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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Analysis of Thermal Conductivity of Thermoplastic Hybrid Yarn Textiles Using the Hot Disc-Method Under Process Requirements
Within the research activities in the Collaborative Research Centre 639 (SFB 639) the processing of fiber reinforced thermoplastics is examined and novel thermoplastic hybrid yarn textiles are considered. Since hybrid yarns are non-rigid, the application of these materials causes different challenges concerning their handling during the whole process chain. Thereby, the thermal conductivity plays a significant role for the consolidation process of textile-thermoplastic composites. Dependent on process parameters as applied pressures and temperatures of the analyzed material different thermal conductivities are expected. This paper presents research on the influence of process parameters on the thermal conductivity of analyzed fiber reinforced materials using the hot disc-method.
Molecular Structure and Thermal Properties of Recycled and Virgin Nylong and Their glass Fiber Reinforced Composites
The effects of molecular weight and molecular structure on non-isothermal crystallization behavior of recycled and virgin nylon and their composites with glass fiber (GF) were studied. Two different recycled nylon resins,namely post-industrial waste (PIW) and post-consumer waste (PCW) were used. The former was obtained from a fiber manufacturer and the latter was recycled from used carpets. Intrinsic viscosity (IV) measurements and 13carbon nuclear magnetic resonance (13C-NMR) were used to characterize the molecular weight and the structure of the resins. Non-isothermal crystallization of the resins was studied using differential scanning calorimetry (DSC). The molecular weights of recycled materials (without glass fiber) were found to be higher than that of virgin PA6, but their crystallization rates (implied by the reciprocal of t1/2) were faster. It is due to their higher cis conformer content and consequently advanced segmental mobility. Recycled materials contain TiO2 which can act as heterogeneous nucleating agent.
Preparation and Biodegradability Study of Polymer Blends of Poly(Lactic Acid) and Poly(R)-3Hydroxybutylate-co-(R)- 3-Hydroxyvalerate)
Polymer blends of poly(lactic acid) (PLA) and poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (PHBV) for biodegrdadable textile application purpose were prepared to improve the flexibility of PLA. using twing screw extruder at 180-190°C. The ratios of PLA:PHBV were varied with 100:0, 90:10, 80:20, 70:30, 60:40, 50:50 and 0:100 by weight. Polyethylene glycol (PEG) having molecular weight of 6000 and 4000 were added to the polymer blends as compatibilizer at 2, 4, 6, 8 and 10 phr. It was found that addition of PEG having molecular weight 4000 g/mol showed better mixing and flexibility. PEG molecular weight 4000 g/mole resulted in higher tensile strength and Young’s Modulus than PEG 6000 g/mole). The biodegradability of PLA/PHBV was analyzed. The crystallization parts in the polymer blends retarded the biodegradation.
3D Simulation of Mucell Microcellular Foam Process in Large Automotive Application
We present a practical study on the large automotive product using a 3D MuCell process CAE tool. Comparisons between conventional injection molding process and MuCell microcellular foam process were done for injection sprue pressure, clamping force, and weight reduction; also, the product warpage were analyzed for two different processes from simulation results. Microcellular cell size distribution and cell density distribution of an automotive instrument panel model were calculated from MuCell process simulation with 30 wt % glass fiber polypropylene and nitrogen super critical fluid, which can provide good reference of determining mechanical properties.
Listening to Your Mold Using Advanced Mold Monitoring Technology
Increasingly mold builders are being asked by their customers if they warranty their work. Traditionally most avoid the question, some answer to it, but very few actually embrace the question. Those that do embrace the topic recognize it as an opportunity to partner with their customer on a common interest: Eliminating unscheduled mold stoppages and downtime. If the mold builder can assist in this, it will differentiate them from others. New tools have been developed in order to enable a mold builder to assist with decreasing mold downtime. A monitor mounted on the mold can be initialized by the mold builder and data can be stored to the monitor device. Among the information to be stored can be the number of cycles that the initial PM should be performed, along with the subsequent intervals for PM's. Also, stored to the device can be maintenance instructions and mold disassembly/assembly drawings. Then, when the molder receives the tool and runs it, the monitor device can be connected to a PC when the mold enters the molder's tool room for service. Once connected, the device sends to the mold builder data on how many cycles have been run and what PM activities have been performed. The mold builder can review this information, and offer any suggestions to the molder in order to avoid any breakdown. In this scenario, the mold builder warrantees the materials and accuracy of the tool, and can monitor that PM's are taking place in order for the performance expectations of the mold to be met.
Effect of Clay Incorporation on the Broadband Dielectric Properties of MWCNT/Polyvinylidene Fluoride Nanocomposites
This study reports on the effect of clay addition on the broadband dielectric properties of multi-walled carbon nanotube/Polyvinylidene Fluoride (MWCNT/PVDF) composites, i.e., 101 – 106 Hz. The three-phase PVDF/MWCNT/Clay composites with different loadings of MWCNT and clay were prepared employing melt mixing method. Characterization techniques, such as X-Ray diffraction and transmission electron microscopy were employed to examine the crystalline structure and morphology of composites, respectively. The dielectric spectroscopy showed that introducing clay into the MWCNT/PVDF composites at the critical MWCNT concentration improved dielectric properties tremendously. For instance, incorporating 1.0 wt% clay into the PVDF/MWCNT composite at the critical MWCNT loading, i.e., 0.5 wt% MWCNT, increased dielectric permittivity significantly (670% at 100 Hz). Furthermore, it was observed that the addition of clay reduced the dissipation factor considerably (68% at 100 Hz).
Fracture Behavior and Mechanical Property of Jute-Glass Hybrid Composite
Jute fiber has gained extensive use in recent years due to its advantage in environmental protection, low cost and low density. However, the limitation of its low mechanical property affects its application. Because of this reason, jute-glass hybrid fiber configuration was considered as an improvement. In this study, 2 kinds of jute-glass hybrid fiber configuration were employed to investigate the mechanical property and fracture behavior in different configuration. At the same time, different plies and different angle of the composite were analyzed. It was found the composite fabricated by B type fabric expressed better properties both on tensile and bending test. Scanning electron microscope observation was also found excellent matching between jute fiber and glass fiber in B type composite.
Low Percolation Threshold and Improved Electromagnetic Interference Shielding Effectiveness of Polypropylene/Carbon Fiber Composites Through Foaming
Injection molding of solid and foamed polypropylene/carbon fiber (PP-CF) composites with different carbon fiber contents (0-20 wt. %) was conducted. ~ 25% void fraction in the foamed composites was achieved using supercritical N2 as the environmentally benign physical blowing agent. The effects of foaming on the percolation threshold, through-plane electrical conductivity, permittivity and electromagnetic interference shielding effectiveness (EMI SE) were investigated. Compared to the solid composites, in addition to the reduced weight of the polymer matrix (25%), introduction of foaming lowered the electrical percolation threshold from 17 wt. % to 11 wt. %. The relationship between the structure and electrical properties was explained in terms of the changes in the fiber orientation and skin layer thickness. At 15 wt. % CF content, the foamed composites yielded an EMI SE of about 25 dB, significantly higher than that of the solid composite (13 dB) with the same CF content. In both solid and foamed composites, the dominant EM attenuation mechanism was found to be wave absorption not reflection. The results reveal the application of injection foam molding technology to manufacture lightweight conductive products with lower fiber content and enhanced EMI SE.
Thermal ageing performance of novel Ultrol® Nuclear 60 year Cables.
Wire and Cable manufacturers generally qualify products for class 1E application by envelope type testing to user specifications and environmental conditions recommended by IEEE standards 323- 1974 and 383-1974. Early cable qualification required only radiation in 1960s. 1960s and early 1970s added thermal aging to ICEA requirement. However the ageing requirement was very minimal (1 week @ 121°C). The long term ageing requirement was not as nearly stringent as present until IEEE 383- 1974 was added to standards. To determine the ability of samples to withstand normal operation, IEEE 383- 1974 introduced ageing samples to “End of Life” condition. Samples were heat aged to a timetemperature condition in excess of 40 years of service life. Federal law and regulation recently allowed electric companies to renew their nuclear plants’ operating licenses for 20 years beyond their original, 40-year license term, which in turn triggered IEEE standard 383-2003 to govern minimum requirements to meet 60 years. General Cable Corporation, GCC simply in this paper, recently completed qualification programs. The major milestones in the development included (a) product life improvement of our established products, Ultol® products, from 40 yrs to 60 yrs. (b) introduction of Ultrol® medium voltage power cable with 60 year life. Cable constructions tested were 600V instrumentation cables, 600V power cables, 600V control cables, 2000V power cables and 15kV Power cables. This paper presents Arrhenius thermal aging data collected for materials used in the qualification programs using IEEE 101-1987 as basis confirms that a 90°C conductor temperature has a life in excess of 60 years.
