scholarly journals An Investigation of the Effect of Chitosan on Isothermal Crystallization, Thermal Decomposition, and Melt Index of Biodegradable Poly(L-lactic acid)

2015 ◽  
Vol 2015 ◽  
pp. 1-5
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Thermal Decomposition ◽  
Lactic Acid ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Decomposition Temperature ◽  
Temperature Zone ◽  
Melt Index ◽  
Analysis Instrument ◽  
Biodegradable Poly ◽  
Higher Temperature

Biodegradable chitosan (CS) was introduced into another biodegradable poly(L-lactic acid) (PLLA) to prepare the PLLA/CS composites, and the effect of CS on thermal behavior and melt index of PLLA was investigated using modern testing technologies including optical depolarizer, thermogravimetric analysis instrument, and melt index instrument. The relevant testing results showed that both crystallization temperature and CS concentration affected the isothermal crystallization behavior of PLLA. Compared to neat PLLA, thet1/2of PLLA/5% CS decreased from 2991.54 s to the minimum value 208.76 s at 105°C. However, thet1/2of PLLA/CS composites in high crystallization temperature zone was different from that in low crystallization temperature zone. The increase of CS concentration and heating rate made the thermal decomposition temperature of PLLA/CS composites shift to higher temperature. The melt index results indicated that 3% CS made the fluidity of PLLA become better.

scholarly journals Effect of 1,4-Naphthalenedicarboxylic Acid Derivative on Crystallization and Performances of Poly(L-lactide)

2021 ◽  
Vol 58 (1) ◽  
pp. 57-68
Author(s):  
Lisha Zhao ◽  
Jun Qiao ◽  
Xueling Shan ◽  
Yanhua Cai ◽  
Jie Zhang
Keyword(s):  
Thermal Decomposition ◽  
Melting Temperature ◽  
Crystallization Temperature ◽  
Crystallization Rate ◽  
Decomposition Temperature ◽  
Organic Additive ◽  
Onset Crystallization Temperature ◽  
Nucleation Sites ◽  
Biodegradable Poly

In this work, biodegradable Poly(L-lactide) (PLLA) was modified through adding a new organic additive N, N -bis(benzoyl) 1, 4-naphthalenedicarboxylic acid dihydrazide (NABH). A comparison on crystallization of the pure PLLA and PLLA/NABH revealed that the NABH as effective heterogeneous nucleation sites enhanced PLLA𠏋 crystallization, and an increase of NABH loading was able to further accelerate crystallization rate of PLLA; whereas a faster cooling rate was not conducive to PLLA𠏋 crystallization, but the appearance of obvious crystallization peak upon cooling at 30şC/min confirmed the advanced enhancing role of NABH for PLLA crystallization again. The investigation on influence of the final melting temperature on the crystallization behavior of PLLA showed that the 170 şC was optimum final melting temperature for enhancing crystallization, even the onset crystallization temperature of PLLA/NABH were higher than 150şC. The melting processes of PLLA/NABH after different crystallization not only could reflect the previous crystallization, but also depended on crystallization temperature and heating rate. Thermal decomposition results showed that the existence of NABH slightly weakened thermal stability of PLLA, and the maximum difference in onset thermal decomposition temperature was only 9.4şC comparing with the pure PLLA. However, the presence of NABH in PLLA matrix seriously weakened optical property.

Thermal behavior of modified poly(L-lactic acid): effect of aromatic multiamide derivative based on 1H-benzotriazole

e-Polymers ◽  
2016 ◽  
Vol 16 (4) ◽  
pp. 303-311 ◽  
Author(s):  
Yan-Hua Cai ◽  
Li-Sha Zhao
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Onset Crystallization Temperature

AbstractThe goal of this work was to synthesis a novel aromatic multiamide derivative based on 1H-benzotriazole (PB) as an organic nucleating agent for poly(L-lactic acid) (PLLA), and investigate the effect of PB on the non-isothermal crystallization, melting behavior and thermal decomposition of PLLA. Here, PB was firstly synthesized through 1H-benzotriazole aceto-hydrazide and terephthaloyl chloride, then PB-nucleated PLLA was fabricated via melt-blending technology at various PB concentration from 0.5 wt% to 3 wt%. Finally, the thermal performances were evaluated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The high thermal decomposition temperature of PB indicated that PB possessed possibility as a nucleating agent for PLLA, and the non-isothermal crystallization behavior confirmed the crystallization accelerating effectiveness of PB for PLLA. Upon optimum concentration of 2 wt%, the onset crystallization temperature, the crystallization peak temperature and the non-isothermal crystallization enthalpy increased from 101.4°C, 94.5°C and 0.1 J·g-1 to 121.3°C, 115.8°C and 35.1 J·g-1, respectively. In addition, the non-isothermal crystallization behavior was also affected by the cooling rate and the final melting temperature. The melting behavior further evidenced the advanced nucleating ability of PB, and the competitive relationship between PB and the heating rate, the nuclear rate and crystal growth rate. Thermal stability measurement showed that PB with a concentration of 1 wt%–2 wt% could slightly improve the thermal stability of PLLA.

