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Conference Proceedings

Studies on the Nature of the Interactions in SB Rubber and Mesoporous Silica Mixtures
Nelson Castaño, León Pérez, Ligia Sierra, Betty L. López, May 2004

The knowledge about the interactions between rubber and its load at a fundamental level is important to understand the physical and mechanical properties of a filled rubber system. This paper presents a comparative study of the interactions of the styrene butadiene rubber (SBR) with mesoporous silica and with Ultrasil VN3 silica, mixed in a mill and annealed at 150 °C for different times. The studies of these samples and their toluene extracted residues, based upon information obtained from Fourier transform infrared (FTIR), thermogravimetry (TGA), differential scanning calorimetry (DSC), show that there is a relation between the strength of the interaction and pore structure characteristics of the silica. The better interaction of mesopororous silica with the SBR, measured as a higher bonded polymer content, is associated with the inclusion of elastomeric chains inside of the mesoporous as can be deduced from the analysis of the different data.

Diffraction and Thermal Effects in Non-Intercalating & Non-Exfoliating Amorphous PET Montmorillonite Packaging
Ajit Ranade, Amit Dharia, Nandika Anne D'Souza, Bruce Gnade, May 2004

While research on a variety of polymers reinforced with montmorillonite layered silicates (MLS) has been conducted, there is limited knowledge about the separability of parameters affecting the polymer. We have found in a self-nucleated semicrystalline PP and nylon nanocomposites a high degree of exfoliation was accompanied by a change in crystallinity of the base resin. This indicates limited separability of the nucleating capability of MLS and the exfoliated dispersion of the MLS. To eliminate the variable of nucleation, we investigated a LLDPE nanocomoposite reported in a concurrent ANTEC submission. Here we investigate an amorphous PET with MLS. The results indicate that in a nonintercalating or exfoliating dispersion, the 002 and 003 reflections shift to higher 2? or lower d indicating compaction of the crystal in the through thickness dimension. The accomopanying lower glass transitions of the nanocomposite point to a new explanation for plasticization of some nanocomposites where no fraction of polymer is constrained between platelets.

Thermomechanical Characterization of Blends of Poly (Vinyl Acetate) with Semicrystalline Polymers for Shape Memory Applications
Changdeng Liu, Patrick T. Mather, May 2004

Shape memory effects of polymeric materials have gathered increased attention recently, prompted by an expanding range of potential end-use applications, especially for development of biomedical engineering tools. On the basis of rubber elasticity combined with vitrification or crystallization, many polymers exhibit shape memory, but with varying characteristics such as strain recovery rate, rate at which the new temporary state is fixed, and work capability during recovery. For high stiffness in the temporary form, a need exists for shape memory polymers with Tg greater than room temperature, but with tailored rubber modulus and elasticity derived from physical rather than chemical crosslinks. We have thus pursued the miscible polymer pair, poly(vinyl acetate) (PVAc) and semicrystalline poly(lactic acid) (PLA). Here, crystallization of PLA from a single liquid phase is controlled by the PVAc content, but resulting in a nearly invariant melting transition Tm ~ 165 °C. Blending PLA with PVAc was found to reduce the crystallinity degree systematically, thus controlling the rubber modulus relevant to recovery work capability. This report gives preliminary results on the thermomechanical properties of such PLA/PVAc blends and the shape memory effects that result. The properties will be further explained in light of the underlying microstructure characterized by x-ray scattering.

Influence of Different Molecular Characteristics of Syndiotactic Polypropylene on Equilibrium Melting Temperature and Crystallization Behavior
Pakin Thanomkiat, Pitt Supaphol, Roger A. Phillips, May 2004

Isothermal crystallization and subsequent melting behavior of metallocene-catalyzed syndiotactic polypropylene resins of varying molecular weights were investigated. Two sets of molecular weight range were synthesized with two different metallocene catalyst systems. Differential scanning calorimetry (DSC) was the main technique used. The kinetics of the crystallization process was assessed by directly fitting the experimental data to the Avrami, Malkin and Urbanovici-Segal macrokinetic models, using a non-linear multivariable regression program. The equilibrium melting temperature of these resins was estimated based on the linear and nonlinear Hoffman-Weeks extrapolative methods.

