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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
THE RELATIONSHIP BETWEEN PROCESSING-THERMOMECHANICAL ENVIRONMENT AND STRUCTURE ON INJECTED FLAT PARTS
S.L. Villarroel , R.A. Morales , A. Gordillo , M. Sánchez-Soto, May 2008
The microstructure of an injection moulding polypropylene part has been varied through systematic changes on the process conditions. The specimens were mouldedmodifying the holding pressure mass caudaland gate design. The skin-core structure was characterized by polarized light microscopy. The thermo mechanical environment imposed during processing was characterized using simulation commercial software.From the mould filling stage two thermo mechanical indices were calculated. The results show the relationship between these indexes and the micro structural features obtained in the moulded specimens
TOWARDS QUALITY PRODUCTS FROM BIO-BASED PLASTICS
Rolf Koster, May 2008
The importance of three inter-dependent factors i.e. (1) materials (2) manufacturing and (3) design and engineering is generally recognized. All factors are indispensable and equally important for product development. Manufacturing is often the least structured factor and many designers and materials experts do not consider themselves capable to deal with it. Fortunately expertise is sufficiently available and the best professionals are able to utilize plastics expertise properly in collaborative product development. For bio-based plastics which are rapidly emerging in some specific markets it is already clear that the relation between the three factors is different and more varied than for the currently well-known plastics. Critical factors for increased successful application of bio-based plastics will be product manufacturing and the expectations of applicators and consumers. From interviewing a variety of professionals it was found that clear true and complete information is currently not accessible for most whereas some assumptions are not realistic or not correct particularly the ones related to degradability and to environmental effects. Better and well-structured information will be needed resulting in fulfillment of elementary consumer expectations.
EXPERIMENTAL VERIFICATIONS OF CAE PREDICTIONSONBIREFRINGENCE OF INJECTION MOLDED LENSES
Huai En Lai , Pei Jen Wang, May 2008
Injection-molded lenses have been widely employed for portable consumer products nowadays. A 3D CAE flow analysis program coupled with Generalized Newtonian Fluid (GNF) models based upon polymer melts and measurements of residual birefringence have been conducted for investigation on effects of prominent processing conditions. Furthermore experimental verifications of the predictions on residual stresses are investigated with two example cases of plastic lenses molded by cyclic-olefin-copolymers. Final results have shown that frozen-in shear stresses in terms of residual birefringence levels are mainly contributed by melt temperature and injection speed during the filling stage.The predictions agree well to the experimental measurements.
SIMULATION OF MULTIFILAMENT FIBER SPINNING
Christopher L. Cox , Young-Pyo Jeon, May 2008
We present a nonisothermal multifilament spinning model applied to a variety of polymer and process conditions.The model combines the flow-enhanced crystallization fiber spinning model of McHugh et al. with a generalization of Dutta's multifilament model. The model predicts fiber and quench air properties throughout the fiber bundle. The McHugh FEC model for a single fiber which includes effects of viscoelastic flow and crystallization has been experimentally validated. We compare the multifilament simulation results to experimental measurements. A secondary goal of the current effort is to develop a model which can be executed on a desktop in 2 to 3 hours or lesscontinuing work.
THE EFFECT OF SCREW DESIGN ON THE QUALITY OF INJECTION MOLDING PRODUCTS
Shai Barkai , Samuel Kenig, May 2008
The melt quality and its effect on the final product quality is one of the least studied subjects in the process of injection molding. Consequently the present study is aimed at investigating the plastification stage in injection molding. A general-purpose screw and a barrier type screw were studied with respect to the effect of melt temperature back pressure and screw rotation speed on product quality. Results indicated that the melt temperature and the back pressure are the decisive factor in the case of the general-purpose screw and the barrier screw respectively. Due to the longer residence times in barrier type screws lower temperatures should be used to avoid melt degradation and inferior mechanical properties.
