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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Windows of Opportunities for Single Site Catalyst
What makes company A produce 50,000 tons/year more of the same PE or PP than company B at the same cost? Catalyst, catalyst and catalyst. Very quietly, catalyst research has brought revolution in the plastics industry. So-called single-site catalysts (many of which are metallocenes) are closely guarded secret of alpha-olefin "big guys". A single metal atom held between two carbon rings builds metallocenes. They might look naive but provide greater control over molecular chain length and structure of polyolefins. These polymers are stronger, purer, and clearer. Upon utilizing these catalysts, material suppliers can accurately design tailor-made resins for specific applications.
Characterization of Polycarbonate – Using Thermogravemetric-Rheology Analysis
The objective of this work is to study the rheological characteristic of the formulations and the processing of plastic production. In this work, introduced two polycarbonate resins were melt blended using two different twin-screw extruders, targeted to investigate the PC blends on the characterization behavior of the grade. Formulation and processing parameters showed an excellent effect on controlling the viscosity. The research aims to identify the underlying science by conducting a systematic study of two stages. First, the polycarbonate 30/70% (Grade-3) was chosen from historical data mining extracted in our project as was showing a high number of adjustment; the material was melt-blended using (Coperion) a Co-rotating twin-screw extruder (SB). The two polycarbonate resins (PC1/PC2) were PC1 content (30wt%-pph) of MFI (25gm/10mins) and PC2 content (70 wt.%-pph) of MFI (6.5gm/10mins). The grades also included four different color pigments and three additives. The second stage, the same material was included the same composition were blended in steps of eleven in a Thermo Haake Mini Lab II twin-screw micro compounder (ML). The steps (%PC1/%PC2) were (100%/0%), (90%/10%), (80%, 20%)… (0%/100%). This resulted in eleven batches. The rheological behavior of the compositions with pigment (WP), without pigments and additive (WOP) at 280 0C have been characterized through experimental measurements. The viscosity measurements of Variation PC blends of (30-70%) and at (0%, 30%, and 100%) were characterized at certain processing of (SB) and (ML). Thermogravimetric analysis (TGA) was performed under the effect of heating rate, Glass transition temperature (Tg) for PCs blends was measured and related it is affected by the minute variation blends, viscosities, and the various interactions indicated a significant effect on color changes.
Durability of Cellulose Nanomaterials under Industry Relevant Shear Stresses
The effects of high-shear flow on cellulose nanocrystals (CNCs) were studied to characterize potential impacts of industrial processing on these materials. A microcapillary rheometer was employed to study the rheological characteristics ofaqueous CNC suspensions at concentrations ranging from 1.5 wt% to 12.1 wt%.Increased cellulose content in the suspensions produced increased viscosities. A Sisko model was successfully fit to the data which display high shear Newtonian plateaus. Shear rate sweeps at these concentrations failed tofullyreduce to a master curve. Furthermore, repeated testing of the same sample volume at nearly 800000 s-1led to a permanent decrease in viscosityfor all samples.Atomic Force Microscopy (AFM) probed CNC morphology to observe any changes in the CNC dimensions which may have contributed to this phenomenon. AFM resultsindicate significant decreases in both height and length of the CNCsafter repeated testing at high shear rates.
Effect of Coating Anisotropy on Scratch Behavior
Three-dimensional finite element method (FEM) modeling has been carried out in this study to investigatethe scratch-induced surface deformation and damage mechanisms in composite coatings applied on polymer substrate. Composite coating systems with anisotropic properties and variation in thicknessare considered in the numerical framework to study the influence of coating anisotropy and layer thickness on scratch behavior. The results show that coating anisotropysignificantly affectsthe scratch resistance of coating systems. Implications of the numerical findings on scratch resistance of coating systems are discussed.
