SPE Library

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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Conference Proceedings

In-Situ PP/PET Nano-Fibrillated Composites: The Effect Of Viscosity Ratio On Fibrillation And Foaming Behavior

Chongxiang Zhao, May 2018

It is widely accepted that the manufacturing of high expansion PP foams with fine cell morphology is a challenging task due to the low melt strength and the weak rheological behavior of the linear polypropylene. In this study we present a novel method to manufacture high cell density, large expansion microcellular foam through nano-fibrilation PP/PET composites. Various studies have been conducted to improve the processability of linear PP foams. Until now, the most successful industrial approach is using the branching PP as it expressed the strain hardening response and the increased melt strength behavior. However, the commercial price of branching PP resins are still doubled or even tripled comparing with linear PP resins, which dramatically limits the branching PP’s applications. Inducing chemical cross-linking is proven to be another effective way to improve the melt strength of PP. However, the cross-linked structure causes difficulty in recycling PP resins. Furthermore, the cross-linking reaction is not evenly initiated throughout the matrix rendering non-uniform cell structure in the final foam product. Implementing inorganic/organic filler is another alternative route for enhancing the foamability. PP reinforced with those fillers has higher viscosity and better elasticity at melting state. Nonetheless, the well-recognized challenging issue is to achieve well distribution and dispersion of nano-size fibers inside the polymer matrix. Because of the large surface to volume ratio, the nano-fibers tend to agglomerate. The well-established methods usually requires complex experimental conditions and normally involves dealing with chemical hazards. By implementing nano-fibrillation technology, all above mentioned draw-backs were overcome. The nano-fibrillation technology is used to manufacture polymer-polymer fibril composite in this study. The nano-fibrillation technology can generate high aspect ratio nano-fibrils uniformly dispersed inside the polymer matrix. The processing can be briefly summarized as: (i) blending immiscible polymer matrix (A) and polymer reinforcement (B) to make polymer (B) dispersed in spherical shape (the melting temperature of polymer B should be at least 30oC higher than polymer A); (ii) applying large deformation on the polymer extrudate by either hot stretching or cold stretching; (iii) carefully choosing a temperature between the melting temperature of polymer A and polymer B to melt the composite without damaging the fibril morphology of polymer B. In this study, three kinds of PPs with different viscosity are reinforced with PET nano-fibrils via melt spinning. The study shows that the high viscosity PP is preferred to generate low diameter nano-fibrils (~200 nm) in a wide concentration range; while the diameter of fibrils in low viscosity PP decreased with raising PET concentration. The oscillatory shear behavior is studied by comparing the storage modulus (G’) and phase angle (tanδ) of the non-fibrillated and fibrillated samples. Differential scanning calorimetry and birefringence optical microscope were employed to study the crystallization kinetics of PP/PET fibril composites. The rheological properties and crystallization kinetics were significantly improved with the presence of PET fibrils. Crucially, benefit from the strengthened rheological behavior and crystallization kinetics, the batch foaming of PP/PET nano-fibril composite is able to product a high cell density polymer foams.

Innovative And Useful Characteristic Values For The Pro-Cessing Of Thermosetting Molding Compounds

Thomas Scheffler, May 2018

Due to their complex flow and curing behavior the quality of parts made from thermosetting molding compounds depends to a high degree on the reactive and viscous char-acteristics during their processing. In the study at hand a newly developed test procedure was applied to examine the dependence of these characteristics on the composition of the pourable molding compound, the amount of hard-ener, the present material humidity and the process pa-rameters. Three thermosetting molding compounds were purposefully impinged with high air moisture, the amount of hardener was partially increased and the resulting flow and curing behavior was determined with the implement-ed testing sensors. A distinct dependence of the flow re-sistance and the reaction kinetics on the tool temperature, the amount of hardener and the material moisture was detected. These results are discussed and the potential of the developed testing device is pointed out.

Simulation Of Mold Filling Charaterization Of Phenolic Injection Molding Compounds With Slip Boundary Condition

Ngoc Tu Tran, May 2018

The present paper shows a rather simple but effective and useful method, namely, the spotwise painting of the mold wall surface to investigate slip of the phenolic melt on the cavity surface. For all processing conditions, it was found that there was a strong slip on the interface between the phenolic polymer and the mold wall surface. Furthermore, a differential scanning calorimeter (DSC) and a plate-plate rheometer are employed to measure degree of cure and viscosity of the phenolic injection molding compounds. In addition, a numerical methodology has been written to fit cure kinetics and reactive viscosity model based on experimental data. The fitted parameters were used to simulate the injection molding process for a phenolic component with slip boundary condition. A good agreement was found in comparison between simulation and experimental results.