Enhancing the Flexural and Impact Properties of Bioplastic Poly(lactic acid) by Melt Blending with Poly(butylene succinate)

2014 ◽  
Vol 931-932 ◽  
pp. 106-110 ◽  
Author(s):  
Naphaporn Lertwongpipat ◽  
Nawadon Petchwatana ◽  
Sirijutaratana Covavisaruch
Keyword(s):  
Lactic Acid ◽  
Flexural Strength ◽  
Flexural Modulus ◽  
Decomposition Temperature ◽  
Poly Lactic Acid ◽  
Flexural Properties ◽  
Butylene Succinate ◽  
Biodegradable Poly ◽  
Higher Temperature ◽  
Blend Ratios

Bio-based biodegradable Poly (lactic acid) (PLA) suffers limitations such as brittleness and slow crystallization. This study aims to resolve the brittle nature of PLA by blending with Poly (butylene succinate) (PBS), a more ductile biodegradable polymer with superior toughness and flexural properties. In this research, a series of PLA/PBS blends was prepared at the blend ratios of 100/0, 80/20, 60/40, 40/60, 20/80 and 0/100. FTIR showed that there was no change in the functional groups of the PLA/PBS blends. Thermal stability assessed by TGA revealed that PBS degraded at higher temperature than that of PLA; the decomposition temperature (Td) at 10% weight loss of PLA and PBS were 330.8 and 356.4°C respectively. The Td of all the blends increased gradually with the addition of PBS. The flexural properties in terms of the flexural strength and the flexural modulus of the blends reduced significantly with PBS content. The PLA/PBS specimens with greater PBS content were softened and flexed more easily, thereby requiring a much lower flexural strength. The flexural modulus of the 80/20 and 60/40 blends dropped from 3.5 GPa for neat PLA to 3.2 GPa and 2.1 GPa while the flexural strength also declined from 105.3 MPa to 90.9 MPa and 69.1 MPa respectively. The toughness of all the blends was greater than that of neat PLA; in particular the 60/40 blend exhibited superior impact strength of 48.7 J/m compared with 30.9 J/m of the neat PLA. The microscopic images of all the blends showed two distinct phases; the 60/40 blend consisted of well dispersed small particles of the tough PBS, resulting in greater absorption of energy upon impact.

A Further Research on the Properties of PLA/TiO2 Nanocomposites

2014 ◽  
Vol 608-609 ◽  
pp. 996-1000
Author(s):  
Yan Bing Luo
Keyword(s):  
Mechanical Property ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Thermal Property ◽  
Deformation Temperature ◽  
Thermal Deformation ◽  
Decomposition Temperature ◽  
Dynamic Mechanical Property ◽  
Thermal Decomposition Temperature ◽  
Inorganic Nanocomposites

Organic/inorganic nanocomposites have been widely focused because of their special properties. By modifying nanoTiO2and polylactic acid (PLA) with lactic acid, PLA/TiO2nanocomposites was prepared, and the test on the dynamic mechanical property, thermal property, and thermal deformation temperature showed that adding nanoTiO2helped improve PLA's mechanics property, thermal decomposition temperature, and thermal deformation temperature to certain extent.

scholarly journals Non-Isothermal Crystallization Kinetics of Poly(4-Hydroxybutyrate) Biopolymer

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2840 ◽  
Author(s):  
Ina Keridou ◽  
Luis J. del Valle ◽  
Lutz Funk ◽  
Pau Turon ◽  
Lourdes Franco ◽  
...  
Keyword(s):  
Growth Rate ◽  
Cooling Rate ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Secondary Nucleation ◽  
Scanning Calorimetry ◽  
Limited Region ◽  
First Case ◽  
Biodegradable Poly ◽  
Insertion Mechanism

The non-isothermal crystallization of the biodegradable poly(4-hydroxybutyrate) (P4HB) has been studied by means of differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). In the first case, Avrami, Ozawa, Mo, Cazé, and Friedman methodologies were applied. The isoconversional approach developed by Vyazovkin allowed also the determination of a secondary nucleation parameter of 2.10 × 105 K2 and estimating a temperature close to 10 °C for the maximum crystal growth rate. Similar values (i.e., 2.22 × 105 K2 and 9 °C) were evaluated from non-isothermal Avrami parameters. All experimental data corresponded to a limited region where the polymer crystallized according to a single regime. Negative and ringed spherulites were always obtained from the non-isothermal crystallization of P4HB from the melt. The texture of spherulites was dependent on the crystallization temperature, and specifically, the interring spacing decreased with the decrease of the crystallization temperature (Tc). Synchrotron data indicated that the thickness of the constitutive lamellae varied with the cooling rate, being deduced as a lamellar insertion mechanism that became more relevant when the cooling rate increased. POM non-isothermal measurements were also consistent with a single crystallization regime and provided direct measurements of the crystallization growth rate (G). Analysis of the POM data gave a secondary nucleation constant and a bell-shaped G-Tc dependence that was in relative agreement with DSC analysis. All non-isothermal data were finally compared with information derived from previous isothermal analyses.

