8:00 am – 11:30 am:
T3-Composites: Processing and Properties-Room S320C


8:00 am – 9:00 am:
KEYNOTE

Nicholas Abbatiello, Dell


9:00 am – 9:30 am:
Influence of Bonding Agents on Fibermatrix Adhesion and Comparison of VCG and RCF Fleece in Epoxy Matrix

Jasmin Mankiewicz, University of Applied Sciences Niederrhein
Temporarily the carbon fiber key market increases intensely because of government putting pressure on industry using lightweight structures. In consequence of production 10–30 % cost-intensive carbon fiber (CF) waste is accumulated by blending fabrics, prepregs which are out of specification and end-of-life products. Since a landfill ban for carbon fibers, environmental aspects and a cost reduction potential there is a stronger focus on CF waste recycling. [1] The CF is regained from polymer matrix by new recycling methods. These fibers are clean but lose their woven structure. One possibility to re-use chopped recycled fibers is through a fiber mat. The University of Applied Science Niederrhein uses the wet-laid process to produce fleece in industrial scale. For recycled fibers without a specific fiber length and sizing there is the challenge to separate them in dispersion to get homogenous fleeces. A surfactant can improve the separation [2], so that virgin fiber fleece and recycled fiber fleeces from different recycling processes can be laid down as optical comparable fleeces. Then the fleece can be impregnated with thermosets by resin transfer molding (RTM). Optical impregnability is inspected and material properties (tensile strength and Young’s modulus) are analyzed and recycled fiber composites are compared to virgin fibers ones to get information on their performance. In addition to that the maximum fiber volume fraction is identified with 50%. Most recently the interrelation between CF fraction and two different bonding agents on the mechanical properties is outlined in the results.


9:30 am – 10:00 am:
Experimental Study on Fiber Matrix Separation during Compression Molding of Fiber Reinforced Rib Structures

Christoph Kuhn, Volkswagen AG
The use of long fiber reinforced polymers in compression molding has significant advantages for application in automotive large scale production due to its suitability for cost-effective, low fiber attrition production. During processing, fiber reinforced material is compression molded into geometries with complex features like ribs, bosses and connector points. Inside ribbed structures, earlier experiments have shown significant deviations in fiber content with longer fibers. These deviations are caused by increasing fiber interaction, leading to a separation of fiber and matrix phase during flow – the phenomenon of Fiber Matrix Separation (FMS). While these early experiments have exposed the leading factors on the appearance of FMS, a deeper understanding of the observed effects is necessary. In the presented paper, experiments in compression molding with a simple ribbed plate tool are conducted. During the experiments, the initial fiber length and charge location are varied and their influence on the fiber filling during processing is investigated. Therefore, the compression molded components are investigated regarding their fiber properties with pyrolysis and CT imaging. Results show, that the fiber length is the most significant factor on FMS in complex geometries and leads to extensive FMS. Generally with longer fibers, more FMS appears. Furthermore, the initial charge position is vital for fiber behavior during filling. With the charge positioned underneath the rib, fibers are prone to display excessive bridging, leading to an increase in FMS. With longer flow paths, the fibers are able to align inside the polymer flow and are smoothly dragged into the upper rib regions with less interaction. A generous rib base radius supports the fiber access and minimizes FMS. In addition to the fiber property analysis, mechanical component tests are conducted. Test results show a significant decrease in mechanical properties due to FMS. In conclusion with the earlier experiments, design guidelines are derived and furthermore, the gathered information is applied to a simulative approach on FMS with a Mechanistic Model.


10:00 am – 10:30 am:
Effects of Different Fillers on the Thermo-mechanical properties and Coefficient of Linear Thermal Expansion of Polypropylene Composites

Mohamed Abdelwahab, University of Guelph
We study and report on the effect of different fillers on the coefficient of linear thermal expansion (CLTE) of polypropylene (PP) by melt extrusion technique. We examine and review the effect of some fibers such as glass fiber and carbon fibers as well as traditional mineral filler like talc. Moreover, we study the effect of new biocarbon as an environmentally friendly filler on the CLTE of neat PP and compare with the previous samples. On the basis of these results, properties and potential applications of PP composites are discussed.


