Hydrolyzable poly(ethylene terephthalate)

Due to the enormous annual increase in the volume of municipal solid waste, society's attention is focused on how to manage the solid waste problem. Plastic materials not only contribute a great deal to the litter problem but also create serious danger to the ecology. Every year, countless birds, sea turtles, and other marine mammals die from eating or getting entangled in plastic litter. Synthesizing degradable polymers can have a great impact on solving the problem of plastic litter. We have modified the structure of poly(ethylene terephthalate) to make it degradable in typical environmental conditions in presence of water. The change of physical properties of modified poly(ethylene terephthalate), resulting from hydrolysis, has been monitored and compared with those of pure poly(ethylene terephthalate).     

Mn-N/TiO_2光催化剂的制备及甲基橙的降解

采用溶胶-凝胶法制备了新型Mn-N共掺杂纳米TiO_2复合光催化剂(Mn-N/TiO_2),采用EDX,SEM,UV-Vis,XRD技术对其进行了表征,并将其用于水中甲基橙的可见光催化降解,考察了制备条件对其光催化性能的影响。表征结果显示:Mn-N/TiO_2光催化剂的粒径约为25 nm,且分散性较好;Mn-N共掺杂可增强TiO_2在可见光区域的吸收。实验结果表明:Mn-N/TiO_2的最佳制备条件为硝酸锰、尿素、无水乙醇、冰醋酸与钛酸四丁酯的摩尔比分别为0.000 6,0.24,10,6,焙烧温度400℃;采用最佳条件下制得的Mn-N/TiO_2于可见光下催化处理初始质量浓度为60 mg/L的甲基橙溶液60 min,甲基橙的降解率达92%。     

Thermal and mechanical properties of poly(lactic Acid) and poly(ethylene/butylene Succinate) blends

In this study, blends of poly (lactic acid) (PLA) with poly(ethylene/butylene succinate) (Bionolle) have been investigated for their thermal and mechanical properties as a function of the concentration of Bionolle. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and tensile tests were used to characterize the blends. From the results of the DMA and DSC, it was found that this blend system was not miscible within the compositions studied. DSC results showed that adding Bionolle aids in crystallization of PLA. It was observed that increasing the Bionolle concentration led to a slight increase in the strain-at-break of the blends but a decrease in the Young’s modulus and ultimate tensile strength. Biaxially oriented films showed an increase in tensile strength, modulus, and strain-at-break.     

TiO2-Cu2O/蒙脱土复合光催化剂的制备与性能

以钠基蒙脱土（MMT）为载体,先采用溶胶-凝胶法将纳米TiO₂引入到MMT层间,再采用化学沉积法将纳米Cu₂O负载在TiO₂/MMT上,制备出TiO₂-Cu₂O/MMT纳米复合光催化剂。采用XRD、SEM、紫外-可见漫反射技术对催化剂进行了表征。以甲基橙为目标污染物,考察了催化剂的光催化性能。表征结果显示：TiO₂与Cu₂O均匀分布在MMT的表面与片层孔隙中;TiO₂-Cu₂O/MMT结合了TiO₂和Cu₂O的特性,拓宽了催化剂的光吸收范围。实验结果表明,在光源为可见光、初始甲基橙质量浓度为20 mg/L、光催化剂加入量为2 g/L的条件下,TiO₂-Cu₂O/MMT纳米复合光催化剂对甲基橙的光催化降解效果明显优于单一负载的Cu₂O/MMT和TiO₂/MMT,大幅提高了催化剂的光催化效率,反应300 min时TiO₂-Cu₂O/MMT对甲基橙溶液的脱色率达到93%。     

