scholarly journals The Synthesis of Biodegradable Poly(L-Lactic Acid)-Polyethylene Glycols Copolymer/Montmorillonite Nanocomposites and Analysis of the Crystallization Properties

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 14
Author(s):  
Jiunn-Jer Hwang ◽  
Su-Mei Huang ◽  
Wen-Yang Lin ◽  
Hsin-Jiant Liu ◽  
Cheng-Chan Chuang ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Silicate Layer ◽  
Polyethylene Glycols ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Study Results

This study makes use of polycondensation to produce poly (L-lactic acid)-(polyethylene glycols), a biodegradable copolymer, then puts it with organically modified montmorillonite (o-MMT) going through an intercalation process to produce a series of nanocomposites of PLLA-PEG/o-MMT. The exfoliation and intercalation of the montmorillonite-layered structure could be found through X-ray diffraction and transmission electron microscopy. The lower the molecular weight of poly (ethylene glycol), the more obvious the exfoliation and dispersion. The nanocomposites were investigated under non-isothermal crystallization and isothermal crystallization separately via differential scanning calorimetry (DSC). After the adding of o-MMT to PLLA-PEG copolymers, it was found that the PLLA-PEG nanocomposites crystallized slowly and the crystallization peak tended to become broader during the non-isothermal crystallization process. Furthermore, the thermal curve of the non-isothermal melt crystallization process of PLLA-PEG copolymers with different proportions of o-MMT showed that the melting point decreased gradually with the increase of o-MMT content. In the measurement of isothermal crystallization, increasing the o-MMT of the PLLA-PEG copolymers would increase the t1/2 (crystallization half time) for crystallization and decrease the value of ΔHc. However, the present study results suggest that adding o-MMT could affect the crystallization rate of PLLA-PEG copolymers. The o-MMT silicate layer was uniformly dispersed in the PLLA-PEG copolymers, forming a nucleating agent. The crystallization rate and the regularity of the crystals changed with the increase of the o-MMT content, which further affected the crystallization enthalpies.

Non-isothermal crystallization kinetics of poly (lactic acid)/graphene nanocomposites

2013 ◽  
Vol 33 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Yanhua Chen ◽  
Xiayin Yao ◽  
Qun Gu ◽  
Zhijuan Pan
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Graphene Nanocomposites ◽  
Solution Blending ◽  
Transmission Electron ◽  
Graphene Nanocomposite

Abstract Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending and the dispersibility of graphene in the PLA matrix was examined by transmission electron microscopy (TEM). The non-isothermal crystallization behaviors of pure PLA and PLA/graphene nanocomposites from the melt were investigated by differential scanning calorimetry (DSC). The results showed that the graphene could play a role as a heterogeneous nucleating agent during the non-isothermal crystallizing process of PLA, and accelerate the crystallization rate. The non-isothermal crystallizing data were analyzed with the Avrami, Ozawa and Mo et al. models and the crystallization parameters of the samples were obtained. It is demonstrated that the combination of the Avrami and Ozawa models developed by Mo et al. was successful in describing the non-isothermal crystallization process for pure PLA and its nanocomposite. According to the Kissinger equation, the activation energies were found to be -154.3 and -179.5 kJ/mol for pure PLA and PLA/0.1 wt% graphene nanocomposite, respectively. Furthermore, the spherulite growth behavior was investigated by polarized optical microscopy (POM) and the results also supported the DSC data.

scholarly journals Poly (L-lactic acid) Modified by N, N -bis(Stearic acid)-1,4-Dicarboxybenzene Dihydrazide: Studies of Crystallization, Melting Behavior and Thermal Decomposition

2022 ◽  
Vol 58 (4) ◽  
pp. 73-83
Author(s):  
Hao Huang ◽  
Shuang-Qing Liu ◽  
Cheng-Pei Li ◽  
Shi-Tianle Luo ◽  
Li-Sha Zhao ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Decomposition ◽  
Lactic Acid ◽  
Stearic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Process ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Melt Crystallization ◽  
Thermal Stability Of

In this study, a new organic nucleating agent N, N -bis(stearic acid)-1,4-dicarboxybenzene dihydrazide (PASH) to improve crystallization behavior of poly(L-lactic acid) (PLLA) along with the effect of PASH on melting behavior, thermal stability of PASH-nucleated PLLA was holistically reported. The melt-crystallization process illustrated that PASH as an effective heterogeneous nucleating agent could boost PLLA�s crystallization rate, but increasing PASH concentration and cooling rate conversely inhibited melt-crystallization process of PLLA in this study. With respect to melt-crystallization process, a larger amount of PASH leaded to a shift of cold-crystallization peak to lower temperature level. Isothermal crystallization revealed, in comparison to pure PLLA, that the half time of overall crystallization of PLLA/PASH was significantly decreased with PLLA containing 3 wt% PASH having the minimum t1/2= 67.3 s at 105şC. The different melting behaviors of PLLA/PASH under different conditions were attributed to the nucleating effect of PASH within PLLA. In particular, the melting behavior at a heating rate of 10�C/min after isothermal crystallization depended primarily on the crystallization temperature. Whereas, the impact of crystallization time on melting behavior was negligible. Nonetheless, the melting behavior was influenced by the heating rate after non-isothermal crystallization. The thermal stability of PLLA was detrimental with the addition of PASH owing to a typical drop in onset thermal decomposition temperature.