THE EFFECT OF SCREW DESIGN ON THE QUALITY OF INJECTION MOLDING PRODUCTS
Shai Barkai , Samuel Kenig, May 2008
The melt quality and its effect on the final product quality is one of the least studied subjects in the process of injection molding. Consequently, the present study is aimed at investigating the plastification stage in injection molding. A general-purpose screw and a barrier type screw were studied with respect to the effect of melt temperature, back pressure and screw rotation speed on product quality. Results indicated that the melt temperature and the back pressure are the decisive factor in the case of the general-purpose screw and the barrier screw, respectively. Due to the longer residence times in barrier type screws, lower temperatures should be used to avoid melt degradation and inferior mechanical properties.
AN EVALUATION OF DIFFERENT INJECTION MOLDING SCREW DESIGNS AND THEIR EFFECT ON MIXING QUALITY USING AN INLINE MELT CAMERA (I.M.C)
Luke M. Miller , Walter S. Smith , Timothy W. Womer, May 2008
Improved color mixing for injection molding can be improved by different variables. Screw speed melt temperature back pressure barrel temperature profiles screw design dispersion discs etc. can all influence color dispersion. The mixing ability of an injection molding screw is an important element in the finished part quality of a part which is why screw design is the focus of this study. An I.M.C will allow examination of the molten melt stream prior to exiting the die to give a quantitative comparison of different injection molding screw designs.
AN EVALUATION OF DIFFERENT INJECTION MOLDING SCREW DESIGNS AND THEIR EFFECT ON MIXING QUALITY USING AN INLINE MELT CAMERA (I.M.C)
Luke M. Miller , Walter S. Smith , Timothy W. Womer, May 2008
Improved color mixing for injection molding can be improved by different variables. Screw speed, melt temperature, back pressure, barrel temperature profiles, screw design, dispersion discs, etc. can all influence color dispersion. The mixing ability of an injection molding screw is an important element in the finished part quality of a part, which is why screw design is the focus of this study. An I.M.C will allow examination of the molten melt stream prior to exiting the die to give a quantitative comparison of different injection molding screw designs.
PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS
Xueliang Jiang , Yinxi Zhang, May 2008
A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene-ethylene butylenes-styrene (MAH-g-SEBS) triblock copolymer and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends. The stiffness and toughness of the blends are in a good balance and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer. The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-g-SEBS.
PREPARATION AND PROPERTIES OF DYNAMICALLY CURED PE/MAH-G-SEBS/EPOXY BLENDS
Xueliang Jiang , Yinxi Zhang, May 2008
A new method concerning with the simultaneous reinforcing and toughening of polypropylene (PP) was reported. Dynamical cure of the epoxy resin was successfully applied in the PP/maleic anhydride-grafted styrene-ethylene butylenes-styrene (MAH-g-SEBS) triblock copolymer, and the obtained blends named as dynamically cured PP/MAH-g-SEBS/epoxy blends.The stiffness and toughness of the blends are in a good balance, and MAH-g-SEBS was acted as not only an impact modifier but also a compatibilizer.The structure of the dynamically cured PP/MAH-g-SEBS/epoxy blends is the embedding of the epoxy particles by the MAH-g-SEBS.
VVARIABLE MOLD TEMPERATURE FOR IMPROVING SURFACE QUALITY OF MICROCELLULAR INJECTION MOLDED PARTS USING INDUCTION HEATING TECHNOLOGY
Shia-Chung Chen , Jeng-Sheng Huang , Ping-Shun Hsu , Jui-Pin Yang , Ho-Hsiang Wang, May 2008
In this study a variable mold temperature method via induction heating combined with water cooling was used to improve surface quality of microcellular parts. It was found that the surface roughness can decreases from 25?¬m to 6.5?¬m when mold surface temperature increases from 100?øC to 160?øC. The flow marks of gas bubbles on the part surface can be removed completely at mold temperature of 160?øC. When the mold temperature over a critical value about 180?øC the surface roughness can reach a saturated value about 5?¬m. Compared to conventional water heating with initial In 60?øC mold temperature surface roughness can be greatly improved by about 80% without a significant increase in cycle time.
