Papers by Keyword: Degradability

Abstract: Polybutylene succinate (PBS) is a biodegradable polymer made from renewable resources and is therefore better suited for disposable products than recycled products. Nevertheless, PBS cannot be degraded in a timely manner (less than 180 days) to be claimed to be a compostable bioplastic. Corn silk is an agricultural waste material that degrades easily in the natural environment due to its small fibers. Therefore, this research aimed to study the degradability of PBS composites filled with corn silk flour (CSF) in small amounts of 5-15 phr and compared them with neat PBS by considering changes in mechanical properties. Corn silk was ground and treated by KMnO4 solution to improve compatibility before use. Both PBS and treated CSF were compounded using a two-roll mill and then shaped using an injection molding process. The obtained specimens deteriorated under natural soil burial and sunlight exposure conditions for 180 days. All specimens were evaluated through physical observation and various techniques to determine mechanical characteristics. The results indicate that the addition of CSF gave a slight improvement to the hardness, flexural strength, and modulus of the composites than those of neat PBS which increased with higher amounts of CSF. However, the impact strength of the composites was lower than that of neat PBS. For the degradability of PBS composites under soil burial condition, all mechanical properties obviously decreased with each increment of CSF content and the period, which revealed that the PBS/15 phr of CSF composites disintegrated within 60 days. Considering the results under the sunlight exposure condition, the CSF content insignificantly reduced the mechanical properties, indicating that the PBS/CSF composites can be preferentially degraded under the condition of soil burial since both PBS and CSF can be degraded by microbial enzymes in soil, whereas only PBS could be deteriorated in the UV exposure condition.

Abstract: Platelet-rich fibrin (PRF) was developed as a barrier membrane in periodontal regenerative therapy. It is known that PRF has a sustained released of growth factor and expected to facilitate the tissue regeneration. Since the PRF membranes have a rapid degradability (1-2 weeks), the regenerative therapy using a PRF membrane should be increased to reduce the degradability using a crosslinking agent which could provide resistance against enzymatic degradation. The aim of this study is to analyze the effect of 0.1% genipin as a crosslinking agent to degradability of PRF. PRF membranes were prepared from 20cc blood of healthy donors and immersed in 0.1% genipin solution as a test group and Phosphate Buffer Saline (PBS) solution as a control group for 2 hours and 72 hours. In order to evaluate degradability, the sample was subjected to 0.01% trypsin. Samples were weighed and the trypsin solution was refreshed every 24 hours. The difference weight represents enzymatic degradation. Degradation degree of sample PRF-crosslinked genipin 0.1% significantly decreased when it compared to the control group. Genipin reacts with primary amines in fibrin, performed a covalent coupling that improves the degradability resistance. This crosslink had to be effective to improve biomechanical properties of PRF as a membrane. This study demonstrated that 0.1% genipin as a crosslinking agent could reduce the degradation-degree of PRF.

Abstract: An optical active Acrylate end-functionalized poly (lactic acid) (DPLA) was synthesized via melt polycondensation, with lactic acid, polyalcohol and acrylic acid as raw materials. The prepolymer products in each process were characterized by FT-IR, ¹H-NMR. The curing PLA coating (CPLA) was prepared using optical active DPLA, reactive diluent and photoinitiator. Gel fraction, thermal stability and degradation properties of the UV curing PLA coating properties were evaluated. The results show that branched structure of hydroxyl-terminated poly (lactic acid) (OHPLA) is beneficial to increase acrylic end capping rate (Da), Da ois as high as 88%. The structure of prepolymer and the performance of the coating are adjusted by changing content of polyalcohol. After crosslinking modification, degradation rate of CPLA is reduced and CPLA has better thermal stability than the pure PLA.

Abstract: The present study describes degradable and temperature/ionic-strength responsive polyurethane (PU) microspheres fabricated using toluene diisocyanate, polycaprolactone, polyethylene glycol, 2, 2-hydroxymethyl-2-propionic acid and triethylamine for drug delivery.^[1] We studied the properties of Temperature-sensitive, Ionic strength effects on SR, Swelling-deswelling reversibility, In vitro degradation, the result showed that: when the increase in temperature between 20°C and 50°C, as well as the ionic strength at certain temperature tended to decrease SR. The swelling kinetics was also investigated showing the presence of good ability to change reversibly at different temperature. The degradable studies using phosphate buffer solvent revealing polymeric matrix easily be tuned by varying polycaprolactam (PCL) composition, thus matching specific requirements.

