scholarly journals Biodegradable polyesters based on succinic acid

2003 ◽  
Vol 57 (11) ◽  
pp. 526-535
Author(s):  
Marija Nikolic ◽  
Dejan Poleti ◽  
Jasna Djonlagic
Keyword(s):  
Succinic Acid ◽  
Adipic Acid ◽  
Enzymatic Degradation ◽  
Degree Of Crystallinity ◽  
Candida Cylindracea ◽  
Candida Cylindracea Lipase ◽  
Unsaturated Polyesters ◽  
Melting Temperatures ◽  
Degradation Tests ◽  
The Degree Of Crystallinity

Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu)4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate), PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation was not enhanced suggesting that not only the chemical structure and molecular stiffness but also the morphology of the spherulites influenced the biodegradation properties.

scholarly journals The influence of antioxidant and post-synthetic treatment on the properties of biodegradable poly(butylene succinate)s modified with poly(propylene oxide)

2007 ◽  
Vol 72 (12) ◽  
pp. 1515-1531 ◽  
Author(s):  
Dragana Pepic ◽  
Marija Radoicic ◽  
Marija Nikolic ◽  
Jasna Djonlagic
Keyword(s):  
Molecular Weight ◽  
Propylene Oxide ◽  
Enzymatic Degradation ◽  
Surface Erosion ◽  
Candida Cylindracea ◽  
Butylene Succinate ◽  
Candida Cylindracea Lipase ◽  
Degradation Tests ◽  
Poly Propylene ◽  
The Impact

Novel poly(ester-ether)s based on poly(butylene succinate) (PBS) as the hard segments and 30 mass % of poly(propylene oxide) (PPO) as the soft segments were synthesized with varying amount of the antioxidant (N,N'-diphenyl-p-phenylenediamine, DPPD). The influences of the addition of DPPD and the impact of post-synthetic treatment by precipitation on the molecular structure, thermal and physical properties, as well as on the storage stability of the biodegradable aliphatic copolyesters, were investigated. The structure and composition of the copolymers were determined by means of 1H-NMR spectroscopy. The molecular weight and polydispersity of the poly(ester-ether)s were evaluated from solution viscosity and GPC measurements. The thermal properties and stability were evaluated, respecttively, by means of DSC and non-isothermal thermogravimetry in an inert nitrogen atmosphere. The biodegradability potential of the polymers was studied in hydrolytic and enzymatic degradation tests with Candida cylindracea lipase by monitoring the weight loss of polymer films after incubation. The weight losses of the samples increased with time and were in the range from 1 to 5 mass % after 4 weeks. GPC analysis confirmed that there were changes in the molecular weight of the copolyesters during both hydrolytic and enzymatic degradation tests, leading to the conclusion that the degradation mechanism of poly(butylene succinate)s modified with PPO occurred through surface erosion and bulk degradation.

scholarly journals Impact of environmental agents on non-woven polylactide/natural rubber agrofiber

2021 ◽  
Vol 285 ◽  
pp. 07034
Author(s):  
Yulia Tertyshnaya ◽  
Maksim Zakharov ◽  
Alina Ivanitskikh ◽  
Anatoliy Popov
Keyword(s):  
Natural Rubber ◽  
Uv Irradiation ◽  
Thermal Characteristics ◽  
Degree Of Crystallinity ◽  
Distilled Water ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Environmental Agents ◽  
The Degree Of Crystallinity

In the work an eco-friendly non-woven fiber made of polylactide and natural rubber with a rubber content from 0 to 15 wt.% was obtained by electrospinning. The influence of distilled water and UV irradiation on the agrofibers has been investigated. The water sorption test showed that the addition of natural rubber into the polylactide matrix does not significantly affect the degree of water absorption of the fibrous materials, which is in the range of 49-50.6%. Thermal characteristics after 180 days of degradation in distilled water at 22±2 oC and UV irradiation at a wavelength of 365 nm during 100 hours were determined using the differential scanning calorimetry. Changes in the values for glass transition and melting temperatures, and the degree of crystallinity were determined.