EVALUATION OF MOLECULAR ORIENTATION IN POLYSTYRENE BY LASER RAMAN SPECTROSCOPY
Koji Yamada , Kiyotaka Tomari, May 2008
Molecular orientation in injection molded polystyrene was investigated by polarized laser-Raman spectroscopy. The relative intensity ratio of two specific peaks in a spectrum was determined as Orientation Index Ior in accordance with an earlier report. Two kinds of orientation peak along the depthwise direction were found in a section of the molded specimen. This result is qualitatively consistent with the orientation model presented by Tadmor. Polarized laser-Raman spectroscopy was applied to a weldline region in which molecular orientation is supposed to be one of main factors to reduce its mechanical properties. The degree of molecular orientation increased along the flow direction in the case of adjacent flow weldline occurring behind an obstructive pin in the flow channel. This means that the orientation along the weldline in the area near the pin is relatively low. The tensile strength of the area nearest to the pin was higher than that of the downstream area despite the fact that the surface V-notch was deepest. This fact insists that the molecular orientation affects significantly to the mechanical properties of weldline in injection moldings.
EFFECTS OF SOLVENT-CASTING CONDITIONS ON THE MORPHOLOGY AND PROPERTIES OF DISULFONATED POLY (ARYLENE ETHER SULFONE) COPOLYMER FILMS FOR POLYMER ELECTROLYTE MEMBRANES
Myoungbae Lee , Ozma Lane , James E. McGrath , Donald G. Baird, May 2008
Disulfonated poly(arylene ether sulfone) (BPSH) copolymers have been shown to be potentially useful in the generation of polymer electrolyte membranes (PEMs) in fuel cells. In our work we find that solvent-casting conditions such as solvent type drying temperature and initial polymer concentration significantly affects the morphology and properties of PEMs produced by means of film casting. The design of the solvent removal process requires a knowledge of the kinetics of phase separation which occurs during the drying process. Block copolymers are found to be much more sensitive to drying conditions than the random copolymers.
THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM
Ming Yi Wang , Nan Qiao Zhou , Gang Jin , Sheng Ping Wen, May 2008
The purpose of this research is to investigate the effect of vibration on cell morphology of PC foam. In this study foamed PC was produced using a dynamic simulation foaming setup designed by ourselves with supercritical CO2 as foaming agent. Cell morphology was compared as vibration frequency varied from 2.5Hz to 10Hz and vibration amplitude varied from 25? m to 100 ? m respectively under the same condition. The cell morphology of foamed samples was characterized by using SEM. It was found that foamed samples with better cell morphology could be obtained as vibration frequency increased?foamed samples with better cell morphology could be obtained as vibration amplitude increased to 75 ? m then cell morphology became worse with further increase of vibration amplitude.
THE EFFECT OF VIBRATION ON CELL MORPHOLOGY OF PC FOAM
Ming Yi Wang , Nan Qiao Zhou , Gang Jin , Sheng Ping Wen, May 2008
The purpose of this research is to investigate the effect of vibration on cell morphology of PC foam. In this study, foamed PC was produced using a dynamic simulation foaming setup designed by ourselves, with supercritical CO2 as foaming agent. Cell morphology was compared as vibration frequency varied from 2.5Hz to 10Hz and vibration amplitude varied from 25?¬ m to 100 ?¬ m respectively under the same condition. The cell morphology of foamed samples was characterized by using SEM. It was found that foamed samples with better cell morphology could be obtained as vibration frequency increased‹¬?foamed samples with better cell morphology could be obtained as vibration amplitude increased to 75 ?¬ m, then cell morphology became worse with further increase of vibration amplitude.
CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS
Yeh Wang , Jiang-F. Yang, May 2008
Blend films of acrylic acid grafted polycaprolactone (PCLgAA) and chitosan (CS) with different compositions were prepared from aqueous acetic acid solution. DSC measurements showed that the melting temperatures and enthalpies of the blends decreased with increasing CS content. From FTIR results it can be seen that the amino groups of CS form covalent bonds with the carboxylic groups of PCLgAA in addition to hydrogen bonds between these components in the blends. Though the crystal structure of the PCLgAA component was not changed as proved by WAXD results blending CS suppressed the crystallinity of the blends. Furthermore the ductility of CS was increased during tensile testing in PCLgAA/CS blends due to enhanced affinity between the two components. However PCLgAA/CS blends showed greater resistance than PCL/CS blends to biodegradation in an enzymatic environment.
