Effect of pine resin derivatives on the structural, thermal, and mechanical properties of Mater‐Bi type bioplastic

Abstract

The effect of three additives derived from pine resin, namely, gum rosin (GR) and two pentaerythritol ester of GR, Lurefor (LF) and Unik Tack (UT), in 5, 10, and 15 wt %, on the properties of Mater‐Bi, based on plasticized starch, poly(butylene adipate‐co‐terephthalate), and poly(ε‐caprolactone) (PCL), obtained by injection molding processes, was studied. The mechanical, microstructural, and thermal properties were evaluated. LF had a cohesive behavior with the components of Mater‐Bi, increasing the toughness of the material up to 250% accompanied by an increase of tensile modulus and tensile strength. UT had an intermediate behavior, conferring cohesive and plasticizing effects, allowing an increase of 105% in impact resistance. GR had a more marked plasticizing effect. This allows processing temperatures of about 50 °C lower than those used for neat Mater‐Bi. In addition, an increase of the elongation at break, toughness, and impact resistance in 370, 480, and 250%, respectively, was achieved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48236.

A Deeper Microscopic Study of the Interaction between Gum Rosin Derivatives and a Mater-Bi Type Bioplastic

“…The blends were further milled into pellets to be processed by injection-molding (Sprinter-11, Erinca S.L., Barcelona, Spain). The injection temperature profile was established based on previous work [8]. That is, from die to hopper, the temperatures for the MB matrix were 165, 160, 160 • C; for the blend of MB and 15 wt % of gum rosin (label as MB-GR), temperatures were 117, 117, 105 • C. For the formulations with 15 wt % of gum rosin derivatives (LF and UT), labelled as MB-LF and MB-UT, respectively, the profile was 145, 140, 135 • C for MB-LF and 120, 115, 105 • C for MB-UT.…”

“…Nevertheless, the currently commercialized bioplastics still present some drawbacks with respect to traditional plastics, currently used in short term applications [7]. These alternative sustainable polymers must also have acceptable mechanical, physical, and morphological properties, to allow them to have similar characteristics to those of traditional plastics [1,3,8].…”

“…For industrial applications, starch is preferably used in its thermoplastic form, that is TPS, rather than in its native form, because the plasticized granules of native starch allow the formation of a continuous and viscous phase, which can be easily processed by traditional plastics processing technologies [8,11]. In fact, during the extrusion process the granular structure of native starch is disrupted, combined by the action of temperature and shear forces and, in the presence of a plasticizer, it forms a melted polymeric system, that is the so called thermoplastic starch (TPS) [12].…”

“…One of the most popular commercial TPS is Mater-Bi ® , a family of modified biodegradable and compostable thermoplastic starches produced by Novamont [16]. Mater-Bi ® mainly consists of corn starch and various synthetic compounds [8,14,17,18], including natural plasticizers and hydrophilic substances biologically degradable from synthetic polymers [11,13]. Although the exact composition of Mater-Bi ® is not known, the literature refers to certain indications [15,17].…”

“…In a previous work [8], to counteract the low interfacial adhesion between PBAT and starch in Mater-Bi ® NF866, different pine resin derivatives were used as Mater-Bi ® NF866 sustainable additives.…”