Polyvinyl alcohol:starch:carboxymethyl cellulose containing sodium montmorillonite clay blends; mechanical properties and biodegradation behavior

Abstract

The focuses of this study were to investigate the effect of sodium montmorillonite clay (MMT-Na) content on the physical properties and extent of enzymatic hydrolysis Polyvinyl Alcohol (PVA): Starch (S): Carboxymethyl Cellulose (CMC) nanocomposites using enzyme <alpha>−amylase. The results of this work have revealed that films with MMT-Na content at 5 wt% exhibited a significantly reduced rate and extent of starch hydrolysis. The results suggest that this may have been attributed to interactions between PVA:S:CMC and MMT-Na that further prevented enzymatic attack on the remaining starch phases within the blend. The total solids that remained after 4320 min were 65.46 wt% (PVA:S:CMC); 67.91 wt% (PVA:S:CMC:1% MMT-Na); 78.43 wt% (PVA:S:CMC:3% MMT-Na); 80.24 wt% (PVA:S:CMC:5% MMT-Na). The rate of glucose production from each nanocomposite substrates were decresed significantly as the MMT-Na percentage increased from 0 to 5% (W/W). At the level of 5% (W/W) MMT-Na, the films showed the lowest rate of glucose production values (18.95 μg/ml h). With the increase of the MMT concentration from 0 to 5%, the UTS increased 5 from 18.36 to 20.38 MPa, however, the strain to break (SB) decreased noticeably from 35.56 to 5.22%.

PVA, PVA Blends, and Their Nanocomposites for Biodegradable Packaging Application

“…Starch is hard to process as a pure polymer because its decomposition temperature (Td = 220 º C) is very close to the melting temperature (Tm = 220-240 º C). The presence of many H-bonds between macromolecules also prevents the mobility of these polymeric molecules [20,56,85,86] . Therefore, plasticisers such as water, polyols, glycerol and urea as low molecular weight and low volatile organic agents, can overcome this limitation in addition to increases in flexibility and processability, as well as reductions of brittleness and Tg for native starch by decreasing its intermolecular forces [8,40,83,87] .…”

“…This phenomenon depended on starch type and content within the films and took approximately 5-45 days according to environmental conditions [2] . Based on research work by Taghizadeh et al [85] , α-amylose with free mobility first degraded from starch.…”

Effect of hydrochloric acid on the properties of biodegradable packaging materials of carboxymethylcellulose/poly(vinyl alcohol) blends

“…This finding was compared to the study of Koc et al ., who conducted a study with modified CMC and CMC–PVA as a miscible polymer blend; they found that the values of TS and E b for the 50:50 w/w CMC–PVA film to be 7.44 ± 0.69 MPa and 2.42 ± 0.52%, respectively. Taghizadeh et al . investigated the mechanical properties of clay‐incorporated CMC/starch/PVA composites.…”

<strong>Using GO and clay to improve properties of PVA polymeric film </strong>

“…Having high aspect ratio, large surface area, and good interfacial properties, layered silicate clay added to a polymer matrix can contribute to significant cost savings as a property enhancer. Clay-containing polymer nanocomposites may offer beneficial properties, such as good mechanical properties, dimensional stability, barrier properties, flame retardant, optical properties, and thermal stability [4][5][6][7][8][9] .…”