Degradation Behaviors of β-TCP/PLGA Composites Prepared with Microwave Energy

2007 ◽  
Vol 342-343 ◽  
pp. 205-208 ◽  
Author(s):  
Hong Chae Park ◽  
Hyeong Ho Jin ◽  
Yong Taek Hyun ◽  
Won Ki Lee ◽  
Seog Young Yoon
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Morphological Changes ◽  
Microwave Energy ◽  
Degradation Behavior ◽  
Soaking Time ◽  
Biodegradable Scaffolds ◽  
Degradation Behaviors ◽  
Sbf Solution

The β-tricalcium phosphate (β-TCP)/ poly(lactide-co-glycolide) (PLGA) composites for biodegradable scaffolds in bone tissue engineering were synthesized by in situ polymerization with microwave energy. The degradation behavior of β-TCP/PLGA composite was investigated by soaking in simulated body fluid (SBF) for 4 weeks. The molecular weight of the β-TCP/PLGA composites decreased with soaking time until week 2, whereas the loss rate of molecular weight reduced after week 2. The incubation time was needed for the degradation of the β-TCP, indicating that the β-TCP should be detached from the PLGA matrix and then degraded into SBF solution. The studies of mass loss of the composites with the soaking time revealed that the degradation behavior of PLGA would be processed with the transformation from the polymer to the oligomer followed by the degradation. Morphological changes, whisker-like, due to transformation and degradation of polymer in the composites were observed after week 2. On the basis of the results, it found that the degradation behavior of β-TCP/PLGA composites was influenced by the β-TCP content in the composite and the degradation rate of the composite could be controlled by the initial molecular weight of PLGA in the composite.

Synthesis of Biodegradable β-TCP/PLGA Composites Using Microwave Energy

2006 ◽  
Vol 510-511 ◽  
pp. 758-761 ◽  
Author(s):  
Hyeong Ho Jin ◽  
Sang Ho Min ◽  
Kyu Hong Hwang ◽  
Ik Min Park ◽  
Hong Chae Park ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Young’S Modulus ◽  
Tricalcium Phosphate ◽  
Bending Strength ◽  
In Situ Polymerization ◽  
Young's Modulus ◽  
Microwave Energy ◽  
Microstructure And Mechanical Properties

Biodegradable β-tricalcium phosphate (β-TCP)/poly (lactide-co-glycolide) (PLGA) composites were synthesized by in situ polymerization with microwave energy. The influence of the β-TCP content in β-TCP/PLGA composites on the molecular weight, crystallinity, microstructure, and mechanical properties was investigated. As the molecular weight of composites decreased, the β-TCP content increased up to 10 wt%, while further raising of the β-TCP content above 10%, the molecular weight increased with increasing β-TCP content. This behavior may be ascribed to the superheating effect or nonthermal effect induced by microwave energy. It was found that the bending strength and Young’s modulus of the β-TCP/PLGA composites were proportional to the molecular weight of PLGA. The bending strength of the β-TCP/PLGA composites ranged from 18 to 38 MPa, while Young’s modulus was in the range from 2 to 6 GPa.

Preparation and Properties of the Polystyrene/Alumina Nanocomposites

2012 ◽  
Vol 557-559 ◽  
pp. 519-522
Author(s):  
Xu Man Wang ◽  
Cai Ning Zhang
Keyword(s):  
Molecular Weight ◽  
Thermal Resistance ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
In Situ Polymerization ◽  
Average Molecular Weight ◽  
Experimental Results ◽  
Solvent Resistance ◽  
Silane Coupling

Silane coupling agent KH-570 was applied to modify the surface capability of the alumina (Al2O3). The modified Al2O3were dispersed in styrene. The in-situ polymerization was used to prepare the polystyrene/alumina (PS/Al2O3) composites, in which azodiisobutyronitrile (AIBN) was used as initiator. FTIR, DSC and TG were applied to characterize the prepared composites. The solvent resistance, thermal resistance of the composites and the average molecular weight of PS in PS/Al2O3nanocomposites were studied. The experimental results demonstrated that the solvent resistance of PS/Al2O3nanocomposites was improved by the adding of Al2O3nanoparticles. The thermal resistance of the composites increased with the increasing of the Al2O3content. Meanwhile, the molecular weight of PS in the composites increased with the increasing of the Al2O3content.

A study on the kinetics and thermal properties of polystyrene/diatomite nanocomposites prepared via in situ ATRP

2018 ◽  
Vol 33 (2) ◽  
pp. 180-197 ◽  
Author(s):  
Khezrollah Khezri ◽  
Yousef Fazli
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Structural Characteristics ◽  
Nitrogen Adsorption ◽  
Linear Increase ◽  
Size Exclusion ◽  
Scanning Calorimetry ◽  
Morphological Studies ◽  
Exclusion Chromatography

Pristine mesoporous diatomite was employed to prepare polystyrene/diatomite composites. Diatomite platelets were used for in situ polymerization of styrene by atom transfer radical polymerization to synthesize tailor-made polystyrene nanocomposites. X-Ray fluorescence spectrometer analysis and thermogravimetric analysis (TGA) were employed for evaluating some inherent properties of pristine diatomite platelets. Nitrogen adsorption/desorption isotherm is applied to examine surface area and structural characteristics of the diatomite platelets. Evaluation of pore size distribution and morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight determinations were carried out using gas and size exclusion chromatography, respectively. Linear increase of ln ( M0/M) with time for all the samples shows that polymerization proceeds in a living manner. Addition of 3 wt% pristine mesoporous diatomite leads to an increase of conversion from 72% to 89%. Molecular weight of polystyrene chains increases from 11,326 g mol−1 to 14134 g mol−1 with the addition of 3 wt% pristine mesoporous diatomite; however, polydispersity index values increases from 1.13 to 1.38. Increasing thermal stability of the nanocomposites is demonstrated by TGA. Differential scanning calorimetry shows an increase in glass transition temperature from 81.9°C to 87.1°C by adding 3 wt% of mesoporous diatomite platelets.

