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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SIMULATION AND VERIFICATION OF GAS-ASSISTED INJECTION MOLDING ON HOLLOWED CORE RATIO OF SPIRAL TUBE
The hollowed core of the part is a very important property for understanding gas-assisted injection molding. In this study, the spiral tube mold was utilized to investigate thickness ratio of the hollowed core. The process parameter effects are explored on thickness ratio of the hollowed core. Both the experiments and simulations were compared for verification. The results indicate that the thickness ratio of the hollowed core increases with the increased melt temperature and gas pressure. However, the increase in delay time reduces the thickness ratio of the hollowed core. The experimental results are in good agreements with those in simulations.
CHARACTERIZATION OF CRACK INITIATION AND SLOW CRACK GROWTH IN POLYETHYLENE WITH CYCLIC CRACKED ROUND BAR TESTS
With the purpose of an accelerated material ranking cyclic test with cracked round bar (CRB) specimens at ambient temperatures of 23C were carried out with eight high density polyethylene materials. Although testing times of only about one week per material were needed, a ranking of the results was in good correlation to Pennsylvania Notch Test (PENT) data. Additional measurements of the crack opening displacement provide further options for investigating the resistance of the materials against crack initiation.
EFFECTS OF THE PROCESSING HISTORY ON THE CRACK KINETICS IN A POLYETHYLENE PIPE GRADE
A PE 80 pipe grade was investigated in order to analyze the impact of morphological variations related to the process history of a material. Specimens were manufactured from a compression molded plate as well as from an extruded pipe. Morphological characterizations were carried out by Differential Scanning Calorimetry and by Dynamic Mechanical Analysis. A measurement of the crack kinetics for a lifetime assessment based on concepts of Linear Elastic Fracture Mechanics was conducted with cyclic tests on Cracked Round Bar specimens at different R-ratios (min. load/max load). The results of the cyclic tests reflected the morphological influence on the lifetime.
STUDY ON RHEOLOGICAL BEHAVIOR OF ULTRA HIGH SPEED INJECTION MOLDING
In this study, the high-speed experiment was conducted to verify moldex3D simulation technology. Mold and melt temperature were kept at 200, 215 and 230 C in the maximum injection pressure condition. The experimental method changed the injection speed from 100 to 1500 mm/s and obtained the pressure drop and flow rate. The experimental results were calculated using some equations and compared with Moldex3D simulation results. Both simulation and experimental results demonstrated that the second Newton area appears starting from 1000 mm/s injection speed. With the increase of melt and mold temperature, the shear rate increases and the viscosity value decreases.
MECHANICAL PROPERTIES OF FUSED DEPOSITION MODELING PARTS MANUFACTURED WITH ULTEM*9085
In this work the influence of the orientation and the toolpath generation of manufactured parts based on the mechanical data are analyzed. Tensile Specimen are generated with the given parameters as well as with changing parameters of the native software based upon the CAD data. The parts then are built up with the Fortus 400mc from Stratasys. First tensile tests show different strength and strain characteristics that depend on the given structure and as a result of the build direction. The influence of the parameters was analyzed with a statistic test method by using the software Design Expert.
NOVEL NANOCOMPOSITES OF MOISTURE SENSITIVE POLYMERS AND BIOPOLYMERS WITH ENHANCED PERFORMANCE FOR FLEXIBLE PACKAGING APPLICATIONS
EVOH, PA, PVOH and, since more recently, some biopolymers are materials with broad application in high barrier packaging due to transparency and superior oxygen barrier. However, these materials suffer from strong plasticization in properties due to sorption of moisture, which handicaps their application under high moisture conditions such as those applied in many packaging cases. This paper shows the development of novel nanocomposites based on a kaolinite grade, commercially marketed as O2Block‹Ÿ?, which exhibit enhanced UV and gas barrier and decreased water permeability and sensitivity.
IMPROVEMENT ON THE MECHANICAL PROPERTIES OF CORK COMPOSITES USING SUBERIN AS COUPLING AGENT THROUGH A REACTIVE EXTRUSION PROCESS
New functionalized composite structures were prepared using low-density polyethylene (LDPE), cork powder and different suberins extracted from cork and birch outer bark as coupling agents to promote interfacial adhesion. The compounding was performed under reactive extrusion and samples processed by compression moulding. The morphology of the functionalized composites showed good adhesion between cork and the polymeric phase. The mechanical results confirm that the addition of suberin acts as coupling agent improving the strength and leads to cork-polymer composite materials with improved strain and lower modulus. When the suberin was added to the composition a slight increase on composite density occurred.
