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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Marisely De Jesus Vega, Smita Birkar, Carol Barry, Joey Mead, May 2013
Hot embossing and injection molding are leading processes for the production of micro and nanostructured surfaces. The ability of these processes to replicate electroformed nickel tooling containing 0.5, 1, 10, and 50-?m positive and negative features was compared using several polymers. The tooling and microstructured parts were measured using scanning electron microscopy and optical profilometry. The processing conditions, replication (quantified using the depth ratio and feature definition), and overall quality of the parts were compared.
Kevin Lucero, Marissa Tierno, Richard L. Lehman, Giorgiana Giancola, May 2013
Thermoplastic immiscible polymer blends were prepared from polytrimethylene terephthalate [PTT] and polyamide 6,10 [PA6,10] by melt processing in a Brabender mixer to assess morphology developed between the immiscible domains. PTT and PA6,10 were selected as a pair of engineering polymers with complementary properties and as a blend prepared to significant extent from bio-based precursors. Overall, a 50/50 blend of these polymers has a renewable content of nearly 50%. The overall objective is to develop an engineering blend with good stiffness, strength, and dimensional stability while simultaneously being easy to process. In the present phase of the work, blend homogeneity was studied as a function of mixing time and temperature in the range of t=0-25 minutes and T=240-260 C. Results are presented in terms of torque versus time and temperature curves that are interpreted in terms of domain formation and SEM micrographs are used to define domain size and overall morphology.
Arya Tewatia, Jennifer Lynch, Thomas Nosker, May 2013
PET, PBT and Poly (trimethylene terephthalate) (PTT), of the polyester resin family, potentially compete for the same engineering-grade thermoplastic market. PTT’s crystallization rate relative to those of PET and PBT, suggests its high suitability for injection molding applications. The aim of this work is to produce a viable PTT candidate for engineering structural applications. To this end, fiberglass (FG) reinforcement, a commonly used method of improving polyester properties, is in a one-step novel process blended with PTT at 10%, 15%, 20%, and 30% FG. The mechanical, rheological, thermal and morphological properties of the FG-PTT composite are presented.
Ido Offenbach, Isik Nugay, Emre Unsal, Mukerrem Cakmak, May 2013
The URS-FTIR is an one-of-a-kind machine developed by our group that allows collection of real-time data, which includes birefringence, true strain, true stress, and simultaneous tracking of full spectrum parallel and crossed polarized infrared spectroscopy of materials during uniaxial stretching of polymer films. This is machine is capable of acquiring both polarizations at 300 spectra/second during the uniaxial stretching. The real-time dichroic ratio is calculated by polarized infrared light, both parallel and perpendicular to the stretching direction; because of this, we are able to observe how the chemical groups behave during stretching, relaxation and subsequent annealing. This is particularly useful in examining semicrystalline polymers, multiphase systems such as copolymers, nanocomposites and their blends on their melting, orientation , relaxation and crystallization behavior enable us to peer into the mechanistic details of each phenomenon being examined, The design of the instrument, its performance and selected preliminary data will be presented on the poster.
Mineral fillers/reinforcing agents such as talc, wollastonite, clay and/or mica in polycarbonate- acrylonitrile butadiene styrene (PC/ABS) blends provide a technological pathway to increase specific mechanical properties like tensile strength, tensile / flexural modulus, simultaneously reduce warp in molded parts / articles fabricated from these formulations, as well as decrease the co-efficient of linear thermal expansion. The main challenge from a property balance perspective is to achieve high impact and toughness values in conjunction with high stiffness and tensile strength properties, since these properties typically tend to go in opposing directions. In this paper, routes based on employing surface treated mineral reinforcements to achieve exceptional impact properties are explored and discussed.
Computer predictive modeling of real-world physical systems has become of great interest in the recent years to optimize the design of manufactured parts. The plastic composites field have also benefited from computer modeling of the injection molding process to achieve the final mechanical properties of the processed part. This simulation uses fiber orientation models to predict the final orientation states throughout the part and then uses micromechanics models to predict the composite’s stiffness. The prediction of the fiber orientation is very complicated due to the fiber-fiber interactions. Several fiber interaction models have been proposed in literature; however, the global mechanical properties have not been compared to experimental testing to determine the most accurate interaction model. In order to compare the stiffness predictions from different fiber interaction models with experimental testing, an accurate simulation must be created to match the experimental conditions of the actual test. However, as typically is the case, the more detailed models require more computer power. In this poster, a two-dimensional model will be compared with a three-dimensional model of an ASTM flexural bar to determine if a two-dimensional assumption still maintains the necessary accuracy in the final predicted stiffness. In addition, a comparison of the inlet conditions of the fiber orientation will be investigated to determine the extent of their effect on the overall fiber orientation and resulting stiffness throughout the flexural bar.
