Development of Poly (Lactide Acid) Foams with Thermally Expandable Microspheres

Abstract

This study presents the investigation of different content of thermally expandable microsphere (EMS) type of a physical blowing agent added to polylactic acid (PLA). The effects of the different doses of EMS, processing temperatures, and d-lactide content of the polylactic acid were analyzed for foam properties and structures. We characterized the different PLAs and the physical blowing agent with different testing methods (gel permeation chromatography, rotational rheometry, isothermal thermogravimetric analysis, and thermomechanical analysis). The amounts of the foaming agent were 0.5, 1, 2, 4, 8 wt%, and processing temperatures were 190 °C, 210 °C, and 230 °C. The foam structures were produced by twin-screw extrusion. We used scanning electron microscopy to examine the cell structure of the foams produced, and carried out morphological and mechanical tests as well. The result of extrusion foaming of PLA using different amounts of EMS shows that an exponentially decreasing tendency of density reduction can be achieved, described by the following equation, ρ(x ) = 1.062 · e − x 7.038 + 0.03 (R2 = 0.947) at 190 °C. With increasing processing temperature, density decreases at a lower rate, due to the effect that the microspheres are unable to hold the pentane gas within the polymer shell structure. The d-lactide content of the PLAs does not have a significant effect on the density of the produced foam structures.

Physical, mechanical, and thermal properties ofDalbergia sissoowood waste‐filled poly(lactic acid) composites

“…The number-average and weight-average molecular weight for this grade of PLA are 100,422 g/mol and 183,177 g/mol, respectively, with polydispersity index of 1.79. [34] D. sissoo (also known as North Indian rosewood) wood waste used in this work was collected from Krishna Timber store Dadhol, Himachal Pradesh, India. The wood waste particles that pass through 60 mesh sieve were taken as reinforcement.…”

Constitutive Modelling of Polylactic Acid at Large Deformation Using Multiaxial Strains

“…It has been the subject of a number of studies of its mechanical properties (e.g., Wei et al [ 21 ], Al-Itry et al [ 22 ]). It has a 1.4 mol% D-lactide content and molecular masses = 107,300 and = 183,180 [ 23 ].…”

Characterization of Polyhydroxybutyrate-Based Composites Prepared by Injection Molding

“…For instance, carbon fibers have been used to improve the thermomechanical and electrical properties of polymers, as well as to strengthen the material [19][20][21][22]. Microspheres are hollow fillers that are often used as a blowing agent to reduce the density of a variety of materials and improve their compressibility with applications ranging from footwear to the space industry [23][24][25]. Finally, polyethylene glycol (PEG) is a biodegradable polyether, used for its plasticizing properties to decrease polymer rigidity, which increases the materials process ability, as well as to provide lubricating coatings and decrease brittleness [26,27].…”