Fracture Toughness Of A Medical Grade Ultra High Molecular Weight Polyethylene Using A Single Specimen Method
Ultra-high-molecular-weight polyethylene (UHMWPE) has been extensively used in total knee arthroplasty because of its superior physical and mechanical properties. Fracture toughness and fatigue crack growth of UHMWPE has been widely accepted as critical to the structural performance of orthopedic implant bearings. Literature search revealed that the most commonly used techniques to determine the fracture toughness of UHMWPE material are the multi-specimen and single specimen normalization method. In this paper, a novel single specimen method was used to determine the resistance to fracture of GUR 1050 material during a stable crack extension. The crack length extension was obtained using digital microscopy and photogrammetric methods. The test results obtained were compared to the other multi-specimen method data published in the literature.
Feedback Control and Disturbance Rejection in Polymer Extrusion
Feedback control is important for commercial manufacturers of polymer compounds, especially in the extrusion process. The inability to respond to disturbances in the extrusion process results in production of off-specification product and down-time. Due to the complexity of the system, it is difficult to accurately model an extrusion process. The technique of active disturbance rejection control (ADRC) requires a small amount of knowledge of a system, and is effective over the traditional proportional integral derivative (PID) controller. ADRC is currently in use in programmable logic control code on multiple production lines of polymer hose extruders for barrel zones temperature control.
Broadening of the foam processing window of polypropylene in extrusion foaming via the incorporation of CO2-philic nanofibers.
Tensile stress growth during extensional flow is enhanced in linear polypropylene (PP) via the incorporation of chemically modified polytetrafluoroethylene (PTFE) nanofibers which demonstrates strong affinity for carbon dioxide (CO2). Foam extrusion of the PP nanocomposite using CO2 as the blowing agent reveals a three orders of magnitude increase in cell density, a ten-fold increase in expansion ratio, and a marked broadening of the foaming window with respect to when no nanofibers were added. The improvement in foaming ability is attributed to the increase in strain-induced hardening and the ability of the nanofibers to act as a reservoir of the blowing agent and facilitate the foaming process.
Solid-State Batch Processing and Structure of Nano-cellular Thermoplastic Polyurethane foams
Two step solid-state batch foaming of TPU/Clay nano-composite as well as melt processed neat TPU was conducted by using CO2 as the physical blowing agent. Nanoclay was dispersed into the TPU by using a twin screw extruder in order to promote cell nucleation. The samples were saturated under CO2 pressures of 30 MPa at room temperature. Subsequently, the solid state foaming step was carried out by immersing the saturated samples in a silicone oil bath at different temperatures around the first thermal transition of the considered nanocomposites assigned by differential scanning calorimetry. A scanning electron microscopy was used to examine the structure of the foams. Depending on the combination of processing parameters, a wide range of cellular structures was achieved. The cell size ranged between 10 ?m and 400 nm and the cell density was between 109 to 1013 cells/cm3. An optimum foaming time and temperature were found wherein the smallest cell size with highest cell density could be produced. This CO2-TPU/Nanoclay system provides a unique frame in which the bulk properties of nano-cellular and microcellular structures can be compared.
Structure-Property Relationships in a New Family of Bio-Based, Compostable Blown Films
This paper is concerned with the influence of processing conditions on microstructure development and performance of a new family of biobased and compostable blown film products based on Mirel? PHB copolymers (product referred to as B5009). The unique combination of performance attributes of B5009 blown films including biobased carbon content and compostability, along with an excellent balance of tear propagation resistance, puncture toughness and tensile strength will be highlighted. The potential applications of the subject film, that has similar to superior mechanical properties compared to LLDPE, will be reviewed. The synergistic advantages that can be garnered with multi-layer film structures (through coextrusion with other polymers) will also be discussed.
Electrical Properties of Polypropylene Composite Foams Reinforces with Long Stainless Steel Fibers
Conductive thermoplastic composite foams are a novel class of materials that can be an excellent candidate for producing cost-effective and lightweight products. In this work, electrically conductive polypropylene (PP) foams of various densities filled with varying contents of long stainless steel fibers (SSF) were successfully fabricated. The foaming of composites was achieved using a batch process and supercritical CO2 as the environmentally benign physical blowing agent. The PP-SSF foams maintained high level of electrical conductivity over a wide range of density reduction, depending on the initial loading of SSF. To better understand the conductivity behavior of solid and foamed composites, statistical percolation analysis was conducted. The analysis showed that the conductivity change with the foam density followed the percolation power law. The critical SSF concentration, calculated based on the sample’s final volume was 0.37 and 0.28 vol.% for the solid and foamed composites, respectively. In the current PP-SSF system, foaming decreased the weight up to ~70-80 % and lowered the percolation threshold by about 25%.
