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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In order to improve compatibility between fillers and matrix, and reduce the scattering effect of the interface flaws on phonons movement, we used carbon fiber(CF) modified with polyamide solution and carbon nanotube(CNT) coated with nickel as fillers to fabricate thermal conductive polyamide(PA) composites. The surface states of different modification methods on CFs were tested with FRA and the microstructures of the composites were analyzed with scanning electron microscope(SEM). The results show that coated nickel CNTs not only disperse in the matrix well, but also attach to the surface of modified CFs easily as well. The thermal conductive network formed between CFs and CNTs through their adsorption of surface functional groups, which is beneficial to increase the mean length of phonons movements. Compare to the composites filled with CFs and CNTs without surface modification, the thermal conductivity of the composites, filled with coated nickel CNTs and surface modified CFs, increase by three times. Meanwhile, their mechanical properties increase also because of improved interface microstructure.
Kevin D. Herrington, Rebecca Minnick, Donald G. Baird, May 2015
The Method of Ellipses (MOE) was applied to long fiber polymer composites in order to quantify the fiber orientation distribution within injection molded end-gated plaques. The effect of matrix viscosity and fiber type on orientation was explored. Orientation was examined along the centerline at the mold-gate interface, near the advancing front and at multiple plaque widths at half of the plaque length. Preliminary data suggests that the matrix viscosity has a larger effect on the orientation of the fibers than if glass fiber (GF) or carbon fiber (CF) is used. A more viscous matrix caused a more distinct shell-core-shell orientation profile. CF appeared to orient faster than GF which is likely due to a shorter aspect ratio. Work is ongoing to obtain the orientation of GF polymer samples with different initial fiber lengths and along the plaque width.
Amanda Flores, Peter Johnson, James Hoover, Jean-Francois Morizur, May 2015
The benefits of polycarbonate include inherent toughness, transparency, relatively high temperature stability, and wide flow range. These properties have long led to usage in applications that require good aesthetics, dimensional stability, and strong mechanical properties. Looking to build upon these benefits, a new polycarbonate has been developed with a UV-active ketone incorporated in to the resin which allows for cross-linking of the polycarbonate when exposed to UV. This UV-active polycarbonate has similar physical properties to standard polycarbonate (tensile strength, Izod impact, melt flow, etc.). Yet after UV exposure, the new resin shows improvements in chemical resistance and flame retardance of polycarbonate.
Microstructure development during polymer processing is of interest for manufacturers in engineering the final properties. Injection molding advancements have facilitated molding components with complex geometries. With industry moving towards minimizing the polymer waste while retaining the component properties, it is necessary to understand the microstructure formation in detail. Progresses in the field of X-ray imaging techniques have made it possible to characterize polymers with sub-micron resolution. In the current work, we show the applicability of X-ray nanotomography in quantifying the skin-core morphology resulting from injection molding.
Linear low-density polyethylene (LLDPE) films containing boron nitride nanoplatelets (BNN) and were fabricated by continuous melt extrusion. The inclusion of BNN led to 10-fold increase of the in-plane thermal conductivity of the nanocomposite (7.7 W/m.K vs. 0.3 W/m.K for pure LLDPE). To increase the surface area available for convective heat transfer, micro-textured films (T-BNN) were produced from a micro-patterned die. Nanoplatelets oriented parallel to the film machine direction. Nanocomposite films lose ductility for a very high BNN content, but retain their stiffness and tensile strength as compared to the base LLDPE. BNN addition to the LLDPE decreased coeffiecent of friction by 50%, and mixrotextures raised this decrease by 7% more.
