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.
In this work, natural fiber and wood composites based on neat and recycled polypropylene (PP) were fabricated by melt processing. Different formulations, including various reinforcement contents, different types of coupling agents, different types of reactive additives, and an impact modifier were developed. The reinforcements were in the form of natural fibers like banana, flax, rice husk and palm fibers and of wood sawdust. For the long fiber composite systems, processing was done by compression molding of piles of long fiber mat and extruded polypropylene film. For the short fiber composite, the samples were prepared by extrusion followed by injection molding. The tensile, flexural and impact performance were characterized and all composites show superior mechanical properties when compared with the pristine matrix. Mechanical performance of the wood composites was also evaluated before and after conditioning in water for 1 and 7 days. Results indicate that the composites resist humidity very well. The results also demonstrate the effect of formulations on the performance of the recycled composites.
Anyone who has worked in the plastics industry, even for a short time, knows that cost is a key if not the key factor in the decision to produce a part or assembly. Controlling production cost is an important step in a profitable molding operation. The most successful molding companies understand their own production costs and can quickly assess the cost effectiveness of producing a given component. It is not the only place, however, that provides opportunities to improve the bottom line.The “real” cost of a component begins with the initial concept. The initial vision of the component begins to lock in shapes and features. These shapes and features have a great influence throughout the design phase. It is during this phase of the process that these features and shapes become tooling and molding dreams or nightmares. It is also during the design phase that a number of significant opportunities exist to create a product which meets performance requirements at the lowest possible cost. This discussion will focus on some of those opportunities and hopefully provide some considerations to help the designer balance the struggle of cost vs. performance.Some of the key design and engineering factors that can influence final component cost are listed below:Concept DevelopmentMaterial Candidate SelectionPart/Assembly DesignDesign Optimization ProcessMold and Injection System Design & AnalysisDesigning for Special Manufacturing Processes
The focus of the present research is on thermal conductivity characterization of fiber reinforced polymer (FRP) composites in three directions (longitudinal, transverse and through-the-thickness). Tested composite samples are made of E-glass, or Carbon fiber in Vinyl ester resin. The characterization has been carried out using ‘Guarded heat flow meter method’ in accordance with ASTM E1530. Results showed that E-glass/Vinyl ester samples have a thermal conductivity of 0.35 ± 0.05 W/ m K, while the conductivity of carbon composites is higher in the fiber direction and lower in through-the-thickness direction. Addition of 10 wt% and 12.5 wt% of graphite additive in neat vinyl ester resin increased the conductivity by 88% and 170% respectively.
The blending technique in this study consists of two sequential stages of mixing and reaction. In the first stage, the PVC is pre-blended with two monomers of the TPU (soft segment and chain extender). In the second stage, the in-situ polymerization of the TPU with the PVC takes place upon the addition of the third monomer of the TPU (diisocyanate). Therefore, the miscibility and reactivity of the TPU monomers with PVC play a role to govern their properties and processing sequence. The effect of chemical structure, isomerism, NCO and OH content of the TPU monomers on the miscibility, thermal and mechanical properties of the reactive blends of PVC/TPU are studied.
Applications of orientation tensors for short-fiber polymer composites introduce a dependence upon higher-order orientation tensors alleviated through a closure. Current fourth-order closures have been demonstrated to neglect shear-extensional and shear-shear coupling effects in material stiffness predictions whereas sixth-order closures are capable of representing this advanced behavior. The newly introduced invariant based sixth-order fitted closure (INV6) is investigated and results demonstrate the INV6 closure accurately captures the complete material stiffness behavior.
Bilayer films of polypropylene (PP) and lowdensity polyethylene (LDPE) were formed by blown film coextrusion process. Scanning electron microscopy (SEM) was used to study the morphology of the components of the final film. Orientation parameters of the individual components were estimated using birefringence, and x-ray diffraction (WAXD). Preliminary results suggest that the process-time difference between onset of crystallization of components of PP and LDPE is an important parameter which could control the orientation and morphology of the second component during PP/LDPE coextrusion. Online Raman spectroscopy enabled measurement of this parameter during PP/LDPE coextrusion.
