scholarly journals Crystallization Morphology Regulation on Enhancing Heat Resistance of Polylactic Acid

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1563
Author(s):  
Yufei Liu ◽  
Siyuan Jiang ◽  
Wei Yan ◽  
Min He ◽  
Jun Qin ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Heat Resistance ◽  
Polylactic Acid ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
High Heat ◽  
Nucleating Agents ◽  
Test Results ◽  
X Ray Diffraction ◽  
Crystallization Morphology

To expand the use of polylactic acid (PLA) in high-temperature environments, crystallization morphology regulation was studied to enhance the heat resistance of PLA. PLA crystallinity was controlled using heat treatment and nucleating agent (zinc phenylphosphonate, brand TMC). The heat deflection temperatures of PLAs with same crystallinities considerably varied using different treatments. The crystallization morphology of PLA (4032D) and PLA/TMC composites was studied using X-ray diffraction (XRD) and polarized optical microscopy. XRD test results show that TMC can improve the crystallization rate and heat treatment can enhance the crystallinity and thickness of PLA, suggesting that the crystallization morphology improved after heat treatment. Nucleating agents can increase the crystallinity of PLA but cannot improve its crystallization morphology. The findings indicate that at the same crystallinity, PLAs exhibit improved crystallization morphology and high heat resistance; these results can provide guidance for improving the heat resistance of PLAs and facilitate the design of new nucleating agents.

Crystallization Behavior of PLA/PEG/Nucleating Agent Blends

2013 ◽  
Vol 807-809 ◽  
pp. 578-581 ◽  
Author(s):  
Jin Xu Dai ◽  
Qiang Yang ◽  
Bao Jian Liu
Keyword(s):  
Crystal Structure ◽  
Polyethylene Glycol ◽  
Crystallization Behavior ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystallization Ability ◽  
Co Precipitation

A series of PLA blends were prepared by solution co-precipitation of polylactide (PLA), polyethylene glycol (PEG) and different crystallization nucleating agents. The crystallization behavior of blends was investigated by differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The results showed that the crystallization ability of PLA blends was accelerated by plasticizer PEG, but the crystal structure of the obtained PLA blends was imperfect; the crystal structure and crystallization rate of the PLA blends were improved with the addition of nucleating agent, moreover, the crystallinity was 34.1% and 36.5%, respectively.

Polylactic Acid Bone Scaffolds Made by Heat Treatment

2012 ◽  
Vol 627 ◽  
pp. 751-755 ◽  
Author(s):  
Jia Horng Lin ◽  
Hsiu Ying Chung ◽  
Kun Da Wu ◽  
Shih Peng Wen ◽  
Chao Tsang Lu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tensile Strength ◽  
Polylactic Acid ◽  
Hollow Structure ◽  
Test Results ◽  
Widespread Application ◽  
Bone Scaffolds ◽  
Lower Porosity ◽  
Plied Yarn ◽  
Thermally Treated

Polylactic acid (PLA) has a widespread application, such as bone scaffolds, in biomedical field. This study creates PLA bone scaffolds, which has a structural stability, by using 150 denier (D) PLA plied yarn. 75 D PLA filaments are combined and then twisted into plied yarn. During the twisting process, the twists per inch (TPI) are varied. The resulting plied yarn undergoes heat treatment, and then is evaluated with mechanical property tests, determining an optimal TPI of 9. The plied yarn is then braided into PLA bone scaffolds. PLA bone scaffolds, thermally treated or not, are observed by a stereomicroscope and tested for porosity and tensile strength. According to test results, the optimal TPI is 9, which results from the optimal tensile strength. However, the variation in elongation of various 150 D plied yarn is not significant. When observed by a stereomicroscope, PLA bone scaffolds, which are thermally treated, have a compact filament arrangement. This is due to thermal bonding between filaments; in addition, the heat treatment duration is short, so the PLA filaments are not melted completely, resulting in a stable, hollow structure. According to porosity and tensile strength test, PLA bone scaffolds that are thermally treated exhibit a lower porosity and tensile strength due to the compact arrangement and tender phenomenon of the filaments. As a result, the optimal PLA bone scaffolds are made of 150 D plied with a TPI of 9, followed by a heat treatment at 165 °C for ten minutes.

N,N′-Bis(benzoyl) adipic acid dihydrazide and talc: nucleating agents for poly(l-lactic acid)

2016 ◽  
Vol 36 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Bai Xue ◽  
Dan Guo ◽  
Jianjun Bao
Keyword(s):  
Lactic Acid ◽  
Adipic Acid ◽  
Polymeric Composite ◽  
Weight Fraction ◽  
Nucleating Agent ◽  
High Heat ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Heat Distortion Temperature ◽  
Composite Samples

