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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Fabrication of TiO2/PU Superhydrophobic Film by Nanoparticle Assisted Cast Micromolding Process
Lotus-like surfaces have attracted great attentions in recent years for their wide applications in water repellency, anti-fog and self-cleaning. This paper introduced a novel process, nanoparticle assisted cast micromolding, to create polymer film with superhydrophobic surface. Briefly, waterborne polyurethane (WPU) sol and nano TiO2/WPU sol were each cast onto the featured surfaces of the PDMS stamps replicated from fresh lotus leaves. After being dried and peeled off from the stamps, PU and TiO2/WPU replica films were created simultaneously. To the former, only high hydrophobic property was observed with static water contact angle (WCA) at 142.5°. While to the later, superhydrophobic property was obtained with WCA more than 150° and slide angle less than 3°. Scanning electron microscopy (SEM) imaging showed that the PU replica film only had the micro-papillas and the TiO2/PU replica film not only had micro papillas but also had a large number of nano structures distributed on and between the micro-papillas. Such nano and micro hierarchical structures were very similar with those on the natural lotus leaf surface, thus was the main reason for causing superhydrophobic property. Although an elastic PDMS stamp from lotus leaf was used in herein process, hard molds may also be used in theory. This study supplied an alternative technique for large scale production of polymeric films.
Temperature and Specific Mechanical Energy Profiles on a Tri-Kneader
A tri-kneader was tested against a traditional reciprocating kneader (ko-kneader) using a proprietary pre-blend of rigid PVC. The specific mechanical energy (SME) consumed was lower on the tri-kneader than in the traditional kneader (36% decrease). It was concluded that temperature control was the dominant factor affecting SME consumption. A second trial was conducted to compare SME consumption on a tri-kneader against a twin screw extruder (TSE) utilizing a proprietary color master batch with special effects. The tri-kneader showed a decrease in discharge temperature (13°C lower) and SME (45% decrease). It was concluded that the reduction in SME was mainly due to a reduction in process length.
Evaluation of Destruction Mechanism on Quasi-Isotropic GFRP
Fiber-reinforced plastic tubes can be used as permanent formwork and external reinforcement for concrete columns. Failure of such columns is often accompanied by audible noise from cracking of concrete and shifting and settling of aggregates, snapping of the inner layers of the jacket, and ultimately fiber fracture. Since the state of the concrete core is not readily visible from the outside, nondestructive evaluation tools such as acoustic emission (AE) can help assess its structural integrity. In this research, we tried to investigate the applicability of AE technique to the quasi-isotropic GFRP materials, and to correlate the AE parameters to the state of stress in concrete. As a result, it was found that the Felicity ratio depends on the internal structure of GFRP. The effect is discussed on the basis of the results of the tensile test, AE measurement, and Felicity analysis.
PLA Thermoplastic Lignin Blends
In this paper, for the first time the PLA/TPL (Thermoplastic Lignin or Plasticized Lignin) blends were developed and investigated. The PLA/TPL blends were prepared by twin-screw extrusion. The lignin and plasticizers were mixed together in the first half of the extruder to complete the plasticization of lignin. Water was removed by devolatilization at mid-extruder and the PLA matrix was mixed with the water- free TPL in the latter portion of the extruder. The PLA/TPL blends comprised 20% and 33% TPL in the PLA matrix. The TPL phase comprised 36% plasticizers in the form of glycerol and sorbitol mixtures. Very fine dispersion of TPL in the PLA matrix was obtained with the particle size less than 1µm based on SEM observation. It was found that the viscosity of the PLA/TPL blends was dramatically increased by adding a small amount of epoxy-based chain extender (CE). The PLA/TPL blends are of great interest for industrial applications such as film-blowing and foaming.
