scholarly journals Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1202
Author(s):  
Joanna Brzeska ◽  
Agnieszka Tercjak ◽  
Wanda Sikorska ◽  
Barbara Mendrek ◽  
Marek Kowalczuk ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Thermal Properties ◽  
Surface Morphology ◽  
Chemical Modification ◽  
Chemical Structure ◽  
Environmentally Friendly ◽  
Degradation Process ◽  
Cross Linking ◽  
Weight Changes

One of the methods of making traditional polymers more environmentally friendly is to modify them with natural materials or their biodegradable, synthetic equivalents. It was assumed that blends with polylactide (PLA), polysaccharides: chitosan (Ch) and starch (St) of branched polyurethane (PUR) based on synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) would degrade faster in the processes of hydrolysis and oxidation than pure PUR. For the sake of simplicity in the publication, all three modifiers: commercial PLA, Ch created by chemical modification of chitin and St are called bioadditives. The samples were incubated in a hydrolytic and oxidizing environment for 36 weeks and 11 weeks, respectively. The degradation process was assessed by observation of the chemical structure as well as the change in the mass of the samples, their molecular weight, surface morphology and thermal properties. It was found that the PUR samples with the highest amount of R,S-PHB and the lowest amount of polycaprolactone triol (PCLtriol) were degraded the most. Moreover, blending with St had the greatest impact on the susceptibility to degradation of PUR. However, the rate of weight loss of the samples was low, and after 36 weeks of incubation in the hydrolytic solution, it did not exceed 7% by weight. The weight loss of Ch and PLA blends was even smaller. However, a significant reduction in molecular weight, changes in morphology and changes in thermal properties indicated that the degradation of the samples should occur quickly after this time. Therefore, when using these polyurethanes and their blends, it should be taken into account that they should decompose slowly in their initial life. In summary, this process can be modified by changing the amount of R,S-PHB, the degree of cross-linking, and the type and amount of second blend component added (bioadditives).

Effects of Molecular Weight of Chitosan on the Biodegradability and Thermal Properties of Polybutylene Succinate/Chitosan Composites

2018 ◽  
Vol 775 ◽  
pp. 26-31
Author(s):  
Sukantika Manatsittipan ◽  
Kamonthip Kuttiyawong ◽  
Kazuo Ito ◽  
Sunan Tiptipakorn
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Thermal Properties ◽  
Water Absorption ◽  
Melting Temperature ◽  
Microbial Degradation ◽  
Decomposition Temperature ◽  
Molecular Weights ◽  
Significant Difference ◽  
Polybutylene Succinate

In this study, the biodegradability and thermal properties the composites of polybutylene succinate (PBS) and chitosan of different molecular weights (Mn = 104,105, and 106 Da) were prepared at chitosan contents of 0-10 wt%. After 10 days of microbial degradation, the results show that the amount of holes from degradation was increased with either decreasing Mn or increasing chitosan contents. However, the size of holes was increased with increasing Mn and chitosan contents. The results from Differential Scanning Calorimeter (DSC) present that the melting temperature (Tm) of PBS was decreased with increasing chitosan contents. Moreover, there was no significant difference between Tm of the composites with different Mn of chitosan. From the TGA thermograms, the decomposition temperature at 10% weight loss (Td10) was decreased with increasing chitosan contents. Moreover, the water absorption of PBS/chitosan composites was increased with increasing Mn and content of chitosan.

Performance of polylactide against UV irradiation: Synergism of an organic UV absorber with micron and nano-sized TiO2

2020 ◽  
Vol 54 (18) ◽  
pp. 2489-2504 ◽  
Author(s):  
Ulas Can ◽  
Cevdet Kaynak
Keyword(s):  
Weight Loss ◽  
Thermal Properties ◽  
Uv Irradiation ◽  
Chemical Structure ◽  
Mechanical And Thermal Properties ◽  
Screw Extruder ◽  
Melt Mixing ◽  
Uv Absorber ◽  
Fluorescent Lamps ◽  
Twin Screw

The main purpose of this study was to investigate mechanical and thermal performance of polylactide specimens against UV irradiation; first when only adding benzotriazole benzotriazole-based organic UV absorber (UVA), micro (200 nm) and nano (50 nm) sized titania (TiO2) particles alone, and then to reveal possible synergism when they are added together. Compounds were prepared by twin-screw extruder melt mixing, while the 2 mm thick specimens were shaped by compression molding. Specimens were exposed to UV irradiation under fluorescent lamps (UVB-313) with 0.50 W/m2 for the periods of 12 and 24 days. Changes in the performance of UV irradiated specimens were evaluated in terms of % weight loss, changes in color and chemical structure, including the decreases in the mechanical and thermal properties. Various tests and analysis revealed that synergistic benefits of using micro and nano TiO2 particles together with benzotriazole-type UVA were not only due to the effective stiffening, strengthening and toughening actions of titania particles, but also due to their very significant “UV screening” actions absorbing the photons of the UV irradiation, thus decreasing the degree of the detrimental photodegradation reactions leading to chain scissions in their PLA matrix.