Isothermal Crystallization Behavior of Poly (L-lactic Acid)/ Surface-Grafted Silica Nanocomposites

2012 ◽  
Vol 268-270 ◽  
pp. 37-40 ◽  
Author(s):  
Yan Hua Cai
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Melt Blending ◽  
Scanning Calorimetry ◽  
Silica Nanocomposites ◽  
Induction Periods ◽  
Sio2 Nanocomposites ◽  
Different Content

The Poly(L-lactic acid)(PLLA)/surface-grafting silica(g-SiO2) nanocomposites were prepared by melt blending. The isothermal crystallization behavior of PLLA/g-SiO2 nanocomposites with different content of g-SiO2 was investigated by optical depolarizer. In isothermal crystallization from melt, the induction periods and half times for overall PLLA crystallization (95°C Tc 120°C) were affected by the crystallization temperature and the content of g-SiO2 in nanocomposites. The results showed that g-SiO2 as a kind of heterogeneous nucleating agent can reduce induction periods and half times for overall PLLA crystallization. The thermal properties of PLLA/g-SiO2 samples were also investigated by differential scanning calorimetry (DSC), The results showed that the crystalline degree of PLLA was improved as the presence of g-SiO2.

PP/MWCNTs composites: Effects of length of MWCNTs on isothermal crystallization behaviors, crystalline structure, and thermal stability

2017 ◽  
Vol 52 (4) ◽  
pp. 503-517 ◽  
Author(s):  
Zheng-Ian Lin ◽  
Ching-Wen Lou ◽  
Yi-Jun Pan ◽  
Chien-Teng Hsieh ◽  
Chien-Lin Huang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Thermal Stability ◽  
Crystalline Structure ◽  
Isothermal Crystallization ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Scanning Calorimetry ◽  
Crystallization Behaviors ◽  
Walled Carbon Nanotubes ◽  
Thermal Stability Of

This study adopts the melt compounding method to prepare /mutli-walled carbon nanotubes composites. The effects of different lengths of the mutli-walled carbon nanotubes on the isothermal crystallization behaviors, crystalline structure, and thermal stability of the polypropylene/mutli-walled carbon nanotubes composites are examined. The PLM results show that the combination of mutli-walled carbon nanotubes prevents the growth of polypropylene spherulites, and thus results in a small size of spherulites. The differential scanning calorimetry results show that the short (S-) or long (L-) mutli-walled carbon nanotubes can function as the nucleating agent of polypropylene, which accelerates the crystallization rate of polypropylene. Avrami theory analyses indicate that the addition of short-mutli-walled carbon nanotubes particularly provides polypropylene/mutli-walled carbon nanotubes composites with a high crystallization rate. The X-ray diffraction results show that the combination of mutli-walled carbon nanotubes does not pertain to the crystal structure. The TGA test results show that long-mutli-walled carbon nanotubes outperform short -mutli-walled carbon nanotubes in improving the thermal stability of polypropylene, and both can significantly improve it.

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.

Isothermal and Non-Isothermal Crystallization Behavior of Poly(L-Lactic Acid) with Nucleating Agents

2011 ◽  
Vol 335-336 ◽  
pp. 1299-1302 ◽  
Author(s):  
Xin Qian ◽  
Mi Zhou ◽  
Dong Xu ◽  
Shu Jun Xu ◽  
Yang Fu Jin
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Peak Temperature ◽  
Crystallization Time ◽  
Nucleating Agents ◽  
Scanning Calorimetry ◽  
Crystallization Peak ◽  
Half Crystallization Time

The effects of Amide type nucleating agents SX , talc and nucleating agents SX combination with talc on crystallization behavior of poly (L-lactic acid）(PLLA) were analyzed by means of Differential scanning calorimetry (DSC)．The results of non-isothermal crystallization showed that SX is an efficient nucleating agent. The crystallization peak temperature and degree of crystallization of PLLA sample with 0.6 wt% SX are both higher than that of PLLA sample with 4 wt% Talc，which proved that the nucleating ability of SX is stronger．Nucleating agent SX and talc combination has obvious coordination effects, the sample of PLLA/0.2 wt % SX + 4 wt % talc has the minimal crystallization undercooling temperature, the highest crystallization peak temperature and crystallinity. Isothermal crystallization kinetics of PLA showed that when the four nucleating agents added in are all with the Avrami exponent n between 2.1-2.5, crystallization tended to be heterogeneous nucleation. When the nucleating agents added in are 0.6 wt%, the crystallization time is greatly decreased to 0.75min. Meanwhile, the PLLA crystallinity could be significantly increased by adding SX nucleating agents; besides, with the decrease of the isothermal crystallization temperature, the half crystallization time of the PLLA/0.6 wt% SX sample was decreased.

