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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An Approach to Couple Mold Design and On-Line Control to Manufacture Complex Composite Parts by Resin Transfer Molding
Resin Transfer Molding (RTM) has been used to manufacture advanced composite parts. In this paper, we present the design and validation of an automated RTM intelligent workstation. A new injection method, which can deliver the resin to various locations within the mold, while still allowing any individual gate to be opened or closed at any time during the filling, was designed and tested.
A 3D-Simulation Study of Barrier Properties of Nanocomposite Films
Nanocomposite polymer-clay films are inherently complex systems. Many classical and recent models study this system in two dimensions via a “brick-like” structure. However, a 2D approach may not sufficiently capture 3D effects. The results of a 3D simulation will be presented which examines the effects of various geometries on the computed diffusion coefficient will be presented. These results will then be compared to existing models.
Minimizing Voids in Pultruded Polymer Composites
A finite difference scheme was used to simulate heat transfer, curing and fluid flow during pultrusion of equal leg angle glass-fiber-reinforced vinyl ester composite profiles. Corresponding experiments were conducted using a commercial resin system cross-linked with styrene. Void formation was inferred from computed velocity and pressure profiles and measured using electron microscopy. Results showed that increasing pull speeds did not necessarily lead to increasing void content. Implications for optimizing the process of manufacturing all-composite bridge decks are discussed.
Process Simulation of Structural Long Fiber Thermoplastic (LFT) Composites with Features of Geometrical Complexity
The use of long fiber thermoplastic (LFT) composites has been increasing in the mass transit and automotive industries, as a result of the progress made in new materials and processing technologies. The present work focuses on process simulation of the extrusion-compression molding process for LFTs. Material and process parameters were varied to investigate the flow front and fiber orientation in typical structural shapes such as flat sections and ribs.
Composites Derived from Post-Consumer Nylon 6 Carpet
Over 2 million tons of post-consumer carpet is landfilled each year. This waste carpet is a potential resource for composites. Since waste carpets can be rapidly identified and sorted by face fiber, this paper focuses on the processing and properties of nylon 6 post-consumer carpet. The carpet is cleaned, shredded and extrusion pelletized. This feedstock is compounded with glass fibers and compatibilizers. Based on the properties achieved and the projected costs, applications are identified.
Fiber-Reinforcement of Composites by Reaction-Induced Phase Separation
A new class of fiber-reinforced composite materials is being designed in our laboratory by using a hybrid of thermoplastic and thermosetting polymers. The thermosetting polymers form separate phase upon reaction-induced phase separation and create morphology on the fiber surfaces. Consequently, strong fiber-polymer bonding of thermosetting composites and high fracture toughness of thermoplastic polymers are obtained from the same composite.
Assessing the Use of Lower Ordered Tensors in Numerical Predictions of Flow-Induced Fiber Orientation
Orientation tensors are widely used to describe fiber distributions in short fiber reinforced composite systems. This paper considers the effect of using lower order tensors in process simulations, and when computing mechanical properties for the composite structure from the flow calculations. Evaluations are performed by reconstructing the distribution function from successively higher order orientation tensors in a Fourier Series representation. Examples of fiber orientations in simple flow fields are provided.
Characterization of Polyetherimide and Polystyrene in Shear Flow
Filled thermoplastic polyetherimide and polystyrene samples were prepared and their morphological and melt processing properties were studied with respect to the processing conditions and filler loadings. The results should provide insights that are needed to solve complex issues encountered in the industry dealing with the recycling and processing of this important class of thermoplastic materials.
Application of Image Processing Technique in Analyzing Microstructure of Nanocomposites
An image processing program suitable for analyzing the microstructure of polymer/organic-montmorillonite (org-MMT) nanocomposites was developed based on the MATLAB software. The TEM photomicrographs of polypropylene/org-MMT were analyzed using the program. It has been revealed that the shape and size of the MMT in nanocomposites can be determined effectively and promptly by using the image processing program.
A Carbon Nanotube Alternative: Graphite Nanoplatelets as Reinforcements for Polymers
Intercalated natural crystalline graphite compounds [GICs] were formed followed by exfoliation and milling to produce sub-micron graphite flakes. SEM and TEM images showed that the average size of graphite became 0.86 um with a thickness of around 5 nm. The cost of this new nano-size graphite material was estimated to be around $5/lb or less. Since exfoliated graphite has superior mechanical, electrical, thermal properties and cost effectiveness, this material has been shown to be a superior potential reinforcement for polymer nanocomposites.
Polyol Modified Epoxy-Montmorillonite Nanocomposites
New nanocomposite materials were synthesized using DGEBA type of epoxy resin and triethylenetetramine curing agent as the matrix, alkyl ammonium modified montmorillonite as the reinforcing agent and polyether polyol as the impact modifier. X-ray Diffraction patterns showed that the interlayer spacing of the modified montmorillonite expanded from 1.83 nm to 3.82 nm. In samples without clay, the impact strength of the neat resin increased by 160 % at 7 weight % polyether polyol. Tensile modulus increased with increasing filler loading, but showed a maximum with respect to the polyether polyol content.