CHARACTERIZATION OF BIODEGRADABLE ACRYLIC ACID GRAFTED POLY(?-CAPROLACTONE)/CHITOSAN BLENDS
Yeh Wang , Jiang-F. Yang, May 2008
Blend films of acrylic acid grafted polycaprolactone (PCLgAA) and chitosan (CS) with different compositions were prepared from aqueous acetic acid solution. DSC measurements showed that the melting temperatures and enthalpies of the blends decreased with increasing CS content. From FTIR results it can be seen that the amino groups of CS form covalent bonds with the carboxylic groups of PCLgAA in addition to hydrogen bonds between these components in the blends. Though the crystal structure of the PCLgAA component was not changed, as proved by WAXD results, blending CS suppressed the crystallinity of the blends. Furthermore, the ductility of CS was increased during tensile testing in PCLgAA/CS blends due to enhanced affinity between the two components. However, PCLgAA/CS blends showed greater resistance than PCL/CS blends to biodegradation in an enzymatic environment.
STUDY ON THE RIB-DESIGNED PART SURFACE QUALITY MOLDED BY EXTERNAL GAS-ASSISTED INJECTION
Shia-Chung Chen , Chia-Yen Tseng , Chien-Chia Su, May 2008
This study investigates the surface quality of parts molded by external gas assisted injection. A flat ABS part was constructed 100 mm long 50 mm wide and 1.5 mm thick (designated T) with four different thicknesses of rib: 0.6T 0.8T 1T and 1.2T. Under external gas assisted molding process the sink mark for 1.2T rib design can be reduced from 26.88?¬m under conventional injection molding to 3.47?¬m. Combined with process condition optimization of parameters such as mold temperature gas pressure and packing time the sink mark can be further reduced (below 1?¬m). Increased cavity surface smoothness created by various polishing techniques also improves sink marks.
RHEOLOGICAL PROPETIES OF BRANCHED POLYSTYRENE PREPARED BY AN ULTRASOUND ASSISTED INTENSIVE MIXER
Hee Jung Kim , Hyungsu Kim , Hooseok Lee , Jae Wook Lee, May 2008
By combining ultrasonic energy which can cause chain scission of polymer molecules and a multifunctional agent (MFA) having double bonds at its ends we were able to modify the molecular structure of polystyrene (PS) from linear to a branched structure during melt processing. The three double bonds in chain ends of MFA were expected to act as sites for trapping macroradicals of PS during the course of ultrasound- assisted mixing process. The transformation of molecular structure of PS was confirmed by the measurements of rheological properties of the modified PS. After the ultrasonic irradiation of PS together with MFA increase in complex viscosities and shear-thinning behavior were observed. The Cole-Cole plot revealed the characteristic features of branched structure.
INSTRUMENTAL INVESTIGATIONS OF PHYSICAL GUMMIINESS OF A MEDICAL GRADE EPOXY-AMINE ADHESIVE AFTER CURING
Xiaoping Guo, May 2008
Various factors that might interfere with reaction stoichiometry and result in physical gumminess of the cured mass were investigated for a medical grade epoxy-amine adhesive system. Dynamic rheometry was used to probe the evolution of dynamic mechanical properties in the adhesive during isothermal curing and a Fourier-transform infrared spectrometer (FT-IR) was utilized to measure the degree of chemical conversion after curing. It has been found that physical gumminess of the adhesive cured under a selected normal curing condition was primarily due to the presences of excessive hardener and also liquid residuals of an industrial cleaner containing hydroxyl and amine functional groups while the presence of excessive epoxy resin at a moderate level arising from non-stoichiometric mixing is unlikely to cause physical gumminess of the cured adhesive mass. Accordingly it is considered that the selection of a proper cleaner and improvement of stoichiometric adhesive mixing prior to adhesive dispensing is of vital importance to developing reliable and strong adhesive bondlines.


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