Abstract In this paper, high-heat-resistant polymeric composite products were prepared via the traditional melt blending process by incorporating N,N′-bis(benzoyl) adipic acid dihydrazide (BAAD) into poly(l-lactic acid) (PLLA), which acted as an organic nucleating agent. The heat distortion temperature (HDT) of the PLLA/BAAD composite samples was measured by an HDT apparatus, and a high value of 96.2°C was achieved at a BAAD loading fraction of 0.5 wt.%, whereas, at the same processing conditions, the HDT of PLLA/talc specimens reached a similar value at a talc content of 20 wt.%, which was much higher than the BAAD content. Differential scanning calorimetry and X-ray diffraction analyses were applied to determine the melting and crystallization behavior of the PLLA/BAAD blends. Polarized optical microscopy was used to observe the crystalline morphologies. Thermogravimetric analysis was employed to study the effect of BAAD on the thermal stability of PLLA. Measurement of the mechanical property confirmed that the addition of BAAD was beneficial to the enhancement of the mechanical properties of the resulting blends. However, the tensile strength of the PLLA/talc composites decreased with increasing weight fraction of talc.

scholarly journals Functionality of Cellulose Nanofiber as Bio-Based Nucleating Agent and Nano-Reinforcement Material to Enhance Crystallization and Mechanical Properties of Polylactic Acid Nanocomposite

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 389
Author(s):  
Siti Shazra Shazleen ◽  
Tengku Arisyah Tengku Yasim-Anuar ◽  
Nor Azowa Ibrahim ◽  
Mohd Ali Hassan ◽  
Hidayah Ariffin
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Cellulose Nanofibers ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Melt Processing ◽  
Dual Function ◽  
Biodegradable Material ◽  
Reinforcement Material ◽  
Single Use

Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA; nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1–6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min–1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min–1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young’s modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.

Effects of Temperature and Concentration on the Nano-Sized Hydroxyapatite Whisker Prepared by Chemical Precipitation Method

2007 ◽  
Vol 353-358 ◽  
pp. 2191-2194
Author(s):  
Yun Qiang Bai ◽  
Mu Sen Li ◽  
Yu Peng Lu ◽  
Ning Cao
Keyword(s):  
Heat Treatment ◽  
Raw Materials ◽  
Chemical Precipitation ◽  
Strength Test ◽  
Precipitation Method ◽  
Test Results ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Synthetic Temperature ◽  
Effects Of Temperature

Chemical precipitation is a popular method for the preparation of hydroxyapatite(Ca10 (PO4)6 (OH)2, HA) because of its simple operation. In this work, nano-sized HA whiskers were synthesized at various synthetic temperatures and concentration by chemical precipitation with Ca (NO3) 2·4H2O and (NH4) 2HPO4 as raw materials. Heat treatment was carried out after they were synthesized. The HA powders were analyzed by using X-ray diffraction (XRD), transmission electron microscope (TEM) and strength test in order to find the favorable growing condition for HA whiskers. The results show that the HA prepared at different synthetic temperatures show no impurity diffraction peak, indicating that they have a high purity. Prior to heat treatment, the crystallinity and length/diameter ratio of the HA whiskers become larger with the increasing of synthetic temperature. So a higher synthetic temperature can promote the growth of the HA whiskers. There is no obvious difference in crystallinity after the heat treatment. Besides, a lower reaction concentration can also promote the growth of HA whiskers. The strength test results show that the compressive strength of the HA prepared gets a maximum value at 50°C.

scholarly journals Effect of Composition on the Crystallization, Water Absorption, and Biodegradation of Poly(ε-caprolactam-co-ε-caprolactone) Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2488
Author(s):  
Yuanyuan Dou ◽  
Xinyu Mu ◽  
Yuting Chen ◽  
Zhenbo Ning ◽  
Zhihua Gan ◽  
...  
Keyword(s):  
Water Absorption ◽  
Crystallization Rate ◽  
Nucleating Agent ◽  
Melting Behavior ◽  
Feed Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Molar Feed Ratio ◽  
Anionic Copolymerization

Poly(ester amide)s have aroused extensive research interest due to the combination of the degradability of polyester and the higher mechanical properties of polyamide. In this work, a series of poly(ε-caprolactam-co-ε-caprolactone) (P(CLA-co-CLO)) copolymers with different compositions were synthesized by anionic copolymerization. The structure, crystallization behavior, water absorption, and biodegradation behavior of these copolymers were investigated by means of nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized optical micrographs (POM). The results indicated that the composition of P(CLA-co-CLO) copolymers can be adjusted by the molar feed ratio. The PCL blocks decreased the crystallization rate of PA6 blocks but had little effect on the melting behavior of PA6, while the crystallized PA6 acted as a heterogeneous nucleating agent and greatly improved the crystallization rate of PCL. Moreover, the introduction of PCL blocks greatly reduced the water absorption of P(CLA-co-CLO) copolymers and endow them a certain degree of degradability.

