Showing papers on "Thermoplastic published in 2008"

Comparison of a Custom-made and a Thermoplastic Oral Appliance for the Treatment of Mild Sleep Apnea

Abstract: Rationale: The efficacy of immediate adaptation of mandibular advancement devices made of thermoplastic material as a treatment option for sleep-disordered breathing (SDB) has been demonstrated in clinical studies. To date, there have been no studies comparing the efficacy of such prefabricated devices with custom-made devices.Objectives: Our purpose was to compare the efficacy of both types of devices in patients with SDB.Methods: A randomized controlled cross-over trial, comprising 4 months of treatment with a thermoplastic and a custom-made device, with a 1-month washout interval.Measurements and Main Results: A total of 35 patients (29 males; age, 49 ± 9 yr; apnea–hypopnea index [AHI], 13 ± 11 events/h; body mass index, 28 ± 4 kg/m2) completed the protocol. AHI was only reduced with the custom-made device (P = 0.005). In addition, this device reduced snoring to a greater extent than the thermoplastic device. The success rate was higher with the custom-made device (60 vs. 31%; P = 0.02). One-third of t...

Processing of fibre reinforced thermoplastic composites

Abstract: With the advent of high performance thermoplastic polymers, structural applications for thermoplastic composites are increasing rapidly. Thermoplastic matrix composites possess distinct advantages vis-a-vis thermoset matrix composites in terms of recyclability, high specific strength and specific stiffness, corrosion resistance, enhanced impact toughness, cost effectiveness, and flexibility of design. Since 1990s, the number of material forms and combinations in fibre reinforced thermoplastic polymers has increased exponentially, thereby expanding application avenues in transportation, automotive, mass transit, marine, aerospace, military and construction sectors. In this paper we review the state of the art in processing of fibre reinforced thermoplastics. We start with a brief description of thermoplastic polymers used in structural applications followed by material forms and methods of impregnation of the reinforcement with polymer. Long fibre based processing methods are described next. A desc...

A Novel Strategy to Incorporate Carbon Nanotubes into Thermoplastic Matrices

Abstract: Multiwalled carbon nanotubes (MWNT) are introduced into thermoplastic matrices (polycarbonate and polyamide) by melt blending using polyethylene (PE) based concentrates with high MWNT loadings (24-44 wt.-%). MWNT surfaces were treated with a metallocene-based complex to afford the in-situ polymerization of ethylene directly from the surface. The resulting concentrates showed excellent MWNT pre-dispersion. Due to the high interfacial energy between MWNT and PE, the nanotubes migrate into matrix polymers with lower interfacial energies, like polycarbonate and polyamide, and thereby remain in their excellent dispersion state. Thus, electrical percolation is achieved at lower MWNT contents as compared to direct incorporation. For polycarbonate it is shifted from 0.75 to 0.25 wt.-%.

Thermal Degradation, Mechanical Properties and Morphology of Wheat Straw Flour Filled Recycled Thermoplastic Composites

Abstract: Thermal behaviors of wheat straw flour (WF) filled thermoplastic composites were measured applying the thermogravimetric analysis and differential scanning calorimetry. Morphology and mechanical properties were also studied using scanning electron microscope and universal testing machine, respectively. Presence of WF in thermoplastic matrix reduced the degradation temperature of the composites. One for WF and one for thermoplastics, two main decomposition peaks were observed. Morphological study showed that addition of coupling agent improved the compatibility between WFs and thermoplastic. WFs were embedded into the thermoplastic matrix indicating improved adhesion. However, the bonding was not perfect because some debonding can also be seen on the interface of WFs and thermoplastic matrix. In the case of mechanical properties of WF filled recycled thermoplastic, HDPE and PP based composites provided similar tensile and flexural properties. The addition of coupling agents improved the properties of thermoplastic composites. MAPE coupling agents performed better in HDPE while MAPP coupling agents were superior in PP based composites. The composites produced with the combination of 50-percent mixture of recycled HDPE and PP performed similar with the use of both coupling agents. All produced composites provided flexural properties required by the ASTM standard for polyolefin-based plastic lumber decking boards.

In situ compatibilization of maleated thermoplastic starch/polyester melt-blends by reactive extrusion

Abstract: This article concerns the utilization of maleated thermoplastic starch (MTPS) in the reactive extrusion melt-blending with poly(butylene adipate-co-terephthalate) (PBAT) in blown film applications. First, MTPS was prepared from cornstarch with glycerol (plasticizer) and maleic anhydride (MA; esterification agent). MTPS was then melt-blended with PBAT in a subsequent downstream extrusion operation. The effects of both polyester and MA contents were studied on the physicochemical parameters of melt-blends. For high polyester fractions (>60 wt%), PBAT-g-MTPS graft copolymers were obtained through transesterification reactions. They were promoted by the MA-derived acidic moieties grafted onto the starch backbone as shown by selective Soxhlet extraction experiments and FTIR analyses. At lower polyester content, no significant reaction occurred more likely due to an inversion in the phase morphology between both components. Tensile properties of PBAT-g-MTPS graft copolymer containing 70 wt% polyester were much higher as the TPS/PBAT melt-blend modified with MA. This can be explained by a finer morphology of the dispersed phase in the continuous PBAT matrix, and an increased interfacial area for the grafting reaction as attested by morphological studies. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.

Effects of Extrusion Temperature and Plasticizers on the Physical and Functional Properties of Starch Films

Abstract: Cornstarch, at 20% moisture content (dry basis, d.b.), was mixed with glycerol at 3:1 ratio to form the base material for extruded starch films. Stearic acid, sucrose and urea, at varying concentrations, were tested as secondary plasticizers for the starch-glycerol mixture. The ingredients were extruded at 110 and 120°C barrel temperatures to determine the effects of extrusion temperature, plasticizer type and their concentrations on the film-forming characteristics of starch, as well as their effects on selected physical and functional properties of the films. The physical and mechanical properties of the films were studied by scanning electron microscopy (SEM) and tensile testing, while the glass transition and gelatinization properties were analyzed using differential scanning calorimetry (DSC). The interactions between the functional groups of starch and plasticizers were investigated using Fourier-transform infrared (FTIR) spectroscopy. The water vapor permeability (WVP) properties of starch films were determined using ASTM standard E96-95. Scanning electron micrographs exhibited the presence of native and partially melted starch granules in the extruded films. The tensile stress, strain at break and Young's modulus of starch films ranged from 0.9 to 3.2 MPa, 26.9 to 56.2% and 4.5 to 67.7 MPa, respectively. DSC scans displayed two glass transitions in the temperature ranges of 0.1 to 1°C and 9.6 to 12°C. Multiple melting endotherms, including that of amylose-lipid complexes, were observed in the thermoplastic extrudates. The gelatinization enthalpies of the starch in the extruded films varied from 0 to 1.7 J/g, and were dependent largely on the extrusion temperature and plasticizer content. The shift in the FTIR spectral bands, as well as the appearance of double-peaks, suggested strong hydrogen bonding interactions between the starch and plasticizers. The WVP of starch films ranged from 10.9 to 15.7 g mm h-1 m-2 kPa-1, depending on the extrusion temperature and the type of plasticizer used.

Preliminary Studies on Single Point Incremental Forming for Thermoplastic Materials

Abstract: This paper presents some preliminary investigations on applicability of Single Point Incremental Forming techniques (SPIF) to thermoplastic materials. A 24-1 fractional factorial design of experiments with three replications was performed to investigate the effects of forming parameters on material formability. To study the formability of the thermoplastic sheets, a cone-shaped part with circular generatrix with varying wall angles with respect to depth was considered. The formability of SPIF to the thermoplastic sheets can be defined in terms of the maximum wall angle reached without tearing and/or failure. This angle was measured at position where the mechanical failure of the deformed sheet occurred such as wrinkling, crushing and tearing. It is concluded that the existing knowledge and know-how of sheet metal on SPIF process can be applied to thermoplastic sheets that has potential and preeminent benefits.

Solid-particle erosion behavior of high-performance thermoplastic polymers

Abstract: Solid-particle erosion tests were carried out to study the effect of matrix material, impact angle, and impact velocity on the erosion behavior of seven types of thermoplastic neat polymers (i.e., polyetherimide, polyetheretherketone, polyetherketone, polyphenylene sulfide, polyethersulfone, polysulfone, and ultrahigh molecular weight polyethylene). Steady-state erosion rates of these polymers have been evaluated at different impact angles (15–90°) and impact velocities (25–66 m/s). Silica sand of particle size 200 ± 50 μm was used as the erodent. These polymers have exhibited maximum erosion rate (E max) at 30° impact angle indicating ductile erosion behavior. Some of these polymers have shown an incubation behavior at lower impact velocities for an impact angle of 90°. Correlations among steady-state erosion rate and mechanical properties and glass transition temperature (T g) were established. Morphology of eroded surfaces was examined using scanning electron microscopy and possible wear mechanisms were discussed.

Fabric having a thermoplastic fusible yarn, process of making a fabric containing a thermoplastic fusible yarn, and fabric article formed with a fabric containing a thermoplastic fusible yarn

Abstract: A fabric that contains a thermoplastic fusible yarn and a process of making a fabric containing a thermoplastic fusible yarn are provided. A fabric article is formed with the fabric containing a thermoplastic fusible yarn.