Effect of Long-Chain Branching on Scratch Behavior of Polypropylene
The effect of long-chain branching (LCB) on scratch behavior of polypropylene (PP) was investigated. In this study, the model LCB PP samples were modified viareactive extrusion process by incorporating increasing amount of polyfunctional monomerin PP. Small amplitude oscillatory shear results show that LCB level in PP increases with increasing polyfunctional monomer introduced. Moreover, increasing LCB content slightly improves the tensile strength of PP. ASTM D7027/ISO19252 standard scratch test was employed to determine the scratch resistance of the model LCB PPs. It is found that incorporation of LCB delays the onset of fish-scale formation.
Fabrication of Multifunctional PVDF/MWCNT Nanofibrous Membrane via Electrospinning for Membrane Bioreactors
Nanofibrous membranes in membrane technology applications for water and wastewater treatment have gained interests among researchers because of their high mechanical and chemical resistances. In this study, Polyvinylidene fluoride (PVDF) nanofibrous membranes were prepared by electrospinning method with 20 wt% PVDF solution. The effects of processing parameters including flow rate, applied voltage, tip-to-collector distance and presence of multiwalled carbon nanotube (MWCNT) on fibers morphology were observed using scanning electron microscopy. The changes of fiber diameters, pore size, and membrane porosity were investigated to investigate the characteristics of nanofibers as a function of processing parameters. The modified membranes with MWCNT were characterized with contact angle analyses and water filtration tests to evaluate the performance of the membranes.
Functional Alkane Solvent Systems
An oligomeric hydrocarbon, Poly(α-olefins) (PAOs), were previously reported as a potential greener solvent to replace conventional alkanes solvent due to its lower toxicity, flammability and volatility. However, its poor solubility toward most organic substrate may limit its applications as solvent. This work demonstrated three strategies to introduce polarity in PAOs and recycle polar additives simultaneously: polymerization of polar monomers onto a PAO anchor, host-and-guest interaction and end-group modification of a PAO anchor, vinyl-terminated polyisobutylene (PIB). In the first method, RAFT polymerization gave a better control of polar polymers onto PIB in order to maintain hydrocarbon solubility over other two polymerizations (hydroboration/O2 initiation, ATRP polymerization). Secondly, the polar polymer, poly(isopropylacrylamide) (PNIPAM) could be successfully brought into and recover back out an alkane phase by treating with chemicals via a hydrogen bond network. The reversible solubilization of PNIPAM were used in recyclable Rhodium catalyzed hydrogenation. Lastly, a hydrophilic moiety (Hexamethylphosphoramide, HMPA) was successfully incorporated onto PIB. The hydrocarbon soluble Lewis base catalyst can be used in allylation of benzaldehyde in PAOs. Other ongoing studies are exploring this molecular recognition based solubilization with other solubilizing agents, other precipitation agents and exploring the use of this chemically responsive solubility both as a tool to prepare new solvent systems and new sorts of recyclable catalysts.
How Poor Selection of Materials, Design, Tooling and Design Errors Affect the Aesthetics of Plastic Parts and What Designers Need to Know About the Science of Color and Appearance - Part 1
Most engineers and designers come from the metal world. Therefore, many of them make assumptions on the predicted performance of plastic properties based on their metals background. Unlike metals, the knowledge of color and appearance is extremely important in the case of plastics. Most plastic parts have dual functions— physical performance and aesthetics. Aesthetics are important since very few of the parts need to be painted or otherwise decorated if designed and manufactured with due diligence. On the other hand, even if we are designing the most aesthetically critical metal components such as exterior automotive parts, we mostly choose the metals and alloys based on the physical properties, weight, and cost. The aesthetics are left to the paint specialist, who will in most cases find a paint system (primer, paint, and application method) that will meet the cost, durability, and cosmetic requirements. In other words, aesthetics and physical properties are quite independent of each other. A vast majority of metal parts meet their aesthetic and environmental requirements just by getting brushed, plated, chromate conversion coated or anodized. Plastic parts not only need to meet the short-term color and appearance requirements, but also need to be resistant to long term color shift and fading. This paper is in two parts. Part 1 - Appearance and Color Factors - Material - Design - Tooling and Processing Part 2 –The fundamentals of Color and Appearance, Specifications, Measurement and Tolerances
Optical 3D Metrology the Ultimate Biomechanics Tool
