Crystalline β‐structure of PHBV grown epitaxially on silicate layers of MMT

Abstract

The poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV)/montmorillonite(MMT) nanocomposites were investigated by wide‐angle X‐ray scattering (WAXS). The aim of the investigation was solution intercalation of MMT with PHBV. Beside the usual orthorhombic unit cell, a stable pseudohexagonal β‐structure of PHBV was obtained. Well known β‐structure has one common WAXS reflection (d = 0.480 nm), which corresponds to the mean distance of PHBV chains in the pseudohexagonal structure. The new β‐structure has two diffraction peaks in the WAXS pattern. It is a three‐dimensionally ordered crystalline structure oriented in parallel with the silica layers of MMT. The new polymorphic form is supposed to be growing on the layers of MMT. Its layers serve as primary nucleation centers for epitaxial growth of the β‐structure. After annealing, this polymorphic form of PHBV disappears and it is transformed into the more stable α‐form leading to an enhanced total crystallinity of the polymer comprised in the nanocomposite. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 751–755, 2009

The chemomechanical properties of microbial polyhydroxyalkanoates

“…This crystal form disappears with annealing [188]. The WAXS reflection (d = 0.480 nm) corresponds to the mean distance of P(3HB-co-3HV) chains in a pseudohexagonal structure.…”

On the use of ball milling to develop poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)‐graphene nanocomposites (II)—Mechanical, barrier, and electrical properties

“…Among the strategies used to balance these physical properties, the use of organic and inorganic nanofillers as reinforcing agents have been extensively used. For instance, inorganic nanofillers such as carbon nanotubes and nanoclays have been used. In the case of organic fillers, cellulose nanocrystals have been the most widely used material for this purpose.…”

Comparison of covalent and noncovalent interactions of carbon nanotubes on the crystallization behavior and thermal properties of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)

“…These results indicate that the PHBV molecules were successfully covalently bonded to the MWCNTs through TDI as a coupling agent. In addition, compared to neat PHBV, the crystalline-sensitive peaks of PHBV at 1277 and 1262 cm 21 (CAOAC stretching mode) clearly became stronger in the PHBV/MWCNT composite. For PHBV-g-MWCNTs, the intensity of the amorphous state of the C@O stretching band at 1740 cm 21 and CAOAC stretching band near 1183 cm 21 increased.…”

“…The carbonyl stretching band of the as-received PHBV could be resolved into an intensive band at 1724 cm 21 and a weak shoulder at 1740 cm 21 [as shown in Figure 1(b)]; these corresponded to the carbonyl stretching bands of the crystalline and amorphous regions, respectively. 18 The bands in the range 1500-800 cm 21 due to the CH 3 and CH bending vibrations and the CAOAC and CAC stretching vibrations heavily overlapped. Compared to those characteristics for neat PHBV, a new absorbance band at Figure 1(a).…”

“…The bands around 3016-2960, 2949-2929, and 2888-2867 cm 21 were assigned to CH 3 asymmetric stretching modes, CH 2 antisymmetric stretching modes, and CH 3 symmetric stretching modes, respectively. The carbonyl stretching band of the as-received PHBV could be resolved into an intensive band at 1724 cm 21 and a weak shoulder at 1740 cm 21 [as shown in Figure 1(b)]; these corresponded to the carbonyl stretching bands of the crystalline and amorphous regions, respectively. 18 The bands in the range 1500-800 cm 21 due to the CH 3 and CH bending vibrations and the CAOAC and CAC stretching vibrations heavily overlapped.…”