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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DETERMINATION OF ENVIRONMENTAL STRESS CRACKING FAILURE MODE IN INVESTIGATIONS OF CPVC FIRE-SUPPRESSION SPRINKLER PIPE FAILURES
This paper discusses three separate failure analysis case studies involving Chlorinated Polyvinylchloride (CPVC) fire suppression sprinkler pipe(s) alleged to have failed due to Environmental Stress Cracking (ESC) from exposure to an incompatible chemical. The investigations highlight the importance of the interpretation of fracture surface morphology, review of background information regarding service history, performing material characterization testing, as well as developing an understanding of the interaction of various chemicals with CPVC material when attributing a failure of CPVC sprinkler pipe to ESC. The case studies discussed are helpful in understanding the ESC mechanism in CPVC sprinkler pipes, which is a complex failure mode. This paper discusses the technical issues that should be addressed in determining whether ESC is the primary cause of failure in a CPVC fire suppression sprinkler pipe system.
TRANSCRYSTALLIZATION OF IN-SITU MICROFIBRILLAR PP/SAN BLEND PARTS MOLDED VIA WATER-ASSISTED INJECTION MOLDING
In this work, the crystal morphology of water-assisted injection molded (WAIM) parts of in-situ microfibrillar polypropylene/acrylonitrile–styrene copolymer (PP/SAN) blends with four weight ratios were studied. The results showed that transcrystalline structures formed in the inner layers of the WAIM PP/SAN blend parts at the SAN contents of 4, 6, and 8 wt%, but were absent at an SAN content of 2 wt%. The formation mechanism of the transcrystalline structures was interpreted with the aid of stress and temperature ?elds of the melt within the mold cavity under high-pressure water penetration during the WAIM. It was found that the high shear stress and cooling rate in the inner layer were responsible for the formation of the transcrystalline structures.
EFFECT OF POLYMER VISCOSITY ON POST-DIE EXTRUDATE SHAPE CHANGE IN COEXTRUDED PROFILES
Bi-layer flow in a profile coextrusion die was simulated. Prediction of post-die changes in extrudate profile was included in the simulation. Mesh partitioning technique was used to allow the coextrusion simulation without modifying the finite element mesh in the profile die. Effect of polymer viscosities on the change in profile shape after the polymers leave the die is analyzed. It is found that a difference in the viscosities of the coextruded polymers can lead to a highly non-uniform velocity distribution at die exit. Accordingly, post-die changes in extrudate shape were found to be widely different when the polymers in the two coextruded layers were changed.
INVESTIGATION OF HIGH POWER ULTRASONICS FOR DEPOLYMERIZATION OF POLYLACTIC ACID
This research work explores the feasibility of ultrasonics to recycle lactic acid by depolymerizing. Post consumer PLA chopped up to 1mm2 was exposed to high power ultrasonics with water or methanol as the suspension media. The treatments were carried out in the presence of organic and ionic salts of alkali metals such a potassium carbonate and zinc chloride as the catalysts. The treatments were replicated by replacing ultrasonics with Hot water bath as the energy source. Analysis with HPLC indicated PLA to Lactic acid conversion was achieved with yields up to 90% utilizing ultrasonics. Energy calculations indicated that Ultrasonics used 30% less energy to achieve the same yield levels as achieve with hot bath technique
ALL GREEN STRUCTURAL COMPOSITES FROM KENAF FIBER AND POLY(FURFURYL ALCOHOL)
The search for natural resource based composites for a spectrum of commercially viable “green products” is drawing a great importance in recent time. In this regard, natural fibers have become an attractive substitute for synthetic glass fibers in polymer composite systems. The natural fibers have advantages such as lower cost, eco- friendly nature, biodegradability, high specific strength, and good mechanical properties as compared to glass fiber. Amongst the biobased matrices, poly(furfuryl alcohol) (PFA), possesses high chemical and heat resistance properties. This makes it suitable for chemical resistance, corrosion resistant and heat stable type applications. As such, an overview of the recent development of PFA based natural fiber composites in terms of their overall properties and their future prospective is evaluated in this work.
