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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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Conference Proceedings
PREDICTION OF POLYPROPYLENE LONG-TERM CREEP BASED ON A SHORT-TERM TESTING
W. Zhou, A. Chudnovsky*, A. Doufas** and R. Andrekanic, May 2010
A method for prediction of polypropylene long-term creep behavior is proposed based on mirror symmetry between stress vs strain rate in ramp tests and stress vs. ductile-failure-time tf in creep. Such methodology has been previously proposed for polyethylene on the basis of power law creep behavior of polyethylene. Here we use more general approach based on Zhurkov-Eyring model that relates strain rate, stress and temperature with help of parameters having physical meaning such as activation energy of the process. The prediction of long-term creep of polypropylene is made based on the tensile ramp tests with variable strain rate and a short-term tensile creep testing. An analysis of the proposed methodology in view of the set of experimental data is presented. Validation of long-term creep predictions based on the short-term testing by comparison with conventional long-term creep data is discussed.
EVALUATION OF ENVIRONMENTAL STRESS CRACKING RESISTANCE IN POLYETHYLENES: BENT STRIP VS. CONSTANTTENSILE- LOAD METHODS
Franco Guastaferro Preda , Delia de Jesús , Johan J. Sánchez, May 2010
For a group of 14 polyethylenes (PE) with different densities (0.924 to 0.966 g/cm3) and melt flow index MFI (0.38 to 42 dg/min) the Environmental Stress Cracking Resistance (ESCR) of each PE was determined by the typical method of bent strip or ESCR at constant strain. The results were compared with those obtained by the evaluations of ESCR by constant-tensile-load method. For both methods the effects of the density and MFI on ESCR were similar and in agreement with those reported in the literature. However the failure time spread measured in the ESCR at constant load is smaller although both methods lead to high experimental errors attributed to limitations or omissions in the experimental protocols described in the standards used for these measurements.
EVALUATION OF ENVIRONMENTAL STRESS CRACKING RESISTANCE IN POLYETHYLENES: BENT STRIP VS. CONSTANT-TENSILE-LOAD METHODS
Franco Guastaferro Preda , Delia de Jesús , Johan J. Sánchez, May 2010
For a group of 14 polyethylenes (PE) with different densities (0.924 to 0.966 g/cm3) and melt flow index, MFI (0.38 to 42 dg/min), the Environmental Stress Cracking Resistance (ESCR) of each PE was determined by the typical method of bent strip or ESCR at constant strain.The results were compared with those obtained by the evaluations of ESCR by constant-tensile-load method. For both methods the effects of the density and MFI on ESCR were similar and in agreement with those reported in the literature. However, the failure time spread measured in the ESCR at constant load is smaller, although both methods lead to high experimental errors, attributed to limitations or omissions in the experimental protocols described in the standards used for these measurements.
CALCULATION OF THE ACTIVATION ENERGY FOR SELF DIFFUSION
Mark D. Wetzel, May 2010
The bonding of semicrystalline polylactic acid (PLA) films was investigated for a broad range of temperatures and contact times above the glass transition temperature in a lap shear joint geometry using an impulse welding system. It was observed that interfacial strength was linearly dependent on the fourth root of welding time until it approached the bulk material strength. Using models based on reptation therories the interfacial strength of lap shear welds was estimated based on thermal histories. In more detail, the activation energy for interfacial healing and self diffusion coefficient were calculated based on shear strength measurements of samples welded with well defined thermal histories. The parameters were then used to predict interfacial strength with varying temperature histories.
INSTRUMENTATION AND CONTROLS INVENTIONS AND INNOVATIONS IMPACTING THE POLYMER PROCESSING INDUSTRY
Mark D. Wetzel, May 2010
The processes to compound and shape polymeric materials into a wide variety of products have made significant and prolonged global economic impacts and have provided enormous societal benefits. Since the advent of the plastics industry many key enabling inventions and innovations in instrumentation and control system technology have been made that engineers now may take for granted. This paper reviews the development and commercialization of several examples of sensing actuation and control methods that are critical in extrusion compounding and other polymer processing operations.
