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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Development of PLA/Cellulosic Fibre Composite Foams Using Injection Molding: Foaming and Mechanical Properties
Poly(lactic acid) (PLA) and northern bleached softwood kraft (NBSK) or black spruce medium density fiberboard (MDF) fibers were melt compounded using a co-rotating twin screw extruder and subsequently microcellular injection molded. The microcellular structure and mechanical properties were investigated. Compared to PLA/PEG, a finer and more uniform cell structure was achieved in the cellulosic fiber composite foams. After foaming, the specific flexural strength and modulus and impact strength of the PLA foams were comparable or higher than these of the solid counterparts. PLA/NBSK/PEG composites had better mechanical properties than PLA/MDF/PEG composites.
Predicting Mooney Viscosity from Online Rheology Measurements
Mooney viscosity is a key specification item for process and quality control for EPDM rubbers but can only be measured in a laboratory instrument. For early process upset detection and reduction of off-grade production, higher data frequency from continuous analysis would be beneficial. However, at this point in time available process analyzers do not deliver Mooney viscosity as a standard feature. In this study, a model was developed based on rheological principles to predict Mooney viscosity from viscosity curve information that can be measured using process rheometers.
The model is evaluated against dynamic mechanical spectroscopy (DMS) data for its general validity, and it was found that only slight adjustments were required to achieve a prediction error of only ±10%. However, prediction of Mooney viscosity from process rheometer data collected using a slit die was less accurate and required a correction factor (-16.6 to 4.8% prediction error).
Study of Ultrasonic Treatment on PP/CNT, PP/GNP and PP/CB Composites Using Continuous Ultrasonic Twin-Screw Extrusion
This study systematically investigated the efficiency of ultrasonic treatment on dispersion of different fillers in polypropylene (PP). PP/graphene nanoplatelets (GNP), PP/carbon nanotube (CNT) and PP/carbon black (CB) were prepared using twin screw extrusion without and with ultrasonic treatment. The ultrasonic power consumption varied with filler concentration exhibiting different trends in these composites: the power consumption increased with concentration for PP/GNP and decreased with concentration for PP/CNT, but for PP/CB, it only slightly increased at high concentration. The difference is related to the bubble concentration in the polymer composites. The efficiency of ultrasonic treatment was verified by rheological, electrical and morphological studies. The morphological study showed that CB exhibited the best dispersion in PP which is followed by CNT, whereas GNP showed the worst dispersion. However, the rheological and electrical percolation threshold from low to high was successively shown in PP/CNT, PP/CB and PP/GNP composites. For PP/CNT and PP/CB composites the storage modulus and complex viscosity at low frequency were increased by the ultrasonic treatment. However, PP/GNP did not show obvious change with ultrasonic treatment. The ultrasonically treated PP/1wt%CNT at an amplitude of 13 um dropped 8 order of magnitudes in electrical resistivity compared with the untreated sample, while PP/5wt%CB dropped 4 orders of magnitudes and PP/5wt%GNP only dropped 2 order of magnitudes. Morphological studies show that the agglomerates and agglomerates area ratio were decreased with ultrasonic treatment for PP/CNT and PP/CB composites, but not for PP/GNP composites. An ultrasonic mechanism is proposed based on the experimental data.
Modeling of Nonisothermal Crystallization Kinetics of Semilinear Polyphenylene Sulfide for Process Simulation
Polyphenylene Sulfide (PPS) has been used as a high performance polymer system in extrusion, pultrusion, coating, and injection molding for decades in a variety of forms produced from different processes. Introduction of PPS from a completely new process requires that the material be characterized for process and application simulation. Since most processes require forming and cooling from the melt phase, characterization of the crystallization kinetics under continuous cooling is an integral step in modeling industrial processes. The nonisothermal crystallization kinetics of semi-linear PPS with 40% glass fiber were evaluated and modeled using Ozawa and Liu-Mo nonisothermal characterization techniques. The Liu-Mo analysis was found to model the behavior of this compound well while the Ozawa model did not. The Nakamura and Malkin models were found to be most appropriate for introduction into simulation codes. The modified Malkin model showed a superior fit to experimental data, and was used to create a crystallization master curve for later introduction in to engineering process simulation.