IMPROVED UTILIZATION OF CO-PRODUCTS FROM BIOFUEL INDUSTRIES IN NEW MATERIALS USES: A MOVE TOWARDS SUSTAINABLE BIOREFINERY
Ever increasing energy demands, instability and uncertainty of petroleum/fossil fuel sources, and concern over global climate change have led to resurgence in the development of alternative energy that can replace fossil transportation fuel. Biomass conversion into biofuels, results a huge amount of residues or downstream products called as co-products such as distillers’ dried grains with solubles (DDGS), protein meals, crude glycerol, hemicellulose and lignin. As the production of biofuel continues to grow, surplus amounts of co-products become a critical issue and new value addition is needed for their effective utilization. A successful biorefinery begins with the productive usage of all components of biological feedstocks for value-added fuels, chemicals or materials that parallels the traditionall approach used in “petro-refineries”. Still biorefienry is risky investment, with respect to commercial benefits and finding value added uses for their co-products creates economic returns and lead to their sustainability. Thus present articles summaries the prospects of improved utilization of co-products from biofuel industries for new industrial applications.
SYNTHESIS OF CROSS-LINKED, PARTIALLY-NEUTRALIZED POLY(ACRYLIC ACID) BY SUSPENSION POLYMERIZATION IN SUPERCRITICAL CARBON DIOXIDE
Particles of cross-linked, partially-neutralized poly(acrylic acid) (PAA) were synthesized in high yield via suspension polymerization of an aqueous solution of acrylic acid and sodium acrylate in supercritical carbon dioxide (scCO2). Siloxane-based surfactants were used to produce particles with an acceptable size range for superabsorbent polymer applications. Several different surfactants were tested and the particle yield was used to compare their performance. The effects of surfactant concentration, degree of neutralization, and agitation rate on the yield and morphology are discussed.
PREDICTING PHASE MORPHOLOGY DEVELOPMENT OF POLYMER BLEND IN CONVERGENT-STRATGHT CHANNEL
Reduced capillary number theory was used to predict the flow field-induced morphology development of polypropylene/polyamide 6 (PP/PA6) blend with a compatilizer in a convergent-straight channel. Numerical simulation was carried out to predict the flow fields in the channel. The predicted results showed that the dispersed phase featured a droplet structure and a fibrous structure near the center line and wall of the channel, respectively. The predicted results were verified by the experiments. Between the center line and wall, a clear transition of the morphology of dispersed phase was predicted. The predicted transition location was compared to the experimentally-determined result and a good agreement was obtained.
POLYMER NANOCELLULAR FIBERS VIA SUPERCRITICAL CARBON DIOXIDE BASED EXTRUSION FOAMING
The quest of novel materials for making lighter fibers for textile and non-woven fabrics applications prompts us to exploit the nanocellular fibers. Thermoplastic polyurethane nanocellular fibers were prepared by extrusion foaming using supercritical carbon dioxide as the blowing agent. Nanoparticles such as nanoclay, multi- walled carbon nanotube, and graphene nanosheets were added as the heterogeneous nucleation agents in order to achieve high-efficiency nucleating effects. Surface functionalizations on nanoparticles were conducted in order to ensure the high-degree dispersion of nanoparticle in the polymer. Optimization of processing conditions is necessary for achieving uniform foams with cell size below 1 m in the fiber having a diameter of less than 30 m. The density of nanocellular fiber was reduced by 30- 50% as compared with that of bulk polymer.
SYNTHESIS OF FUNCTIONAL GRAPHENES FOR HIGH-PERFORMANCE NANOPAPERS
Functional graphenes were synthesized from graphene oxide, which was obtained from low-cost graphite via oxidation. In order to prevent the precipitation of graphene during the reduction process, graphene oxide was partially reduced using sodium borohydride and then treated with diazonium salts having –SO3H or –COOH groups, followed by complete reduction with hydrazine. Functional graphenes were prepared in such a way that they could be well dispersed in water, and as a result, nanopapers could be obtained by flow-directed assembly of individual graphene nanosheets via simple filtration. The presence of functional groups in the graphene also allows the formation of covalent bonds between nanosheets by crosslinking with other polymers. The resulting nanopapers have high electrical conductivity with excellent mechanical properties close to those of steel. These functional graphenes are also promising for the applications in water purifications, ultracapacitors, lithium batteries, and electronic materials.
DISTRIBUTION OF SPECIFIC ENERGY IN TWIN-SCREW COROTATING EXTRUDERS USING ONE-DIMENSIONAL PROCESS SIMULATION
Specific mechanical energy (SME) is a single parameter that represents the energy transfer from the main drive motor through frictional heating for melting, mixing and die pressurization in the compounding process. The calculation of SME is performed using the extruder motor load, screw speed and total throughput to provide energy input on a unit mass basis. Use of one-dimensional computer simulation to analyze the axial distribution of specific energy reveals strategically where this energy is applied in fully-intermeshing, co-rotating twin-screw extruders as a function of screw design.
