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.
The challenges materials processing and compounding face nowadays are related not only with the design and control of better and more efficient machines but, essentially, with the manipulation of the molecular structure of the materials, with a view to obtaining innovative high performing products. Extruders are a fundamental part of any extrusion process and intermeshing co-rotating twin-screw extruders, in particular, have special application niches, being the equipment of choice for blending and compounding operations, mainly because of their good distributive and dispersive mixing capabilities. In fact, they are used in most important modern polymer applications such as compounding of filled polymer systems and masterbatches, polymer melt homogenization, polymer modification and the polymer blending. Very often, the last two operations involve, apart from polymer processing, chemical reactions, classical examples of which are the peroxide induced degradation of polypropylene to prepare grades with controlled rheology, and the grafting of maleic anhydride onto polyolefins to improve their compatibility with other polymers. Although these are widespread value-added processes in the polymer industry, there is often a gap in the fundamental knowledge of the properties and physical and chemical composition of the materials being processed during the extrusion process because the extruders are “black boxes” in which the properties of the initial materials, as well as those of the final product, are known, but not the kinetics of the transformation process. This poses severe limitations to current operations because without this knowledge any optimization effort of material structure and/or properties is done by trial- and-error and, thus, is very time consuming and offers no guarantees that the final product is, in fact, optimal. In this work, we present a review of recent developments in on-line sensors that allow for the monitoring of the rheological, chemical and s
Hydrolytic degradation of two renewable copolymers, poly(trimethylene malonate) (PTM) and poly(trimethylene itaconate) (PTI), was performed in aqueous solutions adjusted to pH values ranging approximately from 5.5 to 11. The influence of the degradation on the elastic modulus of these bioplastics was examined by a new atomic force microscopy (AFM) mode. Elastic modulus was monitored as a function of degradation time (100 to 10000 min) in DI water to determine changes. After degradation for one week the elastic modulus of PTI has decreased by 71 %. PTM was found to be hygroscopic. Due to significant swelling and uneven surfaces—in both the dry and wet state—PTM samples could neither be easily imaged nor its nanomechanical properties evaluated by AFM.
Polyvinyl alcohol (PVOH) was mixed with a nanofibrillated cellulose (NFC) fiber suspension in water followed by casting. The transmission electron scanning (TEM) images revealed that the NFC fibers dispersed well in PVOH. The presence of NFC significantly increased the tensile modulus of the nanocomposites nearly threefold and could serve as a nucleating agent, promoting the early onset of crystallization. However, at a higher NFC content, it led to greater thermal degradation of the PVOH matrix.
Lifetime prediction of plastics is a very difficult proposition, but one that is becoming increasingly important as plastics are used in more demanding and critical applications. The lifetime of a plastic part is influenced greatly by many factors including the type of plastic, stress level, temperature, type of loading, and environmental conditions. All these factors make absolute lifetime prediction a nearly impossible task. However, by understanding how these factors influence plastics over time, one can begin to make educated predictions with some level of accuracy. This paper will discuss techniques that can be used to predict the lifetime of a part. A case study is given on how lifetime prediction was used to understand and ultimately solve the cracking of an industrial fan made of glass reinforced polypropylene
Thermoplastic foams characteristically are good thermal insulators. In contrast, this paper compares two new fabrication techniques to align Graphene NanoPlatelets (GNPs) in Linear Low Density PolyEthylene (LLDPE). These new composites with aligned graphene due to foams possess effective thermal conductivity (keƒƒ) that was up to 13-fold over that of neat LLDPE. SEM micrographs revealed 1-D and 3-D alignment of GNPs by dry-blending and compounding fabrication methods.
Nanostructures have been a topic of great scientific interest for the past several decades for the possibility of their use in enhanced composites. However, the precautions for the safe use of these low bulk density materials are commonly overlooked. The airborne release of these materials, such as carbon nanotubes (CNTs), carbon nanofibers (CNFs) and nanoclays, into the air during compounding is inevitable. In conventional polymer processing these fillers pose a potential threat until they are encapsulated in a polymer matrix. This occurs while transporting or feeding nanostructures into the process. Typically, the operator uses a respirator to avoid inhaling nanostructures into the body that escape engineering controls and it is therefore important to investigate how efficient these respirators are at capturing these airborne materials. To carry out this study, a special device was built to simulate the dynamic breathing process of air inhalation to determine the permeation of nanostructures through various respirators of different safety ratings. This will provide new information concerning the environmental impact of nanostructures in the prevention of exposure to human beings of airborne nanostructures.
Twin screw extrusion technology originated in the early 20th century and it revolutionized material compounding. The technology is used in the polymer, chemical, food, and recently in the pharmaceutical industries. Considering the numerous materials twin screw extrusion can operate with, it is evident that each process behaves uniquely. The problems that occur during these unique processes can be solved or prevented using similar guidelines and strategies. The following paper provides a strategy on successfully troubleshooting the co-rotating twin screw extruder and it offers possible solutions to several problematic scenarios that frequently are experienced.
This paper presents a new process for producing microcellular injection molded plastic parts using water as the physical blowing agent and micro-scaled particles as the cell nucleating agents. Distilled water with dissolved salt were fed through the hopper of an injection molding machine and mixed with polycarbonate (PC) in the machine barrel. Dog-bone bars were molded with different shot volumes, water/salt solution feed rates, and salt concentrations. The resulting surface roughness and microstructure were compared with conventional solid and microcellular injection molded parts.
Polymer nanocomposites have been studied extensively and can provide many benefits, including enhanced mechanical, barrier and fire properties. This paper studies the effect of montmorillonite nanoclay in a primarily amorphous cycloaliphatic terephthalate co-polyester system. The measured tensile properties show increased stiffness coupled with retention of ductility (elongation at break) at low nanoclay loadings, contrary to expected trends. The morphology of these materials was analyzed in an attempt to understand the unusual effects of the nanoclay in this case.
