Enzymatic processes for biodegradation of poly(hydroxyalkanoate)s crystals

2008 ◽  
Vol 86 (6) ◽  
pp. 471-483 ◽  
Author(s):  
Keiji Numata ◽  
Hideki Abe ◽  
Yoshiharu Doi
Keyword(s):  
Enzymatic Degradation ◽  
Crystal Surface ◽  
Heterogeneous Reaction ◽  
Degradation Mechanism ◽  
Polymeric Materials ◽  
Enzyme Adsorption ◽  
Buffer Solution ◽  
Lamellar Crystal ◽  
Pha Depolymerase ◽  
Degradation Rates

Poly(hydroxyalkanoate)s (PHAs) have attracted much attention as environmentally compatible polymeric materials that can be produced from renewable carbon resources. Biodegradation of PHA materials occurs by the function of extracellular PHA depolymerase secreted from microorganisms. Thus, elucidation of the enzymatic degradation mechanism for PHA materials is important to design PHA materials with desirable properties and controlled biodegradability. The solid PHA polymer is a water-insoluble substrate but PHA depolymerases are soluble in water. Therefore, the enzymatic degradation of PHA materials is a heterogeneous reaction on the material’s surface. Two distinct processes are involved during the degradation, namely, adsorption of the enzyme on the surface of PHA material and the subsequent hydrolysis of polymer chains. Atomic force microscopy (AFM) is a powerful tool that has been used for the quantitative analysis of PHA crystal degradation. AFM enables the characterization of the crystal surface nanostructure in a buffer solution. By using in-situ (real-time) AFM observations, we recently succeeded in observing the degradation processes of PHA crystals. Subsequently, we were also able to investigate the degradation rates of PHA crystals using the same technique. In this review, we have attempted to give an overview concerning the direct visualization of the adsorption, as well as the hydrolysis reactions of PHA depolymerases at the nanometer scale. In addition, we present other analytical techniques besides AFM as a complimentary approach to analyze the effect of enzyme adsorption on PHA crystals.Key words: poly(hydroxyalkanoate) (PHA), enzymatic degradation, lamellar crystal, PHA depolymerase.

Evaluation of Abrasive Wear of Polymeric Materials Using Single-Pass Pendulum Scratching

2002 ◽  
Author(s):  
Marcelo Torres Piza Paes ◽  
Antonio Marcos Rego Motta ◽  
Lauro Lemos Lontra Filho ◽  
Juliano Ose´ias de Morais ◽  
Sine´sio Domingues Franco
Keyword(s):  
Deep Water ◽  
Wear Mechanisms ◽  
Degradation Mechanism ◽  
Single Point ◽  
Polymeric Materials ◽  
Scratch Resistance ◽  
Wear Behaviour ◽  
Sediment Layer ◽  
Materials Used ◽  
Energy Dissipated

Scratching abrasion due to rubbing against the sediment layer is an important degradation mechanism of flexible cable in deep water oil and natural gas exploitation. The present study was initiated to gain relevant data on the wear behaviour of some commercial materials used to externally protect these cables. So, Comparison tests were carried out using the single-point scratching technique, which consists of a sharp point mounted at the extremity of a pendulum. The energy dissipated during the scratching is used to evaluate the relative scratch resistance. The results showed, that the contact geometry strongly affects the specific scratching energy. Using SEM imaging, it was found, that these changes were related to the operating wear mechanisms. The observed wear mechanisms are also compared with those observed on some cables in deep water operations.

scholarly journals Enzyme degradation mechanism of white rot fungi and its research progress on Refractory Wastewater

2021 ◽  
Vol 237 ◽  
pp. 01002
Author(s):  
ShiYuan Huang ◽  
Sheng Li ◽  
ZhenYu Wang ◽  
SenHuan Lin ◽  
Jian Deng
Keyword(s):  
Phenolic Compounds ◽  
Enzymatic Degradation ◽  
Enzyme System ◽  
Degradation Mechanism ◽  
White Rot Fungi ◽  
White Rot ◽  
Research Progress ◽  
Degrading Enzyme ◽  
Research Status ◽  
Enzyme Degradation

The lignin-degrading enzyme system of white rot fungi is highly efficient and non-specific, and can degrade a variety of pollutants, including dyes, phenolic compounds and pesticides.The article presents an overview of the mechanism of enzymatic degradation of white rot fungi and its research status in several refractory wastewater were described.

scholarly journals Synthesis, Characterization, and Biodegradation Studies of Poly(1,4-cyclohexanedimethylene-adipate-carbonate)s

