Simultaneous impact modified and chain extended glass fiber reinforced poly(lactic acid) composites: Mechanical, thermal, crystallization, and dynamic mechanical performance

Abstract

Herein, glass fiber (GF) reinforced binary, ternary, and quaternary poly(lactic acid) (PLA) composites were prepared. Toughening, and chain extension of PLA was achieved through the incorporation of impact modifier and chain extender and their concurrent effects on the spectroscopic, crystallization, mechanical, thermal, and thermomechanical properties of the composites were investigated. High mechanical properties of GF influenced the mechanical performance of the composites. However, GF alone could not restrict the chain mobility of PLA due to poor interface and low crystallization activities in the PLA-GF composite. Incorporation of impact modifier and chain extender produced significantly enhanced interaction between GF and PLA. Significantly, the crystallinity, impact strength, and flexural modulus of PLA in the quaternary composite were increased by 58%, 63%, and 66%, respectively. In addition, damping and effectiveness coefficient of the PLA-GF composite were notably reduced by the simultaneous impact modification and chain extension of the reinforced composites.

Influence of Reactive Chain Extension on the Properties of 3D Printed Poly(Lactic Acid) Constructs

“…After the incorporation of Joncryl, the characteristic FTIR bands of PLA appeared in the same wavenumbers, confirming that it did not interrupt the structure of PLA’s backbone [ 49 ]. The peaks of the hydroxyl and carboxyl groups significantly decreased in intensity due to their reaction with Joncryl and the subsequent chain extension.…”

“…In FDM, the filament melts for several seconds in the nozzle of the 3D printer before being extruded out. During extrusion, the polymer chains were oriented inside the nozzle due to the pressure drop [ 48 , 49 ]. Moreover, the lack of adhesion between the deposited layers and the presence of trapped air in 3D-printed objects might be the reason why the values of tensile and compression Young’s modulus were lower compared with the results of nanoindentation testing.…”

Dynamic Mechanical Analysis Investigations of PLA-Based Renewable Materials: How Are They Useful?

“…Since the glass transition temperature of PLA is close to 60 °C, this kind of polymeric material is in the glassy state at room temperature. Various fillers (glass fiber, nanocellulose, wood-based fibres BKSW), modified polyhedral oligomeric silsesquioxane—POSS, reduced graphene oxide—rGO, nanorod-shaped organic-inorganic hybrid material, talc) are used in combination with PLA with the declared aim to improve the load-bearing properties [ 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 ]. In the glassy region a non-logarithmic representation of E’ vs. T helps always to track better the change of E’ modulus and to compare visually composites with variable contents of filler.…”

“…No matter what value of temperature is considered to be the T g (the onset drop of E’ or peaks of E’’ or tan δ), PLAs with different crystallinity or PLAs that include additives (fillers, nucleating agents or plasticizers) show very small variation of this temperature with the perturbing factor. Even a glance at the tables that encompass the main parameters of DMA or DSC results reveals this aspect [ 59 , 63 , 67 , 69 , 80 ]. The reason for this may be the concurrent events that may occur in opposite directions during the glass transition region and the particular morphology of PLA.…”

“…Moreover, the reinforcement effect reflected in increased E’ modulus in the glassy region in PLA composites reinforced with glass fiber [ 59 ] and nanocellulose [ 61 ] is not displayed as a decrease of the tan δ height because of reduced mobility. By contrast, high quantities of nanocellulose caused a major increase of tan δ.…”