Synthesis and Characterization of High Density Polyethlene Clay Nanocomposites
High-density polyethylene/clay nanocomposites were prepared, using a twin-screw extruder. The nanocomposites were characterized with TEM, XRD, DSC, optical microscopy and tensile testing. The results show some exfoliation and indicate that the clay does not affect the melting temperature or crystallinity of the HDPE. However, the clay acts as nucleation agent and reduces the crystallite size. The clay improved the modulus, without causing large decrease in the elongation and impact strength.
LLDPE-g-GMA to Promote Adhesion of LLDPE with Polyesters
LLDPE-g-GMAs were synthesized in a twin-screw extruder by free radical grafting of GMA on LLDPE. The grafted GMA content was varied between 0 and 1.8wt% by changing the initial GMA and peroxide concentrations and the viscosity of the LLDPE. The double cantilever beam (DCB) test was then used to measure the adhesion of these materials with PETG. The effect of the grafting level, the presence of unbound GMA and the viscosity of the material was investigated. Good adhesive strength was developed, in particular when the material was purified to remove unbound GMA monomer and oligomers.
Oxidized Polypropylene and Ionomers Thereof as Compatibilizers for Polypropylene/Nylon-6 Blends
Oxidized polypropylene and ionomers thereof were evaluated as compatiblizers for polypropylene/ nylon-6 (PP/PA-6) blends. For these blends, the ionomer of oxidized PP provided better morphology and physical properties than the oxidized PP. The change in morphology was also reflected in the rheological behaviors that the compatibilized blends showed an increase in melt elasticity. With improvement in flowability and yellowing resistance, the ionomer of oxidized PP also, for the most part, yielded mechanical properties comparable to commercially available maleated PP.
Oxidized Polypropylene as Compatibilizer/Dispersion Agent for Flame Retardants
Oxidized polypropylene has been produced with a controlled level of functionality. Applications of this new polymer in both halogenated and non-halogenated flame retardant (FR) formulations were studied. Benefits include enhancement of flame retardance performance and improvement in mechanical properties, processability, and surface appearance. In the melt stage, rheological measurements of G’ indicate that relaxation time decreases significantly when adding oxidized PP, confirming the improvements in PP-FR interfacial interaction and FR dispersion in the PP matrix.
New Alloying Possibilities with SBM Block Copolymers
SBM is a new family of copolymers constituted of three blocks of linear chains covalently bonded to one another: polyStyrene, 1,4polyButadiene and syndiotactic polyMethylMethacrylate.The polar and apolar moieties on the same molecule render SBM ideal interfacial agents for many incompatible systems, offering innovative possibilities in the design of new high performance polymeric blends.This concept has already been successfully applied to several pairs of incompatible polymers. New achievements with PVDF / PPE are presented.
Stabilization of Dispersed Phase to Static Coarsening: Polymer Blend Compatibilization via Solid-State Shear Pulverization
Absolute compatibilization of immiscible polymer blends via a novel, continuous process, solid-state shear pulverization, and without addition of compatibilizing agents is quantitatively shown for the first time by stability of number-average dispersed-phase domain size to longterm annealing. Compatibilization via pulverization is due to in situ chain scission that is supported by molecular weight analysis of PS before and after pulverization, resulting in polymer radicals that can lead to in situ interfacial block copolymer formation.
Influence of Weight Fraction and Shear Rate on Particle Size in Polymer Blends
A relationship between particle size and volume fraction, viscosity ratio, interfacial tension, and shear stress was suggested, which can be used to estimate quantitatively experimental data of particle sizes in concentrated polymer blends, for simple shear flow. The relationship explains the observation that, for coalescence-suppressed polyethylene/polyamide-6 blends with high viscosity ratio (>>1), to which maleic anhydride grafted polyethylene was added as a compatibilizer, the particle sizes decreased with the increase of the dispersed phase weight fraction.
An In-Situ Process for the Production of Electrically Conductive Polyaniline Fibres from a Polymer Blend
The feasibility of using an in-situ deformation process for producing electro-conductive polyaniline (PANI) fibres embedded in the bulk of a filament-like composite and longitudinally oriented along its axial direction is evinced. Blends of a PANI complex and polystyrene-polybutadinepolystyrene (SBS) were capillary extruded into filaments. The extrudates’ microstructure consisted of elongated domains of the PANI complex embedded in the SBS, displaying a considerable degree of uniformity and continuity, and preferentially oriented in the extrusion direction.
Color and Appearance Measurement and Tolerancing Basics
Unlike properties such as impact or hardness that are directly measured in physical units, Color and Appearance are visual phenomenon that involves a physiological response by an observer. Color and Appearance are personal judgments that depend on how and under what conditions the observation is made. So how do we measure Color and Appearance and how can we set meaningful limits for those measurements?This paper reviews the basics of Color and Appearance measurement, Colorimetry, and addresses some of the important considerations in successful use of numerical tolerances.
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