Thermodynamics of Shrinkage of Fibrous (Racked) Rubber

1958 ◽  
Vol 31 (3) ◽  
pp. 485-498
Author(s):  
J. F. M. Oth ◽  
P. J. Flory
Keyword(s):  
Tensile Force ◽  
The Other ◽  
Degree Of Crystallinity ◽  
Melting Point Depression ◽  
Heat Of Fusion ◽  
Γ Radiation ◽  
Melting Temperatures ◽  
The Degree Of Crystallinity ◽  
Heat Of Transformation

Abstract Highly oriented natural rubber samples of Roberts and Mandelkern, prepared by racking and subsequently crosslinked using γ-radiation, undergo a spontaneous shrinkage upon melting which closely resembles the shrinkage of collagen. If the transformation is arrested by application of a tensile force, a state of equilibrium may be established between two distinct zones, or phases, one being totally amorphous (shrunken) and the other unchanged (i.e., racked). Determination of the stress τeq required for phase equilibrium at various temperatures is described. Extrapolation to τeq=0 gives equilibrium melting temperatures Tmi, which are about 8° below the temperatures Tsi for spontaneous shrinkage. The heat of transformation of racked to amorphous rubber calculated from the dependence of τeq on T is 4.5 cal g−1. Since the degree of crystallinity is only 0.24, the heat of fusion calculated for 1 g of crystalline rubber is ca. 19 cal, which agrees satisfactorily with the value 15.3 cal, deduced by Roberts and Mandelkern through use of the melting point depression method. The shrinkage of racked rubber displays all of the important features associated with the similar contraction of fibrous proteins.

Enzymatic Degradation of Polyester-Nanoparticles by Lipases and Adsorption of Lipases on the Polyester-Nanoparticles

2011 ◽  
Vol 418-420 ◽  
pp. 2302-2307 ◽  
Author(s):  
Meng Meng Ma ◽  
Lian Yuan Wang ◽  
Hai Yan Zhu
Keyword(s):  
Enzymatic Degradation ◽  
Polybutylene Terephthalate ◽  
Candida Cylindracea ◽  
Experimental Conditions ◽  
Langmuir Isotherms ◽  
Degradation Tests ◽  
Pseudomonas Species ◽  
Different Types ◽  
Degradable Polyesters ◽  
Fast Kinetic

Enzymatic degradation tests of polymer in form of nanoparticle (NP) were used to study the biodegradation of two different types of polymers polytetramethylene adipitate (SP4/6) and polybutylene isophthalate (PBI) by two commercially available lipases. The two lipases, which are from the yeast Candida cylindracea (CcL) and Pseudomonas species (PsL) respectively, exhibited sufficient degradation activities both for the aliphatic model polyester SP4/6 and the aromatic model polyester PBI and the use of polyester NPs has dramatically shortened the duration of enzymatic degradation tests. It has also been noticed that the degradation percentage of the polyesters was in the range of 35-50%, probably due to the formation of low molecular weight intermediates that are not accessible to the enzymes. Since biodegradation of polymers is a surface process, the adsorption of lipases on the surface of polyester NPs may play an important role. In order to gain some insights into the adsorption process of enzymes on polymer NPs, the adsorption of CcL and PsL lipases on two hardly degradable polyesters polybutylene terephthalate (PBT) and polyethylene terephthalate (PET) was investigated in this work. The adsorption of lipases on these polyester NPs showed a fast kinetic. Langmuir isotherms were found to be generally suitable to describe the adsorption of lipases on polyester NPs, especially at low lipase concentration under the experimental conditions. However, significant derivations from Langmuir isotherms were observed at high lipase concentrations.

Thermal Crystallization of Polytetrahydrofuran Networks

1991 ◽  
Vol 64 (1) ◽  
pp. 74-82 ◽  
Author(s):  
C. Michael Roland ◽  
Gary S. Buckley
Keyword(s):  
Melting Point ◽  
Crystallization Behavior ◽  
Degree Of Crystallinity ◽  
Melting Point Depression ◽  
Network Architectures ◽  
Experimental Conditions ◽  
Thermal Crystallization ◽  
Melting Temperatures ◽  
Equilibrium Melting Point ◽  
The Degree Of Crystallinity

Abstract The formation of a network in PTHF inhibits the crystallization of chain units in proximity to the crosslinks. From melting-point-depression measurements, it is estimated that the suppression in crystallizability extends to as much as 8 chain units away from a network junction. This estimate is consistent with the degree of crystallinity measured in various crosslinked PTHF rubbers. The equilibrium melting point for linear PTHF was determined to be 361°K. Although this is significantly higher than previously reported values, the present result is congruent with the melting temperatures measured for crosslinked PTHF, and its use leads to satisfactory predictions of their melting-point depression. The distribution in the lengths of network chains exerted a trivial influence on thermal crystallization behavior. Although this distribution must in principle influence crystallization behavior in so far as it governs crystallizable sequence lengths, differences between uni- and bi-modal network architectures were moderate under the present experimental conditions.