Green Plastics: Utilizing Chicken Feather Keratin in Thermoplastic Polyurethane Composites to Enhance Thermo-Mechanical Properties
A 'green', sustainable resource, in the form of chicken feather derived keratin, was used to enhance the thermomechanical properties of polyurethane bio-composites. Solvent–casting–evaporation method was used to incorporate three levels of chicken feather fibers (0, 10 and 20 %·w/w) into a polyurethane matrix. The thermomechanical properties of the resulting composites were then assessed using differential scanning calorimetry, thermogravimetry, dynamic mechanical analysis and stress–strain measurements with hysteresis loops. The uniformity of the dispersion of the keratin fiber in the plastic matrix was investigated via macro photography and optical microscopy. Scanning electron microscopy of fracture surfaces was used to verify that the adhesion between fiber and polymer was effective. Addition of chicken feather fibers to the polyurethane matrix was found to decrease the glass transition temperature, recovery strain and mass loss of the composites but increase the elastic modulus, storage modulus, and char level. The results demonstrate that keratin derived from what is currently a waste product from the poultry industry (with significant disposal costs) can improve the thermo-mechanical properties of composites, simply and cheaply, with potentially large environmental benefits.
Surface Mechanicals and Microscopy Methodologies for Coating Characterization
Performance of a coated surface depends on coating’s mechanical, physical, chemical and architectural properties. For the successful development of coatings it is important to characterize them with appropriate tools to understand various properties, which correlate to the performance. In this study, various different coating systems, prepared by either wet coating or plasma coating technology, were characterized with nano-indentation and high resolution electron microscopy. Depth sensing nanoindentation is used to assess coating mechanical properties and nano-scratch is used to characterize the performance of the coating. Correlation of nano-indentation and Pencil hardness tests reveals that caution should be taken to utilize later alone to screen coating materials. High resolution transmission electron microscopy used to study the layer architecture, thickness and chemical composition of the coating materials. It was found that scratch and abrasion of coating is not only dependent on hardness but also on scratch percent recovery and architecture.
Organic Alkali Metal Salt Estimation by ICP-OES in Thermoplastic
Thermoplastic based films are widely used for electrical and electronic (EE) insulation applications. For EE applications, high flame retardant properties are required with increasingly stricter regulations against chlorinated or brominated formulations. The ongoing research is focused on developing new grades with alternate flame retardant (FR) additives giving comparable VTM0 and V0 ratings. In order to deliver this excellent FR performance, one of the key factor is to control the loading of the FR additive (organic alkali metal salt) as per formulation during the production stage. Hence, there was a need to develop XRF based fast screening method that could be implemented in manufacturing sites for regular monitoring of additive loading in new grade of thermoplastic containing complex inorganic fillers. Establishment of XRF method requires generation of absolute standard values for the organic alkali metal salt with this new formulation. Analytical efforts were tried to extract the FR additive by two extraction techniques followed by analysis using instrumental techniques such as ion chromatography and LC-MS. However the results were not consistent due to insufficient extraction of the salt from the thermoplastic containing complex organic and inorganic matrix and other inorganic fillers due to adsorption issues. To overcome these challenges, absolute method using ICP-OES was developed to quantitatively estimate the potassium content in the organic alkali metal salt in this grade and back calculate the % FR additive. Specific formulations with known concentration of organic alkali metal salt were compounded and analyzed by ICP-OES to generate standard values which were used for XRF calibration. This presentation covers the development of successful XRF method based on ICP-OES results. Details of method development approach, comparison of results obtained by two different techniques (ICP and XRF), translation and implementation of methods to manufacturing sites an
Time Temperature Superposition of Short Term Stress Relaxation Behavior to Understand Retention of Material Modulus over Time
Several engineering thermoplastics, because of their higher mechanicals, thermal and dimensional stabilities, are increasingly being considered for use as injection molded components, in several industrial applications . There are several load bearing applications, such as springs, bearings, gears, valves etc., wherein during short term, it could be subjected to constant strain under varying temperature and humidity levels . It is of interest to have an understanding, if such materials during end-use, has the ability to retain modulus over a short period of time. Therefore, linear visco-elastic limit of the material needs to be determined under the influence of strain, temperature and moisture. To assess such performance attributes of materials, short-term tensile stress relaxation studies were conducted, using Universal Tensile Instrument, under varying strain levels, temperature and humidity in a 1-hour timescale. The study revealed that the material retained linear visco-elastic behavior in the range of 2% strain until 60°C and moisture was found to have no impact. The relaxation modulus measured from this experiment was also extended using a master curve using Time-Temperature-Superposition (TTS) up to 10 hours. Such an analytical technique could be used for material screening by product developers. Going forward, if there is need to assess the performance of the material over a longer period (>10 hours), the laboratory experimental duration can be proportionately increased.
