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Conference Proceedings

A Comparison of Proton NMR and NIR for the Online Analysis of Terpene Resin Distillate Fractions
Mark J. Sullivan, May 2002

The selection of online analyzer technology is determined by numerous practical criteria. NIR has been established as a leading technology for online process analysis due to its versatility and proven reliability. Nevertheless, the robust, multivariate calibrations that are key to the implementation of NIR analyzers can be difficult to develop or transfer and their maintenance over time can add significantly to the cost of the analysis. Recent reports have indicated that, despite the higher initial costs, process N M R m ay offer long term cost advantages over NIR for applications where global NM R calibrations have been developed.The objective of this study was to com pare the accuracy (i.e., standard error of prediction) of multivariate calibrations (PLS)for NIR and NM R on a set of process samples taken from a terpene resin still that were referenced by G C. Particular attention was focussed on whether the uniformity of NM R intensities and the discrete nature of the spectra would offer any inherent advantages over NIR with its superior signal-to-noise.The PLS calibrations on laboratory data showed better results by NIR over NM R for the same total acquisition time. The NIR advantage w as m ore pronounced for the minor components (<5% of the neat mixture) than for the major component (>90% ). The results are consistent with the higher signal-to-noise for NIR over NM R. In both cases, the PLS regression coefficients emphasized resolved spectral features that corresponded directly to functional groups in the pure components. Due to the spectral simplicity of this mixture of small molecules, the selectivity of NM R did not yield any advantage in the calibrations. Additional work would be required to determine if NM R would offer benefits in the actual online environment.

Comparison of Reactive Extrusion in Various Twin Screw Extruders and Their Roles on Mixing
Byung H . Lee, James L. White, May 2002

A comparative modeling of distributive mixing has been investigated in intermeshing co-rotating, intermeshing counter-rotating and tangential counter-rotating modular twin screw extruders. This is based on the Spencer-Wiley premise of representing mixing through interfacial area increase and its relationship to shear strain of the various modular twin screw elements. It is necessary to develop flow analyses for different modular twin screw extrusion machines. We applied this analysis to understand the reactive extrusion process in various twin screw extruders. Our approach is to compute the development of interfacial area for composite modular twin screw extruders and an internal mixer, and a mixing index was determined for each processing device.

Comparison of Structure Development in Processing Syndiotactic and Isotactic Polypropylenes
Dongman Choi, James L. White, May 2002

We investigated the crystallization and orientation development in syndiotactic polypropylene (sPP) during various polymer processing operations and also compared the results with isotactic polypropylene (iPP). This was carried out in fiber spinning, tubular film extrusion and injection molding. Melt-spun sPP fibers exhibit Form I helical structure at low spinline stress levels and zig-zag all trans structure (Form III) at high stress levels. In tubular film extrusion, sPP exhibits Form I structure and the a-axis is preferentially oriented in the film normal direction. Injection-molded sPP samples exhibit very low frozen-in orientation levels due to its slow crystallization rate.

Comparison of Tensile Properties for PET and Acetal Specimens Using Two Different Tensile Testing Units
Rhonda M. Rush, May 2002

The compiled data are for unfilled acetal and filled polyethylene terephthalate (PET) specimens. Various sample sets were evaluated using the ASTM D 638-95 method, “Tensile Properties of Plastics.” These tensile data are used to evaluate material candidates for making molded parts. It is important to determine if the tensile data are the same or if they are different so that selections can be made without repeating the data collection each time a decision is required. Sample sets were evaluated using two different instruments—a SATEC and an Instron. These data were obtained over a number of years by different operators following an iterative approach. One sample set was molded from Delrin® 500*, a medium viscosity, acetal homopolymer (POM). The three addition sets were polyethylene terephthalate (PET) specimens molded from Rynite® SST 35,* Rynite® 545, and Ticona Celstran® PETGF 20-02.