Tactile Enhancement For Input Devices

Abstract: Embodiments related to the tactile enhancement of a computer input device are disclosed herein. In one disclosed embodiment, a method of making removable tactile-enhancing grips for a computer input device is disclosed. The method comprises heating a thermoplastic elastomeric sheet to a temperature at which the thermoplastic elastomeric sheet is capable of receiving and retaining an imprinted feature, pressing onto the thermoplastic elastomeric sheet a plate comprising a pattern, thereby embossing the pattern onto the thermoplastic elastomeric sheet, and cooling the thermoplastic elastomeric sheet to a temperature at which the pattern is retained in the thermoplastic elastomeric sheet. An adhesive layer is then formed on an opposite side of the thermoplastic elastomeric sheet as the pattern.

Composite materials with blend of thermoplastic particles

Abstract: Pre-impregnated composite material (prepreg) is provided that can be cured to form composite parts that have high levels of damage tolerance. The matrix resin includes a thermoplastic particle component that is a blend of particles that have a melting point above the curing temperature and particles that have a melting point at or below the curing temperature.

Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Thermoplastic and Thermosetting Nanocomposites : A Review

Abstract: Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have been successfully incorporated into thermoplastic and thermoset polymers via copolymerization, grafting, blending, surface bonding, or...

Polylactic acid fibers

Abstract: A biodegradable fiber that is formed from a thermoplastic composition that contains polylactic acid, a plasticizer, and a compatibilizer is provided. The compatibilizer includes a polymer that is modified with a polar compound that is compatible with the plasticizer and a non-polar component provided by the polymer backbone that is compatible with polylactic acid. Such functionalized polymers may thus stabilize each of the polymer phases and reduce plasticizer migration. By reducing the plasticizer migration, the composition may remain ductile and soft. Further, addition of the functionalized polymer may also promote improved bonding and initiate crystallization faster than conventional polylactic acid fibers. The polar compound includes an organic acid, an anhydride of an organic acid, an amide of an organic acid, or a combination thereof. Such compounds are believed to be more compatible with the generally acidic nature of the polylactic acid fibers.

Effect of a Novel Coupling Agent, Polybutadiene Isocyanate, on Mechanical Properties of Wood-Fiber Polypropylene Composites:

Abstract: The scope of the present paper is to study the effect of adding a novel coupling agent, polybutadiene isocyanate (PBNCO), on the mechanical properties of hardwood aspen fiber/polypropylene (PP) composites. The resulting properties were compared to those obtained with the most commonly used coupling agent, maleic anhydride modified polypropylene (MAPP). In this study, we determined a value of 24.75 MPa for the tensile strength of pure PP and 22 MPa for the composite containing 30 or 40wt% unmodified fibers. These results indicate that wood fiber behaves merely as filler when incorporated into PP and no reinforcing effect was observed in this case. This occurs because of the chemical incompatibility between the thermoplastic PP and the polar fiber, resulting in low interfacial adhesion. However, it was verified that addition of 3% MAPP and 5% PBNCO to this formulation produced composites with better performance, since the tensile and impact properties were increased up to 30 MPa and 22 J/m2, respectively. T...

Crystallization of PLA/Thermoplastic Starch Blends

Abstract: In this paper, the crystallization of PLA in PLA/thermoplastic starch (TPS) blends was investigated. The TPS was used as the minor component at a concentration varying between 0 and 42 %. ...

low-smoke halogen-free flame retardant thermoplastic elastomer alloy for flexible wire rod and preparation method thereof

Abstract: The invention discloses a low-smoke halogen-free flame-retarding thermoplastic elastomer alloy used for soft wires and a preparation method of the alloy, which is characterized in that: the material comprises thermoplastic polyurethane elastomer, thermoplastic styrene elastomer, compatilizer, phosphorus-nitrogen compound flame retardant, flame-retarding potentiating agent, lubricant, antioxidant and colorant; the weight ratio of the thermoplastic polyurethane elastomer, the thermoplastic styrene elastomer, the compatilizer, the phosphor-nitrogen compound flame retardant, the flame-retarding potentiating agent, the lubricant, the antioxidant and the colorant is 40 to 55 : 5 to 25 : 5 to 10 : 20 to 25 : 3 to 10 : 1.5 : 0.25 : 0.25; the preparation method is that the all components are evenly mixed in a high-speed mixer, and then extruded, drew and granulated at 170 to 210 degree centigrade, and then a low-smoke halogen-free flame-retarding thermoplastic elastomer alloy used for soft wires is obtained. The low-smoke halogen-free flame-retarding thermoplastic elastomer alloy used for soft wires has the advantages of achieving distinct flame-retarding effect at a small quantity of flame retardant dosage, satisfying the flame-retarding requirement of low-voltage wires, adjusting the Shore durometer number of the material between 80 to 95, good pliability, high physical mechanical property and according with the halogen-free and environment-friendly requirement.