Fabrication Of Synergistic Flame-Retardant Unsaturated Polyester Resin Based On Ammonium Polyphosphate And Aluminum Hydroxide

Xingxing Shi, May 2018

The exploration of highly effective flame retardants takes an essential part in the fire-resistant enhancement of matrix. Herein, UP/APP/ATH composites were fabricated by blending ammonium polyphosphate (APP) and aluminum hydroxide (ATH) in various proportions into unsaturated polyester resin (UP) matrix at the curing process. Thermogravimetric analysis (TGA) indicates the UP/APP/ATH composites exhibit a favorable high-temperature stability and an enhanced char yield. The flame-retardant performances were conducted by UL-94 vertical combustion tests, limiting oxygen index (LOI), and microscale combustion calorimetry (MCC). The combination of APP and ATH demonstrates an excellent synergistic flame-retardant effect, UP/APP/ATH sample can reach V-0 rating and LOI values are raised to 33.5 %. SEM and thermogravimetric analysis/infrared spectrometry (TG-IR) tests represent that the formed compact and dense char layer can act as a physical barrier to inhibit the heat transfer, and the volatiles of combustible gases are reduced.

Non-Isocyanate Polyurethane Networks Can Be Melt-Reprocessed With Full Property Recovery Associated With Cross-Link Density: The Case Of Polyhydroxyurethane Networks

John Torkelson, May 2018

Conventional cross-linked polyurethane (PU) or PU networks are unable to be reprocessed in the melt state into reshaped, high-value recycled products. This is because of the irreversible nature of the cross-links in PU, a common feature of thermosets which prevents the cross-linked network or thermoset from ever returning to a melt state. We have recently discovered several chemical platforms for making cross-linked polymers melt-reprocessable by instilling a reversible nature to the cross-links as a function of temperature. Here, we describe our approach for making reprocessable polyhydroxyurethane (PHU) networks that exhibit full property recovery associated with cross-link density after multiple melt-state reprocessing steps. PHUs are a class of non-isocyanate-based polyurethanes (NIPUs) that can be synthesized via reaction of amines with cyclic carbonates; the PHUs contain urethane linkages with adjacent primary or secondary hydroxyl groups. In the presence of appropriate catalyst, we have synthesized PHU networks with robust properties at room temperature and many tens of degrees above room temperature. These networks containing appropriate catalyst can be effectively reprocessed at least three times at 140 degrees C leading to full recovery within error of rubbery-state plateau modulus and room-temperature tensile strength and strain at break.

Frontally Polymerizable Gels For Double-Network High-Performance Resin Systems

Matthew Lampe, May 2018

This paper presents formulation details and initial property information for a new class of high-performance double-network glasses that are created through frontal polymerization of an initially formed gel. It is envisioned that this technology can be used for a variety of applications ranging from new adhesives to composite pre-pregs. Herein, we describe the creation of a new, one pot, liquid system consisting of miscible acrylates and epoxies. This system has the ability to undergo radical polymerization of selected acrylate monomers under long-wave ultraviolet radiation at room temperature. This polymerization produces a free-standing gel that can be incorporated as an adhesive or pre-preg in a composite system. The resulting gel can then undergo cationic, thermal frontal polymerization of the epoxy-based second network to form a cured high-performance resin. The stability of both the liquid mixture and the subsequent gel after the initial polymerization of the first network are discussed. The liquid system retains the capacity to undergo both the gelation and frontal polymerization steps after over and year and a half of storage. The ability to use sequential polymerization steps combined with the stability of the gelled state creates a system that shows promise for creating monolithic shapes, using frontal polymerization, from freestanding gels. Possible applications for this technology include 3D printing, electronics potting, and moldable adhesive films.

Copolyesters As Heat Distortion Temperature Modifiers In Rigid Pvc

Robert Young, May 2018

Exterior Rigid PVC products such as Siding, Cladding, Fencing, Decking and Window profiles are moving to more dark colors to enhance design features. Darker colors pose a challenge for Rigid PVC as infrared radiation absorbtion from the Sun can often raise the temperature high enough to exceed the Heat Distortion Temperature of the PVC causing distortion and sagging. Current technologies such as infrared non-absorbing pigments and coatings and additives, while minimizing the distortion, all have some problems in these exterior applications. Eastman is introducing a new material that solves many of these problems while increasing the Heat Distortion Temperature, enhancing ductility, and little effect on processing. This paper will discuss Eastman’s recent developments.