THE EFFECT OF NANOCLAY ON THE RHEOLOGICAL PROPERTY AND MELT STRENGTH OF POLYPROPYLENE/POLYAMIDE-6 BLEND
Polypropylene (PP) and polyamide-6 (PA6) blend and nanocomposite were prepared using melt intercalation technique by blending PP and PA6 by the incorporation of nanoclay. The melt intercalation of PP and PA6 blend was carried out in the presence of a compatibilizer maleic anhydride grafted polyolyaltha olfin. The rheological property, melt strength and the morphology of PP/PA6 blend and PP/PA6/CN nanocomposite were studied. It was found that the incorporation of nanoclay has positive influence on the rheological property and the melt strength of PP/PA6 blend.
SINGLE-STAGE BLOW MOLDING SIMULATION & CONTAINER PERFORMANCE PREDICTION
For the first time, an analytical computation model has been developed to design and virtually blow preforms on single-stage machines. Due to the complexity of the single stage process, this simulation has been difficult to accurately perform in the past. The model takes into account variables, such as molding temperature and conditioning, to correctly predict the preform profile before blowing. Virtual Prototyping™ software is used to simulate the container blow molding process for round- and oval- shaped containers. The sidewall thickness and mechanical property outputs that are dependent on extent and temperature of stretch are input into finite element analysis software. This enables the computational model to predict container top load and side indentation resistance. A 3L toner bottle case study will show how the computational model was used to evaluate several wide-mouth container preforms for desired thickness distribution and top load performance.
MINERAL REINFORCED IMPACT MODIFIED POLYCARBONATE BLENDS: EXPLORING SPECIFIC FILLER SURFACE INTERACTIONS FOR PROPERTY ENHANCEMENTS
Incorporation of nano to micron scale mineral reinforcements in impact modified polycarbonate blends provides a potential route for achieving high stiffness dimensionally stable blends which are an attractive engineering thermoplastic solution for automotive exteriors and body panels. Designing such blends has traditionally focused on optimizing the flow-impact-stiffness balance. The toughness and impact properties of such reinforced blends are to a large extent dictated by the reinforcing agent characteristics, loading, particle size etc. to name a few. Modifying the surface chemistry of the mineral reinforcements for achieving exceptional toughness and impact properties is the focus of the current paper. The results shall focus on how the interfacial chemistry between the engineering thermoplastic blend and the mineral reinforcement is a key enabler to push the boundaries of flow-impact-stiffness balance in these systems.
A STUDY ON THE PERCOLATION AND DEFORMATION MECHANISM OF POLY(BUTADIENE ADIPATE-CO-TEREPHTHALATE)-LAYERED SILICATE NANOCOMPOSITES
Poly(butadiene adipate-co-terephthalate) (PBAT) is a biodegradable polymer that is used in film applications due to its exceptional elongational properties. Nanoclays such as organically-modified layered silicates are used in an increasing number of applications to improve mechanical, thermal and barrier properties of films. This work aims to elucidate the deformation mechanism and the effects of incorporating a modified MMT clay into PBAT at various clay loading through viscoelastic and tensile measurements, XRD and TEM imaging.
LAYER MULTIPLYING COEXTRUSION OF POLYLACTIC ACID AND POLYVINYL ALCOHOL CAST FILMS
Layer multiplying coextrusion was utilized to produce a films containing polylactic acid and polyvinyl alcohol for food packaging applications. Control films and films containing 9, 25, 73 and 145 layers were produced. The emphasis of this study was to investigate the processability, morphology, barrier, mechanical and biodegradability properties of these multilayer films. The films showed stable layers, high oxygen barrier and mechanical performance that could all potentially be used in a food packaging applications.
