ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Hydrolytic degradation of polyglycolic acid: Tensile strength and crystallinity study (1981)

Chu, C. C.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 26 (1981), S. 1727-1734

add to mindlist on the mindlist

Details

ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: The hydrolytic degradation of polyglycolic acid (PGA) was studied by examining the changes of tensile strength and the level of crystallinity of the suture material. It was found that the breaking stress decreased from 6.369 × 10-1 at 0 day to 3.97 × 10-3 Newton/Tex at 49 days. The sigmodial shape of the stress-strain curves gradually disappeared with increase in the duration of in vitra degradation. The endpoint titration method used to assess the degree of degradation beyond the period of measurable tensile strength showed that the percent of PGA degraded were 42, 56, and 70% at 49, 60, and 90 days, respectively. The level of crystallinity of PGA at various durations of degradation exhibited an initial increase in the degree of crystallinity from 40% at 0 day to an upper limit of 52% at 21 days, then gradual decrease to 23% at 90 days. This observation is essentially parallel to hydrolysis of cellulose and polyethylene terephthalate. The concept of microfibrillar structure of fibers provides the basis for the proposed degradation mechanism of PGA in vitro. It is believed that degradation proceeds through two main stages which are different in rate of degradation.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/app.1981.070260527

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Effects of enzymes and gamma irradiation on the tensile strength and morphology of poly(p-dioxanone) fibers (1984)

Williams, David F. ; Chu, C. C. ; Dwyer, J.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 29 (1984), S. 1865-1877

add to mindlist on the mindlist

Details

ISSN: 0021-8995

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: The objective of this study was to examine how and to what extent a new degradable polymeric fiber, poly(p-dioxanone), used as a surgical suture material, degrades in the presence of enzymes and after γ-irradiation. The degradation of the fiber was studied mechanically using an Instron and morphologically by SEM. Both esterase and trypsin enzymes and their corresponding buffer controls were used. The fibers were γ-irradiated at the dosages ranging from 0 to 20 Mrad, immersed in the solution for up to 70 days, and then removed for tensile strength and morphological examinations. It was found that γ-irradiation alone lowered the tensile strength of PDS fibers and made them more susceptible to hydrolysis. Esterase and trypsin did not accelerate the hydrolytic degradtion of this fiber to any significant level. Both γ-irradiation and enzymes influenced the gross morphological characteristic of PDS fibers when they were subjected to hydrolysis. The most important morphological observations were the formation of surface cracks and chips on the fibers and the subsequent peeling of the chips. Enzyme-treated PDS fibers exhibited similar morphological findings but the size of the chips was smaller. The morphological observations of PDS fibers were consistent with the tensile strength data.

Additional Material: 7 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/app.1984.070290537

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

An in-vitro study of the effect of buffer on the degradation of poly(glycolic acid) sutures (1981)

Chu, C. C.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 15 (1981), S. 19-27

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: The tensile strengths of poly(glycolic acid) (PGA) sutures immersed in buffered and unbuffered aqueous media were compared. The media used were an unbuffered physiological saline solution (pH = 5.0) and a phosphate-buffered physiological saline solution (pH = 7.4). PGA samples were immersed for various periods in each medium, and kept at 37 ± 1°C in a constant temperature oven. The tensile strengths of the specimens were tested immediately after removal from the medium. Stress-strain curves of the specimens were expressed in terms of the stress unit “tenacity,” commonly used in the study of fibrous polymers; it is an appropriate unit for materials of fibrous nature. These stress-strain curves were investigated as functions of buffering and duration of immersion. Degradation reduced the tensile strength of PGA more in the buffered saline solution than in the unbuffered. This higher rate of degradation in the buffered solution might be due to the presence of Na2HPO4, which removed the degradation products, shifted the reaction toward increased hydrolosis, and accelerated the loss of tensile strength in the PGA. A continuous decrease in the pH of the unbuffered solution supports this explanation. Tied-chain segments of macromolecules, a theory widely used in the study of mechanical strength of fibrous polymer may be the key to a comprehensive description of the degradation phenomenon of PGA.

