1:30 pm – 3:30 pm:
TH18-Vinyl Plastics: Additives and Testing
(Moderator: John Scott)/Thermoset Split Session-Room S320B
1:30 pm – 2:00 pm:
Copolyesters as Heat Distortion Temperature Modifiers in Rigid PVC
Robert Young, Eastman Chemical Co.
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.
2:00 pm – 2:30 pm:
Heat Stabilising Flexible PVC with Layered Double Hydroxide Derivatives
Dan Molefe, University
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.
2:30 pm – 3:00 pm:
Temperature Control in Accelerated Laboratory Weathering Testing of Plastics
Andy Francis, Weathering and Corrosion Projects Manager, Q-Lab
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.
3:00 pm – 3:30 pm:
A New Method to Determine TF and Clash Berg Stiffness (ASTM D1043), Using a Rotational Rheometer
Greg Kamykowski, SPE
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.
3:30 pm – 4:00 pm:
Innovative and Useful Characteristic Values for the Pro-cessing of Thermosetting Molding Compounds
Thomas Scheffler, TU Chemnitz – Professur Kunststoffe
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.
4:00 pm – 4:30 pm:
Simulation of Molding Filling Characterization of Phenolic Injection Molding Compounds With Slip Boundary Condition
Ngoc Tu Tran, TU Chemnitz
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.
4:30 pm – 5:00 pm:
Fabrication of Synergistic Flame-retardant Unsaturated Polyester Resin Basd on Ammonium Polyphosphate and Aluminum Hydroxide
Xingxing Shi, South China University of Technology
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.
5:00 pm – 5:30 pm:
Non-isocyanate Polyurethane Networks Can be Melt-reprocessed With Full Property Recovery Associated With Cross-link Density: The Case of Polyhydroxyurethane Networks
John Torkelson, Northwestern University
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.
Matthew Lampe, University of Massachusetts Amherst
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.