The Flameretardancy Study of PVA Using for Furniture Made from Corrugated Cardboard
Corrugated cardboards have truss structure, so these have advantageous in terms of specific strength, workability, price and recycling efficiency. Because of these properties, corrugated cardboards are used as not only packing materials but also furniture etc. When a disaster caused in Japan, refugees sleep directory on the floor with a blanket. It caused the second healthy damage like the economy class syndrome. For prevent refugees from its damage, beds made from corrugated cardboard has been used instead of cots in Japanese shelters. We need to give flameretardancy to the cardboard bed for enhancing safety. In this research, flameretardancy of corrugated cardboards is aimed to using Poly-vinyl alcohol (PVA). PVA is useful for the coat of the cardboard. The coating PVA on the cardboard is possible to be recyclable, because PVA has water solubility. We used 2 kinds of flameretardant in this time. In the result of combustion test, the Halogen, Phosphorous and Nitrogen based compound show great flameretardancy for PVA.
Development of an Injection Molded Automotive Hoop Spoiler
This paper presents the development and application1 of a large injection molded sports hoop spoiler (IMSH) for a pickup truck that replaces an already existing industry norm blow molded sports hoop (BMSH).
The new injection molded design has provided the opportunity to include an internal structure that does not exist in the blow molded design, hence allowing for an increase in the static and dynamic performance as well as provide a lower cost, lighter weight, with less assembly components.
The new IMSH has incorporated design features to compensate for durability and thermal loads that are applied in normal usage, which allows the outer visual structure to move with respect to the inner support structure, without stressing either structure whilst producing a good external craftsmanship finish.
Production of In Situ Microfibrillar Composites as a Novel Approach towards Improved Bio-Based Polymeric Products
In this work, we introduce the in situ microfibrillation of poly (lactic acid) (PLA)/polyamide-6 (PA6) blends as an effective approach in improving PLA’s properties as well as its foaming-ability. The in situ microfibrillation of the PLA/PA6 blends was performed using a facile and cost-effective extrusion process followed by hot stretching of the extrudates. The morphological studies proved the successful formation of fully stretched PA6 microfibrils with diameters as low as 200 nm. Inclusion of a small concentration of PA6 microfibrils (3 wt.%) was shown to lead to significant improvements in the crystallization kinetics and mechanical properties of PLA. In addition, formation of a physically entangled network of PA6 microfibrils improved the melt strength and elasticity of PLA which, in turn, improved the microstructure of PLA foams.
Determination of CO2 Solubility and Volume Swelling in PMMA in Light of Retrograde Vitirification
The solubility of CO? in Poly (methyl methacrylate) (PMMA) and the pressure-volume-temperature (PVT) behavior of PMMA-CO2 mixture were investigated in light of the retrograde vitrification process using a magnetic suspension balance (MSB) and an in-house visualization dilatometer; experiments were carried out 20 to 100 °C at 54 atm. The results indicate that as the temperature decreases the swelling increases, although, when a decrease in temperature caused the phase of PMMA to change from liquid to glassy, the swelling decreased. However the solubility increased throughout the drop in temperature. The increase in the solubility with respect to temperature was not a linear trend, illustrating the effect of phase of PMMA on the solubility of CO?.
Measuring Thermal Crystallinity in PET
The mechanical properties of poly (ethylene terephthalate) (PET) depend on the degree of crystallinity. PET crystallizes from both thermal and strain-induced process paths. Strain-induced crystallization occurs under uniaxial or biaxial stretching, the latter is common in stretch blow molding. Thermal crystallization takes place when cooling from the melt or under sustained elevated temperature which are both common during injection and blow molding. The current work focuses on comparing methods used to quantify the percent thermal crystallinity in injection molded water bottle preforms. An injection molded preform with a gradient of induced thermal crystallinity was examined using Differential Scanning Calorimetry (DSC), Micro X-ray Diffraction (?XRD), and Raman Spectroscopy. Correlating these three techniques for percent thermal crystallinity, helps with the development of nondestructive crystallinity measurement methods to aid with process optimization and part quality.
Mechanical Property and Fractrue Analysis of Wood Powder/PP Composite Molded by Injection Molding
The use of wood plastic composites (WPCs) has been increased in various applications owning to low prices, low density, ecological and economical advantage, less hazards. Due to the wood powder could be produced from offcut materials which can raise the utilization ratio of timber. The objective of this research is to use composite combining with plastic and wood to relieve the depending on timber. At current study, two kinds of materials were developed with wood powder and were compared with polypropylene. Mechanical property including tension and Izod impact were evaluated. The fracture behavior of wood powder composite was observed to analyze the relation between mechanical property and combination between wood and polypropylene.