The Influence of the Finite Step Time on the Measurement of the Viscoelastic Response Functions
Anny Flory, Gregory B. McKenna, May 2004

The ideal stress relaxation experiment is defined as the imposition of an instantaneous strain. In practice, it takes a finite time t1 to reach the constant strain. Various ways in which to account for the finite step time and the subsequent effects on the relaxation modulus G(t) are examined in the present work. First, we consider the “rule of thumb” in which data are ignored until 10 times the strain application time t1. In addition, the Lee-Knauss algorithm is compared with the Zapas-Craft method in which the corrected time of the experiment becomes t-t1/2 where t is the experiment time. A surprising result is that the different correction schemes affect the estimates of the material parameters more than they affect the relative differences between the corrected data and the ideal behavior.

Rapid Method to Assess Effect of Pigments on Photo-degradability of Polymers
Changqing Jin, T.A. Egerton, J.R. White, P.A. Christensen, N. MacDonald, May 2004

A novel method for studying photo-degradation has been applied to the study of several different polymers including a series of polyethylene (PE) samples containing TiO2 pigments with different photo-activities. Infrared (IR) analysis was used to monitor carbon dioxide emitted from samples exposed to ultraviolet irradiation (UV) in atmospheres of differing composition. The experiments were conducted in a specially constructed cell that permits simultaneous UV exposure of the sample and IR interrogation of the vapour in the cell. A single test on one material occupied about 5 hours – very much less than conventional artificial weathering exposures.The TiO2 pigments used included anatase and rutiles with different surface treatments. Anatase-pigmented material gave significantly higher CO2 emission than unpigmented PE. The rutile-pigmented PEs either gave reduced CO2 emission or enhanced emission, according to the surface treatment. The ranking of the pigments as protectants or pro-degradants coincided with that obtained from much more time-consuming laboratory testing and field experience.

Depression of Tg in Polystyrene by Freeze-Drying
Paul Bernazzani, Sindee L. Simon, May 2004

The calorimetric glass temperature of polystyrenes with molecular weights ranging from 3.0 x 103 to 43.7 x 106 g/mol are measured as a function of cooling rate for both bulk material and for samples freeze-dried from dilute solution. We find that Tg is depressed approximately 5 K for samples which can fully entangle and also the same amount for ultrahigh molecular weight samples which cannot achieve full entanglement. The lowest molecular weight samples show only 2 K depression on freeze-drying. Annealing eliminates the depression in Tg. The results indicate that the reduction of the glass temperature due to freeze-drying cannot be due to the reduced entanglement concentration induced by freeze-drying.

A Study on Modification of PP with Aliphatic Diamines
Sofía Vázquez-Rodríguez, Saúl Sánchez-Valdes, Octavio Manero-Brito, May 2004

In previous work, modification with different diamines was reported and the diamine-grafted polypropylene was used as an adhesion-promoting agent to layer of polycarbonate (PC). A study on the technique of adding reactive is reported in this work. Packets of different aliphatic diamines were reacted with polypropylene modified with maleic anhydride (PPgMA) in melting process. The reaction between amine primary groups and maleic anhydride groups was analyzed by FTIR. Differences in viscosity measurements were evident using packets of diamine, samples obtained by packet of diamine showed a low value of viscosity compared with samples produced by diamine-packet. Two-layered films were prepared using PC film and PPgNH2 film. Adhesion strength was measured using T-peel test. All results permit conclude which diamine is promoting the best adhesion between PPgNH2 and PC layers.

The Characterisation and Physical Testing of Micro-Mouldings
Giles R. Greenway, Peter S. Allan, Peter R. Hornsby, May 2004

Nano-indentation techniques are being developed for the mechanical testing and physical characterisation of micro-mouldings. A procedure for the embedding, sectioning and testing of micro-mouldings was described at Antec ’02. The technique has been further refined and a systematic evaluation of injection mouldings with micro-dimensions has been carried out. The results from the nano-indentation tests have been supported by atomic force microscopy measurements relating to the dimensions and geometry of the indentations. The results that will be presented will show that the levels of anisotropy of mechanical properties can be measured in micro-mouldings by the methods described.