Heat Stabilising Flexible PVC with Layered Double Hydroxide Derivatives

Dan Molefe, May 2018

The layered double hydroxide ([Mg0.667Al0.333(OH)2](CO3)0.167·mH2O) (LDH) has found application as a heat stabiliser for PVC. Derivatives of this compound were synthesised using a hydrothermal method. Emulsion grade PVC was plasticised with 100 phr diisononyl phthalate and stabilised with 30 phr of the LDH filler additives. Heat stabilities were determined at 200 C. The dynamic heat stability tests were performed on the plastisols using the torque rheometer method. Static heat stability was evaluated on the fused compounds. It was evaluated from discoloration profiles of strips exposed for various lengths of time to heat in a Metrastat oven. The time dependence of hydrogen chloride evolution was followed with a Metrohm Thermomat instrument. The conventional LDH provided the best dynamic heat stability. However, partial replacement of the magnesium with copper significantly delayed the release of volatile HCl. If instead the replacement was done using zinc, better colour retention was achieved.

Temperature Control In Accelerated Laboratory Weathering Testing Of Plastics

Andy Francis, May 2018

Accelerated weathering testing is used widely to evaluate the performance of outdoor polymeric materials. Test standards have been published by multiple international and other standards bodies for performing testing to simulate outdoor environments. These test methods apply ultraviolet (UV) light, high temperature, and water in the form of condensation, humidity, and spray. Control of temperature during accelerated weathering testing is critical for many plastic materials, both to control the rate of photochemical degradation and to avoid unrealistic failure modes from plastics softening or even melting. Unfortunately, maintaining proper specimen temperature during accelerated weathering testing can be challenging and is often not well-understood.

A New Method To Determine TF And Clash Berg Stiffness (ASTM D1043), Using A Rotational Rheometer

Greg Kamykowski, May 2018

Thermo-rheological testing is important for the vinyl industry, as it indicates the temperature range over which a given vinyl formulation can be used in a specific application. A test that has been used for many years is described in D1043, the Clash-Berg stiffness test. The test typically consists of determining at what temperature a material will have a shear modulus of 310.3 MPa (45,000 psi) after 5 seconds of stress applied in torsion. The instrumentation that is used for this test is antiquated and has become difficult to procure. Modern rotational rheometers are well-suited for this test and can be considered as replacements for the older equipment. In this presentation, we will show test results from Clash-Berg tests on TA Instruments DHR rotational rheometer and will demonstrate the excellent correlation between results from the rotational rheometer and the torsion tester.

UV Light Irradiation Of Fibers In Termoplastic Pultrusion For Higher Surface Energy

Christian Kahl, May 2018

Pultrusion is a common way to produce thermoplastic composites reinforced with different kinds of fibers. There are many different opportunities to improve the properties of a thermoplastic material. Different kind of fibers where pultruded in combination with different thermoplastic materials. The fiber content was set to 30wt% comparing the roving strain with the pultruded strain. UV-C light was integrated in the process to improve the fiber matrix adhesion. The pultruded strain was granulated and injection molded to specimen. The samples were tested in tensile and charpy tests. It could be shown that the concentration of oxygen on the surface of a cellulose fiber can be raised by uv light irradiation. Cellulose fibers show low but best changes of properties after the uv treatment.

"Smart Factories": The Future Of Plastics Production With 4.0 Connectivity & Condition Monitoring System (Cms)

Markus Klaus, May 2018

“Smart Factories” are now a real possibility. Many innovations have been realized over the years, but perhaps none as interesting and valuable as Industry 4.0 and Condition Monitoring Systems (CMS). The ability to achieve complete connectivity along with the need to stay in touch have driven innovation to a point that now allows nearly all equipment to speak to each other. The capability to have full internal communication of equipment coupled to the Injection Molding Machine with nearly instant access to streaming data through the internet may have truly created the next generation of “Smart Factories”. The innovations provided by 4.0 connectivity along with CMS, a system which combines technical sensing components with predictive diagnostic analysis, allow factory monitoring at local and global levels.In this presentation we will review the integration of all injection molding components using 4.0 connectivity. This includes a complete automation system along with all the peripherals – and the connection of these cells to a Manufacturing Execution Systems (MES). We will also review Condition Monitoring Systems (CMS) and how they will affect the future of plastics production. The strategy of condition monitoring is a permanent surveillance of the actual condition of the injection molding machine components with the goal of optimizing, and subsequently, keeping the availability and efficiency at an optimal level, thus reducing their life cycle costs.