Additional Material: 2 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jbm.820150106

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

The effect of pH on the in vitro degradation of poly(glycolide lactide) copolymer absorbable sutures (1982)

Chu, C. C.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 16 (1982), S. 117-124

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: The pH effect on the hydrolytic degradation of Polyglactin 910 copolymer was studied in terms of the tensile properties of the suture specimens. The use of a cord/yarn grip, newly designed specifically for fibrous materials, eliminated the grip-induced failure. Different degrees of hydrolytic degradation of this copolymer at 3 different pH levels were observed. The suture specimens exhibited the best retentions of breaking strength at the physiological pH of 7.44, while the specimens at pH = 10.09 showed the fastest loss of breaking strength. Thus, a maximum retention of tensile properties occurred around the pH level of 7.0, whereas smaller percentages of retention of tensile properties were observed at both acidic and strong alkaline solutions. This synthetic absorbable suture material exhibits the basic characteristic of hydrolysis which is catalyzed by both acid and base.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jbm.820160204

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

The effect of gamma irradiation on the enzymatic degradation of polyglycolic acid absorbable sutures (1983)

Chu, C. C. ; Williams, David F.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 17 (1983), S. 1029-1040

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: The purpose of the study was to examine the effect of γ irradiation on the enzymatic as well as the in vivo degradation of polyglycolic acid sutures. The sutures of size 2-0 were irradiated at dosage levels of 0-20 mrad. The three enzymes chosen for this study, were esterase, α-chymotrypsin, and trypsin. The irradiated sutures were both immersed in the enzyme solutions, their corresponding buffer controls, and implanted in inbred black-and-white hooded hister rats (Liverpool strain). The degradation of PGA sutures was determined mechanically. Among the three enzymes studied, esterase showed the highest enzymatic effect on the degradation of the unirradiated and irradiated PGA sutures. Trypsin's effect on PGA sutures was not observed until 20 mrad. The findings of trypsin demonstrated the hypothesis that synthetic high molecular weight polymers, which are initially resistant to enzymatic degradation, could become prone to enzymatic attack after altering their physical and chemical structures. Implanted PGA sutures maintained a similar or slightly higher mean tensile breaking strength in in vivo degradation compared to in vitro degradation (0.1M tris buffer of pH = 7.5); these degradation profiles suggest that PGA does not display similar behavior in in vivo and in vitro degradations. The magnitude of dissimilarity depends on the radiation dosage and on the duration of degradation, and is speculated to be attributable to the specific action of enzymes with respect to the con-figuration and chemical structure of the PGA sutures.

Additional Material: 4 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jbm.820170612

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

The in-vitro degradation of poly(glycolic acid) sutures - effect of pH (1981)

Chu, C. C.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 15 (1981), S. 795-804

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: Tensile strength of poly(glycolic acid) suture (PGA) of size 2-0 was examined as a function of three pH levels, 5.25,7.44, and 10.09 of the buffer. Cord and yarn grip was used to eliminate grip-induced failure of breaking strength tests. It was found that Dexon sutures degraded significantly faster in pH = 10.09 buffer than the other two lower pH buffers. There was no significant difference in degradation rate at pH = 5.25 and 7.44. At 7 days, PGA sutures lost almost half of its original tensile strength at pH = 10.09, while the same sutures still remained more than 95% of their original breaking strength at buffers of pH = 5.25 and 7.44. After 21 days, no trace of sutures could be detected in the buffer of pH = 10.09 while about 20% strength still remained in the buffers of pH = 7.44 and 5.25. Cage effect in the crystalline phase and pH dependent hydrogen bonding were introduced to explain the difference in degradation phenomenon of PGA at buffers of various pH.

Additional Material: 3 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jbm.820150604

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Electronic Resource

Scanning electron microscopic study of the hydrolytic degradation of poly(glycolic acid) suture (1982)

Chu, C. C. ; Campbell, N. D.

Hoboken, NJ : Wiley-Blackwell

Journal of Biomedical Materials Research 16 (1982), S. 417-430

add to mindlist on the mindlist

Details

ISSN: 0021-9304

Keywords: Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Medicine , Technology

Notes: This article reports the morphological observations on the surface changes of poly(glycolic acid) sutures which have been exposed to various dosages of γ irradiation (0, 2.5, 5.0, 10, 20, and 40 Mrad) and duration of immersion (0, 7, 14, 28, 48, 60, and 90 days) in a physiological saline buffer. The most important gross morphological characteristics of PGA suture hydrolytic degradation is the formation of surface cracks on the filaments. The regularity of the surface cracks increased with an increase in the γ irradiation and the duration of hydrolysis. Surface cracks were not observed in irradiated sutures that had not been subjected to hydrolytic degradation. The arrangement of the surface cracks, their orientation on the filaments, and the direction of crack propagation provide very useful information for depicting the mechanism of hydrolytic degradation in this class of fibrous material. The microfibrillar model of fiber structure has been used as the basis for the proposed degradation mechanism of PGA in vitro. It is believed that hydrolysis occurs initially in the amorphous regions sandwiched between two crystalline zones, as tie-chain segments, free chain ends, and chain folds in these regions degrade into fragments. As degradation proceeds, the size of the fragments reaches the stage at which they can be dissolved into the buffer medium. This dissolution removes the fragments from the amorphous regions, and surface cracks appeared.

Additional Material: 8 Ill.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1002/jbm.820160410

Permalink