Advanced Materials Research Vols. 652-654

Abstract: Polyacrylamide (PAM) was synthesized by combining reverse atom transfer radical polymerization (R-ATRP) with aqueous two-phase polymerization. In aqueous two-phase system, polyethylene glycol 20000 (PEG20000) is used as dispersing agent, potassium persulfate (KPS) and Cu(en)²⁺ are used as initiator and control agent, respectively. In this paper the effect of monomer concentration, the amount of Cu(en)²⁺, reaction temperature, the ratio of Cu(Ⅱ), and ethylenediamine (en) were investigated. The experimental result shows the optimum conditions are as follows: m(AM)∶m(PEG)=1∶1, the monomer concentration is 10%, n(AM)∶n(CuCl₂•2H₂O)∶n(en)∶n(KPS)=3000∶10∶20∶1, polymerization time is 6 h, and polymerization temperature is 45°C. Under these conditions, the monomer conversion is 91.5%，the linear correlation coefficient is 0.9911.

Abstract: Soybean protein Alcalase hydrolysate was further hydrolyzed by adopting Flavourzyme. From this further hydrolysis reaction, bitter of soybean polypeptide mixture was reduced distinctly. The optimal hydrolysis conditions of Flavourzyme was determined as that pH was 7.0 at temperature 50°C and E/S(ratio of enzyme and substrate) was 20LAPU/g. Bitter taste value was reduced to 2 after Flavourzyme hydrolysis reaction for 2 hours in optimal hydrolysis conditions. The change of molecular weight distribution range from Alcalase hydrolysate to Flavourzyme hydrolysate was not obvious. DH (Degree of hydrolysis) of soybean protein hydrolysate was increased to 24.2% which was improved 3.5% than Alcalase hydrolysate. Protein recovery proportion was increased to 73.2% which was improved 0.8% than Alcalase hydrolysate.

Abstract: Soybean polypeptide mixture was decolorized by adopting activated carbon adsorption decolourization process. Anion/cation exchange process was used in the desalination processing of soybean polypeptide. It was showed that excellent decolorizing and desalting effect to soybean peptide solution was gained in the decolourization and desalination process adopted in this experiment. Optimal dosage of activated carbon was 1.2% solution amount (w/w). After decolorizing soybean polypeptide solution color was yellow. Proportion of anion resin and cation resin of ion exchange resin was 2:3(V/V). The volume of solution processed was 5 times as the volume of anion exchange resin. After desalination processing, ash content of soybean peptide solution reduced to 2.11% (dry basis), salinity decreased by 86%, on the other hand taste of soybean polypeptide was lite.

Abstract: Antioxidant activity of the flavonoids from pomelo (Citrus grandis (L.) Osbeck) peel obtained by conventional soxhlet extraction (CSE), microwave-assisted extraction (MAE) and supercritical carbon dioxide (SC-CO2) extraction were investigated. For measuring antioxidant activities, different methods have been used corresponding to different levels of antioxidant action. The results indicated that the extraction yields of flavonoids by MAE and SC-CO2 extraction were higher than that by CSE method, whereas flavoniods by SC-CO2 extraction exhibited the strongest antioxidant activities. Our results indicated that SC-CO2 extraction method could effectively reserve the antioxidant ability of pomelo peel flavonoids.

Abstract: Purpose: To introduce the novel effective Y-shaped silicon stent for treating canalicular laceration. Methods: Fifty-four canalicular laceration cases (54 eyes) underwent the lacrimal surgery using the novel Y-shaped silicon stents were collected, and the stents were removed 3 months after surgery. All cases were followed up for 12 months. The operability of stenting and removing the stent were assessed. The data we collected during each follow-up are: stent position and integrity, aesthetic results, the discomfort, the symptom of epiphora, the patency of lacrimal passage, complications, and patient’s satisfaction. Results: The stenting time was 14.3±5.8 min and the time of removing it was 1.8±0.5 min. Both of the operability of stenting and removing were accessed to be easy in more than 94.4% cases. All stents were in position and integrated. 51 cases (94.4%) had no problems on aesthetic results. Three patients (5.4%) complained about the discomfort. Two cases (3.7%) had the symptom of epiphora, which were obstructed after removing the stents. Fifty-two cases (96.3%) were with patent canaliculus and satisfied with the surgery and symptom improvement. Only 5 cases (9.3%) had complications. Conclusion: The novel Y-shaped silicon stent is an effective stent for treating canalicular laceration.