Polyolefins, (polyethylene and polypropylene) are arguably the most commonly used thermoplastics used today in a broad range of processes and applications. There are hundreds of types of polyolefins that can be produced directly from the polymerization reactor considering co-monomer type and concentration, molecular weight and molecular weight distribution etc. However, even with today?s state of the art process technology, not all of the polymer attributes required by many applications are achievable at the reactor level. Of the polyolefin family, only low density polyethylene inherently exhibits excellent melt strength resulting from it?s highly long chain branched structure. While the physical properties of linear low density polyethylene (higher tear and puncture resistance), high density polyethylene (higher stiffness, toughness) and polypropylene (higher stiffness, clarity, high heat resistance) may be more desirable for a particular application, they all exhibit poor melt strength due to their linear structure.
This paper reviews the history, techniques and practical application of modifying readily available, ?reactor grade? linear polyolefins to produce long chain branching. Some of these materials exhibit rheological properties comparable to or exceed the melt strength of low density polyethylene while maintaining 100% of their original properties. Examples of their commercial practicality will be discussed in terms of value in application.
Iv n L¢pez, Omar Estrada, Juan C. Estefan, Alejandro Betancur, May 2015
A model to estimate the shelf life in oxygen sensitive food products is proposed. The kinetics of oxygen consumption of the food product and the permeation properties of the package are considered. A novel method to characterize the oxygen consumption is discussed. Some results for an oxygen-sensitive product are presented. The model and method proposed are very useful for developing new products and for making decisions about the selection of film and packaging conditions according to the shelf life expectations.
Denis Rodrigue, Brian Vezeau, Bernard Riedl, May 2015
In this work, wood-plastics composites (WPC) were produced at different wood contents (0-40% wt.) in linear medium density polyethylene (LMDPE). In particular, the initial dry-blending of the materials was performed and a comparison is made on the effect of the processing method used: 1) compression molding, 2) melt blending followed by compression molding, and 3) rotational molding. The composite properties are then compared in terms of mechanical properties (tension and flexion) as well as polymer degradation while processing.
Hongyu Chen, Mark J. Cieslinski, Peter Wapperom, Donald G. Baird, May 2015
To couple the effect of average fiber length evolution with fiber orientation, a breakage model based on the semi-flexible orientation model has been developed. In order to test our breakage model and further investigate the effect of fiber length evolution on fiber orientation, our experiments have tracked long fiber (glass) breakage in capillary flow. Initial conditions in terms of fiber orientation and fiber length for future simulations have been obtained inside the capillary rheometer barrel. The fiber length and fiber orientation of the materials exiting the capillary die have also been measured.
Glass-filled polymers with a matching refractive index between polymer and glass might combine improved mechanical and thermal properties with transparency. In this paper the transparency of glass-filled polymers is critically examined. To analize transparency and haze, model-like specimens consisting out of a cuvette filled with oil and glass fillers were prepared. The haze of these specimens is strongly dependent on the refractive index difference between oil and filler material and is close to zero at a matching refractive index. On the basis of these measurements an empirical model for the calculation of transparency and haze is created. The results provided by this model show a good match with the measured values of the specimens and also with results of experiments described in literature. Based on the model, the paper provides calculated graphs to determine the haze of glass-filled polymers in dependence of the specific filler surface area, the refractive index difference, the wavelength and the sample thickness.
Zhongshuang Yuan, David Astbury, Franco Costa, Dan Ward, Matt Prey, May 2015
Part surface defects can be prevented or minimized by using a cascade molding process with valve gates opening sequentially at controlled speeds. The process dynamics of cascade injection molding were investigated and simulated in the Autodesk Moldflow Insight (AMI) simulation software. Molding trials were performed with sequential valve gates opening at full speed and at variable speeds, respectively using Synventive hot runners equipped with SynFlow?. The experimental results were compared with the predicted results from the simulation software and good agreement was obtained.
