Dataset Information

The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites.

ABSTRACT: Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP) films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf), and void content (Vc) were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The tensile property, flexural property, interlaminar shear strength (ILSS), and scanning electron microscopy (SEM) were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites.

SUBMITTER: Kim JW

PROVIDER: S-EPMC5456757 | biostudies-other | 2016 Jun

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Thermoplastic composites consisting of a liquid crystalline polymer (LCP) and poly(lactide) (PLA) have the potential to combine good mechanical performance with recyclability and are therefore interesting as strong and sustainable composite materials. The viscoelastic behavior of both the LCP and the PLA is of great importance for the performance of these composites, as they determine the LCP morphology in the composite and play a crucial role in preventing the loss of mechanical performance upon recycling. Though the effect of the matrix viscosity is well-documented in literature, well-controlled systems where the LCP viscosity is tailored are not reported. Therefore, four LCPs, with the same chemical backbone but different molecular weights, are used to produce reinforced LCP-PLA composites. The differences in viscosity of the LCPs and viscosity ratio between the dispersed phase and the matrix of the blends are evident in the resultant composite morphology: in all cases fibrils are formed; however, the diameter increases considerably as the viscosity ratio increases for the higher molar mass LCPs. The fibril diameter ranges from several hundred nanometer to a few micrometer. A typical layered structure in the injection molded composites is observed, where the layer-thickness is influenced by the LCP viscosity. The LCPs are found to effectively reinforce the PLLA matrix, increasing the Young's modulus by 60% and the maximum stress by 40% for the composite containing 30 wt % of the most viscous LCP. Remarkably, this did not result in an increase in brittleness, effectively increasing the toughness of the composite compared to pure PLLA. The feasible reprocessability of this composite is confirmed, by subjecting it to three reprocessing cycles. The relaxation of the LCPs orientation upon heating is measured via in situ WAXD. We compare the relaxation in an amorphous PLA matrix and in a semicrystalline PLLA matrix with that of the pure LCPs. The matrix viscosity is found to strongly influence the relaxation. For example, in a low viscous amorphous matrix relaxation of the LCP fibrils into droplets dominates the process, whereas a semicrystalline matrix helps in maintaining the fibril morphology and intermolecular orientation of the LCP. In the latter case, the LCPs relax via contraction and coalescence of the polydomain texture and maintains a significant degree of orientation until the PLLA crystals melt and the matrix viscosity decreases. The insights gained in this study on the role of the LCP viscosity on the morphology and performance of thermoplastic composites, as well as the relaxation of LCPs in a matrix, will aid progression toward sustainable and reprocessable LCP reinforced thermoplastic composites.

Dataset Information

The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets