Ageing of soft thermoplastic starch with high glycerol content

Abstract

In this study, a soft and thermoplastic starch with an improved ageing-resistant property was prepared by melt blending method for a biodegradable biomaterial. The glycerol content varies from 30 to 60 wt %. The aging temperature and humidity of the glycerol-plasticized thermoplastic starch (GTPS) was 378C and 50 6 5 RH %, respectively. The retrogradation was characterized by X-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), Fourier transform infrared (FTIR), and the stressstrain mechanical properties. The XRD results suggest that high content of glycerol promotes the formation of single helix structure of V-type, but inhibits double helix structure of B-type. Changing of the tan d, storage modules (E 0 ), and the glass transition temperatures as a function of glycerol content and ageing time was detected by DMTA. FTIR result shows that the shifting speed of the peak of hydroxyl group stretching fell as the glycerol content increased. The glycerol content has no obvious effect on the mechanical properties when it is high enough.Results from all characterizations demonstrate that the ageing speed is closely relative to the plasticizers content. The higher content of glycerol possesses an obviously inhibitory effect on the ageing.

Preparation and characterization of thermoplastic starches and their blends with poly(lactic acid)

“…3b), the A-type crystallization peaks disappeared, only two weak crystallization peaks were detected at 2Â = 14 • and 21 • which were the characteristic peaks of V-type [30]. Besides, an amorphous dispersion band was found at 2Â = 19 • [31].…”

Mechanical and microstructural properties of sugar palm (Arenga pinnata Merr.) starch film: Effect of aging

“…The presentation of peak 2θ at 17 o and 20 o implied the formation of double-helical B-type crystalline. The peak at 2θ=20 o corresponded to the single helical crystal structure of V-type, which indicated the formation of amylose-glycerol complexes during processing [17]. The crystallinity of fresh film increased slightly with the increasing of glycerol content.…”

Influence of plasticizer with different functional groups on thermoplastic starch

“…Citric acid is proven to be a crystallization inhibitor for starch, because of esterification and strong hydrogen bonding interactions with starch. 13,46 Different plasticizer amounts of malic acid displayed no significant differences in retrogradation after 56 days at RH100%. Research of Yu et al 13 showed that citric acid quantities of 3 wt % were enough for suppressing starch recrystallization for 70 days at 100% relative humidity.…”

“…Peaks in the range 1721-1750 cm 21 have been reported for esterification of starch and cellulose samples. [40][41][42][43][44][45][46] Although absorption signals near 1720 cm 21 may also be ascribed to carboxylic acid groups in di-acidic molecules present in the sample. 6 Increased absorption in the range 1200-1300 cm 21 was attributed to C-O stretching in esters.…”