scholarly journals Estimation of the Age of Architectural Heritage Objects by Microstructural Changes of Calcite in Lime Mortars of Ancient Brickwork and Masonry

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 240
Author(s):  
Vladimir Kotlyar ◽  
Victoria Pishchulina ◽  
Alexey N. Beskopylny ◽  
Besarion Meskhi ◽  
Yury Popov ◽  
...  
Keyword(s):  
18Th Century ◽  
Degree Of Crystallinity ◽  
Architectural Heritage ◽  
Natural Conditions ◽  
Relative Age ◽  
Lime Mortars ◽  
Powder Samples ◽  
Diffraction Patterns ◽  
Cultural Monuments ◽  
The Degree Of Crystallinity

Determining the age of ancient architectural and cultural monuments is a significant scientific problem. An approach based on the transformation of portlandite into calcite and subsequent recrystallization of calcite is considered, which allows for estimating the relative age of ancient brickworks for local groups of historic buildings based on the results of diffraction studies of powder samples of carbonate mortars and measurements of samples with a known age. This article presents the results of the study of lime mortars of ancient brickwork. Under natural conditions, the process of transformation of portlandite into calcite takes from 100 to 200 years. The rate of this process is influenced by temperature, humidity, peculiarities of interaction with carbon dioxide contained in the air, etc. Examples show that portlandite is completely transformed into calcite in masonry mortars of the 18th century and that portlandite is not found in older mortars. It was determined that after the transformation of portlandite into calcite, an increase in the degree of recrystallization of calcite is observed, which manifests itself in powder diffraction patterns in the relative broadening of the diffraction peak of calcite hkl 104. In a detailed study, an estimate of the peak width at half maximum (FWHM) associated with the degree of crystallinity is effective. The actual data are given, which show that in older lime mortars the degree of recrystallization of calcite is higher than in younger ones. This fact makes it possible to indirectly determine the relative age of brickwork and masonry of various buildings of architectural heritage, which is especially relevant for the objects with the use of lime mortars of the northern provinces of the Byzantine Oecumene and other periods of various cultures.

scholarly journals Preparation and Characterization of Talc Filled Thermoplastic Polyurethane/Polypropylene Blends

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emi Govorčin Bajsić ◽  
Vesna Rek ◽  
Ivana Ćosić
Keyword(s):  
Thermal Properties ◽  
Thermoplastic Polyurethane ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Polypropylene Blends ◽  
Pp Blends ◽  
The Degree Of Crystallinity ◽  
Better Than

The effect of the addition of talc on the morphology and thermal properties of blends of thermoplastic polyurethane (TPU) and polypropylene (PP) was investigated. The blends of TPU and PP are incompatible because of large differences in polarities between the nonpolar crystalline PP and polar TPU and high interfacial tensions. The interaction between TPU and PP can be improved by using talc as reinforcing filler. The morphology was observed by means of scanning electron microscopy (SEM). The thermal properties of the neat polymers and unfilled and talc filled TPU/PP blends were studied by using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The addition of talc in TPU/PP blends improved miscibility in all investigated TPU/T/PP blends. The DSC results for talc filled TPU/PP blends show that the degree of crystallinity increased, which is due to the nucleating effect induced by talc particles. The reason for the increased storage modulus of blends with the incorporation of talc is due to the improved interface between polymers and filler. According to TGA results, the addition of talc enhanced thermal stability. The homogeneity of the talc filled TPU/PP blends is better than unfilled TPU/PP blends.

The Influence of the Degree of Crystallinity on the Glass Transition Temperature of Polymers

2013 ◽  
Vol 864-867 ◽  
pp. 751-754 ◽  
Author(s):  
Andrey Askadskii ◽  
Marina Popova ◽  
Tatyana Matseevich ◽  
Elena Kurskaya
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Degree Of Crystallinity ◽  
Low Degrees ◽  
The Degree Of Crystallinity

The influence of the degree of crystallinity of polymers on the glass transition temperature Tg of their amorphous domains is quantitatively analyzed. The analysis is made based on the Mandelkerns ideas [ concerning the restrictive effect of crystallization on the mobility of macromolecules within the amorphous domains. At low degrees of crystallinity, Tg of amorphous domains slowly increases, and then increases much faster at high degrees of crystallinity.

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