A series of nanocomposite films based on nylon 6 and nylon 66 were processed through melt-extrusion and were characterized for barrier, mechanical, and thermal properties. These films were then compared to the neat nylon films. Nanocomposite nylon monolayer films containing montmorillonite-layered silicates (MLS) exhibited a 40% improvement in oxygen barrier over the neat films at 0%RH. Co-extruded films of nanocomposite nylons and polyethylene were processed to improve the barrier properties of the hydrophilic nylon films. The optimum formulation, a 250-micron thick multilayer film based on nanocomposite nylon MXD6, exhibited barrier to oxygen of 0.49 cc/(m2-day) at 0%RH.
The demand for environmentally-friendly biodegradable packaging is a growing area, reflecting consumer and retailer awareness of the issues of waste disposal. Compostability has, so far, been the main focus of applications of biobased packaging materials, which is the natural outcome for a vast amount of packaging materials and waste. The aim of this study was to evaluate the degradability of four commercially available Poly (lactide) packages, a bottle, a tray and two deli containers, in real composting and ambient environment conditions. The correlation of the package’s properties changes with time was examined. The physical property breakdown was monitored by visual inspection; GPC, DSC, and TGA.
Barrier properties of Poly (lactide) polymers were studied using a Quartz Crystal Microbalance (QCM). For this purpose, a new system was built up using QCM to measure the sorption of water vapor on polymer films spin coated on a quartz crystal. Sorption experiments were conducted at 23 °C and relative humidity of 20% and 60%. PLA films produced had a thickness of 0.12±0.02 ?m. Water diffusion coefficient values between 0.9 to 1.1 x 10-17m2.s-1 at 20 and 60% RH and permeability coefficients between 0.98 and 2.42 x 10-23 kg.m.m-2.s-1.Pa-1 were determined.
The polymerization kinetics of thermoplastic polyurethanes (TPU) is studied by using differential scanning calorimetry (DSC), Raman spectroscopy, adiabatic temperature rise (ATR) and dynamic rheometry. The objective of this study is to develop the empirical kinetic equation(s) governing the TPU polymerization in a twin screw extruder, as well as including the effects of chemical structure, isomerism, NCO and OH content, catalyst and temperature on the TPU polymerization. The polymerization during the reactive blending process with Poly(vinyl Chloride) (PVC) is presented. The effects of shear rate and pressure on the kinetics model are also considered.
Modern ultrasonic welding systems are capable of processing a wide array of thermoplastic parts and materials by using different welding modes. Determining which mode of operation can be intimidating to the user uninitiated with the applicability and intricacies of each. Welding by time, energy output, peak power output, distance (either reference point or absolute), or even combinations thereof, are all offered on advanced ultrasonic controllers each with its own advantages for a specific welding operation. This paper will explain each mode while suggesting different modes and strategies for the optimization of different types of welding processes performed on various products and materials.
We consider distributive mixing in the single-screw extrusion process. Several mixing measures in the extrusion process were proposed in the literature to quantify the mixing performance. In our previous research, we proposed the “Deformation Characteristics” (DC) as a new deformation measure of the screw extrusion process using the Cauchy-Green deformation tensor.In this work, the fourth-order Runge-Kutta method has been employed for numerical integrations to obtain the residence time and the deformation characteristics, using the three-dimensional velocity fields obtained by the finite element analysis with the periodic boundary conditions along the down-channel direction in the real screw geometry.
This study investigates the effect primary runner length has on fill imbalance characteristics for a geometrically balanced multi-cavity runner system, during a polymer injection molding process. The experimentation utilizes three settings of the primary runner length – long, medium, short – and four injection velocity settings, creating a relationship of fill imbalance to both the primary runner system’s length-to-diameter ratio (L/D) and injection velocity. The experiment’s goal is to provide data that would build on prior studies’ findings on the topic of shear induced flow imbalances in geometrically balanced molds.
Poly(methyl methacrylate) (PMMA) and nanoclay composite was blended as a dispersed phase with polystyrene (PS) in a twin-screw extruder. The mixture was then batch foamed with supercritical CO2. It was found that the cell density of foams based on the blend is higher than that based on the weight average of the two pure polymer components at the same foaming conditions. The cell size decreases and the cell density increases with the increase of the PMMA domain size. One explanation is that large PMMA domains serve as a CO2 reservoir and the nucleation in the PS phase is enhanced by the diffusion of CO2 from the PMMA phase to the PS phase. Very small PMMA domains can not function as CO2 reservoir, so they are not able to facilitate nucleation. A much higher cell density and smaller cell size were observed when nanoclay is located at the interface of the PMMA and PS domains due to the heterogeneous nucleation.