Determination of Specific Aluminum Flake Characteristics in Injection Molded Plastic through Colour and Effect Measurement
An attractive alternative to painting plastic parts with formulations that include metallic pigment has become the inclusion of metallic flake directly in the resin. One of the challenges associated with including metallic flake directly in the resin is that current molding technology limits our ability to control flake distribution during the manufacturing process and achieve a uniform appearance. For many end use applications including automotive interiors, a low-quality appearance is not acceptable; thus, the economic benefits of this method have historically remained out of reach. As a first step towards achieving a uniform finish in an injection-molded part with embedded flake, a method must be established to evaluate the uniformity of colour and flake effect in the end product. Recent developments in colour and effect measurement technology now allow for quantitative characterization of both metallic colour and flake effect. With this method in place, it is possible to begin optimizing all those parameters that affect flake distribution and quantify the customer’s visual impression. This paper describes this measurement method and demonstrates the method’s ability to discriminate between different effect pigments.
High Throughput Methodology for Mechanical Testing of Polymeric Films
Assessment of mechanical properties of thin polymer films under high speed impact is often nontrivial. Standard dart drop tests are not suitable for thin samples, nor does it provide information on stress- strain relationship under load. Other techniques such as tensile/flex and nanoidentation testing can only be performed at relatively low strain rates. A High Throughput Methodology for Mechanical Testing (HTMECH) of freestanding thin films under high speed loading is used in this work. The main advantages of this technique are the high instrumental sensitivity, ability of rapid screening, and simplicity of data analysis. Toughness properties of thin films were measured by HTMECH and compared with dynamic mechanical analysis (DMA) data. The correlation between the two techniques has been established and discussed.
The Effect of Hydroxyl-functionalization on the Structure and Properties of Polypropylene
Hydroxyl-modified polypropylenes (PPOH) with side chains containing OH groups were synthesized by the copolymerization of propylene with undecenyl-oxytrimethylsilane monomer. Copolymers with OH concentration ranging from 1.3 to 3.9 mol% were produced and their properties compared with unmodified polypropylene. The presence of intermolecular H-bonding between the OH groups affected the base polypropylene structure as well as its thermal and rheological properties. As predicted by Flory’s theory of melting point depression in copolymers, the melting point reduced with increasing [OH]. While the crystal structure remained unaffected, the crystal size reduced by approximately 15%. Crystallinity for PPOH polymers was also reduced by as much as 40% because of the hindrance to the ordered packing of backbone chains into the lamellar structure. On the other hand, the rheological properties such as the melt strength and the elasticity increased for the PPOH polymers. PPOH with only 3.9 mol% OH groups displayed a gel-like rheological behavior suggesting the formation of a weak elastic network in the melt.
Slow Crack Growth in High-Density Polyethylene Part 1: Experimental Observations
This paper aims to simulate slow crack growth in high-density polyethylene by using Crack Layer Model. We first derived the analytical approximations of stress intensity factor and crack opening displacement for finite geometries using close form solution of a semi-infinite crack and the numerical solutions for corresponding geometries. We then use the approximate solutions to assess the size of the process zone accompanying the crack, slow crack growth rate and mechanisms as well as the lifetime in brittle fracture of high-density polyethylene.
Virtual Prototyping in Rubber Seal Manufacturing and Testing
This case study highlights the entire design and testing process, virtual prototyping, of an extruded automotive aluminum reinforced rubber seal. First, the expected deformation of two similar shapes of the rubber seal will be analyzed. The design that will provide the required deformation, contact pressure, and reaction force, and hence better sealing performance, will be chosen for production. Two rubber material models are considered for the non-linear plain stress analysis, one being rate dependant (more realistic) and one is rate independent. The difference in behavior of the seal due to the material model used is highlighted. Then, to obtain the required extrusion die profile that will be used to manufacture that seal shape, the process of inverse die design will be implemented. In this procedure, the final seal cross section is used to obtain what the required die lip shape should be so that after die swell the final profile is obtained. Finally, to verify the entire die performance, detailed flow analysis is carried on the entire extrusion die and the flow balance is verified.
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