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Ajay S. Chandure ◽  
Ganesh S. Bhusari ◽  
Suresh S. Umare
Keyword(s):  
Weight Loss ◽  
Enzymatic Degradation ◽  
Hydrolytic Degradation ◽  
Phosphate Buffer Solution ◽  
Film Surface ◽  
Solution Viscosity ◽  
Buffer Solution ◽  
Sem Images ◽  
Titanium Butoxide ◽  
Soil Burial

Aliphatic/alicyclic poly(1,4-cyclohexanedimethylene-adipate-carbonate)s (PCACs) were synthesized by a transesterification from 1,4-cyclohexamethylendimethanol (1,4-CHDM), adipic acid (AA), diethyl carbonate (DEC), and titanium butoxide Ti(OBu)4 as a transesterification catalyst. The synthesized PCACs were characterized by the Fourier transform infrared (FTIR), X-ray diffraction analysis (XRD), solubility, solution viscosity, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) for their structural, physical, thermal, and morphological investigation. The structure of synthesized PCACs was confirmed by FTIR. All TGA curves of PCACs shows 10% weight loss above 270°C, and they reveal good thermal stability. Biodegradability of PCACs was investigated by hydrolytic degradation at (pH 7.2 and 11.5), enzymatic degradation using Rhizopus delemar lips at 37°C in phosphate buffer solution (PBS), and soil burial degradation at 30°C. The hydrolytic degradation shows the greater rate of weight loss in PBS at pH-11.5 than pH-7.2. The hydrolytic and soil burial degradation shows faster rate of weight loss as compared to enzymatic degradation. Biodegradation rate of PCACs follows the order: PCAC-20 > PCAC-40 > PCAC-60. SEM images show that degradation occurred all over the film surface, creating holes and cracks. These biodegradable PCACs may be able to replace conventional polymer in the fabrication of packaging film in near future.

Production of a Brushite/Silk Composite Powder for Coatings

2019 ◽  
Vol 800 ◽  
pp. 75-79
Author(s):  
Sahin Altundal ◽  
Karlis Agris Gross
Keyword(s):  
Calcium Phosphate ◽  
Calcium Chloride ◽  
Composite Powder ◽  
Crystal Surface ◽  
Polymeric Materials ◽  
Hydrolysis Reaction ◽  
Precipitation Method ◽  
Absorption Bands ◽  
Β Sheets ◽  
Particle Attachment

The incorporation of protein based polymeric materials with calcium phosphate (CaP) coatings can provide excellent biological characteristics and biocompatibility with its bone-like protein-CaP composition. Calcium chloride-ethanol catalysed hydrolysis reaction and wet precipitation method was used to prepare silk solution and to precipitate brushite respectively to produce the brushite/silk composite powder. FTIR analyses showed that brushite absorption bands were prominent, overlapping the less intense N-H bands in silk. The most distinct absorptions from the silk were N-H bands. 1g of silk additive to the 300 ml of solution media resulted in arbitrary particle attachment onto brushite crystal surface; most of the brushite particles were covered by the silk β-sheets phase.

Degradation Behaviors of Biodegradable Aliphatic Polyesters and Polycarbonates

2020 ◽  
Vol 14 (2) ◽  
pp. 155-168 ◽  
Author(s):  
Yonghang Xu ◽  
Fangya Zhou ◽  
Danmin Zhou ◽  
Jintang Mo ◽  
Huawen Hu ◽  
...  
Keyword(s):  
Biodegradable Polymers ◽  
Degradation Mechanism ◽  
Polymeric Materials ◽  
Degradation Process ◽  
Biodegradable Plastics ◽  
Research Progress ◽  
Aliphatic Polyesters ◽  
Depth Study ◽  
Degradation Behaviors ◽  
And Control

Aliphatic polyesters and polycarbonates such as polylactide (PLA), polycaprolactone (PCL) and poly(propylene carbonate) (PPC), are well known as biodegradable, biocompatible and environmental-friendly polymeric materials, which have been widely used in various areas ranging from packaging to biomedical materials. The production and usage of biodegradable plastics can greatly alleviate the safety and environmental concerns because of the fairly short degradation periods and low toxicity of catabolite. During the degradation process of polymers, obvious changes appear in polymer structures and the physiochemical properties. Therefore, it is necessary to regulate and control the degradation behaviors and periods of biodegradable plastics such as polyesters and polycarbonates, which is significant for their more widespread popularization and applications. In this context, it is highly desirable to make a review contribution in this field so as to better understand the recent research progress on polymer degradation behaviors and kinetics, as well as the future prospect of biodegradable polymers. Herein, this paper reviews the research progress on the degradation behaviors of biodegradable polyesters and polycarbonates materials including PLA, PCL and PPC. Through an in-depth study of various internal/external factors, the degradation mechanism of these polymers is unraveled, which will motivate future studies into the synthesis of novel biodegradable polymers and the understanding of their degradation behavior on the molecular level.