Effect of Molding Conditions on the Weld Line Property of Injection Molded Jute/PP Composites
Jute fiber is of not only low density and good mechanical property but also natural and degradable property. On the other hand, recyclable Polypropylene (PP) was also good choice for environmental friendly material. Injection molding is one of the most important processes to manufacture plastic composites because it is of high quality products with low cost. However, weld lines are unavoidable when two separate melt fronts rejoin during injection molding. The presence of weld lines not only detracts from the surface quality but also significantly reduces the mechanical strength of injection- molded parts. Although it is not always easy to completely eliminate weld lines, the weld line strength could be improved through suitable adjustment of molding conditions such as melt temperature, mold temperature, hold pressure, injection speed, and so on. Therefore, in this paper the weld line property of injection molded jute/PP dumbbell shape specimen was investigated. Pultrusion technique was adopted to fabricate jute/PP long fiber pellets (LFT) and the re-compound pellets of LFT, i.e. RP was made to improve the fiber distribution. Then LFT, RP were used to mold dumbbell shape specimens with or without weld line. In particular, the influence of back pressure and holding pressure on weld line strength of injection molded jute/PP dumbbell shape specimens was discussed based on tensile test and SEM observation.
New method of characterizing the fatigue behavior of thin films for acoustic applications at high frequencies
In the present work a new method to characterize the fatigue behavior of polymer films, which are used as loudspeaker membranes, with thicknesses down do 5 ?m at application relevant frequencies is presented. Furthermore the anisotropic fatigue behavior of different films was studied. Stress controlled Wöhler tests were performed at a frequency of 100 Hz in uniaxial cyclic tension. The failure mode and crack growth kinetics were described via linear elastic fracture mechanics. An extruded film exhibited significant anisotropy with superior fracture toughness in machine direction. By contrast, a solvent cast film showed only neglectable anisotropy in the fatigue-experiments.
Recent Advancements in Transparent Lexan SLX Resins: Weatherability and Phsical Properties
A new family of transparent Lexan* SLX resins, based on resorcinol phthalate, has been developed that dramatically improve the cost/performance balance over existing resorcinol phthalate containing resins. Like polycarbonate, they have an excellent balance of clarity, toughness and good processability. Unlike PC, the ITR containing resins have dramatically improved weatherability as a result of a photogenerated UV absorber (UVA) on the surface of a part. The photo generated UVA has been found to suppress the photo induced degradation of the resin which would lead to the loss in optical properties (color, transmission and haze) and a loss in physical properties.
Thermoplastic Polyurethane/Polylactic Acid Tissue Scaffold fabricated by Twin Screw Extrusion and Microcellular Injection Molding
Polylactic acid (PLA) and thermoplastic polyurethane (TPU) are two kinds of biocompatible and biodegradable polymers that can be used in biomedical applications. They possess rigid and flexible mechanical properties. The TPU/PLA blend tissue scaffolds at different ratios were fabricated via twin screw extrusion and microcellular injection molding techniques (a. k. a. MuCell) for the first time. Multiple test methods were used in this study. Fourier transform infrared spectroscopy (FTIR) verified the presence of the two components in the blends. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) confirmed the immiscibility between TPU and PLA. Scanning electron microscopy (SEM) images affirmed that the PLA was dispersed as spheres or islands inside the TPU matrix, and that the phase morphology further influenced the surface roughness of cells. The blends exhibited a wide range of mechanical properties that cover most human tissue requirements. It was found from DMA and viscosity tests that 25% PLA significantly reinforces the blends at low temperatures or deformation frequencies.
Plastic Composite Material of Bamboo and Bamboo Charcoal
The use of natural fiber reinforced composites has continuously increased during recent years due to their low density, low cost and environmental friendliness. The use of bamboo biomass plastic has been examined by various researchers because bamboo has a regenerative power, and is leading the bamboo reinforced composites as biomass resources. On the other hand, the bamboo charcoal has various functions, then the following effects can be expected: Good adsorption performance, removal effect for harmful gas and moisture adjustment capability. As current study, a preliminary investigation on the mechanical properties and morphologies of polypropylene (PP) reinforced by bamboo powder and bamboo charcoal were carried out. Additionally, the effect of sandwich structure of bamboo powder and bamboo charcoal on the composites has also been carried out.