Scratch Behavior of Polyurethane Elastomers with Variation in Soft Segment Type
An investigation on the effect of soft segment type on the scratch performance of cast polyurethane elastomers (CPU) is reported. A series of CPU were synthesized by the same isocyanate and chain extender, 4,4'-methylene diphenyl diisocyanate (MDI) and 1,4-butane diol (BDO), to form the same type of hard segment, with four different soft segments (polyols): polytetramethylene ether glycol (PT), polycaprolactone (PC), ethylene oxide and propylene oxide based polyether polyol (PET) and adipic anhydride based polyester polyol (PES). Scratch tests were carried out according to the ASTM D7027-13 standard. CPU-PET system is observed to exhibit the worst scratch resistance while CPU-PT shows the best. Coefficient of friction measurement, quasi-static uniaxial compression tests as well as dynamic mechanical analysis (DMA) were investigated to correlate with the observed differences in the scratch performance of the CPU model systems.
High Performance High Density Polyethylene (HDPE) for Hot Fill Closure Applications
High performance bimodal high density polyethylene (HDPE) was developed for the hot fill closure applications. Performance of the bimodal HDPE was benchmarked versus incumbent unimodal HDPE resins. The bimodal HDPE resin delivered better environmental stress cracking resistance (ESCR) than a conventional HDPE homopolymer while maintaining a good heat deflection temperature (HDT) and a good Vicat softening point. The high performance HDPE also exhibited greater shear thinning behavior, indicative of good processability under the high shear rates typically encountered in the injection molding process. In addition, the closures made from the new HDPE resin are advantaged with respect to the removal torque.
Comparative Testing of Pre-Pigmented and Natural Compound plus Black Coloring Master Batch HDPE Pipes for Potable Water Applications
A study was initiated to demonstrate that the use of HDPE natural compound plus coloring master batch can be used to meet the requirements of ISO 4427:2007 potable water pipe standard. A test matrix was developed to evaluate a pre-pigmented black HDPE compound and two versions of blended natural compound plus black coloring master batch for conformance to the requirements in three different parts of ISO 4427:2007. One blend version used a typical North American black coloring master batch with a nominal carbon black particle diameter of 58 nm. The other blend version evaluated a black coloring master batch that met the ISO 4427:2007 carbon black average particle diameter requirement (10 – 25 nm). 110 mm PN16 pipe (standard dimension ratio of 11) was produced from all three materials using the same extrusion equipment, temperature profile and extrusion rate. The results of the conformance testing are discussed as well as recommended steps for the use of natural compound and coloring master batch in regions of the world with experience in pre-pigmented HDPE pipe compounds.
Enhancement of Paint Adhesion with Polyolefin Blends
Adhesion of coatings to molded polyolefin articles is a well-known challenge due to the low surface energy of polyolefin materials. This study examines the influence of substrate composition and morphology on adhesion. It has been observed that the composition of the substrate plays a role in the adhesion performance of paint systems due to changes in the surface morphology and chemistry. By engineering the surface morphology of the molded polyolefin, adhesion of paint can be significantly improved and may ultimately lead to a path for low cost, facile decoration of materials in markets where they are currently not in use today.
Influence of Elastomer on Morphology and Mechanical Properties of Nylon 6/OMNT/Elastomer Composite
Nylon 6/OMMT/elastomer composite was first prepared by molten compound method and then how its rheological properties, mechanical properties, micro morphology and the shape of fracture surface vary with elastomer content was investigated. The results indicate: With the increase of elastomer content, impact strength increases significantly, tensile strength, flexural strength and modulus decline and elongation at break declines first but then increases?the SEM images of fracture surface go well along with the results of impact tests, and critical matrix thickness for the composite materials of brittle ductile transition layer is 0.14?m. With the increase of elastomer content, the apparent viscosity increases first but then declines, non-Newtonian index declines and the activation energy declines first but then increases. So adding elastomer makes it possible for Nylon 6/OMMT/elastomer composite to flow steadily in a wide temperature range under a constant shear stresses and makes the composite easy to fabricate.
Microscopy of Intentionally Oxidized Polypropylene-Based Mesh Material
Surgical mesh and sutures made from polymer materials have long been utilized as medical devices. Several polymeric materials have been employed to manufacture these devices, including polypropylene. PROLENE® fibers, comprised of polypropylene-based material with added antioxidants, pigment, and processing aids are fiber spun and used in medical sutures and pelvic mesh implants. Claims of in vivo degradation of mesh devices, including PROLENE®, have been investigated by others [1-7]. Surgical mesh is typically surrounded by tissue during and after implantation. Histological dyes such as Hematoxylin and Eosin (H&E) can be used to stain surrounding tissue on explanted devices. Using optical microscopy, we demonstrate that non-implanted, intentionally oxidized, PROLENE® fibers do not stain with H&E. The inability of PROLENE® to become stained is an important finding as it provides histologists and others a means of delineating between biological material surrounding mesh and the fibers that are used to construct the mesh.
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