Mechanical performance of carbon fibre-reinforced composites based on preforms stitched with innovative low-melting temperature and matrix soluble thermoplastic yarns

Abstract: In order to achieve a superior overall mechanical performance of composites based on stitched preforms for demanding aircraft applications, innovative thermoplastic stitching yarns are comparatively evaluated in carbon fibre-reinforced epoxy composites. Low-melting temperature yarns based on polyamide and phenoxy in comparison to a standard polyester yarn allow prestabilisation of the dry preforms by thermobonding and lead to significantly reduced laminate disturbances following liquid composite moulding; thereby minimising the degradation of the resulting composite strength properties. While the softening polyamide yarns allow partial rearrangement of the carbon fibres during the resin injection process, the dissolution and subsequent phase-separation of the phenoxy can induce a further local toughening of the epoxy matrix. The improvements in overall composite performance when using stitching yarns are partly due to the particular yarn material but also depend on variations in linear yarn density. Last but not least, it is demonstrated that stitching seams close to a bolted joint have only little effect on the bolt bearing strength of the stitched composite whereas seams running directly through the hole and oriented in the load direction induce small degradation of the bolt bearing strength.

Thermoplastic resin composition

Abstract: The invention is directed to a thermoplastic resin composition comprising 100 parts by mass of a thermoplastic resin derived from a plant (A), 5 to 50 parts by mass of a cellulose fiber (B), 15 to 40 parts by mass of a polyarylate fiber (C), an organic nucleating agent (D), a hydrolysis inhibitor (E) and a flexibility imparting agent (F) and can provide a thermoplastic resin composition which enables molding in a practical molding cycle while having practical heat resistance, sufficient impact resistance and high biomass content

Study on characterization and properties of nanosilica-filled thermoplastic vulcanizates

Abstract: Thermoplastic vulcanizates (TPVs) are a special class of thermoplastic elastomer, produced by simultaneously mixing and cross-linking a rubber with a thermoplastic at elevated temperature. Dicumyl peroxide-cured TPVs based on blends of maleated ethylene propylene rubber (m-EPM) and polypropylene (PP) thermoplastic using maleated-PP as a compatibilizer have been developed. To reinforce the properties of these TPVs, nanosilica was added at different levels. With the increase of nanosilica concentrations, significant improvement in tensile strength, modulus, and impact strength of TPVs have been achieved. Morphology study shows that nanosilica is uniformly dispersed in the polymer matrices. Dynamic mechanical analysis shows that tan δ value at low temperature decreases with increasing nanosilica concentration indicating less damping characteristics. Thermogravimetric study revealed that thermal stability of TPVs is improved in presence of nanosilica. Equilibrium swelling study confirms that solvent resistance of TPVs could be improved by nanofiller incorporation. Rubber process analyzer found a very useful tool to understand the melt rheology of nanosilica filled TPVs in terms of dynamic functions over a wide range of strain amplitude and frequency. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Support for separation membrane, and method for production thereof

Abstract: A support for a separation membrane includes a long-fiber nonwoven fabric composed of thermoplastic continuous filaments.

PVT Behavior of Thermoplastic Poly(styrene-co-acrylonitrile)-Modified Epoxy Systems: Relating Polymerization-Induced Viscoelastic Phase Separation with the Cure Shrinkage Performance

Abstract: The volume shrinkage during polymerization of a thermoplastic modified epoxy resin undergoing a simultaneous viscoelastic phase separation was investigated for the first time by means of pressure-volume-temperature (PVT) analysis. Varying amounts (0-20%) of poly(styrene-co-acrylonitrile) (SAN) have been incorporated into a high-temperature epoxy-diamine system, diglycidyl ether of bisphenol A (DGEBA)-4,4'-diaminodiphenyl sulfone (DDS) mixture, and subsequently polymerized isothermally at a constant pressure of 10 MPa. Volume shrinkage is highest for the double-phased network-like bicontinuous morphology in the SAN-15% system. Investigation of the epoxy reaction kinetics based on the conversions derived from PVT data established a phase-separation effect on the volume shrinkage behavior in these blends. From subsequent thermal transition studies of various epoxy-DDS/SAN systems, it has been suggested that the behavior of the highly intermixed thermoplastic SAN-rich phase is the key for in situ shrinkage control. Various microscopic characterizations including scanning electron microscopy, atomic force microscopy, and optical microscopy are combined to confirm that the shrinkage behavior is manipulated by a volume shrinkage of the thermoplastic SAN-rich phase undergoing a viscoelastic phase separation during cure. Consequently, a new mechanism for volume shrinkage has been visualized for the in situ polymerization of a thermoplastic-modified epoxy resin.