Compressive strain data of as-is closures are obtained as a function of time and stress using a modified probe in a DMA instrument at 930C. Data are modeled using a strain equation which involves stress exponent and time exponent. The model describes the data obtained from different types of closures made of high density polyethylene (HDPE) and polypropylene (PP) very well. It is also in line with what is expected for deformation resistance regarding the molecular weight and density of HDPE and type of polymers (PP vs. PE). In addition, the predicted compressive creep data agree well with field observations on two HDPE closures. The tendency of the deformation of these two HDPE closures might be related to their crystallization rates and crystalline structures. The methodology may be useful to provide a rapid and cost-effective means for closure deformation prediction, resin comparison on the same closure design and correlation with some end-use closure properties in a sealed system.
Sebastian Kammer, Marco Arras, Thomas Schr”der, May 2015
Finite element methods are a powerful tool to determine mechanical properties of injection molded parts prior to start of production. However, it is still a challenge to predict the weld line quality of a fiber reinforced thermoplastic precisely. Thus the verification of simulation results is necessary to tap the full potential of lightweight materials. In this study the verification of a structural analysis was split into three minor objectives in order to better understand what affects a weld line:
In this study the verification of a structural analysis was split into three minor objectives in order to better understand a weld line: (1.) Influence of process parameters on the mechanical properties of weld lines (2.) Influence of glass fibers on the mechanical properties of weld lines (3.) Verification of a structural analysis regarding breaking stress and fiber orientation and length distribution
A design of experiments (DoE) was used to carry out injection molding dependent effects. Therefore, two gated tensile bars where molded to induce a weld line and then analyzed with a tensile testing machine. The analytical methods of fiber length scanning and æ-CT were used to verify the fiber-length distribution and the configuration of the fiber orientation in the weld line. The experimental results were then compared with the results of the simulation.
The Six Sigma methodology is generally used for a Management sponsored, disciplined, team based approach to find solutions to system wide issues of vital importance to an organization such as low or no profits, chronic quality deficiencies, missing delivery schedules, etc. While an organization may or may not choose to use Six Sigma to improve a system wide issue, individual tools within the methodology can be used to systematically fix issues on specific products or processes. Some of the more common tools are Pareto Analysis, 5 Whys. Fishbone Analysis, FMEA and Design of Experiments, to name a few. This paper will use selected case studies to highlight the proper use of some of these tools.
The focus of the present research is the development of a new family of bio-epoxy nanocomposites for coatings and other high performance applications. A sorbitol glycidyl ether (SGE) epoxy resin has been cured with two different aliphatic polyetheramines: a poly(ethylene oxide) diamine (PEO) and a poly(propylene oxide) diamine (PPO). The degree of dispersion of commercial organo-montmorillonite clay (Cloisite 93A, C93A) was assessed optically in both the neat resin components and cured films. In general, the compatibility of the polyetheramines with the nanoclay was found to be good. While this would seem to imply enhanced dispersion, in practice it is well-known that poly(ethylene oxide), for instance, will intercalate but not exfoliate montmorillonite layers due to its inability to screen interactions between adjacent layers. Curing behavior of all samples was followed by Near-IR (NIR) spectroscopy. The extent of epoxy conversion is very high for SGE/PEO and SGE/PPO networks. The effect of the C93A in the systems is related to interactions between the curing agents and the clay modifier as well as the silicate layers themselves. When C93A was added to the systems, a slight enhancement in the rate of epoxy-amine conversion was observed prior to gelation in the SGE/PPO system as compared to the SGE/PEO system. Consistent with greater levels of dispersion in the neat resin, this may imply that the resin components have greater access to the clay modifiers, which are known to have catalytic properties in epoxy polymerizations, resulting in a greater degree of polymerization within vs. outside of the interlayer galleries. In order to quantify these effects, gelation times were studied by viscosity measurements. Consistent with the aforementioned arguments, shorter gel times were detected in the SGE/PEO compared to the SGE/PPO system. In addition to cure kinetics, mechanical properties were also studied. The SGE/PPO/C93A system displayed a larger increase in Young?s mod
Naresh Budhavaram, Bing Lu, Christopher D. McGrady, Michael Combs, Karthik Vaideeswaran, May 2015
Cellulose acetate (CA) is one of the oldest plastics, with an application history dating back over 100 years. Recent drivers towards an engineered bio-based material that can be used in demanding applications have caused revitalization in CA product development. This paper illustrates the ability to fine-tuning mechanical and thermal properties through plasticizer selection. A case study is also presented where CA can be used to enhance the bio-content of the petro-based plastics such as polypropylene (PP) while improving performance of the final blend.
