Role of Organically-Modified Zn-Ti Layered Double Hydroxides in Poly(Butylene Succinate-Co-Adipate) Composites: Enhanced Material Properties and Photodegradation Protection

Abstract

In this research, the effects of Zn-Ti layered double hydroxide (Zn-Ti LDH) as a UV-protection additive, which was added to the poly(butylene succinate-co-adipate) (PBSA) matrix, were investigated. Stearic acid was used to increase the hydrophobicity of Zn-Ti LDH via ion-exchange method. Transmission electron microscopy images of PBSA composites showed that modified Zn-Ti LDH (m-LDH) well-dispersed in the polymer matrix. Due to the effect of heterogeneous nucleation, the crystallization temperature of the composite increased to 52.9 °C, and the accompanying crystallinity increased to 31.0% with the addition of 1 wt% m-LDH. The additional m-LDH into PBSA copolymer matrix significantly enhanced the storage modulus, as compared to pure PBSA. Gel permeation chromatography and Fourier transform infrared spectroscopy analysis confirmed that the addition of m-LDH can reduce the photodegradation of PBSA.

Enhancement of Gas Barrier Properties and Durability of Poly(butylene succinate-co-butylene adipate)-Based Nanocomposites for Food Packaging Applications

“…In parallel, the degree of crystallinity decreases very slightly when introducing LDH particles into neat PBSA. The lower T c and X c suggest that there is no nucleating effect of LDH in the polymer matrix, but the LDHs are rather obstacles for the polymer chains to initiate crystallization growth [ 20 ]. Changes in the crystalline properties of nanocomposites can implicate changes in the overall mechanical and gas barrier properties, which are investigated in the following sections.…”

“…From Figure 6 a, it can be seen that, in addition to the expected light scattering, the SORBACID ® 911 LDH starts absorbing at a range of wavelength below 335 nm, and therefore absorbs UV-radiation emitted both from the solar radiation and the Hg-lamp used in the accelerated photoaging chamber (see Figure S3 in the Supplementary Materials ). As reflected in Figure 6 b, a relatively weak absorption of light in the range of 250–320 nm was observed for PBSA, which is attributed mainly to the absorption of the carbonyl groups in the PBSA polymer backbone beside the slight absorption of internal and external chromophoric impurities in PBSA [ 18 , 20 ]. Concerning the nanocomposites, there is an overall increase in UV-absorbance upon the addition of LDH into the neat PBSA, which increases with increasing LDH loading.…”

“…Accordingly, PBSA composites based on SORBACID ® 911 are expected to be UV-stabilized. Recent studies have also reported the UV-stabilizing effect of LDH based fillers in nanocomposites [ 20 ].…”

“…Although the use of LDHs as heat stabilizers and acid scavengers in halogenated polymers (such as PVC) is well known and is used on industrial scale [ 17 ], their use in biodegradable polymers to tune the durability and gas permeability properties has only just recently been reported. For example, recent studies have shown that addition of LDH to neat PBSA can enhance mechanical and gas barrier properties as well as prolong thermal and photo-durability [ 18 , 19 , 20 , 21 ]. Furthermore, previous studies have reported that LDH fillers have in general a catalytic effect on the biodegradation or hydrolytic degradation of different biodegradable polyesters such as poly(lactide acid) and polycaprolactone [ 22 , 23 , 24 ].…”