络合-电沉积法制备TiO_2纳米管负载Ag光催化剂

采用柠檬酸钠作为络合剂,通过络合-电沉积法制备了TiO2纳米管负载Ag光催化剂(Ag/TiO2NTs),通过FE-SEM和XRD等手段对Ag/TiO2NTs进行了表征。以偶氮染料甲基橙(MO)为目标降解物,考察了不同制备条件对Ag/TiO2NTs光催化性能的影响。表征结果显示,柠檬酸钠可以有效调控Ag+的电化学还原过程,实现Ag纳米颗粒在TiO2纳米管表面的均匀负载。实验结果表明:以在n(柠檬酸钠)∶n(Ag NO3)=1、电流密度为0.4 m A/cm2、煅烧温度为500℃的条件下制得的Ag/TiO2NTs作为光催化剂(Ag负载量为1.97%(x)),处理初始质量浓度为20 mg/L、初始溶液p H为9的MO溶液,光催化反应120 min后MO去除率为86.53%;经过6次的重复使用,Ag/TiO2NTs催化剂光催化降解MO的去除率基本稳定在80%以上。     

Influence of poly(bisphenol A carbonate) and poly(ethylene terephthalate) on poly(vinyl chloride) dehydrochlorination

Recycling of poly(vinyl chloride) (PVC) waste is a serious problem because of its high chlorine content. Dehydrochlorination of PVC-containing polymer waste produces solid residue char, for which conversion to pyrolysis oil in a petrochemical plant seems to be an attractive way of recycling PVC waste. Unfortunately, some polymer admixtures react with HCl and cause formation of chloroorganic compounds in a char. This article describes the influence of polycarbonates and poly(ethylene terephthalate) on thermal feedstock recycling of PVC wastes using a two-stage method. It was found that the presence of polycarbonate causes the formation of small amounts of benzyl chloride and other chloroaryl or chloroalkylaryl compounds. Poly(ethylene terephthalate) interacts with HCl forming significant amounts of various chlorocompounds – mainly chloroethyl esters of terephthalic and benzoic acids, but derivatives possessing chlorine directly connected to the aromatic ring are also formed.     

Properties and biodegradability of chain-extended copoly(succinic anhydride/ethylene oxide)

Chain-extension reactions were carried out using titanium-iso-propoxide (TIP) as a catalyst for a series of polyesters or copolyesterethers with low molecular weights (M _n =1500–10,000) synthesized by the ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO). The copolymers having aM _n from 25,000 to 50,000 of different properties were obtained. Both the melting point (T _m ) and the fusion heat (H), which indicate the crystallinity of the copolymers, rose with an increase in SA content in the copolymers. Semitransparent films were prepared by compression molding of the copolymers. The biodegradation of the copolymer films was evaluated by enzymatic hydrolysis by lipases and by an aerobic gas evolution test in standard activated sludge. The hydrolyzability of these copolymers by three kinds of lipases was affected by their copolymer composition SA/EO, form, andM _n . The copolyesterether (SA/EO=43/57,M _n =48,900) was more easily biodegraded by standard activated sludge compared to the polyester (SA/EO=47/53,M _n =36,300).Presented at the Pacifichem-95, December 17–22, 1995, Honolulu, Hawaii.     

Zn2+/TiO2薄膜光催化剂的制备及对NO的去除

为研究Zn^2＋／TiO2薄膜光催化剂对NO的去除效果,以钛酸四正丁酯和Zn（NO3）2为前驱体、石英玻璃片为基片,用在溶胶中进行浸渍提拉的方法,于500℃下煅烧制备出Zn^2＋加入量不同的Zn^2＋／TiO2薄膜光催化剂,重点考察了Zn^2＋加入量对NO去除率的影响。实验结果表明,Zn^2＋的加入可进一步提高NO的去除率,当Zn^2＋加入量为4％时,NO最高去除率为89％。对各种试样的扫描电镜和X射线衍射表征结果表明,适当加入Zn^2＋可改善纳米TiO2的分散状态,减小粒径尺寸,从而达到提高NO去除率的目的。     

Aminolysis and aminoglycolysis of waste poly(ethylene terephthalate)