A Comparison of the Axisymmetric and Planar Elongational Viscosities of a Polymer
Peter Beaupre, Mahesh Gupta, May 2002

The elongational viscosities of a low density polyethylene in axisymmetric and planar flows are compared. The experimental data on entrance pressure loss is matched with the corresponding finite element predictions to estimate the parameters in the elongational viscosity model proposed by Sarkar and Gupta. The entrance losses in the capillary and slit rheometers are used to predict the elongational viscosities for axisymmetric and planar flows respectively. The power-law region of the axisymmetric as well as planar elongational viscosity is found to follow the time-temperature superposition principle.

Comparison of the Experimentally Observed TSE Melting Lengths with those Predicted from Simple Plastic Energy Dissipation Compressive Experiments (Part I: Experimental)
Costas G. Gogos, Bainian Qian, David B. Todd, Myung-Ho Kim, May 2002

In the last few years our group has demonstrated experimentally the dominant role which Plastic Energy Dissipation (PED) plays in the heating/melting of solid polymer (compacted) particulate beds in compounding processing equipment, such as twin screw extruders and counter-rotating continuous mixers/melters. We have also developed simple empirical methods of predicting the total axial distance in specific processing/compounding machines needed for melting as well as the melting rates, all based on the mechanical energy dissipated during solid particulate compression. This work explores how PED behavior of single-component polymers may affect the PED (and the melting) behavior of multi-component polymer blend.

Comparison of the Mechanical Performance and Crystallinity of Medium Density Polyethylene Films Manufactured on IBC and Conventional Blown Film Extrusion Lines
G. Milligan, A. Marks, G.M. McNally, W.R. Murphy, M. Leathem, May 2002

A range of films was manufactured from a medium density polyethylene (MDPE) resin of MFI 2.0 (g/10min) and density 0.94 g/cm 3 using a 75mm extruder fitted with a 290mm diameter Blown Film Die and a die gap of 0.9mm. The films were manufactured at different haul off rates and a constant blow up ratio of 1.24, using both conventional air ring and internal bubble cooling (IBC) systems. The line speed of the IBC extrusion line was approximately three times that of the conventional blown film line. Tensile analysis of the films at room temperature showed significant increase in break strength and break modulus in the machine direction for the IBC films, at all draw down ratios. Differential Scanning Calorimetric (DSC) analysis showed IBC quenched films to be more crystalline than the conventionally quenched blown films. The results also indicated the potential for significant down gauging of film thickness (by up to 25%), without reduction in film mechanical performance by using IBC systems in blown film extrusion processes.

Comparison of the Mechanical Properties of a Wood-Fibre and a MDF Polymer Composite
M. Billham, W.R. Murphy, G. Garrett, G.M. McNally, May 2002

Natural fibres at levels up to 20% have been used for years as fillers to improve the rigidity of polymers. In the past five years up to 60% wood sawdust has been used in a rapidly increasing wood polymer composite market, particularly in the US. A series of composites, using spruce sawdust and MDF sawdust at different levels, with three polypropylenes, have been produced using a single-screw extruder and an injection moulder. The impact energy, tensile and flexural strengths of these composites were measured. The results show significant differences between the impact, tensile and flexural strengths from two types of wood as well as the type of polypropylene.

Compatibilization of Poly(Phenylene Ether) and Polyamide-6,6 Blends by Functionalized Polystyrenes
Hui H. Chin, May 2002

Polymer blends of Poly(phenylene ether) (PPO) and Polyamide-6,6 (PA-6,6) remain an interesting subject for many researchers. In this paper the compatibilizing effect of a polystyrene, synthesized via controlled free radical polymerization and endcapped with an epoxy function in the immiscible blends of PPO and PA-6,6 was investigated. The properties being examined were notched Izod impact and tensile of injection molded parts. The morphology was also examined by scanning electron microscope. Results had shown that mechanical properties improved with addition of this compatibilizer.