scholarly journals Multi Self-Healable UV Shielding Polyurethane/CeO2 Protective Coating: The Effect of Low-Molecular-Weight Polyols

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1947
Author(s):  
Mohammad Mizanur Rahman ◽  
Rami Suleiman ◽  
Md. Hasan Zahir ◽  
Aasif Helal ◽  
A. Madhan Kumar ◽  
...  
Keyword(s):  
Molecular Weight ◽  
In Situ Polymerization ◽  
Outdoor Exposure ◽  
Low Molecular Weight ◽  
Self Healing ◽  
Polydimethyl Siloxane ◽  
Molecular Weights ◽  
Uv Shielding ◽  
Ceo2 Coating

We prepared a series of polyurethane (PU) coatings with defined contents using poly(tetramethylene oxide)glycol (PTMG) with two different molecular weights (i.e., Mn = 2000 and 650), as well as polydimethyl siloxane (PDMS) with a molecular weight of Mn 550. For every coating, maximum adhesive strength and excellent self-healing character (three times) were found using 6.775 mol% mixed with low-molecular-weight-based polyols (PU-11-3-3). Defined 1.0 wt% CeO2 was also used for the PU-11-3-3 coating (i.e., PU-11-3-3-CeO2) to obtain UV shielding properties. Both the in situ polymerization and blending processes were separately applied during the preparation of the PU-11-3-3-CeO2 coating dispersion. The in situ polymerization-based coating (i.e., PU-11-3-3-CeO2-P) showed similar self-healing properties. The PU-11-3-3-CeO2-P coating also showed excellent UV shielding in real outdoor exposure conditions.

PE/Clay Nanocomposite with Bimodal Molecular Weight Distribution Produced Via In-Situ Polymerization

2013 ◽  
Vol 24 (2) ◽  
pp. 416-423 ◽  
Author(s):  
Sadegh Abedi ◽  
Majid Abdouss ◽  
Majid Daftari-Besheli ◽  
Ali Moghimi ◽  
Seyed Mehdi Ghafelehbashi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
In Situ Polymerization

scholarly journals In-Situ Polymerization of High-Molecular Weight Nylon 66 Modified Clay Nanocomposites with Low Apparent Viscosity

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 510 ◽  
Author(s):  
Xiaochao Duan ◽  
Yanpeng Wu ◽  
Zhao Chen ◽  
Tonghui Yang ◽  
Yongchang Cheng ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cross Sections ◽  
Apparent Viscosity ◽  
In Situ Polymerization ◽  
Ammonium Bromide ◽  
Nylon 66 ◽  
Modified Clay ◽  
Viscosity Reducer

High-molecular weight nylon 66/modified clay (Mclay) nanocomposites with a low apparent viscosity were prepared by in-situ polymerization and post solid-state polycondensation. Thermogravimetric analysis and X-ray diffraction patterns of the Mclay revealed that cetyltrimethyl ammonium bromide successfully inserted into the interlayers of the clay. Scanning electron microscope images of the cross sections showed that the Mclay was well-dispersed in the nylon 66 matrix. The effects of clay on the mechanical, rheological, and thermal properties of the nanocomposites were investigated using an Instron 5969 machine, a capillary rheometer, and a differential scanning calorimeter. The results indicated that the incorporation of a very small amount of Mclay considerably decreased the shear viscosity of the nanocomposites and increased the melt index, acting as a viscosity reducer. More importantly, the mechanical properties and spinnability of the nylon 66/Mclay nanocomposites were not affected by the viscosity reducer.

Solution properties of polyaniline/carbon particle composites

2016 ◽  
Vol 36 (3) ◽  
pp. 299-307
Author(s):  
Huseyin Zengin ◽  
Erdal Bayir ◽  
Gulay Zengin
Keyword(s):  
Molecular Weight ◽  
Composite Material ◽  
Composite Materials ◽  
In Situ Polymerization ◽  
Carbon Particle ◽  
Conductive Polymer ◽  
Ionic Conductivities ◽  
Solution Properties ◽  
Different Temperatures

Abstract This study reports on the synthesis of polymer polyaniline, a conductive polymer by nature, and the preparation of polyaniline/carbon particle (PANI/CP) composites by in situ polymerization. The solution properties and conductivities in solution of synthesized PANI and PANI/CP materials were analyzed. The viscosity of PANI and PANI/CP composite materials in N-methylpyrrolidinone (NMP) solvent at different temperatures was measured to examine their behavior in solution. Initially, the viscosity-molecular weight of PANI polymer was measured and calculated to be 78,521. The viscosities of PANI and PANI/CP composite materials decreased as the temperature increased. However, the viscosities of PANI/CP composite materials increased as the percent CP content in the composites increased. The ionic conductivities and pH changes in NMP solvent, measured at different concentrations of PANI and PANI/CP composite materials, and prepared in different ratios, were measured to investigate their behavior in solution. The ionic conductivities of PANI/CP composite materials increased as the percent CP content in the composites increased. Changes in the pH of PANI/CP composite materials decreased as the percent CP content in the composites increased. The conductivity of PANI/10% CP composite material in solution was greater than that of neat PANI polymer in solution; this indicated that CPs in PANI/10% CP composite materials made important positive contributions to the conductivities.

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