SPE Library

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
Simulations of Scratch Resistance and Recovery in One and Two-Phase Polymers
Witold Brostow, J. Adam Hinze, Ricardo Simões, May 2004
We have used molecular dynamics to simulate the behavior of polymers in scratch tests. We start by creating a material on the computer consisting of chains with varying molecular mass, orientation and second phase concentration.Scratching is simulated by moving a force along the surface of the material. We measure the resulting deformation and we study penetration depth and recovery. We find that these depend on the local structure of the material as well as on the distribution of the second phase.Our simulations allow us to better understand scratching and scratch recovery. This helps in the creation of materials with improved tribological properties.
Impact Fatigue Properties and Failure Mechanisms of Glass Fiber-Reinforced Thermoplastics
Takafumi Kawaguchi, Takashi Kuriyama, Kazunori Ito, Hidemitsu Sorimachi, Hiroyuki Nishimura, Takashi Inoue, May 2004
The impact fatigue properties of four kinds of glass-fiber or glass-bead reinforced polymers were studied through uni-axial and multi-axial fatigue. In performing fatigue tests, the authors paid special attention to the effect of interval times between loading and loading mode on the fatigue properties of those materials. It was found that the numbers of cycles to failure were strongly dependent on the duration of the interval time and loading mode. The failure mechanisms were investigated with acoustic velocity measurements and optical microscope (OM) observations. OM studies revealed that the fatigue life is strongly affected by the features of damage such as breakage of glass, micro-voiding, change in the orientation of glass fibers, and plastic deformation. The degree of damage localization also had a strong effect on the fatigue life. The difference in the damage development mechanisms were found to be caused by the difference in the elastic response of the specimens due to the different loading mode (uni-axial or multi-axial) and the interval time.
An Experimental Study of Accumulating Damage in E-Glass FRP Specimens with Acoustic Emission
Paul H. Ziehl, Terrell A. Green, May 2004
Current codes governing the design of fiber reinforced polymeric (FRP) components are generally based on ultimate strength testing. A large safety factor is then imposed for purposes of design. This approach ignores the onset of damage in the component. The onset of damage is related to the structural integrity of the component and its fatigue life.An experimental investigation has been conducted to determine the onset of damage in small coupon specimens with the acoustic emission technique. Damage was found to occur at different stages of loading for coupons made with different resin types and different fiber geometries.
DMA Viscoelastic Analysis of Two Cross-Linked and One Thermoplastic Rubber
Charles J. Aloisio, G. Samuel Brockway, May 2004
Dynamic Mechanical Analysis (DMA) was used to characterize three polymers that display rubbery behavior around room temperature. Oscillatory modulus data were collected at zero degrees centigrade and above for these three rubbery materials: a thermoplastic olefin (TPO), an EPDM rubber and a silicone rubber. The in-phase modulus, out-of-phase modulus and tan ? data were synthesized into mastercurves using the principle of time-temperature superposition and compared. As expected, the TPO, the only non-cross-linked system, showed the most time dependence, while the silicone rubber was very nearly perfectly elastic, basically conforming to rubber elasticity theory. The EPDM data, while still superposable into a smooth mastercurve, showed evidence of an incomplete cure. Subsequent testing and analysis confirmed the incomplete cure. A cured sample of the EPDM polymer behaves in a fashion consistent with classical rubber elasticity theory. These DMA data are also shown to be useful for time-dependent, small-deformation stress and strain analyses.
Effect of Material Properties on the Mechanical and Thermal Performance of Metallocene Catalysed LLDPEs
S. Walker, G. Mc Nally, P.J. Martin, May 2004
A range of metallocene and Ziegler-Natta catalysed LLDPEs were prepared by injection moulding to determine the effects of density, molecular weight, MFI and polydispersity on their mechanical performance. Tensile results showed that hexene based mLLPDEs exhibited higher elongation to break while Young’s modulus of the materials was found to be more influenced by density. Impact results demonstrated that metallocene LLDPEs have superior impact strength at room temperature over conventional LLDPEs. Further analysis using differential scanning calorimetry and dynamic mechanical thermal analysis was performed to study the influence of the metallocene catalyst and co-monomer type on the properties of the materials.