The Effect of Melt Temperature and Extrusion Rate on the Die Swell of Metallocene and Conventional Polyethylenes
B.G. Millar, G.M. Mc Nally, W.R. Murphy, P. Laughlin, May 2004

A range of metallocene and conventional PE resins of various comonomer types, were extruded from a single capillary rheometer, at different melt temperatures and extrusion rates. Analysis shows that die swell increases with increasing extrusion rate and decreasing melt temperature. GPC analysis elucidated the influence of molecular characteristics on die swell. Increased die swell was found for the broader MWD (3.5-3.8) conventional PEs, in comparison with the narrower mPEs (2.1-3.1), and in the higher molecular weight resins. Furthermore, long chain branching was found to increase die swell.

Design, Fabrication, and Assembly of a Polymer Electrolyte Membrane Fuel Cell (PEMFC)
Derek Weber, Christopher C. Ibeh, May 2004

This report will include the way to design, fabricate, and assemble a Polymer Electrolyte Membrane Fuel Cell (PEMFC) to maintain a low voltage source, near one volt, that runs at operating temperatures near 80 degrees Celsius. Creating a stack of cells will provide an energy solution that is more efficient than the system in place today. The PEMFC runs off of pure hydrogen and air (oxygen) and will provide a power source that is non-pollutant and renewable since hydrogen is readily available through the electrolysis of water. The problems with this experiment are maintaining moisture control on both the cathode and anode and the other problem is in controlling the hydrogen gas supply since hydrogen is very explosive when combined with oxygen. With these problems taken into consideration the PEMFC could be the energy source for the future.

Polymer Defect Detection and Classification Utilizing Camera Optics, Real Time Computation and Small Scale Resin Sample Processing
Simon Dominey, Werner F. Goeckel, May 2004

This paper discusses a technique for identifying and analyzing defects in plastic compounds. Its primary use is in resin or master batch production or as a general purpose QC or investigative instrument.Initially the resin is processed in a simulation of typical production conditions, by producing blown or cast film on a small scale ( < 2 Kg/hr )The film is passed through the optical field of a CCD line scan camera Data from the camera is processed in hardware and software to capture the continuously moving image.The image data is then analyzed to automatically discriminate and classify a wide range of defects, flaws and process induced variables.The Authors will presentThe special considerations of the extrusion processThe optical design for 5 micron detection resolution of a moving webAlgorithms employed to classify and present data in real time at high speedThe late stage development of this system to detect clear particle contamination in a clear film.

Melt Processing of Tailored Acrylic Copolymers
Michael J. Bortner, Vinayak A. Bhanu, James E McGrath, Donald G. Baird, May 2004

Steady shear rheology of acrylonitrile (AN) terpolymers provides an indication of the melt stability of tailored AN copolymers. It has been found that AN can be copolymerized with methyl acrylate (MA) to produce a material with up to 88 mole percent AN that possesses suitable melt stability at elevated temperatures for processing into carbon fiber precursors. A third copolymer, acryloylbenzophenone (ABP), is copolymerized in 1-2 mole percent to act as a UV stabilizing agent that activates crosslinking following fiber formation. Boric acid (BA) is also added as a “free radical quencher”, which enhances the thermal stability of the terpolymer.

Structural BioComposites from Natural Fibers and Biopolymers
Lawrence T. Drzal, A.K. Mohanty, M. Misra, May 2004

BioComposites are emerging as a viable alternative to glass-reinforced composites. Natural fibers have advantages over man-made fibers (e.g. glass and carbon) in areas such as low cost, low density, competitive specific mechanical properties, reduced energy consumption, carbon dioxide sequestration, and biodegradability. The combination of bio-fibers like kenaf, hemp, flax, henequen and sisal with polymer matrices from both non-renewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention to the biofiber-matrix interface, and its resulting adhesion, as well as to the processing methods used to produce these materials. The development of useful biocomposite materials also requires that water-based sizings or dry coupling agents be used to improve fiber-matrix adhesion.. Through bio-fiber surface treatment, biopolymer modification, and adequate processing techniques, novel bio-composites can be designed and engineered so as to substitute/supplement glass fiber composites in various applications.