FOAMING PROCESS AND DAMPING CAPACITY OF BELL STRUCTURE
Minoru Shimbo , Shirei Koshida , Akihiro Misawa, May 2010
This study has examined the forming process and its characteristics of bell structures with the use of batch type foaming that the blowing agent of a supercritical fluid was used. In this study, various forming methods have been tried for bell structures together with a series of impact tests and acoustic tests of the structures, followed by evaluation of shock absorption and sound insulation for inclusion of particles. The trial succeeded in forming the bell structures including steel balls by means of batch type foaming. It was also verified that these bell structures exhibit required shock absorption and sound insulation performance.
WATER VAPOR TRANSPORT PROPERTIES OF SHAPE MEMORY POLYURETHANE NANOCOMPOSITES
I. Sedat Gunes , Feina Cao , Sadhan C. Jana, May 2010
In this paper water vapor permeability (WVP) of thermoplastic polyurethane nanocomposites with crystalline soft segments was evaluated. Organoclay nano-size silicon carbide (SiC) and a high structure carbon black (CB) were mixed with shape memory polyurethane (SMPU) based on semi-crystalline soft segments. All nanocomposites were prepared by bulk polymerization using a Brabender internal mixer. Compression molded specimens were used in the determination of WVP. The results indicated that the presence of silicon carbide augmented WVP by reducing the soft segment crystallinity whereas that of organoclay reduced the WVP considerably due to excellent exfoliation.
WATER VAPOR TRANSPORT PROPERTIES OF SHAPE MEMORY POLYURETHANE NANOCOMPOSITES
I. Sedat Gunes , Feina Cao , Sadhan C. Jana, May 2010
In this paper, water vapor permeability (WVP) of thermoplastic polyurethane nanocomposites with crystalline soft segments was evaluated. Organoclay, nano-size silicon carbide (SiC), and a high structure carbon black (CB) were mixed with shape memory polyurethane (SMPU) based on semi-crystalline soft segments. All nanocomposites were prepared by bulk polymerization using a Brabender internal mixer. Compression molded specimens were used in the determination of WVP. The results indicated that the presence of silicon carbide augmented WVP by reducing the soft segment crystallinity, whereas that of organoclay reduced the WVP considerably due to excellent exfoliation.
REVIEW OF PE PIPE LIFETIME PREDICTION BASED ON PENT TEST
I. Sedat Gunes, Feina Cao, Sadhan C. Jana, May 2010
A new method of evaluating polyethylene (PE) pipe brittle failure time has been recently proposed. The method consists of an extrapolation of the failure time in standard PENT test to brittle failure time of PE pipes of arbitrary diameter and wall thickness at various loads and temperatures. The method is based on several assumptions that have not been adequately addressed in [1]. This paper presents a detailed review of the theoretical and experimental basis of the extrapolation proposed in [1] and reveals its limitations. A fracture mechanics analysis of the PENT test is presented. It requires evaluation of parameters in power law" equation of the slow crack growth (SCG). Thus a specimen whose stress intensity factor (SIF) is independent of crack length has been used to serve this purpose. Such specimen allows an accurate determination of crack growth rate vs. SIF relationship and thus predicts the duration of SCG stage of brittle fracture process at various temperatures. The study indicates that the formula proposed in [1] can be used for materials ranking with respect to SCG resistance within a limited temperature range but is inadequate for estimation of lifetime in brittle fracture."
INFLUENCE OF PROCESSING PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF A POLYETHERIMIDE JOINED BY FRICRIVETING: INVESTIGATION OF ROTATIONAL SPEED
Sergio T. Amancio Filho , Jorge F. dos Santos, May 2010
FricRiveting is a new and promising spot joining technique for polymer-metal structures recently introduced at ANTEC 08. It is well known that processing in joining technology plays a central role in dictating joint properties and so understanding it is important for producing reliable connections. Rotational speed is an important controlling parameter in FricRiveting. This study experimentally determines the influence of rotational speed on FricRiveting’s joint microstructure local and global strength and thermal history for a thermoplastic polyetherimide joined by threaded aluminum rivets.
INFLUENCE OF PROCESSING PARAMETERS ON MICROSTRUCTURE AND PROPERTIES OF A POLYETHERIMIDE JOINED BY FRICRIVETING: INVESTIGATION OF ROTATIONAL SPEED
Sergio T. Amancio Filho , Jorge F. dos Santos, May 2010
FricRiveting is a new and promising spot joining technique for polymer-metal structures, recently introduced at ANTEC 08. It is well known that processing in joining technology plays a central role in dictating joint properties and so understanding it is important forproducing reliable connections. Rotational speed is an important controlling parameter in FricRiveting. This study experimentally determines the influence of rotational speed on FricRiveting's joint microstructure,local and global strength, and thermal history for a thermoplastic polyetherimide joined by threaded aluminum rivets.
