Evidence for the Soft and Hard Epitaxies of Poly(l-lactic acid) on an Oriented Polyethylene Substrate and Their Dependence on the Crystallization Temperature

2020 ◽  
Vol 53 (5) ◽  
pp. 1745-1751 ◽  
Author(s):  
Li Li ◽  
Jian Hu ◽  
Yunpeng Li ◽  
Qigu Huang ◽  
Xiaoli Sun ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Crystallization Temperature ◽  
Oriented Polyethylene

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

Tacticity-Dependent Epitaxial Crystallization of Poly(l-lactic acid) on an Oriented Polyethylene Substrate

2020 ◽  
Vol 53 (19) ◽  
pp. 8487-8493
Author(s):  
Li Li ◽  
Rui Xin ◽  
Huihui Li ◽  
Xiaoli Sun ◽  
Zhongjie Ren ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Epitaxial Crystallization ◽  
Oriented Polyethylene

Origin of Epitaxial Cold Crystallization of Poly(l-lactic acid) on Highly Oriented Polyethylene Substrate

2013 ◽  
Vol 46 (13) ◽  
pp. 5215-5222 ◽  
Author(s):  
Ce Tu ◽  
Shidong Jiang ◽  
Huihui Li ◽  
Shouke Yan
Keyword(s):  
Lactic Acid ◽  
Cold Crystallization ◽  
Oriented Polyethylene

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.

Effect of Poly(Hexamethylene Succinamide) on Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 302-307
Author(s):  
Panadda Yueagyen ◽  
Amornrat Lertworasirikul
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Crystallization Temperature ◽  
Crystallization Rate ◽  
Weight Percent ◽  
Degree Of Crystallinity ◽  
Nucleating Agents ◽  
Melt Polymerization ◽  
The Degree Of Crystallinity ◽  
Aliphatic Amide

Poly(L-lactic acid) (PLA) has good mechanical properties and is biodegradable. However, its crystallization rate is slow, crystallization period long, and its crystallization temperature high at 116 °C. Consequently, long processing cycles are required for the production of high crystallinity poly (L-lactic acid). Addition of nucleating agents is an efficient way to solve this problem. Aliphatic amide such as N,N-ethylenebis(12-hydroxystearamide) and ethylenebis-stearamide are reported as nucleating agents for poly (L-lactic acid). In this study, the effect of the aliphatic polyamide, poly (hexamethylene succinamide) on the crystallization behavior of PLA was investigated. Poly (hexamethylene succinamide) was synthesized by melt polymerization. Between one and ten weight percent poly (hexamethylene succinamide) was blended with poly (L-lactic acid) by melt extrusion. The crystallization temperature and crystallization period decreased with increasing poly (hexamethylene succinamide) content. The degree of crystallinity increased with the addition of poly (hexamethylene succinamide). A poly (hexamethylene succinamide) content of 5%wt provides optimum conditions for production of poly (L-lactic acid)-poly (hexamethylene succinamide) blend with good mechanical properties. The polymers obtained are entirely from renewable resources.

Melting behavior of poly(l-lactic acid): Effects of crystallization temperature and time

Polymer ◽  
2007 ◽  
Vol 48 (18) ◽  
pp. 5398-5407 ◽  
Author(s):  
Munehisa Yasuniwa ◽  
Koji Iura ◽  
Yusuke Dan
Keyword(s):  
Lactic Acid ◽  
Crystallization Temperature ◽  
Melting Behavior

Injection Moldable Poly(Lactic Acid)-Poly(Butylene Succinate)-Activated Carbon Composite Foams: Effects of PLA/PBS Ratios

2019 ◽  
Vol 798 ◽  
pp. 322-330
Author(s):  
Kittipong Hrimchum ◽  
Darunee Aussawasathien ◽  
Todsapol Kajornprai
Keyword(s):  
Lactic Acid ◽  
Activated Carbon ◽  
Cell Density ◽  
Void Fraction ◽  
Crystallization Temperature ◽  
Poly Lactic Acid ◽  
Flow Index ◽  
Foam Density ◽  
Butylene Succinate ◽  
Composite Foams

Poly (lactic acid) (PLA)-poly (butylene succinate) (PBS)-activated carbon (AC) composites were foamed via an injection molding process. Azodicarbonamide (ADC) was used as a chemical blowing agent. The effect of PLA/PBS ratios (0/100, 10/90, 20/80, 30/70, 40/60, 50/50 wt% and vice versa) on the cell formation and properties of composite foams such as cellular structure, foam density (ρf), void fraction (Vf), cell density, melt flow index (MFI), thermal and mechanical properties and crystallinity were investigated. At same ADC and AC loadings (5 phr), PBS acted as nucleating sites for cell generation and expansion at low contents ( 40 wt%). However, the cell size had a tendency to decrease at high PBS concentrations (> 40 wt%). The cell density of composite foams was somewhat constant at PLA/PBS ratios up to 60/40 wt% and then continuously increased as the PBS dosage was higher than 40 wt%. The maximum reduction of foam density with the void fraction of 20% was obtained at the PLA/PBS ratio of 60/40. The melt viscosity of composite foams increased with the increase of PBS loadings. The tensile strength and Young’s modulus of composite foams decreased while the elongation at break and impact strength increased as the proportion of PBS increased. The cold crystallization temperature (Tcc) of PLA in the composite foam tended to decrease with the reduction of PLA contents while the melting temperatures (Tm) of PLA in composite foams fluctuated without any trend compared with those of the unfoamed PLA. The Tcc of PLA in composite foams could not be detected when the content of PBS was higher than 40 wt%. The crystallization temperature (Tc) and Tm of PBS in composite foams was almost unchanged for each PLA/PBS proportion compared with those of the unfoamed PBS. The crystallinity (Xc) of PLA in composite foams increased compared with the unfoamed PLA at PBS contents of 0-20 wt% due to the nucleating effect of PBS and AC. The Xc of PLA (at PBS > 20 wt%) and PBS in composite foams decreased with the reduction of each polymer.

Sign in / Sign up

Export Citation Format

Share Document