scholarly journals Preparation and Physical Performance of Green Poly(L-lactic acid) Composition by Blending with Starch

2017 ◽  
Vol 11 (1) ◽  
pp. 22-28
Author(s):  
Yan-Hua Cai ◽  
Qian Zheng ◽  
Wen-Jiang Guo
Keyword(s):  
Lactic Acid ◽  
Crystallization Rate ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Temperature Zone ◽  
X Ray ◽  
Melt Index ◽  
Neat Plla ◽  
Maximum Value ◽  
Green Polymer

Objective: To develop more green polymer composites and further know the performance of green composites, the composites based on green poly(L-lactic acid) (PLLA) and starch were fabricated by a counter-rotating mixer. And effect of starch on the fluidity and nucleating performance of PLLA was investigated using melt index instrument, optical depolarizer and wide angle X-ray diffraction instrument, respectively. Method and Conclusion: The fluidity of PLLA/starch composites showed that, compared to the neat PLLA, the addition of starch made the fluidity of PLLA increase significantly and the melt mass flow rate of PLLA/5%starch sample had the maximum value 13.36 g/10min. In addition, the introduction of starch could also increase the crystallization rate of PLLA through isothermal crystallization measurement and x-ray diffraction analysis, the maximum value of crystallization rate of PLLA/starch composites appeared in low crystallization temperature zone, and 10 wt% starch could make the t1/2 of PLLA decrease from 3999.4s to 421.4s.

Effect of Nano-CuO on Luminous Intensity of Pyrotechnics Composite Containing KClO4 and Al

2012 ◽  
Vol 217-219 ◽  
pp. 669-672
Author(s):  
Shu Hong Ba ◽  
Zhe Zhang ◽  
Ming Hui Yan ◽  
Zhe Xing Sun ◽  
Xin Peng Teng
Keyword(s):  
Thermal Decomposition ◽  
Spherical Shape ◽  
Decomposition Temperature ◽  
Luminous Intensity ◽  
Precipitation Method ◽  
Thermal Decomposition Temperature ◽  
Direct Precipitation ◽  
Analysis Instrument ◽  
Average Size ◽  
Direct Precipitation Method

Nano-CuO had been successfully synthesized by using direct precipitation method. The prepared sample was characterized by XRD. The luminous intensities of pyrotechnics composite containing KClO4, Mg and nano-CuO were measured. The catalysis of CuO nanocrystal on KClO4 was investigated by thermal analysis instrument. The results show that the average size of nano-CuO is 19 nm and has spherical-shape. When nano-CuO is added into the pyrotechnics composites containing KClO4 and Al, it can improve the igniting and burning performance. The luminous intensity of trinary pyrotechnics composite is also greatly increased. On the other hand, nano-CuO can make thermal decomposition temperature of KClO4 to decrease 97.7 °C, the decalescence amount also reduced to 79.07 J/g. It is obviously that nano-CuO has strong catalysis to KClO4 thermal decomposition. The conclusion is consistent with the measure results of luminous intensity.

scholarly journals Crystallization and Melting Behavior of Biodegradable Poly(L-lactic acid)/Talc Composites

2012 ◽  
Vol 9 (3) ◽  
pp. 1569-1574 ◽  
Author(s):  
Yan-Hua Cai
Keyword(s):  
Lactic Acid ◽  
Heating Rate ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Melting Behavior ◽  
Melting Peak ◽  
Melt Crystallization ◽  
Biodegradable Poly ◽  
Crystallization And Melting Behavior ◽  
Double Melting Peak

Crystallization and melting behavior of Poly(L-lactic acid)(PLLA)/Talc composites with different talc content were investigated in detail. The addition of talc can increase the overall crystallization rate of PLLA, 5%talc makes the melt-crystallization peak temperature of PLLA increase from 96.28 °C to 105.22 °C, and the crystallization enthalpy increases from 1.379 J•g-1to 28.99 J•g-1. The melting behavior of PLLA/5%talc composites at a different heating rate during non-isothermal crystallization at different cooling rate shows that heating rate can affect the melting behavior of PLLA, with increasing of heating rate, the double melting peak degenerates to single melting peak. Melting behavior after isothermal crystallization and after cold isothermal crystallization and hot isothermal crystallization indicates that the double-melting peak of PLLA/5%talc composites results from melting-recrystallization.

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