Multiple melting behavior of poly(lactic acid)-hemp-silica composites using modulated-temperature differential scanning calorimetry

2014 ◽  
Vol 34 (9) ◽  
pp. 895-903 ◽  
Author(s):  
Izan R. Mustapa ◽  
Robert A. Shanks ◽  
Ing Kong
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heat Capacity ◽  
Lactic Acid ◽  
Melting Behavior ◽  
Woven Fabric ◽  
Melting Peak ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Modulated Temperature ◽  
Multiple Melting

Abstract Poly(lactic acid) (PLA)-hemp-nanosilica (PHS) composites were prepared by impregnation of hemp woven fabric with PLA solution. Nanosilica was dispersed in the PLA solution to introduce a matrix reinforcing nanophase within the composite. The melting behavior of PLA composites was obtained by using differential scanning calorimetry (DSC) and modulated-temperature DSC (mT-DSC). Multiple melting which appeared in the non-isothermal heating curve showed that the temperature of a low melting peak increased when using a slower scanning rate. The incorporation of nanosilica in PLA composites affected the melting temperature (Tm) and sufficiently formed nucleation sites that promoted the growth of PLA crystals. Composites analyzed by a temperature-modulated program showed a broad exothermic peak before the melting peak in the non-reversing heat capacity and endothermic melting in the reversing heat capacity curve. This behavior was explained by a process of partial melting, recrystallization and remelting (mrr). The mT-DSC resolved that hemp fiber induced recrystallization and nanosilica acted as an effective nucleating agent, which promoted small and imperfect crystals that changed successively into more stable crystals through a melt-recrystallization process.

RETRACTED: Fabrication of Poly(Lactic Acid) Nanofibers by Cotton Candy Method

2017 ◽  
Vol 728 ◽  
pp. 193-198
Author(s):  
Rutchaneekorn Wongpajan ◽  
Supaphorn Thumsorn ◽  
Hiroyuki Inoya ◽  
Masayuki Okoshi ◽  
Hiroyuki Hamada
Keyword(s):  
Differential Scanning Calorimetry ◽  
Lactic Acid ◽  
Thermal Properties ◽  
Electron Microscope ◽  
Air Pressure ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Cotton Candy ◽  
Nozzle Temperature ◽  
Scanning Electron

The poly (lactic acid) (PLA) fiber of biodegradable polymer was fabricated by cotton candy method with small nozzle. The air pressure was varied from 0.2-0.5 MPa with nozzle temperature of 210-260°C. The morphology of fiber was determined by scanning electron microscope (SEM). Thermal properties were examined using differential scanning calorimetry (DSC). SEM results suggested that diameters the PLA fiber at temperature 250°C and air pressure of 0.2 MPa were smaller than the fiber at low and high temperature. The sizes of the fibers were lower than 1 μm and the fibers were irregular size. Crystallinity significantly decreased when increasing barrel temperatures while it slightly changed when varied air pressure. The productivity of PLA fibers was around 30-180 g/h depended on controlled the nozzle temperature and the air pressure.

Multiple melting behavior of poly(lactic acid) filled with modified carbon black

2009 ◽  
Vol 47 (20) ◽  
pp. 1971-1980 ◽  
Author(s):  
Zhizhong Su ◽  
Qiuying Li ◽  
Yongjun Liu ◽  
Guo-Hua Hu ◽  
Chifei Wu
Keyword(s):  
Lactic Acid ◽  
Carbon Black ◽  
Melting Behavior ◽  
Poly Lactic Acid ◽  
Multiple Melting Behavior ◽  
Multiple Melting

Step-Scan DSC Study on the Melting Behavior of Polypropylene/Attapulgite Nanocomposites

2011 ◽  
Vol 284-286 ◽  
pp. 763-768
Author(s):  
Li Li Sun ◽  
Kun Hu ◽  
Lin Chen ◽  
Kang Zheng ◽  
Xing You Tian
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Melting Behavior ◽  
Secondary Crystallization ◽  
Screw Extruder ◽  
Scanning Calorimetry ◽  
Twin Screw ◽  
Multiple Melting ◽  
Scanning Electron

Attapulgite(AT) was modified by grafting with butyl acrylate(BA) via polymerizations initiated by Gamma radiation. The polypropylene(PP)/AT nanocomposites were synthesized via melting extrude in a twin-screw extruder. The thermogravimetry(TG) and scanning electron microscopy (SEM) were used to assess the graft ratio of the hybrid materials and the dispersion of AT, respectively. Step-scan differential scanning calorimetry(SSDSC) was used to study the influence of AT on the crystallization and subsequent melting behavior. The results indicated that PP and PP/AT nanocomposites underwent multiple melting and secondary crystallization processes during heating. The melting behaviours of PP and PP/AT nanocomposites varied with the variation of crystallization temperature and AT content.

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