The goal of this work was to develop a composite material, a membrane, based on polylactic acid (PLA) reinforced with cellulose microcrystalline (MCC). Membranes based on PLA were fabricated using electrospinning. The fabrication parameters, fiber morphology, and mechanical properties were analyzed. For fabrication, 12 mL of solution (12%, weight basis, of PLA in chloroform) was used and three different injector-collector distances and three voltages were employed. The fiber morphology was observed using a scanning electron microscope (SEM). To fabricate reinforced membranes using microcrystalline cellulose (MCC), an amount of 1.0%, 3.0%, and 5.0% of MCC, based on the polymer mass, was used. The MCC distribution was observed using SEM. The membranes were tested via tensile and tearing tests according to the corresponding ASTM D882-12 (2012) and ASTM D1938-14 (2014). It was observed that plain fibers tended to form, depending on the injector-collector distances. Additionally, microfiber porosity was observed, which was attributed to the solvent evaporation. Moreover, the addition of 1% of MCC was translated into an important increase of tensile strength, which in some cases reached a 476% increase; similar effects were observed in the tear test results.

In this work, we present an optical and mechanical characterization of the behavior of an inhomogeneous biopolymer sample through the use of an in-plane electronic speckle pattern interferometer with a pulling system along the y direction. The characterization of the sample subjected to stress comprised the acquisition of speckle patterns for 1360 states. Displacement maps and their corresponding strain maps were computed for every state. Since the information of the maps changes with size due to the sample being pulled at the upper end while it is clamped at the lower end, a scaling method to relate the maps to each other, point-to-point, is presented. The method allows the correct evaluation of sequential strain maps, which depicts the mechanical evolution of the material. Upon managing to relate the strain maps, it is possible to extract strain values for zones of interest from every map in order to build the respective stress–strain curves. Three stress–strain curves associated with three zones in the sample (upper, middle, and bottom) are constructed. When sequential displacement and deformation maps are optically obtained by the interferometer, we present a full-field characterization, along with the obtention stress–strain curves associated with the three zones of strain maps. The curves represent the inhomogeneous performance of the sample. Three different elastic moduli ( E u = 2.59 M P a , E m = 1.97 M P a , and E b = 1.67 M P a ), associated with three respective zones, were obtained. The experimental results for a biopolymer sample here presented show that the technique, in conjunction with the scaling method, is a novel proposal to characterize inhomogeneous materials.

Reinforcement of Synthetic ElastomersMica Fillers in Vulcanized GR-S Rubber Q OOME recent theories of rubber reinforcement identify true reinforcement with chemisorption mechanisms which seem to be restricted largely to interactions between carbon fillers and unsaturated polymers (6,9, 70). Although carbon blacks are the most effective fillers, mica also may have unique properties. Published evidence to support the hypothesis that mica can be more than an inert extender is relatively meager. Some uses of mica have been reported in carbon-free insulating compositions (3, 5, 8), and mica fillers in natural rubber have been studied (7, 2). No systematic evaluation of the reinforcement effect has been reported using procedures that allow easy comparisons of mica with carbon black.Most commercial grades of mica are difficult to disperse in rubber. One grade which lends itself to ordinary compounding procedures was selected. The reinforcement was evaluated in one stock of vulcanízate base mix of butadienestyrene (GR-S) rubber by comparing the upgrading of tensile properties resulting from equivalent volume loadings of carbon and mica.