Propylene-1-Hexene Copolymer Obtained with Ph2C(Flu,Cp)ZrCl2 Homogeneous and Heterogeneous System
Daniela Emília Bastos Lopes, Indira Ribeiro da Silva, Juliana Barreto Brandão, Maria de Fátima Vieira Marques, May 2004
This work deals with metallocene homogeneous and heterogeneous catalysts (Ph2C(Flu,Cp)ZrCl2 and Ph2C(Flu,Cp)ZrCl2/HM) to obtain syndiotactic polypropylene and propylene-1-hexene copolymers. The effects of polymerization temperature, comonomer concentration and different reaction solvents were studied.S-PP of 138/152°C melting temperature was obtained with these catalysts. Both homogeneous and heterogeneous systems showed the comonomer effect. By changing the solvent from toluene to hexane a decrease in activity and an increase in polymer melting temperature and crystallinity were observed.
Characteristics and Properties of Metallocenic Syndiotactic Polypropylene
Érica Gervasoni Chaves, Hélio Scarpelli Jr., Sabrina Saraiva Mafra, Maria de Fátima V. Marques, May 2004
This work investigates the characteristics and properties of syndiotactic polypropylene produced by Ph2C(Flu)(Cp)ZrCl2/MAO metallocene catalyst system. The obtained s-PP presented melt temperature around 120°C, being more amorphous as the polymerization temperature increased. From the data obtained through HAAKE mixture chambers we could carry out the rheological characterization of the polymer, which presented a non-Newtonian pseudoplastic behavior, as expected. The polymer also had a good mechanical performance compared to conventional i-PP.
Copolymerization of Ethylene and 1-Hexene by Homogeneous and Supported Metallocene Catalysts
Daniela Emilia Bastos Lopes, Juliana Barreto Brandão, Indira Ribeiro da Silva, Maria de Fátima Vieira Marques, May 2004
In this work, the performance of the homogeneous catalyst system based on Ph2C(Flu,Cp)ZrCl2 was evaluated on ethylene copolymerization and 1-hexene. The influence of the support material was studied using acid mordenite HM zeolite and the characteristics of the produced polymers were also investigated. A study was performed to compare the influence of polymerization solvents as toluene, hexane and hexane/TIBA. An increase in activity was observed in relation to the comonomer addition for homogeneous and supported systems.
Effect of Maleated Polypropylene on the Melt Compounding of Polypropylene/Clay Nanocomposites
Yeh Wang, Feng-B. Chen, Yann-C. Li, Kai-C. Wu, May 2004
Polypropylene/clay nanocomposites modified with different levels of maleic anhydride grafted polypropylene (PPgMA) compatibilizers were compounded on a twin-screw extruder. The effect of PPgMA compatibilizers, including PB3150, PB3200, PB3000, and E43, were studied. The structure was investigated with X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The relative complex viscosity curves also revealed a systematic trend with the extent of exfoliation and showed promise for quantifying the hybrid structure of the nanocomposites. Mechanical properties and thermal stability were determined by dynamical mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. An optimum level of compatibilizers was found to yield the greatest improvement of composite properties. Though PPgMA with low molecular weight and high MA content could lead to good clay dispersion, it resulted in less improvement in both mechanical and thermal properties of PP/clay nanocomposites.
Different Clamping System for Plastic Molds
Riza Sagun, David Ceccato, May 2004
The desire to decrease unproductive time of injection moulding machines explains why the clamping systems are becoming increasingly more powerful.After significant studies, three families of clamping system supports are currently recognised : mechanical, hydraulic and magnetic supports. The choice of the appropriate production system remains to be made by taking into account the return on investment.Whereas the sales of the mechanical and hydraulic systems remain stable, the magnetic systems represent a remarkable evolution. In spite of its price, which is relatively high, the industrialists recommend this system because of its remarkable. However the prices, which remains a real barrier to its expansion, are falling thanks to an increase in sales.