3D Digital Image Correlation (DIC) provides the ability to measure non-contact 3D coordinates, displacements and strains of materials and structures. Although widely accepted in mechanical engineering and materials engineering, this tool as yet to prove its capability within the biomechanics industry with soft tissues, bones and most medical-specific materials. Known for its unique capability to be used for rapid full-field measurements from material characterization to full component testing, providing the equivalent of the results of over 10,000 contiguous strain gauges or displacement sensors, this technique is now recognized and certified (NIST, Boeing...) as equivalent to standard mechanical testing tools in the aerospace and automotive industries. 3D DIC is used across industries for improving the quality and the accuracy of the data collected to best understand mechanical behaviors of components or validate FEA models. This work focuses on the integration of the DIC technology with load frame such as Instron, MTS and Zwick for simple coupon testing of soft tissues, implants and prostheses. It was shown that DIC could in fact provide a more flexible measurement platform with capabilities for any coupon size, very small to large strains with a single instrument as well as multi-axial data in every direction for each and every one of the biomechanics applications evaluated.
Quantitative Determination of Interfacial Strength of Multilayer Films Using an Instrumented Machine
The ASTM D3359 and ISO 2409 standards are currently utilized to rank the adhesive strength between the coating layer and substrate by quantifying the damaged area across the crosshatched region after a tape pulling. However, these standards neither specify the forces needed to cut the film and rub the tape nor spell out the speed and angle of the tape required during peeling. These uncertainties lead to inconsistent results. Another issue is that the current standards only apply to rigid substrates. Consequently, the above methods cannot be applied to soft multi-layer films for adhesive strength determination. In this study, a new test methodology has been developed for quantitative determination of adhesion in soft thin multi-layer polymeric films. The depth of the surface cutting was controlled using an instrumented machine. The processes of attaching, rubbing, and peeling the tape were also automated by the instrumented machine to allow for repeatable and reliable test results. Lastly, instead of using visual assessment to rank adhesive strength of the multi-layer films as instructed in the standards, our proposed new method will quantify interfacial adhesion between the top-layer and in-layer of the multilayer films based on the principle of energy conservation. Fundamental structure-property relationships on multilayer films can now be established.
Ship Less Air –Flexible Chip Bag Filling Simulation for Sustainability
The snack flexible packages on the market today, such as potato chips, pita chips, taco chips, tortilla chips, etc., are typically sold by weight, that is, the packages need to fulfill the label claims by weight. However, the size of the packages is determined by the overall volume of the products. The determination of the overall volume of a given product weight is not trivial. The volume is a function of chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), VFFS machine type, etc. Traditionally, the size of the bag is determined by trial & error process through iterative lab testing and production trials. This approach typically results in unnecessary large bags due to the concerns of sealing contamination induced leakage issues in the case of the bag being too small. This leads to significant sustainability issues in shipping and distribution since the shipping trucks are often cubed out by volume (not by weight) for chip/snack packages. The energy is wasted by shipping more air (thus, less chip/snack packages) during distribution. In this work, authors propose a novel approach of bag size determination by using a virtual simulation of the VFFS chip filling process, where the potential influential attributes, such as chip broken rate, chip size distribution profile, bag width, bag film gage and material, production line speed (bag/minute), and VFFS machine type, can be modeled and their impact on the bag size can be quantified. A progressive 3-case simulation is performed and presented in this paper. The results are directionally correct based on the authors’ observation and past experience. Currently, authors are looking for industry partners (brand owners, co-packers and machine manufacturers) to collect production data and validate the analysis model. The intent of this paper is to bring the awareness of applicability of the simulation technology regarding to the bag size determination and chip/snack filling process, and ultimately help the industry in adopting the technology to make the chip bag filling process more sustainable, i.e., to ship less air.
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