Effects of Molecular Weight Changes on the Foaming Behavior of Thermoplastic Polyurethane (TPU) and its Acoustic Properties
This paper investigates the effects of molecular weight changes on the foaming behavior of thermoplastic polyurethane (TPU) and its acoustic properties. In order to vary the molecular weight of TPU, the additional melt extrusion processes are introduced and the foam samples are manufactured via injection foam molding technology. The effects of each additional extrusion process on the molecular weight changes are examined by analyzing heatcycle and rheological behaviors. In addition, the cellular morphologies and acoustic properties of injection foam molded samples are evaluated and their relationships with molecular weight changes are discussed. The foaming behaviors are varied significantly due to reduced molecular weights and different foam structures result in different acoustic performances. In general, the foamed samples from the processed TPU resin are able to achieve higher acoustic absorption coefficients.
Long-Wavelength Laser Welding of Clear Plastics Without Absorbers
The newest advancement in laser welding of plastics involves laser welding of non-pigmented plastic components with a wavelength above 1070 nm. Thermoplastics are partially absorbing in a range above 1500. When exposed to infrared energy within this wavelength range, the work pieces are heated through volumetric absorption and a weld can result. In this study, several commonly used thermoplastics, of varying thicknesses, were welded using a 1908 nm diode laser source. All thermoplastics included in the study were successfully welded. The capabilities of this approach were demonstrated with film and plaque samples.
A Device for Simulataneous In Situ Structuring and Measurement of Rheological Properties of Polymer Blends and Composites
A prototype In Situ Structuring Rheometer (ISSR) was developed to study the shear behavior of polymer blends and composites in tandem with forming material components into a variety of fine-scale structural types. The ISSR utilizes a regime of fluid mechanics known as chaotic advection which enables progressive structure development, whereby specific blend morphologies are derived in sequence from in situ structural transitions. The ISSR resembles a conventional parallel plate rheometer and as such can be incorporated into commercial rheometer instruments. The ISSR provides new means to explore interactions between material components at the micro- and nano-scales, validate theoretical rheology models, and characterize melt properties to support manufacturing processes. The ISSR design and results of initial trials are presented.
Sourcing Bioplastics from Plant-Based Wastes: Examples of Progress
Biobased plastic materials have captured much attention recently, but the raw materials for their building-blocks are typically food crops – not an ideal or sustainable approach. However, obscure biochemical processes are being used to transform organic wastes into useful compounds for polymers and plastics. This paper reviews some recent developments in researchers’ efforts toward exploiting wastes as raw materials, especially plantbased food and industrial wastes. The paper will also discuss the practical issues and commercial limitations of “upcycling” these waste materials into biobased plastics.
Thermo-physical and Optical Parameter Estimation for Pyrolysis Modeling of Fiberglass Reinforced Polymer Composites
To explore the potential use of modeling for the development of fiberglass reinforced polymers (FRPs) with good fire characteristics, parameter estimation based on comprehensive pyrolysis modeling of an FRP composite is conducted. Kinetic modeling is performed using data from TGA and DSC experiments. Different kinetic models are proposed and their effect on pyrolysis modeling is evaluated using a screening process that involves simulation of 1D FRP pyrolysis. This procedure shows that changes in simulation results (mass loss rate) are minor when different kinetic models are applied. Following this work, a sub-set of these kinetic models are used in a parameter estimation process to examine their effect on the estimated parameters. The results show that different kinetic models affect the successful completion of the estimation process. When completed successfully the estimation process demonstrates the possibility of applying numerical optimization to estimate model parameters that can be reproduced from independent standard measurements.
Predicting the Long-Term Ductile Failure of PE-100 Grades Based on Short-Term Testing
In this work, a method to predict long-term ductile failure using short-term testing is presented and validated for a high density polyethylene (PE100) pipe grade. Constant strain rate experiments, performed at different temperatures, are used to characterize the plastic flow kinetics. Combined with the hypothesis that failure occurs when a critical amount of plastic strain is surpassed, this enables prediction of the time-to-failure. We demonstrate that this method enables accurate long-term predictions of pressurized pipe certification tests (time-scale 1 year), based on an experimental procedure that takes approximately two weeks.