During the injection molding process, high shear conditions developed in the runner can create significant material and melt temperature variations across its diameter. As the melt continues into the cavity, laminar flow conditions segregate these melt variations and cause them to be distributed into distinctly different regions within the part. The resultant uncontrolled distribution of these melt variations may be the root cause of warpage in many plastic parts. It must be understood that these melt variations cannot be controlled by the molding machine. However new methods demonstrated in this paper show that they can be controlled within the melt delivery system of the mold. This paper presents the results of a study which proves that the segregated melt conditions developed in a runner are a significant contributor to warpage. Additionally the paper presents new methods of controlling the resultant warp through the strategic positioning of these melt conditions within the part.
The major objectives of this research are to modify the surface characteristics of poly(L-lactic acid) (PLA), a poly(hydroxyalkanoate) (PHA), and their blend films by grafting hydrophilic polymers and to study the effect of the surface modification on bulk properties of these films. The surfaces of solvent-cast films were activated by UV irradiation. Hydrophilic monomers acrylic acid and acrylamide were then photopolymerized from the film surface. The film surfaces resulting from each reaction step were analyzed using ATR-FTIR spectroscopy and contact angle goniometry. The effect of the surface modification procedure on the bulk properties of the films was studied to determine whether properties were adversely affected. Representative bulk properties, including Young’s modulus, tensile strength, % elongation, and toughness, were measured after photografting.
Nanoclay composite materials provide low specific gravity and high modulus properties that are superior to many other composite materials. Recent developments in Nylon 6 nanoclay composites have achieved more than a 100 % increase in flexural and tensile moduli with 8 wt% total nanoclay loading; total nanoclay referring to the sum of the organic surfactant and inorganic clay content. However, the weldability of nylon nanocomposites has never been reported. This study evaluated the weldability of nylon 6 nanocomposites with 0 wt%, 5 wt% and 8 wt% total nanoclay loadings using vibration welding. A threefactor (weld pressure, weld amplitude and meltdown) and two-level DOE was conducted to evaluate the weldability of these materials. It was found that the weld strength of the 8 wt% nanoclay loaded nanocomposite was 19% lower than the unfilled nylon 6.
On-line measurement of birefringence was conducted in high speed in-line drawing process of poly(ethylene terephthalate) filament by using a diameter monitors and an optical retardation measurement apparatus. Birefringence of filament increased steeply in the vicinity of necking deformation and the position of that slightly shifted to upstream with increasing draw ratio. Birefringence measured in the spinning line showed lower values than that in the in-line drawing line at the same diameter, because the steep increase of birefringence started at larger diameter in the drawing process. On the other hand, time-course changes of diameter and birefringence in the vicinity of neck-like deformation in the spinning line could be clearly obtained, and it is important to note that the necking deformation in the high speed in-line drawing process occurs accompanying unique periodic diameter fluctuation of about 130 Hz.
The melt rheological properties of an ethylene/alpha-olefin copolymer polymerized by a supported metallocene catalyst, which have been developed as the easy processing polyethylene by Sumitomo Chemical, were evaluated and compared with conventional polyethylenes. The melt viscoelastic properties of the copolymer exhibit a shear rate dependence similar to that of high-pressure low density polyethylene that is considered to be caused by the wide molecular weight distribution and long chain branched molecular structure.In the latter part of this presentation, we have focused on the performance of the above copolymer. This copolymer exhibited superior processability in the fabrication of blown film such as low temperature and high output processing, leading to the production of a clean film without any additives and with low odor and taste.
Capillary valve (CV) is one of the passive valves used to control the fluid flow in microfluidics. Many designs and applications have been based on the capillary valve including the compact-disk microfluidic platform technology. However, the valve loses its function when being used to hold the protein solutions or subject to protein solutions which are applied to treat the surface for non-specific binding. A novel fishbone" micro-valve design based on the concept of superhydrophobicity was developed in this study. The experimental results showed that the valve remains its function even being subject to the protein solutions. It was also tested on the CD microfluidic platform in which the flow control was demonstrated during disk rotation under various conditions."
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Brown, H. L. and Jones, D. H. 2016, May.
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ANTEC 2016 - Indianapolis, Indiana, USA May 23-25, 2016. [On-line].
Society of Plastics Engineers
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