Optimization of Nucleating Product Forms to Achieve Handling Ease and Robustness at Maximum Dispersion Efficiency in Polypropylene
Elisabeth S. Papazoglou, Subramanian Narayan, Robert E. Lee, May 2004
Nucleating agents are very beneficial additives in polypropylene because by promoting crystallization they improve molding productivity, enhance thermal properties, achieve simultaneously high impact and strength and provide improved clarity for special applications. Uniform dispersion of the nucleating particles throughout the polymer matrix is critical in achieving the desired performance. Additives fed as powders are intuitively thought to provide the best dispersion, but suffer from handling difficulties, including loss of the additives in the feeding / transport system. Designing a non dusting blend (NDB) form that can feed as a pellet but at the same time will disperse uniformly in polypropylene during extrusion is a challenging task. In this paper we report several NDB forms that achieve dispersion equivalent to the powdered blends and compare with systems where such dispersion could not be achieved. The influence of appropriate co-additives, as well as selection of the optimum NDB manufacturing process are discussed. Crystallization temperature and haze measurements were used to quantify the quality and extent of the dispersion.
Structure and Property Relationship of TLCP/PEN/PET Ternary Blend Fibers
Jun Young Kim, Eun Su Seo, Seong Hun Kim, May 2004
Thermotropic liquid crystalline polymer (TLCP) / poly(ethylene 2,6-naphthalate) (PEN) / poly(ethylene terephthalate) (PET) ternary blends were prepared by melt blending, and were melt spun to fibers to improve fiber performance and processability. The mechanical properties of ternary blend fibers could be significantly improved by annealing. This result was attributed to the development of more ordered crystal structures and the formation of more perfect crystallites. Multiple melting behaviors observed in the annealed ternary blend fibers depended on annealing temperature and time, which were caused by the different lamellae thickness distribution.
Mechanical and Physical Properties of PEN/Silica Nano-Composites
Seon Hoon Ahn, Seong Hun Kim, Seung Soon Im, Seung Goo Lee, May 2004
Silica nano-particle filled PEN composites were melt-blended to improve mechanical and physical properties, and processability. Tensile modulus and strength were improved adding silica nano-particles to the PEN. The melt viscosity of the nano-composites during the process was decreased by adding small amount of the fumed silica, and hence the processability of those was improved. Dispersity and compatibility of silica nanoparticle filled PEN composites will be investigated near future. Non-isothermal crystallization kinetics and spherulite growth rate were analyzed by Ozawa equation and image analysis, and the calculated Avrami exponents revealed three dimensional growth of crystallite, and the crystallization rate constants were increased with increasing silica contents. Fumed silica may act as a nucleating agent in the PEN matrix, and the same results were obtained by calculating nucleating activity.
Morphological, Thermal and Mechanical Properties of Epoxy Based Nanocomposites
Cigdem Basara, Ulku Yilmazer, Goknur Bayram, May 2004
Diglycidyl ether of bisphenol-A (DGEBA) based epoxy resin was reinforced by natural and organically modified montmorillonites, namely Cloisite Na+ and Cloisite 30 B. The process involved mechanical and ultrasonic mixing of the epoxy resin with clay particles and diffusion of the resin into the space between the silicate layers. SEM analysis indicated that as the clay loading increased, the particle size of the clay agglomerates increased. X-ray analysis showed that in nanocomposites with 3-weight % Cloisite 30B, the d-spacing increased from 1.83 nm to 3.82 nm. Adding 0.5 weight % organically modified clay improved the impact strength of the neat epoxy resin by 137.1 %.
Polycarbonate/Ferrite Nanocomposites: Processing and Properties
Ajit Bhaskar, Nathan Tortorella, Charles L. Beatty, May 2004
Nanocomposites using Polycarbonate and Ni- Zn based ferrite nanoparticles were prepared using a reactive twin-screw extruder. They were found to be quite transparent and were characterized using tensile testing, XRD, DSC and TEM. Their mechanical behavior was found to be more brittle than pure polycarbonate. Also, the viscosity of the nanocomposite was significantly lower than the original polymer. This was explained on the basis of the nature of the material used to coat the nanoparticles, and the melt processing conditions employed for preparing the nanocomposites. It was also found that if the nanoparticles were not coated, they agglomerated and hence, the nanocomposites were no longer transparent.
