Effect of processing conditions on the development of morphological features of banded or nonbanded spherulites of poly(3‐hydroxybutyrate) (PHB) and polylactic acid (PLLA) blends

Abstract

Two semicrystalline poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLLA) blends with and without poly (vinyl acetate) (PVAc) were prepared by dissolving different ratios in hot chloroform at 50 8C to obtain promising alternative biodegradable materials for eliminating plastic waste. The miscibility, crystallization, melting behavior and vibration modes of the prepared samples were characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM), Fourier transform infrared spectroscopy (FTIR), and wide angle X-ray diffraction (WAXD) techniques. DSC analysis showed that only one crystallization temperature for blends with PVAc (single homogeneous phase) and two crystallization temperatures for blends without PVAc (immiscible blends) were obtained. The POM results indicated that the morphological structures of B 381 , B 551 , and B 831 samples consist of two types of spherulites (fibrils and banded) which created at different crystallization temperatures. The irrelevant interaction between PHB and PLLA structures was detected from FTIR spectra. The addition of PVAc caused an obvious decrease in the peak position of the carboxyl group C¼ ¼O from 1752 to 1724 cm 21 due to dipoledipole interactions. WAXD indicated that the lattice parameters are changed in blends with PVAc and unchanged without PVAc. Our results indicated that, the PVAc can be used as compatibilizer and improved the compatibility between PHB and PLLA. POLYM. ENG.

The effect of additives interaction on the miscibility and crystal structure of two immiscible biodegradable polymers

“…For example, the addition of a suitable amount of PVAc to both PMMA and PPC makes the blends fully miscible [20] . The addition of PVAc to the two immiscible polymers namely PLLA and PPC [7,9] served to improve the physical properties of the blend [8,21] . However, it has been demonstrated that increasing the PVAc in its blends with the PDLA [22] reduces the enzymatic degradation rate of PLLA.…”

“…has investigated that the addition of a small amount of PHB to PLLA can used as accelerating agent for improving the crystallization process in PLLA [6] . PLLA is immiscible with PHB [7] , two phase separations was found in 50%/50% wt (PLLA/PHB blends) [7] but a small amount of PHB (<25%) is miscible with PLLA [6] . PVAc was used as compatibilizer to improve the miscibility between PLLA and PPC.…”

“…It is known that neat PLLA, PPC, PVAc and PHB have glass transition temperatures of cr. 60 °C [26] , 40 °C [4] , 30 °C [21] and 5 °C [7] , respectively. For The glass transition temperatures (T g ), cold crystallization peak temperatures (T cc ) and melting peak temperatures (T m ) of all PLLA/PPC blends under investigation (with and without additives) were determined from the DSC second heating runs.…”

“…PLLA is immiscible with PHB [7] although a small amount of PHB is miscible with PLLA resulting in a lower Tg value [6] . PLLA is also immiscible with PPC [8.9] , butadiene-styrene copolymer (ABS) [10] , poly(-caprolactone) PCL [11] , low density polyethylene blends [12] , poly(vinyl acetate-co-vinyl alcohol) [13] , poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBco-PHV) [14,15] , starch [16,17] and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) PHB/HHx [18] , polystyrene (PS) [19] .…”

Effect of homopolymer poly(vinyl acetate) on compatibility and mechanical properties of poly(propylene carbonate)/poly(lactic acid) blends

“…More importantly, it is interesting to note that the addition of PVAc into the PPC/PLA blend gives rise to not only a peak shifting of the C=O stretching band (from 1742 to 1739 cm -1 ) but also an obvious peak broadening, suggesting that PVAc is likely to improve the interaction between PPC and PLA molecules. The potential molecular mechanisms for the enhanced interaction may be the CH 3 … O=C interaction, as in the case for PHB/PLA/PVAc blends proposed by El-Hadi [28]. To give a direct evidence on the validity of this assumption, the FTIR spectra of neat PPC, PLA, and PPC/PVAc and PLA/PVAc blends were measured.…”