Effect Of High Speed Twin And Quad Screw Compounding On The Molecular Weight, Molecular Weight Distribution, And Mechanical Properties Of Polyethylene Composites

Mansour Albareeki | Stephen B. Driscoll| Carol F. Barry, May 2018

In this study, a particulate-filled polymer composite was compounded with ultra-high-speed twin and quad screw extruders to investigate the effects of screw speed and intermeshing area on 1) the molecular weight and molecular weight distribution and 2) the mechanical properties of the resultant composites. In general, the quad screw extruder produced significant decreases in the molecular weight of the neat polymers, with greater decreases observed with higher molecular weight polyethylenes. Examination of Gʺ/Gʹ crossover points showed that higher screw speeds produced decreases in molecular weight, but narrowing of the molecular weight distribution. These results were more affected by material system than extruder type. Since the quad screw extruder provided better filler dispersion combined with reductions in molecular weight, it produced no change in elongation at yield and break for filled LDPE, decreases in elongation at yield and increases in elongation at break for MDPE, and increases in modulus that were not significantly affected by screw speed. The flexibility of the materials created Izod impact results that showed no major changes with extruder type or speed.

3D Characterization And Mechanical Analysis Of Polyethylene Foams Processed In Rapid Rotational Foam Molding

P. Karimipour-Fard | W. Y. Pao | R. Pop-Iliev | G. Rizvi, May 2018

Rapid Rotational Foam Molding (RRFM) products are integral cellular composites that consist of a solid skin which encapsulates a foamed core. This paper focuses on characterizing the morphologies in 3D and identifying the key mechanical properties of respective integral-skin polyethylene (PE) cellular structures produced in RRFM by making use of Micro-CT Scanner. Two types of PE grades were used to produce the foamed core, whereas a PE and a PP grade were used to produce the surrounding solid skin layer. The effects of varying relevant processing parameters such as: foam filling directions, processing temperatures and skin temperatures on the quality of the obtained foams were studied. In addition, the correlations between the resulting cellular structures, cell size distributions, and cell densities have been assessed. Finally, simultaneous stress-strain behavior and 3D structure changes were monitored with in-situ compression testing. The experimental results revealed that foam layers adjacent to the integral skin solid layer demonstrate a higher cell density compared to those located in the core, which affects the compressive strength of the material by 0.2 MPa. It was also observed that higher processing and skin temperatures cause increase in cell size, and conversely, decrease in cell density. Mechanical analysis results indicated that cellular structures near the skin have higher compressive strength, and in general, the manufactured LLDPE foam exhibited higher mechanical properties than the sHDPE foam. Compression tests revealed that foam cell size decreases through compression, while cell density was not specifically affected with increased strain.

3D Printing Feedstock From Recycled Materials

Nicole Zander, May 2018

United States Army warfighters in theater are often faced with the challenge of broken, damaged, or missing parts necessary to maintain the safety and productivity required. Waste plastics can be utilized to improve the self-reliance of warfighters on forward operating bases by cutting costs and decreasing the demand for the frequent resupplying of parts by the supply chain. In addition, the use of waste materials in additive manufacturing in the private sector would reduce cost and increase sustainability, providing a high-value output for used plastics. Experimentation is conducted to turn waste plastics into filament that can be used in fused deposition modeling. The effect of extrusion temperature and number of extrusion cycles on polymer viscosity and crystallinity are explored. The effect of blends and fillers to impart additional functionality are also examined. Tensile specimens were tested and compared to die-cut and injection molded parts. Parts printed from recycled polyethylene terephthalate had the highest tensile strength of all recycled plastics evaluated (35.1 ± 8 MPa), and were comparable to parts printed from commercial polycarbonate-ABS filament. Elongation to failure of all recycled plastics was similar to their injection molded counterpart. In addition, select military parts were printed with recycled filament and compared to original parts. This research demonstrates some of the first work on the feasibility of using recycled plastic in additive manufacturing.