Shahid Ahmed, Remon Pop-Iliev, Ghaus Rizvi, May 2015
Three input variables to the extrusion process - temperature, screw speed, and feed rate, are investigated for their impact on colour pigments dispersion vis-…-vis plastics coloration. Pigments dispersion is quantified using scanning electron micrography and image analysis. A correlation between processing conditions and distribution graphs for pigments particle size and inter-particle distance is discussed and compared with colorimetric data. The results obtained through these investigations could help plastics compounders achieve consistency in output colour of plastics.
Anshuman Shrivastava, Litsa Rubino, Elizabeth J. Moore, May 2015
Nucleating agents are frequently applied to improve crystallization rates in the efforts of improving processing times and properties. This study evaluates the efficacy of various commercially available nucleating agents such as zinc compounds, mica, talc, boron nitride, and mixes of organic & inorganic compounds in polyamide 66 (PA66) formulations. Thermal analysis through DSC was performed on unfilled and glass filled formulations for various loadings of nucleating agents. The data presented in this study compares the initiation of crystallization and crystallization peak temperatures to determine the effectiveness of these processing aids. Particle size and structures of the nucleating agents are then analyzed to correlate with the observed results. Effect on impact properties as a consequence of higher nucleation rate is further explained.
John P. Quigley, Kevin D. Herrington, Donald G. Baird, Michael Bortner, May 2015
Supercritical carbon dioxide (scCO2) was used as a processing aid to disintegrate multi-walled carbon nanotube (MWCNT) bundles followed by melt compounding the MWCNTs with polycarbonate to generate nanocomposites with improved surface conductivity. The process incorporates the rapid expansion of a scCO2/MWCNT mixture to separate large primary carbon nanotube agglomerates followed by single screw melt compounding. High levels of deagglomeration of Baytubes? C 150 P and NanocylTM NC-7000 MWCNT bundles were observed on the macro- and nano-scale with scCO2 treatment, resulting in 30 fold and 50 fold decreases in bulk density, respectively, with median agglomerate sizes < 8 ?m in diameter. It was found that a temperature and pressure of 40oC and 7.86 MP resulted in maximum deagglomeration without damage to the MWCNTs. Following pretreatment with scCO2, PC/MWCNT nanocomposites were generated using melt compounding, yielding nanocomposites with enhanced electrical properties and improved dispersion.
ENERGYSAFE pigments are designed to substantially increase the solar reflectance properties of plastics across a very wide color space. This pigment class reflects incident sun rays, i.e. near infrared radiation (NIR), visible light (VIS) as well as ultraviolet radiation (UV) - independently of the substrate. ENERGYSAFE functions inherently and thus does not need a reflective substrate. Surfaces of plastic articles with high solar reflectivity will stay cooler under the sun's powerful radiation. ENERYGSAFE pigments will contribute to decreasing the rate of absorption of sunlight. This effect can lower the overall heat build-up, thus leading to plastics with reduced surface temperature. ?Cool Plastics? are consequently less prone to warping and torsion. Diverse colors from black to brown, from yellow to red, from white to silver can be achieved. Colorful plastics that are inherently solar reflective can extend the use of plastic materials, particularly for outdoor applications.
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Any article that is cited in another manuscript or other work is required to use the correct reference style. Below is an example of the reference style for SPE articles:
Brown, H. L. and Jones, D. H. 2016, May.
"Insert title of paper here in quotes,"
ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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