CURE KINETICS OF POLY (PHENYLENE ETHER)/EPOXY RESIN SYSTEM
Yu Pin Tsai, , Chi Feng Hsu, Ray Quen Hsu, May 2010
The cure kinetics of poly(phenylene ether)/epoxy resin (PPE/EP) cure system was investigated by using an advanced isoconvensional method (AICM). The curing experiments of PPE/EP cure system with different PPE/EP ratios were carried out by means of nonisothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20 oC/min. From the DSC curves it can be shown that the curing mechanism of PPE/ER is so complicated that PPE content effects most cure kinetic parameters. A variation of the effective activation energy with the extent of conversion was obtained by AICM and analysized.
STUDY ON THE IN-MOLD PUNCHING OF THE THERMOPLASTIC INJECTION MOLDING
Yu.Pin Tsai , Chi Feng Hsu , Ray Quen Hsu, May 2010
An in-mold punch device was designed; the shear break mechanism was installed in the position of the holes of the product. The surface of the product is integrated during the plastic injection forming process; therefore, no appearance defect like weld lines will occur. Experimental results showed that lower processing temperature and faster shear velocity are helpful to reduce the difference between the punch dimension and the hole dimension. The shorter cooling time is advantageous for the product shrink; while if the point is the smoothness of the circular hole; the correct way is to enhance the punch velocity and prolong the cooling time.
COMPONENT MICRO - INJECTION MOLDING TECHNOLOGY FOR MANUFACTURING OF HIGH PRECISION MICRO PARTS: A SYSTEMATIC PROJECT APPROACH
R.A. Morales, M. V. Candal, May 2010
The project set itself the goal of the new possibilities of micro-injection molding of shotweight-optimized two component micro parts in regards of quality, flexibility and cost, including in-line measurement and testing with the stages of assembly, handling and logistics in the territory of the production of micro-optical systems. Based on the new machine concept of a two-component micro ƒ?? injection machine (2C-?¬IMM) a flexible and compact example of supply chain for the production of reliable optical systems were developed. The process chain contains the technologies of high precision micro injection molding technology, quality-control by optical control and geometric dimension and shape measurement, separation procedures of the runner and further assembly steps. A process-handling technology with special grippers combines and automates the individual process steps. An optoelectronic sensor, and an application with microfluidic functions for Biotechnology (so called Demonstrators) were selected to test the developed system. In both cases, all stages of product development from product design to be included on replication by injection molding, assembly and integration of handling opereations of the components had to be evaluated. The development of a scalable manufacturing technology for both examples is essential, and will be pursued as a priority. The project provides a variety of results: A novel, multiflexible manufacturing plant for the production of future-oriented products, innovative individual modules, new and improved production methods and advanced microoptic products.
NAVIGATING SYSTEM FOR HOT-RUNNER DESIGN WITH KNOWLEDGE MANAGEMENT
Shyh-shin Hwang, Ching-hsin Hu, Hon-Jen Sung, Peming Hsu,, May 2010
Hot-runner is getting more popular in injection molding process especially for the high surface-quality product. This work is to develop a navigating system for the hot-runner design with knowledge management. This web-based system provides step-by-step functions to guide the user through the sub-processes of product specification, manifold design, component assembly, spacer design and cylinder plate. Moreover, the knowledge database provides easy access of standard components which can be assembled automatically or semi-automatically. The system can provide the proven 3D hot-runner design with much shorter time.
EFFECT OF ORGANOCLAY ON THE MECHANICAL / THERMAL PROPERTIES OF MICROCELLULAR INJECTION MOLDED PBT-CLAY NANOCOMPOSITE
Shyh-shin Hwang , Ching-hsin Hu , Hon-Jen Sung, May 2010
An organically modified montmorillonite (MMT) was compounded with Polybutylene Terephthalate (PBT) in a twin-screw extruder. The organoclay PBT nanocomposites were then injection molded by conventional and microcellular methods. Nitrogen was used as the blowing agent. The effect of organoclaycontent, organoclay size (8 and 35 ?¬m), and speed of thescrew (80 and 100 rpm) on the mechanical and thermal properties were investigated.The results showed that when the MMT content was 1.0 wt%, the nanocomposites have maximum tensile strength, wear resistance, and cell density. Moreover, the larger the particle size, the greater the tensile strength. The screw speed during compounding also affected the mechanical strength. The higher speed of the screw increased the tensile strength of the nanocomposites. The addition of MMT also helped the thermal stability of the PBT/Clay nanocomposites. The WXRD results showed that when MMT loading is 1.0 wt%, the nanocomposites have maximum d-spacing structure. TEM results showed that MMT is well dispersed on the nanocomposites at a MMT loading of 1 .0 wt%.
DESIGN AND THEORETICAL ANALYSIS OF MINI-PLUNGER SPRAYER USED IN SW2502 FUSED DEPOSITION MODELING RAPID PROTOTYPING SYSTEM
Paul Mills, May 2010
The fused deposition modeling rapid prototyping system is based on the manufacturing principle of layer by layer. The sprayer is the key component. Based on the polymer rheological properties, the structure design and theoretical analysis of the mini-plunger sprayer of SW2502 fused deposition modeling system are studied. The plasticizing capacity of the mini-plunger sprayer is analyzed in theoretically. It is very important for the fused deposition modeling process to maintain a stable plasticizing capacity. The driving force of ABS feed is related to several parameters such as structure form of sprayer and material property, etc. The barrel and nozzle design should be fit for mobility, purity, and mechanical property of ABS feed. The modified ABS feed adopts self-pressure-adding driving method to decrease the pressure losses of barrel and nozzle. The plasticizing capacity of the sprayer is more than 20g/h.
PROCESSING COSTS AND ENVIRONMENTAL IMPACT OF BIO-PLASTICS
Julius Vogel , David Grewell , Rob Anex, May 2010
This work studied bio-plastics such as polylactic acid (PLA) and protein based plastics form corn and compared to petroleum based plastics such polyethylene (PE) and polystyrene in terms of their ecological as well as economical performance from a “Cradle to Grave” perspective. This study included energy input emissions output of green house gases and costs from their life cycle steps of raw material acquisition to the final product disposal. It was found that products manufactured from bio-based feedstocks were relatively higher in cost they resulted in less green house gas emissions.
VIRTUAL SIMULATION OF TOP LOAD PERFORMANCE OF PLASTIC BOTTLES
Art Schubert, May 2010
A novel analytical computational model was developed to predict Top Load and Side Load performance of oval containers. The performance of oval and other non round containers is dependent on the thickness distribution achieved during blow molding. Simulating blow molding and performance of containers using Virtual Prototypingƒ?› Software and feeding the input for Finite Element Analysis provides an accurate mechanism to predict container performance. A 24oz. generic oval container with aspect ratio of 1.58 was simulated for empty and filled top load performance. A critical part of blow molding oval containers is the ability to achieve a more uniform thickness profile along the circumference of the container at any given height. This isachieved by using preferential heating where the infra-red?ÿ heating ovens have special slotted reflector plates that allow the preform to be heated differently 90?ø apart. For the 24oz. oval container with a high aspect ratio it was observed that the use of preferential heating is necessary to achieve uniform thickness distribution in the range of 0.3mm-0.4mm. A non preferentially heated preform resulted in container thickness being 0.4-0.6mm in a concentrated region adjoining the minor axis. The preferentially heated performs resulted in containers having better empty and filled Top load. The side grip load was the only performance characteristic that was higher for the non preferentially heated containers but that works only in a small region and the non uniformity of thickness makes the container not aesthetically pleasing and would not be acceptable in a production process due to inconsistency in material distribution.
EPOLYPROPYLENE - CUP CONVERSION FROM INJECTION MOLDING TO THERMOFORMING
Piaras de Cléir, May 2010
Food containers such as cups can be made by injection molding (IM) or thermoforming (TF). Typical materials are high density polyethylene (HDPE) polypropylene (PP) and high impact polystyrene (HIPS). For many years the preferred choice for polypropylene cups was IM because it produces a high quality part with excellent part-to-part consistency. Conventional TF to make similar containers in PP results in wider dimensional tolerances. On the other hand in-line trimin- place thermoforming overcomes many of the limitations of conventional TF and allows for the production of high quality containers. This paper outlines the conversion from IM to trim-in-place for a 235-ml cup and compares the physical properties of cups from each process.


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