scholarly journals Corrosion Behavior and Degradation Mechanism of Polymeric Materials

2002 ◽  
Vol 51 (12) ◽  
pp. 542-548
Author(s):  
Masatoshi Kubouchi
Keyword(s):  
Corrosion Behavior ◽  
Degradation Mechanism ◽  
Polymeric Materials

scholarly journals Cellulase - Enzymatic degradation mechanism of native cellulose.

1988 ◽  
Vol 35 (4) ◽  
pp. 253-277 ◽  
Author(s):  
Gentaro OKADA ◽  
Yoshimasa TANAKA
Keyword(s):  
Enzymatic Degradation ◽  
Degradation Mechanism ◽  
Native Cellulose

TEM Studies of Protective Al Coatings on Kapton H

2004 ◽  
Vol 851 ◽  
Author(s):  
Judith C. Yang ◽  
Huiping Xu ◽  
Long Li ◽  
Deborah Waters ◽  
Bruce Banks
Keyword(s):  
Mass Loss ◽  
Erosion Rate ◽  
Protective Coatings ◽  
Degradation Mechanism ◽  
Polymeric Materials ◽  
Growth Conditions ◽  
Low Earth Orbit ◽  
Cross Sectional ◽  
Coated Materials ◽  
Al Coating

ABSTRACTPolymeric materials undergo rapid erosion when exposed to the harsh low-earth-orbit (LEO) environment. Coatings can reduce the erosion rate of polyimide Kapton from atomic oxygen (AO) attack. Specifically, we are investigating how thin Al coatings can protect Kapton. Protective Al layers with variations in layer thickness and growth conditions were deposited on Kapton H. The quality of these protective coatings were evaluated by mass loss measurement and compared to Kapton alone and the SiO2 coating, where dramatically decreased erosion rate was noted. To understand how these coatings protect Kapton as well as how the AO interacts with the coatings, we are investigating the microstructure of these coated materials by plane view and cross-sectional transmission electron microscopy (TEM) methods. To understand the AO degradation mechanism, we attempted to correlate the mass loss with growth conditions and microstructures. We noted a slight improvement in erosion resistance of the Al coating due to the presence of the dendrimer, but a major improvement when the Al coating is deposited under ultrahigh vacuum conditions.

scholarly journals Pyrolytic kinetics of coconut shell waste using Ramped PyrOx

2018 ◽  
Author(s):  
Imtiaz Ali ◽  
Haitham Bahaitham ◽  
Raed Naebulharam
Keyword(s):  
Activation Energy ◽  
Biomass Conversion ◽  
Degradation Mechanism ◽  
Coconut Shell ◽  
Heating Rates ◽  
Experimental Conditions ◽  
Degradation Rates ◽  
Shell Waste ◽  
Mass Conversion ◽  
Kinetics Of

Biomass pyrolysis is an efficient and economical conversion process. The kinetics of biomass conversion is still not fully understood mainly because this complex material is composed of numerous compounds with very different reactivities. In this work an inverse model is used to determine the nonparametric probability density function p(Ea) of activation energy (Ea) for coconut shell waste (CSW) pyrolysis via the Ramped PyrOx (RPO) method from the time-series and temperature-series mass conversion data. In this method, the degradation rates are described by inverting distributed activation energy model (DAEM). This method does not require p(Ea) to follow any particular parametric form furthermore the modelling results are independent of experimental conditions such as heating rates. The pyrolytic kinetics is modelled considering first-order degradation mechanism.

Enzymatic degradation of poly(ε-caprolactone) film in phosphate buffer solution containing lipases

1997 ◽  
Vol 56 (2) ◽  
pp. 209-213 ◽  
Author(s):  
Zhihua Gan ◽  
Qizhi Liang ◽  
Jie Zhang ◽  
Xiabin Jing
Keyword(s):  
Phosphate Buffer ◽  
Enzymatic Degradation ◽  
Phosphate Buffer Solution ◽  
Buffer Solution
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