GAS-ASSISTED HEATING TECHNOLOGY USING IN HIGH ASPECT RATIO MICRO-STRUCTURE PARTS OF INJECTION MOLDING
In this study, hot gas is used for heating the cavity surface. Different mold gap sizes were designed. Mold surface temperature was heated to above glass transition temperature, then, the mold will closed for melt injection. The cavity surface can be heat to 130oC for assisted the melt filling at micro feature. Hot gas heating can improve the filling process and achieve 91% the high aspect ratio micro groove (about 640.38 m of the maximum of 700 m). It was found that the mold gap size can affect the heating speed and heating uniformity.
ON-LINE OPTIMIZATION OF INJECTION MOLDING
An auxiliary controller was designed, implemented, and validated for on-line process and quality optimization. The architecture relies on a multivariate process model to perform optimization interleaved with the molding process. Two different experiments investigated the controller's ability to adjust the process subject to material and cycle time variances. In every case, the controller was able to reduce the value of the objective function while also improving the part dimensions relative to tight tolerance specifications. The use of a process model greatly speeds convergence and facilitates the consideration of various cost and quality terms in the objective function.
EXTRUSION INSTRUMENTATION AND CHARACTERIZATION
A tubing extrusion process was heavily instrumented and the resulting process signals acquired. A design of experiments (DOE) was conducted for nine different factors. Three different models were developed based on DOE factor settings, thirteen process signals, and a combination of six process and ƒ??virtualƒ? states. The latter model had the highest fidelity, far surpassing the predictive capability of the DOE factor-based model. The results indicate that current practice of monitoring melt temperature and pressure should be augmented to tightly control the air pressure, free length between the die and the water bath, puller speed, and melt viscosity.
EFFECT OF LLDPE CONTENT ON HEAT SEAL PROPERTIES FOR HDPE/LLDPE FILM
HDPE compounded with 0 to 20 wt % LLDPE was cast into film. Heat seal tests were carried out for the film. The bar temperature was controlled at 123 and 125 ?§C. The seal time for applying heat and pressure was varied from 0.5 to 1.5 sec. The molecular structure developed during the heat seal process was evaluated by DSC and WAXD and relationships were studied against heat seal strength measured by T-peel test. By compounding LLDPE, heat selability at lower temperature was realized. Actually less than 3 wt% LLDPE affected heat seal properties due to preventing crystallization of HDPE.
ACOUSTIC TRANSMISSION PROPERTIES OF PLASTICS COMPOUNDS
The acoustic properties of plastics compounds are an important consideration for many industrial applications. One such property of particular interest is the sound transmission loss(STL). Currently there is no standard test for this but there is a standard method for the determination of sound impedance and absorption. The equipment used for this standard can, however, be adapted to measure the sound transmission property. The presentation will describe the initial results on a project that is evaluating the test method for STL and some of the relationships between the STL and the physical structure of materials will be discussed.
COLOR MEASUREMENT OF IRREGULAR SHAPED OBJECTS
Conventional color spectrometry involves measurement of opaque, translucent or transparent objects. The ideal sample is regular, flat, opaque, stable and a matte surface finish. Customers samples fall short of this rigorous description. The colorist has information that does not adequately represent the sample. The colorist is forced to make acceptance, quality and processing decisions regarding the color appearance of objects. There is a tremendous gap between the color appearance of objects and the desired color appearance. This is a primary cause for unanticipated costs, poor customer relations, customer returns, and less than expected sales.
STRUCTURE AND MORPHOLOGY OF NYLON 6 FIBERS PRODUCED BY NOZZLE-LESS ELECTROSPINNING
Electrospinning is a fiber spinning technique based on the utilization of electrical forces to draw polymer solution jets into fine fibers. As an approach to increase fiber production rate and fabricate fiber mats with large surface areas, the technique of nozzle-less electrospinning has been developed. During nozzle-less electrospinning, numerous electrified polymer jets eject from the surface of a charged electrode. Focus of the study is to examine the internal structures associated with electrospun fibers spun by the nozzle-less setup and to highlight the unique differences between the nozzle-less and nozzle based electrospinning system.
