In recent years the plastics market is moving towards biopolymers and the increasing demand of not oil derived products has led to the development of new composites deriving from renewable resources. Undoubtedly themost studied biopolymer is poly(lactic acid) (PLA). This work is focused on the use of rigid inorganicfillers astoughening agents, in order to obtain a rigid and tough PLA composite and enlarge the range of applications forPLA. The rigidfiller toughening mechanism has been studied and, as toughening agent, commercial calciumcarbonate particles with and without surface treatment have been compared. Because of the PLA intrinsic fra-gility, a plasticization of the matrix was necessary to favor the plastic deformation and consequently thestretching of interparticle ligaments.In particular, in this work, the effect of both the plasticizer and the particles surface treatment with stearicacid were analyzed. It has been observed that the surface treatment alone is not able to provide a significantincrease in the PLA toughness. In fact, the particle surface coating favors the particles dispersion and reduces theadhesion with the matrix, favoring debonding, but the plastic deformation of the matrix around the voids is notsignificant without a plasticizer addition. Moreover, the best impact performance and ductility were achievedwith the surface treated calcium carbonate, in agreement with a more controlled growth of voids formationduring material solicitation, as resulting from tensile dilatometric tests.
Rigid filler toughening in PLA-Calcium Carbonate composites: Effect of particle surface treatment and matrix plasticization
Laura Aliotta;Patrizia Cinelli;Maria-Beatrice Coltelli;Andrea Lazzeri
2019-01-01
Abstract
In recent years the plastics market is moving towards biopolymers and the increasing demand of not oil derived products has led to the development of new composites deriving from renewable resources. Undoubtedly themost studied biopolymer is poly(lactic acid) (PLA). This work is focused on the use of rigid inorganicfillers astoughening agents, in order to obtain a rigid and tough PLA composite and enlarge the range of applications forPLA. The rigidfiller toughening mechanism has been studied and, as toughening agent, commercial calciumcarbonate particles with and without surface treatment have been compared. Because of the PLA intrinsic fra-gility, a plasticization of the matrix was necessary to favor the plastic deformation and consequently thestretching of interparticle ligaments.In particular, in this work, the effect of both the plasticizer and the particles surface treatment with stearicacid were analyzed. It has been observed that the surface treatment alone is not able to provide a significantincrease in the PLA toughness. In fact, the particle surface coating favors the particles dispersion and reduces theadhesion with the matrix, favoring debonding, but the plastic deformation of the matrix around the voids is notsignificant without a plasticizer addition. Moreover, the best impact performance and ductility were achievedwith the surface treated calcium carbonate, in agreement with a more controlled growth of voids formationduring material solicitation, as resulting from tensile dilatometric tests.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