Nucleation Agent Choice of Li2O–Al2O3–SiO2 Glass Ceramic Having Ideal Micro Spherical Crystal Grains

2011 ◽  
Vol 311-313 ◽  
pp. 1332-1335
Author(s):  
Hao Lv ◽  
Yao Ming Ding ◽  
Ai Mei Liu ◽  
Ju Fang Tong ◽  
Xu Nong Yi ◽  
...  
Keyword(s):  
Glass Ceramic ◽  
Crystallization Behavior ◽  
Nucleating Agent ◽  
Nucleating Agents ◽  
X Ray Diffraction ◽  
Nucleation Agent ◽  
X Ray ◽  
Spherical Crystal ◽  
Crystal Grains ◽  
Scanning Electron

The nucleation and crystallization of Li2O-Al2O3-SiO2(LAS) glass ceramic with one(P2O5, TiO2, ZnF2) and two nucleating agents(P2O5+TiO2, P2O5+ZnF2) are investigated by the differential thermal analysis(DTA)，X-ray diffraction(XRD) and the scanning electron microscopy(SEM). Research results show that the LAS glass ceramic with nucleating agent of P2O5can obtain ideal micro spherical crystal grains and the crystallization behavior can be better controlled.

Morphology and thermal properties of clay based biocomposites

2018 ◽  
Vol 38 (8) ◽  
pp. 785-793 ◽  
Author(s):  
Leila Bounabi ◽  
Naima Bouslah Mokhnachi ◽  
Amar Djadoun ◽  
Nabila Haddadine ◽  
Regis Barille
Keyword(s):  
Crystallization Rate ◽  
Layered Silicate ◽  
Nucleating Agent ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
Low Weight ◽  
The Matrix ◽  
Poly Ethylene ◽  
Temperature Melting

Abstract Carboxymethylcellulose/poly(ethylene glycol) (CMC/PEG) blend and CMC/PEG/montmorillonite (MMT) nanocomposites were produced by the solvent casting method. The clay, a sodium MMT, was incorporated in the polymer matrix at low weight loadings (from 1 wt% to 7 wt%). The MMT dispersion in the matrix was evaluated by X-ray diffraction, which revealed an intercalated structure of the nanocomposites. Different levels of intercalation have been detected. The changes in morphology caused by the addition of layered silicate on CMC/PEG blend were investigated by scanning electron microscopy (SEM). The SEM images of CMC/PEG blend containing 5% of MMT displayed more homogenous morphology than CMC/PEG blend. The compatibilizing performance of the filler was investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The effect of the introduction of the clay on the crystallization temperature, melting temperature and crystallization degree of CMC/PEG revealed that clay behaved as a nucleating agent and enhanced the crystallization rate of PEG. Furthermore, it was demonstrated that the addition of a small percentage of montmorillonite (1%) was enough to improve the thermal stability of the nanocomposites.

Crystallization Kinetics and Heat Treatment Temperature on Microstructure of Na2O-CaO-P2O5-TiO2 Glass System

2018 ◽  
Vol 766 ◽  
pp. 151-156
Author(s):  
Pratthana Intawin ◽  
Sukum Eitssayeam ◽  
Gobwute Rujijanagul ◽  
Tawee Tunkasiri ◽  
Kamonpan Pengpat
Keyword(s):  
Heat Treatment ◽  
Crystallization Kinetics ◽  
Glass Ceramics ◽  
Crystallization Rate ◽  
High Heat ◽  
Treatment Temperature ◽  
Treatment Technique ◽  
Crystalline Phases ◽  
Thermal Analyzer ◽  
Quenching Method

Bioactive glass ceramics from Na2O-CaO-P2O5-TiO2 system have been fabricated by conventional melt quenching method. In order to change the fabricated glass to glass ceramic samples, a heat treatment technique was employed using temperatures ranging between 700 and 900°C for 2 h. Glass transition and crystallization temperature were analyzed via differential thermal analyzer (DTA). In addition, phase formation and microstructure of the glass-ceramics were also investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). From the crystallization kinetics, the crystallization rate constant (n) of the glass was found to be close to the value of 3, indicating the two-dimensional growth of crystals occurred in the glass ceramics. From the XRD results, the major crystalline phases were sodium titanium phosphate and calcium sodium phosphate along with titanium dioxide as the minor crystalline phases presented in high heat treatment temperatures (750-900°C) of the glass ceramics. SEM of the crystallized base glass Na2O-CaO-P2O5-TiO2 system, showed that crystallization of dendritic-like growths in the glass ceramics.

Preparation and characterization of poly(3-hydroxybutyrate)/ Cloisite25A nanocomposites

e-Polymers ◽  
2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Matko Erceg ◽  
Dražan Jozić
Keyword(s):  
Crystallization Rate ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Tg Analysis ◽  
Solution Intercalation ◽  
X Ray ◽  
Thermal Stability Of

Abstract Poly(3-hydroxybutyrate)/Cloisite25A (PHB/25A) nanocomposites were prepared by solution-intercalation method. The intercalation of PHB chains between the layers of Cloisite25A was observed by X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and non-isothermal thermogravimetry (TG) analysis were performed to study the thermal properties, crystallization and the thermal degradation of the prepared nanocomposites. DSC analysis indicates that Cloisite25A acts as a nucleating agent and increases the crystallization rate of PHB, but due to intercalation reduces its overall degree of crystallinity. TG analysis shows that addition of Cloisite25A enhances the thermal stability of PHB.

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