Nano- and Micro-Structural Evolution of UHMWPE by Ion Beam

2007 ◽  
Vol 1020 ◽  
Author(s):  
F. Calzzani ◽  
B. Chhay ◽  
R. Zimmerman ◽  
A. Oztarhan ◽  
D. Ila
Keyword(s):  
Molecular Weight ◽  
Surface Morphology ◽  
High Molecular Weight ◽  
Chemical Structure ◽  
Ion Beam ◽  
Aerospace Industry ◽  
Structural Evolution ◽  
Before And After ◽  
Polyethylene Devices ◽  
Ultra High Molecular Weight

AbstractIt is important to produce uniform nano-patterns with no possibility of surface exfoliation on polyethylene devices used in medical and in aerospace industry. We studied the change in the surface morphology of polyethylene at nanoscale using MeV ion beam. We have investigated the change in the surface morphology before and after ion bombardment. We have made an attempt to change the morphology to produce a uniform surface with reduced cracks and reduced granularity. For this process we have chosen ultra-high-molecular-weight polyethylene (UHMWPE). Coupons of these materials were exposed to various fluences of MeV Ag+ ions. The surface morphology and the change in the chemical structure were studied using scanning micro Raman, FTIR and AFM.

scholarly journals Fabrication of Novel Ball-Like Polystyrene Films Containing Schiff Base Microspheres as Photostabilizers

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1185 ◽  
Author(s):  
Emad Yousif ◽  
Dina Ahmed ◽  
Gamal El-Hiti ◽  
Mohammad Alotaibi ◽  
Hassan Hashim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Schiff Base ◽  
Surface Morphology ◽  
Ultraviolet Light ◽  
Schiff Bases ◽  
Infrared Spectra ◽  
Ultraviolet Irradiation ◽  
Weight Reduction ◽  
Casting Method

Polystyrene films containing a low concentration of three highly aromatic Schiff bases were prepared using the casting method. The polystyrene films were irradiated with ultraviolet light (300 h). The polystyrene infrared spectra, weight loss, molecular weight reduction and the surface morphology were examined upon irradiation. The Schiff bases acted as photostabilizers and reduced the photodegradation of polystyrene films to a significant level in comparison to the blank film. The images recorded of the surface of the miscible polystyrene/Schiff base blends showed novel ball-like microspheres with a diameter of 3.4–4.3 µm. The Schiff bases were able to endow excellent protection to polystyrene against ultraviolet irradiation.

scholarly journals Seawater degradation of PLA accelerated by water-soluble PVA

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 759-772
Author(s):  
Dan Huang ◽  
Zhi-De Hu ◽  
Tian-Yuan Liu ◽  
Bo Lu ◽  
Zhi-Chao Zhen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Polyvinyl Alcohol ◽  
Early Stage ◽  
Degradation Process ◽  
Water Soluble ◽  
Natural Seawater ◽  
Rapid Dissolution ◽  
Degradation Test ◽  
Degree Of Degradation

AbstractIn order to promote the degradation of PLA in seawater, a series of seawater-degradable polyester blends PVA/PLA were prepared by blending biodegradable polylactic acid (PLA) with water-soluble modified polyvinyl alcohol (PVA) in this paper. ADR 4370S was introduced to bring a certain degree of improvement in compatibility of PVA/PLA blends. The results of degradation test in natural seawater for 180 days show that the weight loss of PVA/PLA blends in seawater is much higher compared with that of pure PLA. PVA can be used as an effective hydrolysis accelerator for PLA matrix, helping to significantly reduce the molecular weight of PLA. The channels caused by dissolution/swelling of PVA facilitate the entry of water and microorganisms into the materials to contact with PLA, thereby promoting the degradation process of PLA matrix itself. Thus, both dissolution/swelling of PVA and degradation of PLA occur in PVA/PLA blends, and the degree of rapid dissolution of PVA in the early stage determines the degree of degradation of PLA.

scholarly journals Spruce Bark-Extracted Lignin and Tannin-Based Bioresin-Adhesives: Effect of Curing Temperatures on the Thermal Properties of the Resins

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3523
Author(s):  
Sunanda Sain ◽  
Leonidas Matsakas ◽  
Ulrika Rova ◽  
Paul Christakopoulos ◽  
Tommy Öman ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
High Temperature ◽  
Chemical Structure ◽  
Hot Water ◽  
Cross Linking ◽  
Compression Moulding ◽  
Hot Water Extraction ◽  
Spruce Bark ◽  
Modified Lignin