This paper describes the chemical degradation of waste poly(ethylene terephthalate) (PET) with polyamines or triethanolamine, the characteristics of the products, and a search for ways to use these products. Solvolysis of the polymer ester bonds was caused by diethylenetriamine, triethylenetetramine, and their mixtures, as well as mixtures of triethylenetetramine and p-phenylenediamine or triethanolamine. Products of aminolysis or aminoglycolysis of PET obtained in reactions performed at 200–210°C (with a molar ratio of the recurrent polymer unit to amine of 1 : 2) have been characterized using nuclear magnetic resonance (NMR). Viscosity and hydroxyl number measurements have been done for PET/triethanolamine products. Substances from aminolytical reactions with polyamines were tested as hardeners for liquid epoxy resins, and the product of polymer aminoglycolysis with triethanolamine was tested as an epoxy resin hardener, e.g., for water-borne paints, and a polyol component for rigid polyurethane foams. The compositions of epoxy resin hardeners have been characterized using DSC and rheometry. Comparative analyses of the hardened epoxy materials have been done on the basis of glass temperature and mechanical properties data, as well as some specific properties of the coating materials and rigid polyurethane foams. Received: September 15, 2000 / Accepted: September 21, 2000     

Characterizations of the Photocatalytically-Oxidized Cross-Linked Chitosan-Glutaraldehyde and its Application as a Sub-Layer in the TiO2/CS-GLA Bilayer Photocatalyst System

Photocatalytically-oxidized cross-linked chitosan-glutaraldehyde (CS-GLA) was obtained via irradiation of a simple assemblage of an immobilized layer-by-layer TiO₂/CS-GLA system on a glass plate with a 45-W fluorescent lamp. The oxidation process was observed to occur only in the presence of oxygen and TiO₂ within 5 cycles (10 h) of irradiation. Characterizations studies of the oxidized cross-linked polymer involving swelling index, pH-potentiometric titration and ionic conductivity measurements, as well as CHN, FTIR, ¹³C solid-state NMR,UV–Vis DRS and photoluminescence spectroscopy analyses generally indicated that the oxidation led to the formation of carbonyl groups, partial elimination of some un-reacted amino groups and change of visual color to be more brown without altering much of the whole molecular structure of the CS-GLA. This study also indicated that the photocatalytic performance of TiO₂/oxidized CS-GLA system was higher than both TiO₂/CS-GLA system and TiO₂ single layer for the removal of phenol. Moreover, the adsorption effect was extremely negligible and the photodegradation of phenol was mainly due to the photocatalytic process.     

Poly(ethylene oxide)-coated granular starch-poly(hydroxybutyrate-co-hydroxyvalerate) composite materials

Granular cornstarch was coated with several biodegradable polymers in an effort to improve the mechanical properties of starch-poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) composites. Only samples containing poly(ethylene oxide) (PEO)-coated granular starch showed a large improvement in tensile properties over uncoated starch. For example, a 50/50 blend of PEO-coated starch and PHBV had a tensile strength of 19 MPa and an ultimate elongation of 23%, compared to 10 MPa and 11% for a similar blend containing uncoated starch. PEO may act as an adhesive between the starch and the PHBV and/or increase the toughness and resistance to crack growth of PHBV around the starch granules.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

纳米TiO2-石墨烯光催化剂的水热合成及其光催化性能

以钛酸四正丁酯和石墨为原料,通过水热法制备了锐钛矿型为主的纳米TiO2复合光催化剂（纳米TiO2-石墨烯）,并采用XRD,FTIR,FESEM,TEM技术对其进行了表征。通过紫外光照射降解溶液中的罗丹明B（RhB）研究了TiO2-石墨烯的光催化活性,分析了初始罗丹明B质量浓度、催化剂加入量、溶液pH和催化剂使用次数等影响降解效果的因素。实验结果表明：在初始RhB质量浓度为20 mg/L、溶液pH为7.10、催化剂加入量为1.000 g/L的条件下,紫外光照射30 min时,纳米TiO2-石墨烯对RhB的降解率高达98.69%,明显高于纳米TiO2的44.69%;纳米TiO2-石墨烯稳定性较强,可多次重复使用。     

Synthesis of a block copolymer of poly(3-hydroxybutyrate) and poly(ethylene glycol) and its application to biodegradable polymer blends

