Functionalisation of polybutylene succinate nanocomposites: from structure to reinforcement of UV-absorbing and mechanical properties

International audienceCinnamic derivatives intercalated into ZnAl layered double hydroxides by coprecipitation are subsequently dispersed into a biodegradable polymer, polybutylene succinate (PBS). The structure and composition of the associated organic-inorganic hybrid assemblies are first characterized by X-ray diffraction (XRD) and UV spectroscopy, and then PBS extruded nanocomposite derivatives are evaluated against UV exposure. Using a combination of the PBS nanocomposite structures and the UV and rheological properties relationship, the effect of radiation time on the macromolecular changes undergone by the polymer chains, i.e. chain scissions and cross-linking, as well as on the UV-barrier evolution, is also scrutinized by means of transmission and emission spectroscopies. The combination of organically modified hydrotalcites with PBS could be used as an innovative route for sustainable development of UV protected materials and reduce the environmental impact of UV absorbing chemicals

Lignosulfonate interleaved layered double hydroxide: a novel green organoclay for bio-related polymer.

International audienceNew organic inorganic layered double hydroxide (LDH) organoclays are assembled through coprecipitation with lignosulfonate (LS) interleaved inorganic host structure sheets. The biopolymer is found to accommodate the interlayer space adopting a bilayer molecular arrangement resulting in a basal spacing of 2.54 nm. However the crystallinity of the resulting bio-organoclay is weak, probably due to the difficulty of the inorganic sheets to be built on amorphous polymer chain, the latter inducing low structural ordering. An organoclay of composition Zn2Al/LS is subsequently used as filler in three bio-related polyesters, poly(lactic) acid (PLA), poly(butylene) succinate (PBS) and poly(butylene adipate-co-terephthalate) (PBAT). Melt polymer extrusion using 5 wt.% organoclay loading yields polyester nanocomposite with a nanocomposite structure largely intercalated for both PLA and PBS (Δd (expansion) > 6 nm) while a non miscible structure is obtained for PBAT. The incorporation of hydrophilic Zn2Al/LS platelets decreases the water/polymer contact angle of about 10° for the LDH/LS PBAT composite only. A strong increase of the complex viscosity |η*| is observed for both nanocomposites Zn2Al/LS PLA and PBS compared to the polyester itself. This is explained on the basis of a chain extender behavior of the intercalated Zn2Al/LS platelets towards polymer chains as evidenced on the Cole Cole representation showing an increase of the real viscosity in the low-ω region. In opposition a strong decrease in |η*| is observed for PBAT, underlining a plasticizing effect of the organoclay filler. Comparatively, the thermal stability of PLA is slightly enhanced with an increase of T0.5 value while PBS and PBAT bio-nanocomposites degrade at slightly lower temperature

Chain extender effect of 3-(4-hydroxyphenyl)propionic acid/layered double hydroxide in PBS bionanocomposites

International audience3-(4-Hydroxyphenyl)propionic acid (HPPA), a biobased hydroxy acid, has been used as organic modifier in layered double hydroxides (LDHs) based on ZnAl and MgAl cations. PBS bionanocomposites have been prepared via in situ polymerization (with both types of clays) and melt blending (just with ZnAl-HPPA) obtaining completely green materials, potentially fully biodegradable. The filler loading is included within the range 1–10 wt%. The materials have been studied in terms of morphological, thermal and viscoelastic properties, resulting to have high thermal stability and huge mechanical reinforcement thanks to an excellent filler/polymer interfacial interaction highlighted by rheology experiments. HPPA, hosted by LDH, has a great chain extender effect toward the matrix. In particular, the melt blended samples, even if WAXD analysis evidence the formation of intercalated structures, show a tunable chain extender effect proportional to the composition and no gel-like structure has been produced. Moreover, LDHs, besides being bio and food compatibles, decrease the gas and solvents permeability of matrix and are potentially antibacterial and antioxidant; therefore such hybrid system is multifunctional and could be exploited in a wide range of applications

X-ray diffraction and rheology cross-study of polymer chain penetrating surfactant tethered layered double hydroxide resulting into intermixed structure with polypropylene, poly(butylene)succinate and poly(dimethyl)siloxane

A series of layered double hydroxides interleaved with surfactant using saturated alkyl chain carboxylate anions CH3(CH2)mCOOH, even number m between 6 (C8) and 16 (C18), obtained by coprecipitation method was dispersed by melt polymer extrusion into polypropylene (PP), poly(butylene)succinate (PBS) and polydimethylsiloxane (PDMS). The hybrid LDHmaterials were investigated by means of X-ray diffraction and Fourier transform IR spectroscopy resulting in the presence of contracted basal spacing over the entire variation of m. Dispersion into polymer was found to yield intermixed polymer structures regardless of either the polymer or of the alkyl chain length. PP polymer chain was able to diffuse into the interlayer space, long alkyl chains (m 65 14) were found to reinforce while shorter chains (m 64 12) induced a plasticizing effect. For PBS and PDMS, a chainextender- type behavior was observed. The relative change in viscosity within the frequency sweep stress linear response was visualized by the Cole- Cole representation. The molecular weight change relative to polymer free of filler and obtained from the power-law of the zero-shear viscosity \u3b7\u20320 was found to be linearly dependent of the basal spacing increase in the three cases. Such cross-study using XRD and melt polymer rheology was able to unravel the attritive or plastizicing role of the organoclay as function of the basal spacing expansion in the intermixed polymer structure, and to respond whether LDH interleaved platelets were of interest for polar and non-polar polymer and finally to predictively monitor the interfacial attrition by the alkyl chain length of the surfactant molecule tethered to the LDH platelets