The Complex Effects of Long Chain Branching on the Blown Film Performance of LLDPE Resins
Ashish M. Sukhadia, May 2002

Long chain branching (LCB) has long been recognized as an important molecular parameter that significantly influences both processing and property performance of polymers. In this study, we report on the effects of LCB on the blown film processing and performance behavior of both narrow and broad molecular weight distribution (MWD), linear-low density polyethylene (LLDPE) resins. The LCB was introduced by peroxide addition and by varying the finishing stabilization additives. The results showed that while improvements in some processing characteristics were observed with LCB addition, this generally came at the expense of physical properties. Thus, in contrast to the general belief in the literature, we contend that LCB addition in LLDPE type film resins involves a trade-off in improved processing at the expense of film properties.

Composite Films of Polypropylene from Post-Consumer Plastics Waste to Substitute Cellulose Paper
Ruth M. Campomanes Santana, Sati Manrich, May 2002

The aim of this work is to obtain composite films of polypropylene (PP) to substitute paper. The plastic component is PP from mineral water bottle (PPb) collected from municipal plastic waste (MPW) and the filler component is CaCO3. Composite films with weight ratio of PPb and CaCO3 (70:30) were prepared. These films were surface treated by corone discharge. Preliminary results have shown a good printability with pencil and pen ink on these films without treating and an improved printability with ink jet after surface treatment. These films were then compared to cellulose paper by physico-chemical characterizations.

Computer Aided Optimization of Extrusion Dies
Stefan Kaul, Walter Michaeli, May 2002

In an extrusion process polymer is melted and conveyed through the extrusion die. In the die the form of the melt is converted from a cylindrical into a requested cross-section of the profile. The primary objective of the rheological design of extrusion dies in polymer processing is to obtain an even melt velocity distribution at the outlet of the die. For a given complex cross-section of a profile, yet no procedure is known to calculate or predict the die flow channel geometry with respect to an even velocity profile at the outlet. By designing a complex profile extrusion die an iterative process has to be performed to optimize the flow channel.In this paper a new calculation method is presented which uses a combination of the Finite-Element-Analysis (FEA) and the 'network-theory'. With the aid of this method it is possible to accelerate the iterative optimization process for the design of profile extrusion dies. Furthermore, this method is combined with an optimization scheme based on the evolution strategy. The result is an algorithm to optimize the flow channels in extrusion dies automatically.

Computer Simulations of Crack Formation and Propagation in Two Phase Polymeric Materials
Witold Brostow, Ricardo Simões, António M. Cunha, May 2002

We have used computer simulations to study the phenomena of crack formation and propagation in two-phase polymeric materials. The simulated materials are subjected to constant-force tensile stress resulting in deformation. We use computer graphics to create animations of the cracking phenomena.We are trying to answer the key question where the cracks form: inside the flexible matrix, inside the rigid phase, or at the interface. Computer simulations provide answers to this and other questions which cannot be answered by conducting experiments.The results obtained guide us in the creation of real materials with improved mechanical properties.

Concurrent Engineering Based Mold Development
Goran D. Putnik, Miguel Ângelo S. de Lima, May 2002

In the “mold development” designation it is comprehended a process composed by the (sub)processes of the mold specification, contracting, design, planning, manufacturing, “in-field” service, etc. By the Concurrent Engineering (CE) principle, all these processes are performed simultaneously (with higher or lower degree) which reduces the mold development time, through the minimization of changes in the mold subprocesses procedures.The CE principles imply application of teamwork. These teams are composed by experts from different functional areas (for specific mold development subprocesses).It is presented a CE model based upon mold development processes to fulfill the increasing needs of design and mold making industry.