This paper aims to simulate slow crack growth in high-density polyethylene by using Crack Layer Model. We first derived the analytical approximations of stress intensity factor and crack opening displacement for finite geometries using close form solution of a semi-infinite crack and the numerical solutions for corresponding geometries. We then use the approximate solutions to assess the size of the process zone accompanying the crack, slow crack growth rate and mechanisms as well as the lifetime in brittle fracture of high-density polyethylene.
The benefits of using a multivariate analysis system to improve closed loop control of a wire or cable extrusion line in order to improve process control are being studied. Multivariate analysis systems are currently most common in injection molding processes, but their potential for increased process monitoring on extruder systems is significant. The use of a multivariate analysis system has the potential to increase automation, process consistency, increase productivity, and reduce labor costs. The focus will be on biaxial dimensional stability through the monitoring of puller speed, screw speed, and the temperatures of the water bath, melt, and die.
Polymer melts under micro injection molding process experience high shear rates and high thermal gradients, resulting in some unique morphology features. This paper examined the morphology of Pebax 7233 SA01 under designed experimental conditions. With measurement by cavity pressure and temperature (PT) sensors, shear rates and thermal gradients were quantitatively evaluated and related to morphology evolution. Unique spherulites were formed beside the skin layers, having a much larger size than its adjacent larger while the central region had no visible spherulite structure. Their formation, and the related thermomechanical history, were examined. Macro mechanical properties and local mechanical properties of micro molded samples and micro features were evaluated by tensile testing and nano-indenation. The relationship between process, morphology and properties were evaluated and correlated by statistical analysis.
Longhao Yan, Aldo Crugnola, Robert Whitehouse, May 2013
In this thesis, sisal fibers were pretreated by alkaline and acetylation. Observed by the scanning electron microscope, the acetylation surface modification resulted in the best interfacial adhesion between fibers and polymer matrix. The pretreatment washed away the wax and impurities on the fibers surfaces and roughened the surfaces. Two fiber lengths of 3 mm and 10 mm were pretreated by alkaline, but the composites of them showed similar tensile properties. The sisal fibers and polymer matrix materials were mixed by wire coating and batch mixing (with a weight portion of 1:9). Batch mixing was found to offer a more complete surface contact between two phases. Prepared by compression molding, the composites of the acetylation pretreated fibers showed superior Young’s modulus than the composites of alkaline pretreated fibers, untreated fibers, or polymer matrix. The tensile strength of the composites was generally lower than polymer matrix. Moreover, both polymer matrix and composites exhibited similar glass transition temperatures. The composites from alkaline pretreated and ground fibers showed the highest storage modulus below the glass transition temperatures, and the storage modulus of the matrix polymer was lower than the one of composites above the glass transition temperatures.
Ultra High Molecular Weight Polyethylene (UHMWPE) infused with vitamin E, utilized in the manufacture of implantable medical devices, will be characterized for the safety and improved wear rate of the material for use in this application. The following experiments will analyze the chemical and mechanical properties of E-CIMA, a compression molded, irradiated, and mechanically annealed material to a vitamin-E infused UHMWPE that has not been mechanically annealed. This will be done through the use of Tensile, Izod, DSC, and FTIR tests. ASTM standard procedures will be used in the characterization of the materials. We anticipate that removing the step of mechanical annealing, does not have an adverse effect on the mechanical and chemical properties of the material, and still shows an enhancement from standard use non-modified UHMWPE.
A major design consideration and benchmark for a high quality injection molding hot runner system is color change performance. The focus of this project was to evaluate the effect of temperature uniformity on color change performance and frozen layer formation. Trials were conducted using three different hot-sprues representative of typical configurations. The thermal profile of each sprue was mapped at steady state conditions prior to processing. Sprue pulls were then performed to study the efficiency of each color change and results were compared with data obtained from mold filling simulations. It was determined that temperature uniformity greatly altered a system’s color change performance. Cool regions in the sprue formed frozen layers of the original material that would remelt over subsequent cycles negatively impacting the color change performance.