Super High-Flow Polycarbonate Copolymers: Development and Overview of Physical and Mechanical Properties
A new super high-flow polycarbonate copolymer derived from bisphenol-A (BPA) and specific biosourced monomer derived from castor bean oil is reported. This copolymer belongs to the class of Lexan* HFD resins known for their improved melt flow and ductility balance compared to standard polycarbonate yet with similar high optical clarity and light transmission properties. These super high- flow HFD copolymers are designed to have all attributes of the Lexan*HFD resins such as lower temperature processing capability, longer injection molding flow lengths and improved low temperature ductility versus a standard polycarbonate material but with superior flow characteristics as the name suggests. The superior flow would enable molding of thinner parts with similar practical impact to standard PC
Recent Advancements in Opaque Lexan* SLX Resins: Weatherabillity and Physical Properties
A new family of Lexan* SLX resins, based on resorcinol phthalates, has been developed that expands the cost/performance envelope. These resins have an excellent balance of weatherability, processability and polycarbonate-like physical properties. The unique weatherability of these resins comes as a result of a photogenerated UV absorber (UVA) on the surface of the part. These resins have excellent gloss and colorability and physical properties in addition to good retention of these properties on exposure to UV radiation making them useful in a wide variety of outdoor applications.
Hybrid Joining Technology - A New Method for Joining High Load Thermoplastic-Metal Mixed Components
The extended utilization not only of mixed joints but also of higher-strength steel and aluminum materials in the automotive and in other fields of the sheet processing industry is setting more stringent requirements on joining technology. These are leading to the increased utilization of low-heat joining methods. In many cases, conventional (thermal) welding and brazing processes exert a negative effect on the base material properties (e.g. reduction in strength) and on the joint attributes (such as increases in hardness and hardening cracking). Moreover, the corrosion resistance may be affected by the burning-off of protective coats. In recent years, combinations of plastics, composite materials and mixed-material structures consisting of metal and plastic are being utilized for either lighter or better- value fabrication. These multimaterial structures can no longer be joined with simple classic joining methods such as welding. A process that has been used since many years is the use of metal inserts in injection molds to join thermoplastic-metal composite structures. In spite of that, there is an increasing need for joining methods which are suitable for assembly and series production for the reliable joining of large-area thermoplastic components with metallic components. One approach to solving these joining technology problems on thermoplastic-metal mixed joints is offered by the combination of mechanical joining and hot-melt adhesive bonding which is presented below. These initial results illustrate the potential. In this article, the method is still carried out in two stages. The simultaneous execution in one process step is under development.
Wedge Ring Coupler: A New Approach for Easy Jointing of Large Bore PE Pipes
We have developed a totally new concept of electrofusion jointing method for large bore PE pipes, d1000 mm and above. The new method completely revolts existing practice with respect to easy installation, fast progress and minimal energy consumption. Compared with standard EF fittings in large dimensions the new technique allows a dramatically reduction in processing time, eases installation and does not require additional devices on site. Basic design criterion of the fittings is maximum reliability in processing of the joint under rough site conditions as well as durable operation of the pipe system. The presentation introduces the new concept, shows the advantages of the new method and highlights processing with respect to practical and economical aspects.
Degradation Mechanism of GFRP in Hot Water and Ultrasonic Wave Inspection
This study was proceeded to understand the degradation mechanism of glass fiber reinforced plastic (GFRP) immersed in hot water. The degraded process of GFRP was investigated through the surface and cross section observation, the weight change, and the bending test with acoustic emission (AE) measurement. As a result, the internal defect of GFRP grew up in the following order, debonding, crack, and delamination, with increasing the immersion time. Firstly, the debonding was appeared as split around the single fiber. Secondly, the crack was generated as connecting to each debonding in fiber bundle. Finally, the delamination was appeared by connecting their defects, and opening layers in GFRP, and then, the bending strength was decreased. In addition, the ultrasonic wave inspection was conducted to detect the internal defect of GFRP nondestructively. The ultrasonic wave echo parameter V value was used to estimate the damage of GFRP. As a result, the V value was decreased with increasing the immersion time by extension of the internal defect of GFRP.
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