Thermodynamic Mechanical Properties Research Articles

Physiochemical and thermodynamic mechanical behavior of injection molded sized and de-sized CF/PP composites

ABSTRACT In this paper, a cheaper and an environment friendly hot water treatment method is developed to de-size the carbon fiber surface without significantly affecting its chemical nature. The surface characterization of the sized (without hot water treatment) and de-sized (hot water treated) carbon fiber was evaluated from the scanning electron microscopic, atomic force microscopic, X-ray photoelectron spectroscopic, and Fourier Transform Infrared Spectroscopic test data. The effect of carbon fiber surface treatment on the physiochemical, static, and thermodynamic mechanical properties was studied. Also, the impact of carbon fiber surface treatment on the long-term durability and energy of activation of sized and de-sized CF/PP composites was evaluated by using the time-temperature-superposition principle. It was found that hot-water treatment changes the physical nature of CF by giving rise to a little surface roughness. However, its major functional groups (chemical composition) do not change significantly albeit their concentration changes to some extent. The de-sized CF/PP composites showed improved interfacial shear strength, Izod impact resistance, tensile and thermodynamic mechanical properties as compared to the sized CF/PP composites.

Effect of de-sizing on the structural and mechanical properties of carbon fiber reinforced polypropylene composites molded by the novel direct fiber feeding injection molding technology

Carbon fiber reinforced thermoplastic composites are rapidly emerging as alternative materials for auto parts due to recyclability, excellent stiffness, and strength to weight ratio. In the present study, the influence of carbon fiber de-sizing on the structural and mechanical properties of the sized and de-sized Carbon Fiber Reinforced Polypropylene (CFPP) composites molded by the recently developed novel Direct Fiber Feeding Injection Molding technology was studied. The effect of carbon fiber de-sizing on the structural properties was studied from the fiber dispersion status, fiber orientation factor, fiber volume fraction, and the fiber length. The surface morphology of the sized and de-sized carbon fibers was studied from the Scanning Electron Microscopy (SEM) and Atomic Force Microscope images. The static mechanical properties were studied based on the tensile tests at different loading rate and temperature. The Dynamic Mechanical Analysis tests were conducted to analyze the dynamic viscoelastic behavior of the sized and de-sized CFPP composites. The SEM images were used to observe the failure mechanism. The preliminary results indicated that de-sized composites had better fiber dispersion as compared to the sized CFPP composites. It was found that de-sizing the carbon fiber surface does not significantly affect the carbon fiber length, fiber volume fraction, and fiber orientation in the CFPP composites. Also, the de-sized composites showed better static and thermodynamic mechanical properties caused by the enhanced fiber matrix interaction in CFPP composites as compared to the sized CFPP composites. [Formula: see text]