Abstract: In this paper, collagen modified polylactide (CPLA) was synthesized by means of graft modification, and its structure was confirmed by FTIR and FITC-labeled fluorescence spectra. The performance of CPLA was characterized with hydrophilicity test and degradability test. The results showed that collagen had successfully grafted on the polylactide (PLA) and the graft ratio of collagen on CPLA was about 5%. The water absorotion of CPLA was significantly higher than PLA and its hydrophilicity was better than PLA. Moreover, there was no obvious acid-catalyzed self-accelerating degradation behavior in the degradation process of CPLA. The results suggested that CPLA showed a great potential as particles for drug delivery.

Abstract: Through experimental study on industrial wastewater of NanFengRiHua by Anaerobic Biological Filter process (AF), AF was proved as an efficient treatment process for refractory industry wastewater. AF process can change molecular structure and improve the biodegradability of nonbiodegradable organic, so AF process has very good practical prospects

Abstract: Cellulose-graft-poly (L-lactide) (Cellulose-g-PLLA) was prepared in homogeneous conditions. The polymer was successfully synthesized via ring-opening polymerization (ROP) by using 4-dimethylaminopyridine (DMAP) as an organic catalyst in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl). The structure of the polymer was characterized by 1H NMR, FT-IR, TGA, WAXD and TEM. The TEM micropicture revealed that the morphology of polymer dissolved in DMSO is globular. Degradability of the polymers was evaluated by the soil burial test. From the correlation analysis, it was revealed that degradability decreased with a further increase of the extent of grafting.

Abstract: Photodegradable polyethylene films have attracted considerable interests in recently years for its environmental degradability. However, it would be a scientifically and technological challenging issue to assess the degradable process. In order to explore the effect of the photo sensitizer on natural environment degradation characteristics of photodegradable polyethylene film, we investigated the changes of the tensile strength and elongation at break of the PE film (as the control group) and the PE photodegradable film along with the time in the ambient conditions. Photodegradable PE films showed the greater decrement of the tensile strength and elongation at break than that of the control group after 90 days explosion in ambient conditions which indicated its excellent degradability. Thus, the photo sensitizer being used in the PE films could improve the degradability of the PE films in the ambient conditions to a great extent.

Abstract: Through inclusion of different polymer chains with different properties into polyurethane matrix, such as poly(ethylene glycol) (PEG), poly(ε-caprolactone) (PCL), poly(lactic acid) (PLA), or poly(tetramethylene oxide) (PTMG), degradable polyurethane foams (PUFs) with different molecular structure were prepared. Influences of molecular structure on PUF materials’ performance were studied systematically. When PEG, PCL, PLA, and PTMG serve as soft segment, PUFs’ storage modulus and glass transition temperature (Tg) of PUFs decrease with following order: PLA>PCL>PEG>PTMG (flexibility of PUFs varies oppositely). And degradability decreases according to following order: PEG>PLA>PCL>PTMG. With increasing content of PEG or PLA chains in PU matrix, mechanical performance of PUFs decrease gradually, but remains on the same order with conventional non-degradable PUFs. Through control on the contents of different kinds of polymer chains in soft segments of PUFs, fairly good degradability can be achieved, at whilst their basic mechanical performance is well guaranteed.

Abstract: The CaCO₃-polyethylene (PE) film was prepared by filling method, and the filling amount of calcium carbonate in film was 20%(w/w). The effects of natural weathering, ultraviolet light irradiation on the tensile strength, breaking elongation and molecular weight of the CaCO₃-PE film was investigated comparing with the photosensitizer-PE film. After being located in the open air for 30 d, the average tensile strength, average breaking elongation and the mean molecular weight of CaCO₃-PE film decreased 80.6%, 99.3% and 25.3%, respectively, as for the photosensitizer-PE film, the corresponding items decreased 18.8%, 45.0% and 11.7%, respectively. After ultraviolet light irradiation for 120 h, the average tensile strength of CaCO₃-PE film decreased 29.9%, the average tensile strength of the photosensitizer-PE film, however, increased 20.5%. The average breaking elongation of CaCO₃-PE film and photosensitizer-PE film decreased 97.3% and 84.1% respectively, the mean molecular weight of both films decreased 66.7% and 26.6% respectively. After covered by soil for 200 d, the weight loss of the CaCO₃-PE film and photosensitizer-PE was 2.15% and 0.22%, respectively. The results showed that the degradability of CaCO₃-PE film is superior to the photosensitizer-PE film.