VALIDATION OF PREDICTIVE MODEL FOR COMFORT IN POLYURETHANE FOAMS USED FOR AUTOMOTIVE SEATING APPLICATIONS
High resiliency polyurethane (PU) foams are used to provide superior comfort in automotive seating. An existing industry need is to reduce the foam thickness in the seat in order to improve passenger head space and seat weight. In order to maintain the current level of comfort while reducing seat thickness, the underlying physical mechanisms that provide comfort must be well understood. Previously, we presented a method to evaluate dynamic comfort based on a modified Voigt viscoelastic model, and the use of a servo-hydraulic frame to generate model parameters . In this paper, we report the validation of the method and model. Two comparative evaluations were carried out: (1) The transmissivity and damping characteristics of high resiliency (HR) foams were measured by the industry standard Japanese Automobile Standard (JASO) method and compared with the new dynamic oscillatory hysteresis analysis method (DOHA) reported in this paper. (2) Evaluation of the role of foam thickness on dynamic comfort using the new DOHA method. The results showed that the DOHA method compared well with the JASO method for predicting comfort in PU foams. Thus a simple and easy to implement servo-hydraulic method can be quickly leveraged to obtain comfort characteristics of any given foam. A comparison between actual JASO and DOHA predicted transmissivities show good match in terms of shift to higher resonance frequency and amplitude with decreasing foam thickness. Hence DOHA method is an effective tool for studying effect of foam thickness.
TRANSIENT PARTICLE FLUX DURING INJECTION OF COMPOSITE POLYMER COMPOUNDS AND THE RELEVANCE OF SUBSEQUENT MANIFESTATIONS IN MULTI-CAVITY TOOLING
An experimental analysis of the degree of particle diffusion is conducted and analyzed, focusing on multi-cavity tooling. Highly reinforced composite resins are injected into multi-cavity tooling and subsequently analyzed by thermal and mechanical approaches to uncover the degree of shear-induced particle diffusion manifesting under varying injection velocities, mold temperatures, and primary runner aspect ratios. Results indicate that shear induced diffusion is occurring in the length and time scales employed, yet the imposed environments, favorable to particle diffusion, show relatively low influence on cavity-to-cavity gradients in particle concentrations with net migrations occurring opposite to theoretical notions under molding environments. A significant local migration is found to occur radially within the melt delivery. Mechanical properties exhibit a dependence on the rheological history of the polymer in.
MOISTURE RESISTANT TECHNOLOGIES FOR WOOD COMPOSITES
Synthetic fiber reinforced thermoplastic composite materials have become staples for automotive, construction, defense, aerospace and consumer products. Most of these composites are derived from glass or carbon fiber reinforced engineering thermoplastics. However, polyolefin based composite materials are being applied in cost sensitive applications that demand higher performance. Examples include glass reinforced polypropylene (PP) composites and natural fiber reinforced polyolefin composites. Wood composite based products (WPC’s) have rapidly penetrated non-structural wood applications because they offer the consumer low maintenance attributes and durability. However, the best wood composites on the market today are ½ the strength, twice the weight, and as much as five times the cost of pine and cedar! Additionally, there is a need for composites to have improved resistance to moisture and the elements. This work describes new interfacial modifiers for natural fiber and wood filled polyolefin composite materials that have been recently developed by Interfacial Solutions.
SUSTAINABILITY AND THE PLASTICS INDUSTRY
In the past green business evolution among business organizations has gone through “three waves of change” (Makeower, 2009, p. 12). In the 1960s businesses started being green with the notion “Do no harm” and companies started minimizing the environmental impacts (Makeower, 2009, p. 12). In the 1960s, companies mainly focused on pollution control that included stopping illegal activities such as “spewing smokestacks and drainpipes” (Makeower, 2009, p.12). In the 1970s, the U.S. Environmental Protection Agency and similar agencies were formed in the United States and in the other countries with standard laws about pollution of air and water (Makeower, 2009, p. 9). The second wave occurred in the 1980s and emphasized “Doing well by doing good” as companies realized that taking a few proactive steps could reduce costs and enhance a company’s image (Makeower, 2009, p. 10). Later, companies started being concerned about issues like pollution prevention, waste reduction, and energy efficiency. Then in the 1990s came the third wave: “Green is green” (Makeower, 2009, p. 12). During the third wave companies paid more attention to the environmental issues. As stated by Makeower (2009), “Companies recognized that environmental thinking can do much more than improving the bottom line i.e. it can help grow the top line through innovation, new markets, and new business opportunities”. In September 1996, the ISO 14001 environmental management system was issued and applied, establishing “a baseline set of rules for how companies should be organized environmentally” (Makeower, 2009, p. 10). According to Makeower (2009), “as companies scrutinized their operations, they understood how much of their environmental impacts were affected by their external stakeholders hence Supply-chain Environmental Management became the watchword after that the concepts of industrial ecology, zero waste, and carbon-neutrality emerged” (p. 11). Today companies are finally concerned about the “S-word, sus
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