and the ways in which different materials behave under typical terrestrial conditions.
Quinacridone chemistry provides impressive high performance organic pigments for diverse applications and industries. These heterocyclic compounds achieve color range abilities through auxochromic substitutions such as methyl and chlorine groups, as well as polymorphism. Solid solutions of mixed quinacridone molecules further the already expansive coloring options. Chemical fortitude of lightfastness, bleed and heat resistance can generally be attributed to molecular lattice interactions and surface chemistry. With bright tones and good tinting values, quinacridone pigments permit coloration with high performance characteristics. This paper provides an overview of quinacridone pigments from molecular identification to color point position as well as typical polymer suitability and performance.
The ability to achieve enhanced mechanical properties through in-plane orientation of platelet-like nanofillers is a challenge for nanocomposite fabrication and performance. Here we use forced assembly to orient graphene nanoplatelets in PMMA/PMMA-graphene films produced through multilayer coextrusion. Electron microscopy confirms the alternating layer structure of PMMA and PMMA containing oriented graphene. Relative reinforcement of 11 % at a concentration of 0.2 wt % graphene in the total film was achieved without loss of toughness. The reinforcement is attributed to the planar orientation and improved dispersion of the graphene as the layer thickness decreases.
Antifog (AF) agents are chemicals that prevent the condensation of water as small droplets on hydrophobic surfaces which resemble fog. Antifogs function by minimizing the water surface energy, thus resulting in a continuous film of water rather than single droplets. Inside a greenhouse, the temperature and humidity are usually higher than the outside temperature and fog will thus appear on the inner surface of the PE film. In the present work, a new method of controlled migration of AF is described, by grafting AF molecules to the surface of sub-micron inorganic particles. Glycerides and fatty acids are used as AF. During the grafting reaction two fractions are formed: attached AF fraction to the inorganic particles’ surface, a fraction which cannot be detached by extraction, and an unreacted, thus unattached AF fraction. Aging tests, developed in the present work, have shown a significant decrease of the AF migration rate.
For over one hundred years, components made of elastomers have been commonly used in practice. However, the knowledge concerning the aging behavior of the material lags behind the existing demands of modern day industries. The property spectrum of elastomeric components extends across a broad range. Areas of application for such materials include aerospace, automotive, and mechanical engineering, plant construction, shipbuilding and civil engineering sectors. When considering the moldability, workability, flexibility and adhesion of elastomers, it is unsurprising that these materials are employed in so many industries. Yet, despite their application in numerous fields, only limited amounts of research has been carried out concerning these materials, and hardly exceeds basic examinations. Hence, intensive studies are necessary in this area. Previous research has already verified that the mechanical properties of elastomers change over time. These scientific findings make intensified research regarding the long-term behavior of elastomers indispensable. Chemical aging studies are highly significant, because the molecular structure and the networking of the material change during the aging process. Due to these changes, various material properties may also alter. In order to be able to make more accurate predictions concerning the life span and durability of elastomeric components, all environmental influences must be intensively researched experimentally. Basic research in the field of chemical aging is essential. In this paper, the aging behavior of natural rubber was tested using the media air, distilled water, and 3%- and 6% de-icing salt solutions.
The effects of the use of a surfactant for the dispersion of the nanoparticles in a nano-clay/PET composite have been evaluated. An increase in the amount of surfactant improved the dispersion of the particles and consequently led to an enhancement of the mechanical properties of the nanocomposite. The composites were melt-blended using co-rotating intermeshing twin screw extrusion technology and although there was degradation of the surfactant during processing, it did not affect the dispersion of the nano particles in the PET. A range of techniques used to characterise these materials will be discussed, including morphology, differential scanning calorimetry, (DSC), Scanning electron microscopy (SEM), including experimental techniques like mechanical property evaluations.
Coconut shell and torrefied wood are bio-sourced and renewable materials that can be used as fillers in various polymer matrices. Torrefied wood material can be produced from numerous cellulose based materials, such as wood, sunflower hulls, flax shive, hemp and oat hulls. These bio-fillers would replace talc and glass bubbles which are not a renewable resource. Additionally, the implementation of torrefied wood and coconut would reduce the carbon footprint and improve sustainability of Hyundai and Kia vehicles. In this study, coconut and torrefied wood filled polypropylene properties are tested for a HVAC Case application.
Interest in alternatives to electroplated chrome is expanding dramatically. Color and appearance affects are limited with traditional chrome electroplating and successful “paint-on-chrome” applications are expensive and highly proprietary. Collectively the automotive, home appliance and cosmetic market are actively searching for alternatives with the appearance and durability of electroplating, but without the environmental side effects, appearance and functional design limitations, and costs associated with this decades old process. “Chrome look” processes and coatings for decorative and automotive lighting PVD applications have been used in the UV curable coating industry for over twenty years. As development of UV curable coatings for PVD has progressed, so has the understanding of the process and its unique capabilities and applications. This paper will address the advantages of PVD as a chrome alternative to include functional / design capabilities that are either cost prohibitive, or impossible to achieve with electroplated applications, as well as describe some of the tradeoffs associated when using coatings systems as an alternative for chrome electroplating.
The purpose of this work was to perform a comparative analysis of various candidate nitrile coated fabric materials supplied by potential vendors to be used as fuel storage tanks and compare the results to the currently fielded polyurethane storage tanks. Our results demonstrate that the nitrile coated fabrics performed well in our evaluation. Their breaking strengths are about equal to the currently fielded urethanes and they performed much better as barrier materials after ageing.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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