10:30 am – 11:00 am:
Inline UV Light Irradiation of Celluloase and Glass Fibers in Pultrusion of Thermoplastic Composites

Christian Kahl, University of Kassel
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.


11:00 am – 11:30 am:
Property Characterization of Injection Molded Hybrid Composites

Gangjian Guo, Bradley University
Hybrid composites with two or more fillers offer advantages such as improved mechanical properties and balanced performance/cost ratio. They have been increasingly used in many industries such as automotive and aerospace industry. The properties of hybrid composites largely depend on the matrix material, the type and the content of fillers, the filler distribution in the matrix, and the interfacial bonding between the fillers and the matrix. Wood fiber (WF), glass fiber (GF), and carbon fiber (CF) have been used in a variety of polymer composites applications. This study applies the injection molding process, and investigates the tensile properties, water absorption, burning behavior, and surface roughness of pure polypropylene (PP), PP/WF composites, PP/GF composites, PP/CF composites, PP/WF/GF hybrid composites, and PP/WF/CF hybrid composites. This study would provide guidance for choosing composites for different applications in consideration of cost and performance.


8:00 am – 11:30 am:
T4-Engineering Properties and Structure: Polymer Physical Properties I
(Moderators: Hoang Pham and Michail Dolgovskij)-Room S320B


8:00 am – 8:30 am:
Quantitative Characterization and Modeling of Thin Film Conformability

Alexander Chudnovsky, University of Illinois at Chicago
In this paper we present a brief review of large body of publications related to conformability of multilayer system. Conformability of thin film with a curved geometry substrate on which the film is applied is commonly manifested in formation of blisters, wrinkles and other forms of delamination. The delamination is driven by elastic energy of thin film associated with the film deformation required by film application. A simple method of observation and quantitative characterization of delamination and its evolution in time is proposed. A continuous growth of delamination over many hours is observed on a number of plastic films. The time dependency of delamination results from an interplay between the stress relaxation within the film and viscous flow of adhesive that support the film deformation. Thus, the conformability of multilayer system is characterized by a combination of the film rigidity and relaxation as well as the time dependent strength of adhesive. A design of conformability tester, measurements of delamination growth, modeling of the observed process and an algorithm for quantitative characterization of delamination are presented. A practical application of the conformability tester is illustrated by ranking of a number of thin plastic films with respect to conformability.


8:30 am – 9:00 am:
Correlation of Chain Dynamics to Mechanical Properties of High Performance Crosslinked Systems​

Shaw Hsu, University of Massachusetts
The merits of crosslinked polymers (thermosets such as epoxy, imine and phenolics) include high mechanical performance and dimensional stability especially at elevated temperatures. However, these attractive physical attributes are also the reasons making them extremely difficult to characterize. In our laboratory, we have used a combination of techniques (DSC, infrared and low field NMR) to clarify the underlying structure responsible for the macroscopic properties observed. DSC provides information regarding the onset curing temperature and the extent of curing. Both near and mid-infrared spectroscopy provide information regarding the chemical structures being formed. We found the low field NMR (LFNMR) to be extremely informative regarding segmental mobility of the crosslinked chains. This unconventional usage of NMR has shown to be effective in establishing the correlation between the spin lattice relaxation time and the mechanical properties obtained for the various types of crosslinks employed. We have analyzed two types of crosslinked systems, one based on phenolics and a second one based on well-characterized epoxies with known crosslink density. By fitting the spin lattice relaxation data at different temperatures to theory, the average activation energy for the molecular motion were obtained. Therefore, the increase in the activation energy to achieve mobility and the broadening of relaxation distribution can be determined quantitatively. The results of our study provide the foundation to analyze the crosslinking process and the resultant structure of high performance crosslinked systems.