In this study, formaldehyde-free bioresin adhesives were synthesised from lignin and tannin, which were obtained from softwood bark. The extraction was done via organosolv treatment and hot water extraction, respectively. A non-volatile, non-toxic aldehyde, glyoxal, was used as a substitute for formaldehyde in order to modify the chemical structure of both the lignin and tannin. The glyoxal modification reaction was confirmed by ATR–FTIR spectroscopy. Three different resin formulations were prepared using modified lignin along with the modified tannin. The thermal properties of the modified lignin, tannin, and the bioresins were assessed by DSC and TGA. When the bioresins were cured at a high temperature (200 ℃) by compression moulding, they exhibited higher thermal stability as well as an enhanced degree of cross-linking compared to the low temperature-cured bioresins. The thermal properties of the resins were strongly affected by the compositions of the resins as well as the curing temperatures.

scholarly journals Effect of Ultraviolet Irradiation on Polystyrene Containing Cephalexin Schiff Bases

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2982
Author(s):  
Anaheed A. Yaseen ◽  
Emaad T. B. Al‐Tikrity ◽  
Emad Yousif ◽  
Dina S. Ahmed ◽  
Benson M. Kariuki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Surface Morphology ◽  
Carbonyl Group ◽  
Schiff Bases ◽  
Infrared Spectra ◽  
Ultraviolet Irradiation ◽  
Recent Past ◽  
Polystyrene Waste ◽  
High Yields

The scale of production of polystyrene has escalated in the recent past in order to meet growing demand. As a result, a large quantity of polystyrene waste continues to be generated along with associated health and environmental problems. One way to tackle such problems is to lengthen the lifetime of polystyrene, especially for outdoor applications. Our approach is the synthesis and application of new ultraviolet photostabilizers for polystyrene and this research is focused on four cephalexin Schiff bases. The reaction of cephalexin and 3-hydroxybenzaldehyde, 4-dimethylaminobenzaldehyde, 4-methoxybenzaldehyde, and 4-bromobanzaldehyde under acidic condition afforded the corresponding Schiff bases in high yields. The Schiff bases were characterized and their surfaces were examined. The Schiff bases were mixed with polystyrene to form homogenous blends and their effectiveness as photostabilizers was explored using different methods. The methods included monitoring the changes in the infrared spectra, weight loss, depression in molecular weight, and surface morphology on irradiation. In the presence of the Schiff bases, the formation of carbonyl group fragments, weight loss, and decrease in molecular weight of polystyrene were lower when compared with pure polystyrene. In addition, undesirable changes in the surface such as the appearance of dark spots, cracks, and roughness were minimal for irradiated polystyrene containing cephalexin Schiff bases. Mechanisms by which cephalexin Schiff bases stabilize polystyrene against photodegradation have also been suggested.

scholarly journals The Role of the Mechanical, Structural, and Thermal Properties of Poly(l-lactide-co-glycolide-co-trimethylene carbonate) in the Development of Rods with Aripiprazole

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3556
Author(s):  
Artur Turek ◽  
Jakub Rech ◽  
Aleksandra Borecka ◽  
Justyna Wilińska ◽  
Magdalena Kobielarz ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Thermal Properties ◽  
Pore Formation ◽  
Tensile Tests ◽  
Mechanical Tests ◽  
Lag Phase ◽  
Trimethylene Carbonate ◽  
Hot Melt

In this work, we aimed to determine the role of the mechanical, structural, and thermal properties of poly(l-lactide-co-glycolide-co-trimethylene carbonate) (P(l-LA:GA:TMC)) with shape memory in the formulation of implantable and biodegradable rods with aripiprazole (ARP). Hot melt extrusion (HME) and electron beam (EB) irradiation were applied in the formulation process of blank rods and rods with ARP. Rod degradation was carried out in a PBS solution. HPLC; NMR; DSC; compression and tensile tests; molecular weight (Mn); water uptake (WU); and weight loss (WL) analyses; and SEM were used in this study. HME and EB irradiation did not influence the structure of ARP. The mechanical tests indicated that the rods may be safely implanted using a pre-filled syringe. During degradation, no unfavorable changes in terpolymer content were observed. A decrease in the glass transition temperature and the Mn, and an increase in the WU and the WL were revealed. The loading of ARP and EB irradiation induced earlier pore formation and more intense WU and WL changes. ARP was released in a tri-phasic model with the lag phase; therefore, the proposed formulation may be administered as a delayed-release system. EB irradiation was found to accelerate ARP release.

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