Amongst the performance additives for property enhancement and improved processing for polyolefins, scratch resistant additives, especially for the automotive interiors have become very attractive. Increased amounts of polyolefins are being used in different components in cars, and while the general performance is good, there are ever more stringent requirements that need to be met. This paper is going to present testing data of a commercially available silicone-based pellet, GENIOPLAST® Pellet S in comparison to reference samples, as well as other silicone and organic materials currently used in these applications.
The environmental stress cracking (ESC) behavior of injection molded polycarbonate (PC) plates in carbon tetrachloride (CCL4) was investigated. Molecular orientation was determined by birefringence measurement, which was used to study the effect of microstructure on crack development. It has been found that crack occurred in the edge surface of the molded PC plates after immersed in CCL4. The crack formation and location was correlated with molecular orientation and residual stresses of the parts. The effects of processing conditions on ESC behavior of molded PC parts were also elucidated in terms of microstructural analyses.
New polycarbonate blends afford the first UV stable resins with low color, low smoke and low OSU Heat Release values (< 65/65). In addition, the resins can be prepared with good melt flow and excellent ductility. The excellent colorability and UV stability, combined with the compliance to the FAA/OEMs fire, smoke and toxicity regulations, allows for the fabrication of interior opaque components such as interior aircraft windows frames, seat parts, grilles and personal service units.
Understanding interfacial characteristics between a polymer and its associated tool surface is critical to successful optimization of processes such as injection moulding, embossing and extrusion used to produce polymer parts. One of the factors characterizing the strength of the polymer-tool interaction is the adhesion energy and it is specific for a particular polymer-tool pair. Its magnitude depends upon the tool material, tool coating and surface contamination, where relevant, polymer chemical structure, processing conditions and the surface roughness of the tool substrate. This paper presents the results of an experimental study aimed at determining the effect of selected tool surface characteristics on the work of adhesion, by measuring contact angles of polymer droplets on the surfaces. The experimental set-up, selection of test parameters and main challenges faced to date are described and experimental results presented.
This Paper will review the newest Anti-Yellowing and Weather Resistant WHITE Pearlescent Pigment based on Mica. This NEW AY-W (anti-yellowing and Weather resistant) pigment will be called experiment #1 AY-W , for ease of reference . This New pigment consists of a mica platelet coated with titanium dioxide (TiO2). It is just this TiO2 coating that can contribute to yellowing under certain conditions. Through a revolutionary technology, a new product that has encapsulated the TiO2 surface with an additional coating to make it less reactive. Now your plastic and print applications can maintain a long-lasting silver-white appearance.
In this study, the effect of dissolved CO2 on the thermal behavior of PLA with various D-contents (with and without talc) has been investigated during the cooling process at atmospheric pressure in a regular differential scanning calorimeter (DSC) and a high-pressure DSC. The results show that the crystallinity of PLA samples improves by increasing the CO2 pressure, reducing the D-content, and adding talc. Also, Tg and Tm shift to lower temperatures as the pressure increases, due to the plasticization effect of CO 2.
Antioxidants can increase durability of polyethylene, and clay nanoparticles can improve the mechanical properties of polyethylene. This paper describes models that predict oxygen and antioxidant diffusion and reaction with free radicals in thick polyethylene and its clay nanocomposites. Predicted antioxidant degradation is compared to experimental antioxidant profiles measured by oxidative induction time. To achieve qualitative agreement between model and experimental results, the initial free radical concentration in nanocomposite has to be higher than in polyethylene.
Depolymerization of PET to high molecular weight oligomers could introduce opportunities to re-use PET waste via chemical recycling. Hydrolysis of PET in the presence of water/steam was carried out in a twin screw extruder, at barrel temperatures of 265°C and 300°C with screw speeds of 20, 60 and 200 rpm. The extruded products were characterized to determine intrinsic viscosity (IV) of samples as well as thermal properties (DSC) and rheological behavior. Proton nuclear magnetic resonance (HNMR) analysis was used to estimate carboxyl end group content. The results showed that the average molecular weight (Mw) of extruded polymer was reduced to less than 10,000 g/mol
POM or polyoxymethylene is an engineering resin used primarily for injection molded parts that replace metal. POM’s usefulness is derived from the combination of strength, stiffness, toughness, creep resistance, and lubricity. POM homopolymer and copolymer compete in this market space. Homopolymer grades have some mechanical advantages while copolymer grades have better thermal and chemical stability. In 2010 Ticona introduced a new high strength, high viscosity POM copolymer with the mechanical properties of a typical homopolymer, while maintaining copolymer stability. This paper introduces an improved flow, high strength POM copolymer, its property profile, salient features and potential applications.
A significant barrier to widespread application of nano-engineered devices is the interfacing of small components. Current macro-manufacturing systems do not have the capability for the precise alignment nano-features require. In this paper, a novel method of self-alignment and assembly is discussed. This approach uses kinematic coupling and elastic averaging across multiple length scales to ensure alignment of the smaller features. Physical realization with ion beam etching, deposition, and thermal imprint lithography are also discussed.
Securing the right form of intellectual property protection is sometimes overlooked during the development of a new product. However, intellectual property protection should not be ignored. The right combination of patent and trademark protection can give a company long-term control over its invention. For lifetime protection of product designs, companies should consider using design patents and trademarks together. Design patents can initially be used to exclude others from copying the design. This will provide a company time to develop consumer recognition in the design so that it can continue to be protected as a trademark even after the patent expires.
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Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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