The Effect of Weathering on Wood-Polymer Composites
P. Douglas, W.R. Murphy, G. McNally, M. Billham, May 2004

A range of wood-polymer blends, containing 20, 40 and 60% w/w MDF sawdust (212-850 microns) were prepared using polyethylene, polypropylene and polyvinyl chloride. The blends were melt compounded using a Killion single screw extruder with a barrier type screw design. Over a weathering period of 2 months (fluctuating wet and dry) the mechanical properties decreased in all composites with water retention evident when the composites were “dry”. The rate of water absorption increased during the second wetting period. The diffusivity of water through the wood-polymer composites was found to be greatest for the PVC based composites.

Injection Molding of a Starch Based Polymer Reinforced with Natural Fibers
A.R. Campos, A.M. Cunha, R. Ben Cheikh, May 2004

Biodegradable composites were developed by compounding a commercial corn starch polymer with pine and Alfa fibers on a counter-rotating twin screw extruder. Subsequently, the compounds were injection molded under optimized conditions and characterized for the respective mechanical behavior and morphological features.The obtained results establish by evidence that this kind of composites present mechanical performance (in terms of stiffness and strength) within the range of the polymeric systems based on high consumption thermoplastics. In comparison with pine fibers, Alfa based composites presented a better performance as result of various advantageous morphological and interfacial aspects.

Effects of CBA on Extrusion Processing of Foamed Plastic/Wood-Flour Composites
G.M. Rizvi, C.B. Park, G. Guo, K. Wang, May 2004

It has been established that the production of foamed structure in plastic/wood-flour composites (PWC) is overwhelmingly dominated by the gaseous emissions/volatiles released by the wood-flour. By adopting effective processing strategies, the role of these volatile emissions on foam morphology of plastic/wood-flour composites can be largely suppressed. This paper discusses these strategies, and presents the results obtained from extrusion processing when the chemical blowing agents (CBA) predominantly control the density reduction. The effects of CBAs on extrusion processing of PWC are discussed. Although the used CBAs produced fine-celled structures, the processing window for density reduction was quite narrow.

An On-Line Analytical Method for Quality Control for Bio-Fiber Reinforced Composites
Shankar Godavarti, May 2004

Wood fiber reinforced thermoplastics are a recent introduction and are finding increased acceptance in a range of industries. Quality control tests for these composites are expensive and time consuming. A quantifiable, reliable method of quality control in real time is increasingly becoming critical with increasing demand and longer production runs.This paper discusses the development of a new method using analytical techniques to monitor quality based on the free, unreacted acid in the composite. The results from this test correlate well to composite physical properties. This test is also useful for process design and optimization studies.

Optimization of Coupling Agent Characteristics for Maximizing Performance of Wood Fiber Thermoplastic Composites
Shankar Godavarti, May 2004

Wood fiber reinforced thermoplastics are a recent phenomena. Their usage has been growing with increasing acceptance in a variety of industries. Applications range from non-structural to load bearing structural components.The multitude of applications requires diverse performance attributes. Performance of these composites is based on the efficiency of coupling the non-polar thermoplastic matrix to the polar wood fibers. Maleic anhydride grafted polymers are widely used for achieving this coupling. Selection criteria for appropriate performance attributes are based on a complex web of process, material and design variables.This paper presents the results of a designed experiment wherein the best combinations of compatibilizer characteristics, molecular weight and percent maleic anhydride grafting level and wood fiber moisture level were determined, to achieve the optimum balance of responses.

A Low-Cost Composite Bicycle Frame Produced by RTM: From Concept to Reality
Nikos G. Pantelelis, May 2004

In this paper the complete design and the manufacturing of an innovative composite bicycle frame is presented. The initial target and the concept are described to produce a lightweight frame using unsaturated polyester, glass fiber preforms, closed foam core and metal inserts. The final composite body frame has comparable weight and stiffness with a corresponding aluminum tube frame. For the mass production of the frame the resin transfer molding technique with a closed mould has been explored. Furthermore the extension of the method to use epoxy resins and carbon fibers is straightforward resulting in considerable weight reduction and strength increase but also to a moderate increase of the material costs.










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