9:00 am – 9:30 am:
Chasing the Bottom of the Energy Landscape: Vapor Deposited Amorphous Fluorocarbons

Gregory McKenna, Texas Tech University
One of the major challenges in the study of the behavior of glass-forming materials, including polymers, is to know the equilibrium behavior below the glass transition temperature Tg. This is due to the need for a fundamental understanding of the equilibrium behavior in order to have a baseline to the non-equilibrium response inherent in the deep glassy state where materials are used[1]. In the present work we describe experiments in which we have used vapor deposition methods to make extremely stable amorphous fluorocarbon polymer films which have fictive temperature reductions relative to the Tg of nearly 60 K[2]. Hence, they are deep into the energy landscape[3]. By making viscoelastic measurements on films of these materials one can establish upper bounds to the equilibrium relaxation times and, consequently test theories of the glass transition and potentially distinguish among different theories. In particular, one can compare the dynamics with those expected by the theories, but now far below Tg. Initial work suggests that, consistent with prior results [4] on an ancient amber material, theories that predict a divergence of time-scales at a finite temperature are not consistent with the present upper bound results. Rather it appears that there is a strong deviation of the response from, e.g., WLF behavior, towards an Arrhenius-like response, albeit with a high activation energy.


9:30 am – 10:00 am:
Realizing Resource Saving Tire through Innovative Tough Polymer Composite

Katsuhiko Tsunoda, Bridgestone Corporation
Synthesis, structure and properties of specially designed elastomeric polymer for tire application will be discussed.


10:00 am – 10:30 am:
Understanding the Deformation Behavior of Nanocomposites with Discrete Carbon Nanotubes

Clive Bosnyak, Co-Founder and Chief Scientific Officer, Molecular Rebar Design LLC
This paper will first address the general challenges of dispersing discrete multiwall carbon nanotubes in polymers followed by detailed morphological and tensile deformation studies of polyvinylidene fluoride blends with carbon black and discrete carbon nanotubes, commercially available as MOLECULAR REBAR®. The specific carbon nanotubes employed here are about 13nm in diameter and about 900nm in length. In thermoset, or materials which fail in a brittle mode, the discrete carbon nanotubes show improved crack initiation and propagation resistance via a crack pinning mechanism. In ductile, or elastomeric materials the tubes are seen to align with the principal stretch direction. In semi-crystalline materials the carbon nanotubes may act as crystal nucleators, but are small enough to be able to be excluded from crystal domains as they form. This crystallization behavior with discrete nanotubes results in quite complex structures, highly dependent on fabrication processes. The ability to control the structure and placement of discrete carbon nanotubes creates new opportunities for advanced materials.


10:30 am – 11:00 am:
Quantitative Evaluation of Mar Visibility Resistance of Polymer Films

Shuang Xiao, Texas A&M University
Susceptibility to visible mar damage of polymers significantly affects their aesthetic appearance. Quantitative evaluation of mar damage on polymer surfaces is highly desired for the design of mar resistant polymers and structures. In this study, an effective mar testing and evaluation methodology is introduced that is capable of evaluating mar damage for white and transparent thin polymer films, which are the most difficult colors for mar detection. Here, the mar damage is imaged and evaluated based on the contrast differences between the marred area and virgin background along the mar path. It is found that mar contrast results obtained by this method show good correlation with the assessment by human eyes. This methodology provides a quantitative measure of mar that correlates well with “human perceptions through visualization”. This method of mar surface analysis can be a potential methodology employed to investigate the fundamental structure-property relationship between polymer material properties and mar behavior.


11:00 am – 11:30 am:
Mechanical Characterization of Polycarbonate Reinforce with Woven Glass Fiber

Omar Solorza-Nicolas, Instituto Politecnico Nacional/Polimeros Y Compositos S.A de C.V
This work presents the physical and mechanical characterization of a polycarbonate reinforced with 4 % woven glass fiber oriented at 0/90° and ± 45° produced by film injection and compression molding process.Fiber alignment, volume fractions, and density were measure; these results showed an improvement of 141% in tensile strength for the specimens reinforced with 0/90º glass fiber, as compared to the specimens without reinforcement. The film injection-compression process reduces fiber misalignment in a range of 1.16° to 2.13°. This result proves the potential for the fiber-woven polycarbonate as a useful material for thermoplastic polymers. The production of composites by film injection-compression molding presents the advantage of being manufactured with faster production cycles than thermosets.