Three-Dimensional Simulations of the Inkjet Printing Process for PLED Display
Kun-Lin Hsu, Shiu-Wu Chau, Shia-Chung Chen, Tong-Miin Liou, Kuan-Chen Shih, May 2004
Because the inkjet deposition process reduces manufacturing costs and process steps when compared with the traditional etching and/or lithography, it seems to be an attractive alternative in the PLED display manufacturing processes. However, some microflow issues in the deposition process should be carefully treated to ensure the manufacturing quality of the PLED display. The droplets dispensing from the inkjet head, which generally contains an array of nozzles, have a volume in several picoliters, while each nozzle responds very quickly and jets the droplets into cavities on substrates with micrometer size. The nature of droplet impingement depends on the material properties, the initial state of droplet, the impact parameters and the surface characteristics. The commonly chosen non-dimensional numbers to describe this process are the Weber number, the Reynolds number, the Ohnesorge number, and the Bond number. This paper discusses the influence of droplet initial velocity on microflow characteristics in the deposition process via a numerical approach. The numerical investigations show that for the studied droplet and cavity size, an acceptable velocity range has been found to ensure the deposition quality, while this result agrees well with existing industrial experiences. The numerical simulation seems to be an efficient and reliable way to evaluate the inkjet deposition process.
The Effect of ? -Rays on PES/PA6 Blends
C. Albano, R. Perera, P. Silva, Y. Sánchez, C. Rosales, M. Becerra, May 2004
In this work, the effect of ? -rays irradiation and post-irradiation storage time onto different PEs, PA6 and their blends was studied by means of ESR spectroscopy, FTIR and DSC. These techniques can provide relevant information concerning the reaction mechanism of the polymers structural modifications that take place during their irradiation. The experimental results suggest that allyl, alkyl and polyenyl radicals are generated in the materials after the irradiation process. The dynamics dominating the process kinetics are crosslinking, chain scission and a coexistence of both, depending on the sample composition. The storage time produces a change in the kinetics dynamic.
Determination of the Pressure Coefficient of Polymer Melts from Shear Flow
Tomas Sedlacek, Martin Zatloukal, Anezka Lengalova, Petr Filip, Petr Saha, May 2004
A modified capillary rheometer was used to measure strain rate-temperature-pressure dependencies of shear viscosity for injection molding grades of polymers. The modification consisted in the addition of a second chamber and a restricting needle valve below the main die, and its purpose was to determine the effect of pressure on the shear viscosity of different polymer melts. The modified White-Metzner model was employed to simultaneously fit the measured viscosity data and determine the pressure and temperature coefficients, ? and ?. It has been found that not only the temperature but also the pressure factor significantly influences viscosity, and both of them are useful for the description of a polymer behaviour.
Testing the Effects of Hold Pressure on Hold Time in Various Materials and through Various Gates
J.J. Gropp, May 2004
The holding phase of the injection molding process can be critical to producing quality parts. This paper studies the relationship between hold pressure and hold time with a variety of gate types and materials. The materials will be broken into groups such as semicrystalline, amorphous, and filled materials. In addition, parts will be created with a variety of different sized and shaped gates. From this, it is believed that a pattern will be recognized with regards to the setting of hold pressure on the necessary hold time. This pattern is intended to give processors a theory with which to base their thought process when optimizing injection molding machines.
The Affects of Shear Induced Imbalance on the Concentricity of Injection Molded Gears
Brock Allen, Thomas Lacey, May 2004
A number of studies in recent years have shown that shear induced melt variations developed in the runner result in cavity to cavity filling imbalances in molds with eight or more cavities. This study looks at the affects of the shear induced melt variation when molding high precision parts in molds with as few as two cavities. In particular is the case of gears which require high concentricity. The shear induced melt variations developed in the runner continue into the cavity creating irregular filling and non-concentric part shapes.This study evaluates a two cavity, three plate, cold runner, center gated gear mold. Gears are molded from a variety of different engineering resins, and the effects of the shear induced melt variation are evaluated.

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