A block copolymer {P[(R,S)-HB-b-EG]} of atactic poly[(R,S)-3-hydroxybutyrate] {P[(R,S)-HB]} and poly(ethylene glycol) (PEG) was prepared by the ring-opening polymerization of -butyrolactone in the presence of a macroinitiator (PEG/ZnEt₂/H₂O) which had been produced by the reaction of ,-dihydroxy PEG ( _n=3000) with ZnEt₂/H₂O (1/0.6) catalyst. The block copolymer ( _n=10,500, _w/ _n=1.2) was an A-B-A triblock copolymer comprising atactic P[(R,S)-HB] (A) and PEG (B) segments. The miscibility, physical properties, and biodegradability of binary blends of microbial poly[(R)-3-hydroxybutyrate] {P[(R)-HB]} with the block copolymer P[(R,S)-HB-b-EG] has been studied. The glass-transition temperature (T _g) data showed that the P[(R)-HB]/P[(R,S)-HB-b-EG] blend was miscible in the amorphous state. The P[(R)-HB] film became flexible and tough by means of blending with P[(R,S)-HB-b-EG] block copolymer. The enzymatic degradation of blend films was carried out at 37°C and pH 7.4 in a 0.1M phosphate solution of an extracellular PHB depolymerase fromAlcaligenes faecalis. The enzymatic degradation took place solely on the surface of the blend films.     

Effect of Compatibilizing Agent on the Properties of Highly Crystalline Composites Based on Poly(lactic acid) and Wood Flour and/or Mica

This article contains a concept of the mechanical properties improvement of the highly crystalline poly(lactic acid) (PLA) and filled composites. PLA as a semi-crystalline thermoplastic polymer was plasticized with poly(ethylene glycol) and filled with 30 vol% of organic and/or inorganic filler. The degree of crytallinity was intentionally increased by annealing. The filler/polymer matrix interphase was modified with the addition of 4, 4′-Methylenediphenyl diisocyanate (MDI). The effect of compatibilizing as well as plasticizing agent on the thermal and mechanical properties, the water-absorption behaviour and crystallization characteristics were studied. The results indicated that high content of filler and crystallites have a strong influence on the composite′s mechanical properties despite of the plasticizer content, showing a high Young modulus. The MDI seems to react in preference easy with plasticizing agent and then alternatively with filler due to the low functionality of commercial PLA grade.     

Effects of Waste Paper Sludge on the Physico-Mechanical Properties of High Density Polyethylene/Wood Flour Composites

The objective of this work was to determine some physical and mechanical properties of the high density polyethylene (HDPE) composites reinforced with various mixtures of the paper sludge and the wood flour, and to evaluate the coupling agent performance. The waste sludge materials originating from two different sources including paper making waste water treatment sludge (PS) and ink-eliminated sludge (IES) were characterized in terms of physico-chemical properties. In the experiment, four levels of paper sludge (20, 30, 40 and 60 wt%), three levels of wood flour (20, 40 and 60 wt%), and two levels of coupling agent (MAPE) content (2 and 3 wt%) were used. The flexural properties of the composites were positively affected by the addition of the sludge. Especially, tensile modulus improved with the increase of paper sludge content. With the addition of MAPE, flexural properties improved considerably compared with control specimens (without any coupling agent). The results showed that the water absorption (WA) and thickness swelling (TS) values of the samples decreased considerably with increasing sludge content in the composite, while they increased with increasing wood flour content. It is to be noted that with incorporation of MAPE in the composite formulation, the compatibility between the wood flour and HDPE was enhanced through esterification, which reduced the WA and TS and improved the mechanical properties. Composites made with IES exhibited superior physico-mechanical properties compared with the PS filled composites. Overall results suggest that the waste paper sludge materials were capable of serving as feasible reinforcing fillers for thermoplastic polymer composites.     

Tensile Properties of Polylactide/Poly(ethylene glycol) Blends

The blends of polylactide (PLA) and poly(ethylene glycol) (PEG) with different contents (0, 5, 10, 15, and 20 wt%) and molecular weights (\( \overline{M}_{w} \) 6000, 10,000 and 20,000, called respectively as PEG 6000, PEG 10,000, and PEG 20,000) were prepared by means of melt blending method. The effects of tensile speed, content and molecular weight of the PEG on the tensile properties of the PLA/PEG blends were investigated using a universal testing machine at 24 °C. With increasing tensile speed, the tensile modulus, strength and stress at break of the PLA/PEG blends marginally increased, while the tensile modulus and stress at break declined non-linearly, and the tensile strength dropped nearly linearly with increasing PEG 10,000 content. When the PEG 10,000 content was 5–15 wt%, the tensile strain at break of the PLA/PEG 10,000 blend markedly increased, and then decreased as the PEG 10,000 content exceeded 15 wt%. With increasing the molecular weight of PEG, tensile modulus and strength increased, whereas the tensile strain at break decreased. This showed that the application of right amount of lower molecular weight PEG was more conducive to improving the tensile toughness of the PLA/PEG blends, which was attributed to its better miscibility with PLA and increased mobility of PLA molecular chains.     