Preparation and Isothermal Crystallization Behavior of Poly(lactic acid)/Graphene Nanocomposites

2011 ◽  
Vol 284-286 ◽  
pp. 246-252 ◽  
Author(s):  
Yan Hua Chen ◽  
Xia Yin Yao ◽  
Zhi Juan Pan ◽  
Qun Gu
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Graphene Nanosheets ◽  
Nucleating Agent ◽  
Optical Microscope ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Avrami Model ◽  
Graphene Nanocomposites ◽  
Solution Blending

Poly(lactic acid) (PLA)/graphene nanocomposites were prepared by solution blending using chloroform as a mutual solvent. Transmission electron microscopy (TEM) was used to examine the quality of the dispersion of graphene in the PLA matrix. The isothermal crystallization behaviors of PLA and PLA/graphene nanocomposites were investigated by differential scanning calorimetry (DSC). The isothermal crystallization kinetics were analyzed by Avrami model based on the DSC data. The results showed that the well dispersed graphene nanosheets could act as a heterogeneous nucleating agent and lead to an acceleration of crystallization during the PLA isothermal crystallization process. According to the Arrhenius equation, the activation energies were found to be -106.9 and -46.6 kJ/mol for pure PLA and PLA/0.1 wt % graphene nanocomposite, respectively. The crystal morphology were characterized with polarizing optical microscope (POM).

Isothermal Crystallization Behavior and Kinetics of Poly (lactic acid) Filled with a Novel Nucleating Agent

2014 ◽  
Vol 887-888 ◽  
pp. 716-722
Author(s):  
Nai Xu ◽  
Xing Hui Wang ◽  
Li Sha Pan ◽  
Su Juan Pang ◽  
Xuan Chen ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Nucleation Effect ◽  
Amide Derivatives ◽  
Aromatic Amide ◽  
Kinetics Of

The crystallization behavior and crystalline structure of poly (lactic acid) (PLA) filled with a novel nucleating agent (TMC328), which is a kind of aromatic amide derivatives, were investigated using differential scanning calorimetry (DSC) and wide angle X-ray (XRD). In isothermal crystallization from the melt, the present of TMC328 remarkably affected the isothermal crystalline behaviors of PLA. PLA/0.5% TMC328 sample exhibited very short crystallization half-times at 90-130 °C. Furthermore, the Avrami theory was used to describe the isothermal crystallization kinetics of PLA/TMC328 samples. It is confirmed that TMC328 showed a significant heterogeneous nucleation effect on the crystallization of PLA matrix. Moreover, XRD measurement indicates that TMC328 is a kind of α-form nucleating agent for PLA.

scholarly journals Investigation of Polyetherimide Melt-Extruded Fibers Modified by Carbon Nanoparticles

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7251
Author(s):  
Elena Ivan’kova ◽  
Gleb Vaganov ◽  
Andrey Didenko ◽  
Elena Popova ◽  
Vladimir Elokhovskiy ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Fiber Direction ◽  
Scanning Calorimetry ◽  
Orientation Degree ◽  
X Ray ◽  
Orientational Drawing ◽  
X Ray Scattering ◽  
Carbon Nanofiller

The fibers based on thermoplastic partially crystalline polyetherimide R-BAPB modified by vapor grown carbon nanofibers (VGCF) were prepared by melt extrusion, exposed to orientational drawing, and crystallized. All of the samples were examined by scanning electron microscopy, X-ray scattering, and differential scanning calorimetry to study how the carbon nanofiller influences on the internal structure and crystallization behavior of the obtained R-BAPB fibers. The mechanical properties of the composite R-BAPB fibers were also determined. It was found that VGCF nanoparticles introduced into R-BAPB polyimide can act as a nucleating agent that leads, in turn, to significant changes in the composite fibers morphology as well as thermal and mechanical characteristics. VGCF are able to improve an orientation degree of the R-BAPB macromolecules along the fiber direction, accelerate crystallization rate of the polymer, and enhance the fiber stability during crystallization process.

Effect of Poly(D-Lactic Acid)-co-Polyethylene Glycol on the Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 283-289 ◽  
Author(s):  
Ployrawee Kaewlamyai ◽  
Amornrat Lertworasirikul
Keyword(s):  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Weight Ratio ◽  
Crystallization Rate ◽  
Heat Stability ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry

Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

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