Abstract: Using virginica stem bark as raw material, extracted with hydrochloric acid, sulfuric acid, and tartaric acid through an orthogonal experiment. Then, the structure of pectin was analyzed and compared with mulberry pectin. The result showed that the pectin extraction rate was stable and relative high when using tartaric acid diluents as extracting solution, with pH value at 2 and extraction time of 90 minutes. There were certain differences about the color of the pectin when extraction process was different. Infrared spectrum analysis showed that the composition of the pectin in virginica stem bark was basically same as that in mulberry branch bark.

Abstract: A series of biodegradable segmented liquid crystalline poly(ester-urethane)s were prepared by solution polymerization of poly(L-lactic acid) (PLLA), mesogenic diol prepolymer poly(butylene terephthaloyldioxy dibenzoates) (MD), and hexamethylene diisocyanate (HDI). The MD content was varied from 0 to 40 mol% so that the effects of the mesogen content on the thermal and physical properties, and hydrolytic degradation were examined respectively. It was found that introducing mesogens units could increase the thermal stability and the elastic properties, while reduced the phase transition temperatures and the hydrolytic degradation rate.

Abstract: Substituted aromatic heterocyclic phosphate salts were synthesized by a new method and characterized by fourier transform infrared spectroscopy(FT-IR) and thermogravimetry (TG) method. The characteristic absorption bands ascribed to the stretching vibration of P=O group and P-O group verify the successful synthesis of substituted aromatic heterocyclic phosphate salts. When compared with sodium salt, the thermal stability of other salts declines. Their nucleation effects on isotactic polypropylene(iPP) were investigated with differential scanning calorimeter(DSC) and influences on mechanical, optical properties of iPP were also studied. The DSC result shows that with 0.15wt% nucleating agents incorporated into iPP, monovalent salts have a good performance, bivalent salts have less nucleation effect on the crystallization temperature. But the mass fraction of crystallinity of iPP with manganese salt could be increased by 5.2% even it has a weak ability relatively on crystallization temperature. And the mechanical and optical properties of iPP with manganese salt almost reach to iPP containing lithium salt. The results demonstrate that bivalent manganses salt is a kind of new effective nucleating agent when designing compound nucleating agents.

Abstract: In this paper, a new heat stabilizer was prepared, which has shown not only excellence thermal stability, but also shown obvious oxidation resistance and anti-aging properties. This multifunctional heat stabilizer was prepared by organic acid, rare earth and thiourea. The lauric acid as best stuff was chosen from some normal fatty acid and lanthanum nitrate as most potent rare earth was picked up too. Using these raw materials, the best heat stabilizer was synthesized under this conditions of synthesizing at 80°C, reacting 40min, adding 1.0mol/L sodium-hydroxide for keeping PH at 8 and making certain the amount of raw material(lauric acid : thiourea : lanthanum nitrate) at the proportion as 4∶1∶1. The thermal stability was examined by the change time of Congo red, and the result proved this heat stabilizer having good thermal stability for up this time to 40min. When this rare earth stabilizer was joined into PVC, the PVC can keep its color not changing during 48h under ultraviolet radiation, and the tensile strength and elongation at break of the PVC added rare stabilizer changed more little under ultraviolet radiation compared with the traditional heat stabilizer system. So this rare earth heat stabilizer acting as a good heat stabilizer, anti-oxidant and anti-aging agent is a new multifunctional heat stabilizer.

Abstract: EVA / PU are used as the polymer elastomer in this paper by the approach of graft copolymerization. By the scan analysis of EVA / PU flexible tensile fracture surface, it could be found, with the augment of EVA, the cross-section shows the transition from brittle fracture to ductile fracture, as well as a clear plastic deformation in the micro-fracture zone. The phenomenon of graft copolymerization between the EVA and PU can be observed by scanning probe micrograph . What’s more, while the height of the molecules increases，the molecules become increasingly small, indicating that the grafting reaction occurs between the free hydroxyl in EVAL and PU prepolymer.