Considerations in the Roughness of the Molds Surface and the Molded Parts Utilized in Injection Molding
Alejandro Pereira, Primo Hernández, May 2002

The methodology of this work is based in the performance of tests to study the influence of the process parameters on the final properties of molded parts (roughness, Ra and Rz).First of all it was necessary to design and manufacture a mold to observe the roughness of different surfaces. EDM and turning were chosen as typical processes for injection mold machining.Finally some preliminary results are included, illustrating the dependence of the average roughness of the molded parts with respect to the machining process and injection molding conditions.

Constitutive Modeling of Crystallizable Shape Memory Polymers
I.J. Rao, May 2002

Shape memory polymers are novel materials that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. In this paper, we develop constitutive equations to model the thermo-mechanical behavior of crystallizable shape memory polymers. This is done using a framework that was developed recently for studying crystallization in polymers ([1],[2]). The constitutive equations are formulated in a full thermodynamic framework using the notion of multiple natural configurations. Here, we outline the main components of such a model and investigate its response for a crystallizable shape memory polymer undergoing a typical thermo-mechanical cycle. The results of the model compare favorably with experimental observations.

Control of State Parameters in Blow Moulding
R. DiRaddo, P. Girard, I. Laroche, May 2002

The blow moulding industry has achieved a good understanding of the process, which has been in large scale operation since the 1960's. Consequently, control of machine settings such as heater band temperatures, die gap position, die and mould temperatures is quite advanced. However, to date, little work has been done to address the control of state parameters describing material behaviour during processing, such as parison weight and temperature distribution. Control of state parameters is essential as material property changes, environmental factors and machine operating drifts can significantly change the dynamic operating point of the machine.

Controlling Warpage for the Decorating and Assembly of Plastic Parts
Jordan I. Rotheiser, May 2002

Nothing is more frustrating to decorators and assemblers of plastic parts that attempting to perform these functions with parts that are warped and out of specification. Injection molding is the process used to produce the bulk of these parts. There are three principal causes of warpage in injection molded parts: differential shrinkage, internal stresses and distortion resulting from ejection of the part from mold. Often, two or three of these conditions exist simultaneously, thereby complicating the solution significantly. This paper discusses the causes of these conditions and the means to control them through design.

Cooperative Development of Moulds and Parts
Joaquim Menezes, Rui Soares, Pedro Rocha, May 2002

With the emergence of today’s new geography model, where the omnipresent electronic place coexists with the physical one, the challenge is now to take advantage of the available technology to build and coordinate efficient and innovative business relationships, in order to draw strengths from the diverse and worldwide distributed knowledge, experience, expertise and competencies.In July 1998, an international consortium was established between three SME’s, two research and development institutes and one governmental organization. Six organizations from four different countries (Portugal, Germany, Mexico and People’s Republic of China) united by a shared goal: the development of the project “Round the Clock – 24 Hours Collaborative Product Development Work”[1].The basic idea, behind the project conceptualization was to take advantage of the time gap between the several organizations located in different time zones, for the establishment of a continuous non-stop product development cycle at a planetary scale based on the suitable use of a communication platform and coherently supported by an efficient work methodology.

Copolymers of Ethylene and a Highly Branched Unsaturated Comonomer
Juliana D. Rego, Maria de Fátima V. Marques, May 2002

The diversity of possible structures in copolymers of ethylene and a wide variety of comonomers provides an interesting field for research.Low-density polyethylene exhibits special properties not yet surpassed by other polymers such as linear low-density polyethylene.In this work, a highly branched unsaturated comonomer (HBU) was synthesized and copolymerized with ethylene by using Et(Flu)2ZrCl2/MAO catalyst system. Reactions were performed in a 500ml autoclave equipped with mechanical stirrer. Toluene and MAO were added to the reactor under nitrogen atmosphere. Ethylene was introduced until constant pressure of 2 bar at 90°C. Catalyst activity and polyethylene characteristics were evaluated and compared to LDPE. The results showed that the catalyst activities for the copolymerization were surprisingly higher when compared to the homopolymerization of ethylene and in the same order of magnitude of the copolymerization with 1-octene.







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