The relationship between blend miscibility and biodegradation of cellulose acetate and poly(ethylene Succmate) blends

The miscibility of cellulose acetate (CA; degree of substitution = 2.5) and poly(ethylene succinate) (PES) has been investigated using a variety of thermal techniques and by solid-state carbon13 NMR spectroscopy. The blends containing greater than ca. 70% CA were found to be miscible. In the case of blends containing less than ca. 70% CA, a combination of thermal and NMR analyses suggests that these blends are not fully miscible on a 2.5- to 5-nm scale. On the scale which can be probed by dynamic mechanical thermal analysis (15 nm), the low-percentage CA blends exhibit “significant local concentration fluctuations≓. Investigation of the biodegradation of the blend components and of the blends revealed that PES degraded relatively rapidly and that CA degraded slowly. The blends degraded at a rate essentially identical to that of CA. Miscibility (75% CA blend) or crystallization of PES (30% CA blend) had no significant effect. These data suggest that a significant mode of degradation ófPES during composting involves chemical hydrolysis of the polymer followed by biological assimilation of monomers. Degradation of the blends is initiated in the amorphous phase. Because CA is a significant component of the amorphous phase, a small amount of CA significantly impacts the biodegradation rates of the blends.     

Recovery of benzene-rich oil from the degradation of metal- and metal oxide-containing poly(ethylene terephthalate) composites

Pure poly(ethylene terephthalate) (PET) resin and metal-/metal oxide-containing PET composites were thermally decomposed in the presence of Ca(OH)₂ using a tube reactor. The effects of batch and continuous processing, the presence of Ca(OH)₂, and PET size on benzene production were investigated. A maximum benzene yield and purity of 82.9 % and 78.8 wt%, respectively, were obtained at 700 °C in the presence of Ca(OH)₂ when using small PET particles; further, a continuous feed reactor was favored over a batch reactor. Effective contact between PET and Ca(OH)₂ was important in the PET degradation, which promoted hydrolysis of PET and decarboxylation of terephthalic acid, whereas pyrolysis was suppressed. Furthermore, the results of thermal decomposition of PET-based waste—PET-based X-ray films, magnetic tape, and prepaid cards—indicated that the metal and metal oxides contained in the waste had no significant catalytic effect on PET degradation or on the recovery of benzene-rich oil in the presence of Ca(OH)₂.     

Recycling of Tannery (chrome) sludge into sludge biochar (SB) /TiO2 nanocomposite via chemical activation through hydrothermal pre-treatment

Journal of Material Cycles and Waste Management - The preparation of biochar from Tannery (chrome) sludge has gained recent attention among many scientists globally. Hydrothermal pre-treatment...     

Effect of Interfacial Modifiers on Mechanical and Physical Properties of the PHB Composite with High Wood Flour Content

To explore the commercial viability of Polyhydroxybutyrate (PHB)/wood flour (WF) composites, systems were produced at industry-standard levels of fiber loading. Further, four interfacial modifiers were selected to improve the mechanical properties of PHB/WF composites, including maleated PHB (PHB-g-MA), a low molecular weight epoxy, a low molecular weight polyester, and polymethylene-diphenyl-diisocyante (pMDI). Results showed that all modifiers resulted in improvements in tensile strength and modulus, however, pMDI showed the highest improvements. The pMDI modifier also improved water uptake of the composites. Study of the fracture surfaces showed signs of improved fiber bonding, as did morphological studies by dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). Interpretation of the DSC and DMA results indicate possible reactions with lubricant, and interactions between PHB and wood fibers with the addition of pMDI.