PROPERTIES OF PC-ABS-MULTIWALL CARBON NANOTUBE COMPOSITES
In our research we focus on thermoplastic composites of multiwall carbon nanotubes. Different composition of multiwall carbon nanotube and polymers were produced by a special mixing unit called Infinitely Variable Dynamic Shear Mixer (IDMX). ABS and polycarbonate polymers were used as matrix materials. Concentration series were manufactured and investigated. The prepared materials were characterized by scanning electron microscopy, mechanical and thermal properties of the materials were also determined. Correlation was found between the yield stress and the nanotube content.
SUSTAINABILITY IN REINFORCED AND UNFILLED POLY (PHENYLENE-ETHER) BASED THERMOPLASTIC ELASTOMERS
Recycling of unfilled and reinforced poly (phenylene ether) (PPE) based thermoplastic elastomers (TPEs) was studied in detail. Improvement in mechanical properties upon recycling of the unfilled quaternary blend comprising of styrene-ethylene-butyllene-styrene (SEBS)/ethylene vinyl acetate (EVA)/PPE-PS (polystyrene) was correlated with the formation of crosslinked network. PPE based TPEs have been reinforced by incorporating nanofillers and with the formation of crosslinkinked TPEs or thermoplastic vulcanizates (TPVs). This study also provided an in-depth conceptual understanding of the recycle behavior PPE based TPE behavior upon reinforcement with silica nanoparticles and silica sol-gel precursors.
DEVELOPMENT OF AN APPARATUS FOR MEASURING NORMAL ADHESION FORCE DURING TPU INJECTION MOLDING PROCESS
In integrated circuit (IC) packaging encapsulation, epoxy molding compound (EMC) adheres to mold surface after curing process. This phenomenon is called mold adhesion effect and it happens not only to thermosetting material but also to thermoplastic material. In this study, a mechanism designed with a mold that could measure normal adhesion force in injection molding process was successfully developed. The apparatus quantified the normal adhesion force. So engineers can use the measured adhesion force to understand the effectiveness of mold release agent and adhesion release coating.
THERMO AND PHOTO OXIDATIVE BEHAVIOR OF POLY (PHENYLENE ETHER) BASED THERMOPLASTIC ELASTOMERS
The present work describes the thermo and photo-oxidative behavior of a series of novel thermoplastic elastomers (TPEs) from styrene-ethylene-butylene-styrene (SEBS), ethylene vinyl acetate (EVA) and poly (phenylene ether) PPE polystyrene (PS). A representative composition (based on the mechanical performance) of the quaternary blend was exposed at different temperatures for 2000 hours. Thermal degradation profiles of change in tensile strength and percent elongation at break of blends were monitored and half-life temperature was estimated based upon tensile strength. Photo-oxidative degradation was monitored through optical and mechanical measurements on the injection molded TPE. Change in chemical functionalities was monitored using ATR-FTIR.
STUDY ON MISCIBILITY OF PC/POLY(BUTYLENE ADIPATE-CO-TEREPHTHALATE) BLENDS
Polycarbonate (PC) and poly(butylenes adipate-co-therephthalate) (PBAT) were melt blended using twin screw extruder. The phase morphology of PC/PBAT blends were observed by scanning electronic microscopy (SEM), indicated a homogeneous phase structure. The dynamic mechanical analysis revealed that there is shift of two tan ?? toward each other. It is thought that this is result from transesterification occurred in molten state. Also, thermogravimetric analysis showed that the thermal stability of PC/PBAT blends increases as PC contents increases. It suggests that PC can improve the thermal properties of PBAT in overall compositions.
THERMAL AND MECHANICAL PROPERTY OF PLA STEREOCOMPLEX WITH IMPACT MODIFIERS
Polylactide, polyester derived from renewable resources, can be synthesized using either L-lactide or D-lactide. A unique crystallization behavior of poly(L-lactide) (PLLA)/poly(D-lactide) (PDLA) stereocomplex(SC) was observed when a PLLA/PDLA blend was subjected to the specific melting conditions. Therefore, we tried to blend PLLA and PDLA at overall compositions to form PLA stereocomplexes. Moreover, impact modifier was added to enhance the mechanical properties such as impact strength. The presence of the SC in the PLLA matrix was verified by differential scanning calorimetry (DSC). Thermal and mechanical property of stereocomplexes were investigated by DSC, HDT, Izod impact tester, UTM.
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