Roll-to-roll (R2R) lithography is a continuous manufacturing process used to create patterns on a polymer substrate. Thermally curing of R2R embossed features is time consuming, and is commonly replaced with faster UV or chemical curing. A technique of induction heating the lithography stamp in a R2R process has been conceived for heating, forming and cooling along the perimeter of the roll. The patterned polymer surface needs no additional curing steps, which increases efficiency of the R2R lithography process. The results of initial investigation prove the feasibility of said conceptual process, and initial experiments confirm heating of the lithography roll by induction heating.
Thermoforming is an important converting technique. Predicting how well a material will perform during thermoforming is difficult without a trial run. The thermoforming index (TFI) was used as a measure of a material’s performance in thermoforming. The TFI test measures a material’s viscous and elastic properties under thermoforming conditions and quantifies how well the material will perform based on those properties. In this study, the thermoformabilities of liquid crystal polymer (LCP) materials were observed using the TFI. Dynamic frequency sweeps were used to estimate the optimum forming temperature. The test was repeated on LCPs with two different levels of filler. Polypropylene (PP) homopolymer, polystyrene (PS) and high density polyethylene (HDPE) were also tested as controls. The relative TFI values found for each control material correlate with their known forming behavior. The filled LCP materials had lower TFI values, which would suggest poor performance. However, the TFI values for filled LCP do not portray completely the observed behavior, as these materials have shown sufficient thermoformability.
Flame Retardants (FR) are often compounded into plastics to ensure fire safety. However, some types of halogenated FR additives are environmentally persistent and toxic to humans. Here we report the development of an alternative FR additive based on polyphenol-titania complex that exhibits a combination of radical scavenging and char forming properties. The thermal stability and heat release capacity of blends of this complex with polypropylene are compared to those containing conventional halogenated FR.
Polyamides are widely used in variety of electrical applications because of their good melt flow, chemical resistance, impact, and electrical properties. For applications requiring a glass-filled polyamide composition, with a high degree of flame retardancy, flame retardant additives must be added to the composition. Metal dialkylphosphinates are the preferred flame retardants for polyamides, but they are expensive and must be used in relatively high concentrations. We have discovered that in glass-filled polyamide compositions, desirable flammability, flow, heat and mechanical properties, can be achieved with reduced loadings of Exolit® organic phosphinates, by including specific poly(phenylene ether) masterbatches in these polyamide compositions.
The concept of sustainability is often stated in a number of ways but four core principles appear throughout: Protect the environment, promote human health, conserve resources, and assure social and economic well-being to the global population. PVC resin has intrinsic properties that allow finished products to meet all four of these objectives. PVC resin and products compare favorably to other materials in life cycle assessments when reviewing key impacts of resource and energy conservation, and greenhouse gas emissions. Sustainability assessments at the business level are excellent tools to promote these principles and track performance. This paper was prepared for the Society of Plastics Engineers Annual Technical Conference (SPE ANTEC) Vinyl Session, April 22, 2013 in Cincinnati, Ohio.
From end of screw return melt residence through injection to ejection of a molded part to screw return end time is the thermal dynamic molding process cycle. A micro-bead melt sensor indicates the imposed strains of temperature and radial force strain as melt density “K” electro-motive force (emf) readout. A nozzle melt density sensor profiled consecutive molding cycles of melt fill to final peak pack. The melt pack interruption by screw return time to final mold cure will be presented.
In the field of thermal shielding for aerospace applications Cf/SiC composites are raising great interest, provided that they are protected from oxidation by suitable coatings. Conversely, ultra high temperature ceramics, and in particular HfB2, are among the best oxidation resistant materials known. A coating made of a HfB2/SiC composite (20% weight SiC) was tested as an oxidation protection on a Cf/SiC composite.
Pharmaceutical melt extrusion has attracted much attention recently due to broad applications such as bioavailability enhancement, controlled release and taste masking. This article summarizes the characterization methods utilized in the field of pharmaceutical extrusion, and focuses on three applications: characterization of solid dispersion, process analytical technology (PAT) and solubility measurement of drugs in polymeric materials
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Brown, H. L. and Jones, D. H. 2016, May.
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