Year: 2010
Type: article
Abstract: A series of chemically modified starches were synthesized in the present study: (1) a starch modified with an anionic group and benzoyl group; (2) a starch modified with an anionic group and hexanoyl group; (3) a starch modified with a cationic group and benzoyl group; and (4) a starch modified with a cationic group and hexanoyl group.The glass transition temperatures of the modified starches were found to be lower than that of natural starch.The modified starches synthesized in the present study are found to be hydrophobic and can biodegrade in composting.Blends of a modified starch and poly(ethylene-co-vinyl alcohol) (EVOH) were prepared by melt blending.Phase diagrams of the blends exhibited a lower critical solution temperature.The DSC thermograms of the blends showed a single glass transition temperature and melting point depression.The crystallization of EVOH in the blends was interrupted by the hydrogen bonds formed between the hydroxyl groups in the modified starch and EVOH.The crystalline structure of EVOH in the blends had an orthorhombic lattice in the quenched specimen and evolved into a monoclinic lattice when the annealing temperature was increased.The nanocomposites based on a modified starch and EVOH were prepared.Natural clay (montmorillnite, MMT) and two commercial organoclays (Cloisite 30B and Cloisite 15A) were employed to investigate how the functional groups in the modified starch influence the dispersion characteristics of nanocomposites.Anionically modified starch was found to be very effective in exfoliating organoclay aggregates due to the x 2.15 X-ray diffraction diagrams of (top) granular waxy maize starch and (bottom)TPS materials stored at various temperatures and humidity.From bottom to top: quenched and stored for 2 weeks; stored at 40% relative humidity (RH) for 2 weeks; stored at 60% RH for 2 weeks; stored at 70% RH for 8 months; and stored at 90% RH for 2 weeks.……………………………………………..….46 2.16 Effect of Cloisite Na + on the XRD patterns of TPS nanocomposites: (a) Cloisite Na + ; (b) TPS/Cloisite Na + (97.5/2.5 wt %); (c) TPS/Cloisite Na + (95.0/5.0 wt %); (d) TPS/Cloisite Na + (90.0/10.0wt %); and (e) TPS.…………............................…48 2.17 TEM image of TPS nanocomposite containing 5 wt % of MMT…………...……..48 4.1 FTIR spectra of (a) natural starch (NS), (b) starch modified with anionic group and benzoyl group (AS-B), and (c) starch modified with anionic group and hexanoyl group (AS-LF).………………………………...…………………..……...61 4.2 FTIR spectra of (a) natural starch (NS), (b) starch modified with cationic group and benzoyl group (CS-B), and (c) starch modified with cationic group and hexanoyl group (CS-LF)………………... …………………………………..……...62 4.3 1 H-NMR spectra of a starch modified by hexanoyl group……………………….…654.4 Moisture absorption of modified starch: (•) NS; (■) AS; (▲) CS; (▼) AS-LF; (◆) AS-B; (□) CS-LF; and (〇) CS-B….……..…………………...………………..66 4.5 Thermal degradation temperatures of chemically modified starches…………..…...68 4.6 DSC thermograms of (a) AS, (b) AS-LF, and (c) AS-B………………………….…714.7 DSC thermograms of (a) CS, (b) CS-B, and (c) CS-LF………………………...…..71 4.8 Weight loss of modified starch during composting: (•) NS; (■) CS-LF; (▲) LD-PE; (▼) CS-B; (◆) AS-LF; and (□) AS-B……...……………………..…73 5.1 Phase diagrams of the blends of a modified starch and EVOH: (•) (AS-B)/EVOH blend; (〇) (AS-LF)/EVOH blend; (▼) (CS-B)/EVOH blend; and (▽) (CS-LF)/ EVOH blend………….…….………………..…………...………………………....77 5.2 DSC thermograms of the blends of (AS-B)/EVOH: (a) neat EVOH; (b) blend of 20/80 (AS-B)/EVOH; (c) blend of 40/60 (AS-B)/EVOH; (d) blend of 70/30 (AS-B)/EVOH; and (e) neat AS-B…………………………….......................79 xi 5.3 DSC thermograms of the blends of (AS-LF)/EVOH: (a) neat EVOH; (b) blend of 20/80 (AS-LF)/EVOH; (c) blend of 40/60 (AS-LF)/EVOH; (d) blend of 70/30 (AS-LF)/EVOH; and (e) neat AS-LF……………….…………..……..…..79 5.4 DSC thermograms of the blends of (CS-B)/EVOH: (a) neat EVOH; (b) blend of 20/80 (CS-B)/EVOH; (c) blend of 40/60 (CS-B)/EVOH; (d) blend of 70/30 (CS-B)/EVOH; and (e) neat CS-B………………….………..………..…..80 5.5 DSC thermograms of the blends of (CS-LF)/EVOH: (a) neat EVOH; (b) blend of 20/80 (CS-LF)/EVOH; (c) blend of 40/60 (CS-LF)/EVOH; (d) blend of 70/30 (CS-LF)/EVOH; and (e) neat CS-LF……………………………………...80 5.6 DSC thermograms in the glass transition region for the blends of (AS-B)/EVOH: (a) neat EVOH; (b) blend of 20/80 (AS-B)/EVOH; (c) blend of 40/60 (AS-B)/EVOH; (d) blend of 70/30 (AS-B)/EVOH; and (e) neat AS-B……………………………………………………………………83 5.7 DSC thermograms in the glass transition region for the blends of (AS-LF)/EVOH: (a) neat EVOH; (b) blend of 20/80 (AS-LF)/EVOH; (c) blend of 40/60 (AS-LF)/EVOH; (d) blend of 70/30 (AS-LF)/EVOH; and (e) neat AS-LF………………………………………………………………...…83 5.8 DSC thermograms in the glass transition region for the blends of (CS-B)/EVOH: (a) neat EVOH; (b) blend of 20/80 (CS-B)/EVOH; (c) blend of 40/60 (CS-B)/EVOH; (d) blend of 70/30 (CS-B)/EVOH; and (e) neat CS-B……………………………………………………………..……..84 5.9 DSC thermograms in the glass transition region for the blends of (CS-LF)/EVOH: (a) neat EVOH; (b) blend of 20/80 (CS-LF)/EVOH; (c) blend of 40/60 (CS-LF)/EVOH; (d) blend of 70/30 (CS-LF)/EVOH; and (e) neat CS-LF……………………………………………………………..........84 5.10 FTIR spectra in the hydroxyl group stretching region for: (a) neat EVOH; (b) neat modified starch AS-B; and (c) blend of 70/30 (AS-B)/EVOH………..….87 5.11 FTIR spectra in the hydroxyl group stretching region for: (a) neat EVOH; (b) blend of 70/30 (AS-LF)/EVOH; and (c) neat modified starch AS-LF…....…...87 5.12 FTIR spectra in the hydroxyl group stretching region for: (a) neat EVOH; (b) blend of 70/30 (CS-B)/EVOH; and (c) neat modified starch CS-B…………....88 5.13 FTIR spectra in the hydroxyl group stretching region for: (a) neat EVOH; (b) blend of 70/30 (CS-LF)/EVOH; and (c) neat modified starch CS-LF………....88 CHAPTER I
Author: Lin Frank Song
Institution: University of Akron
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W986016784