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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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.
MODIFICATION OF BIOPOLYMERS, ESPECIALLY POLYLACTIDES, FOR TECHNICAL APPLICATIONS
Next to the established packaging market the interest for biopolymers in technical application increases more and more. Especially automotive industry is interested in substituting oil-based polymers with biopolymers. In view of that, the focus of the work described here was on optimization of injection molding of polylactide (PLA) in order to improve material performance for technical applications. Furthermore, the effects of poly-D-lactide (PDLA) as nucleating agent, fibers and modifiers on material properties (e.g. heat resistance, mechanical properties) are reported.
DEVELOPMENT OF A CHANGEABLE MANUFACTURING SYSTEM FOR THE PRODUCTION OF THERMOPLASTIC FUCTIONAL ASSEMBLIES
New and innovative production systems are required in order to withstand the growing pressure of costs and competition in the plastics processing industry. Changeable manufacturing systems are one potential solution. These enable companies to adjust to repeatedly changing market conditions by themselves. At the University of Kassel's Institute of Materials Engineering, a changeable production system has been developed which is specially tailored to the requirements of plastics processing. The potential and limits of a changeable system for plastics processing are to be established on the basis of the pilot plant that is currently under construction.
STUDY ON THE EFFECT OF VARIOUS WF, GF AND POLYMER TYPES ON CHARACTERISTICS OF DIRECTIONAL COMPRESSION MOLDED WPC AND COMPARISON WITH PROFILE EXTRUDED WPC
A compression molding system was custom built to impart directional flow properties in Wood plastic composites (WPC). Wood fiber (WF) and glass fiber (GF) of two different fiber lengths and HDPE of two different melt flow index (MFI) was used as matrix polymer to study their effect on mechanical properties of WPC. Tensile strength and flexural strength of the composites were determined. Experiments were also carried out to compare flexural strength of profile extruded and compression molded WPC with various WF contents to understand changes in mechanical property. The paper presents these results and compares with each other.
INFLUENCE OF PROCESSING CONDITIONS ON THE THERMOFORMABILITY OF PP-SHEET MATERIAL
The quality of semi-finished products, as they are used in thermoforming, highly depends on the raw material used and their processing history. As a consequence, variations in sheet quality are often observed with their influence on processibility and product properties. Currently, there is no standard test for thermoforming sheet materials available, which means it is not possible to accurately predict how a material will behave in thermoforming. This study deals with the prediction of the thermoformability of sheet materials. A novel test method (Thermoforming Material Characterization TMC) to predict thermoformability is presented.
IN VITRO DEGRADATION OF LACTIDE BASED POLYMERS AND COPOLYMERS
This study evaluates the in vitro degradation of scaffolds and films prepared from lactide based polymers and copolymers. The materials studied were poly(L-lactide)(PLLA), poly(DL-lactide)(PDLLA), a poly(L-lactide/æ-caprolactone) copolymer (PLCL) and a poly(DL-lactide/glycolide) copolymer (PLGA). The effect of the addition of bioactive particles such as hydroxyapatite and bioglass in the degradation kinetics was also investigated. It was found that the degradation in cast films was faster than the degradation in porous scaffolds; in addition, bioactive particles delayed the degradation of polymers studied.
IMPROVING INTERFACIAL ADHESION IN WOOD PLASTIC COMPOSITES
The aim of this work was to improve the interfacial adhesion between the matrix and the wood particles in polypropylene based wood plastic composites with the addition of chemical agents at the wood particle surface. We found, that with the addition of rather small, linear molecules, e.g. e-Caprolactone, interfacial adhesion, and therefore tensile strength, was improved up to 10% additionally to the benefits of a common maleic anhydride based compatibilizer. Furthermore, we found that also the chemical composition of the molecules added at the surface shows an influence at the extent of the improvement.
EFFECT OF AGING ON MECHANICAL BEHAVIOR OF A BIODEGRADABLE POLY(LACTIDE-CAPROLACTONE) COPOLYMER
Poly(L-lactide/æ-caprolactone) (PLCL) was physically aged at 36§C and 40% of relative humidity (RH) to study the evolution of its structure and mechanical properties with time. Samples with an initial amorphous PLCL matrix, obtained by fast quenching from the melt were characterized before and during aging. The changes in structure and mechanical properties were studied using differential scanning calorimetry (DSC), X-Ray diffraction (WAXS) and tensile tests. As a result of aging, PLLA crystals were formed within the multiblock copolymer prompting to an increase in stiffness and to a loss of its elastomer-thermoplastic behavior of PLCL.
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