Zincated Nanoclay Polymer Composites (ZNCPCs): Synthesis,Characterization, Biodegradation and Controlled Release Behaviour in Soil

Novel zincated nanoclay polymer composites (ZNCPCs) with variable percentage of commercial bentonite and nanobentonite (8%, 10% and 12% of monomer for each case) were synthesized. Polyacrylic acid-Polyacrylamide copolymer was synthesized using N, N-Methylene bisacrylamide as crosslinker and ammonium persulfate as initiator. Clays as well as ZNCPCs were characterized by XRD, SEM, TEM and FTIR. 12% nanoclay containing formulation showed slowest release rate. ZNCPCs containing 8% clay recorded highest Zn content as well as highest equilibrium water absorbency. Biodegradation study revealed that Aspergillus spp was more effective as compared with Trichoderma spp in degradation of ZNCPCs.     

Blending Modification of PHBV/PBS/PEG and its Biodegradation

This study used poly(butylene succinate) and poly(ethylene glycol) to modify poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The results showed that the incorporation of poly(butylene succinate) and poly(ethylene glycol) improved the mechanical properties of blends. The results showed that crystallinity of the poly(ethylene glycol)-containing blends decreased, so do the crystallization temperature and melting temperature of the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends. Poly(butylene succinate)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/poly(ethylene glycol) ratio of 50:20:30 was chosen owing to its good properties. The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) component of blends can be degraded completely by Pseudomonas mendocina DS04-T, whereas this strain cannot degrade poly(butylene succinate) and poly(ethylene glycol). Apart from poly(butylene succinate), Fusarium sp. FS1301 can also biodegrade poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ethylene glycol).     

Preparation,Characterization and Biodegradation Characteristics of Poly(adipic anhydride-co-D,L -lactide)

Poly(adipic anhydride-co-D ,L -lactide) (P(AA-LA)) has been synthesized by ring-opening polymerization of adipic anhydride (AA) and D ,L -lactide (LA) using stannous octoate as catalyst in bulk and in solution. The copolymers were characterized by IR, nuclear magnetic resonance, gel permeation chromatography and differential scanning calorimetry. The physical properties can be tailored by varying the copolymer compositions, and showed low glass transition temperature, melting temperature and good solubility in common solvents. In vitro tests showed that after rapid weight loss in the first day, a constant degradation rate was observed. The release profiles of model drugs, bovine serum albumin and norethindrone over 16 days followed closely that of the degradation of copolymers containing higher amounts of AA (AA>64mol%), suggesting that the release mechanism was controlled predominantly by surface erosion. However, a large deviation from the close correlation of polymer degradation and drug release was observed for copolymers containing lower amounts of AA (<30mol%). These materials may be useful in protein delivery systems. © 1997 SCI.     

The Processing and Characterization of Polyester/Natural Fiber Composites

The mechanical, thermal, and morphological properties of polycaprolactone (PCL) and bamboo fiber (BF) composites were evaluated. Composites containing maleic anhydride-grafted PCL (PCL-g-MA/BF) exhibited noticeably improved mechanical properties due to better compatibility between the two components in comparison to PCL/BF. The dispersion of BF in the PCL-g-MA matrix was clearly more homogeneous due to the creation of branched and cross-linked macromolecules via reactions between anhydride carboxyl groups in PCL-g-MA and hydroxyl groups in BF. The tensile strength and elongation of the PCL-g-MA/BF composites at break was considerably greater than that of PCL/BF composites. In a soil environment, PCL/BF biodegraded slightly faster than PCL-g-MA/BF. Finally, the PCL-g-MA/BF composites not only provided a plateau tensile strength at break up to 40 wt% BF but also provided more easily processing properties.     

桐油成膜材料的生物降解性研究

以土壤和活性污泥中的微生物来降解桐油缓(控)释肥料的成膜材料,通过测定试样在降解过程中的CO2释放量、质量损失百分率和表面形貌来综合评价成膜材料的生物降解性能。结果表明,用桐油作为成膜材料制备缓(控)释肥料,养分释放后残留在土壤中的包膜肥料壳囊可以被生物降解,对环境友好。     

Evaluation of Some Factors Affecting the Performance of Polyester Hot-Melt Adhesives

Abstract

A study was carried out to establish the importance of Theological, thermal, and chemical variables in the performance of polyester hot-melt adhesives. The performance criteria are based on the shear strength of Al-Al lap shear joint formed under optimal conditions.

The results are presented showing the effects of: application and testing temperatures, chemical composition of the adhesive, linear vs. branched polymer, crystallinity, rate of crystallization and molecular weight.     

PBAT/棕榈酰氯酯化改性秸秆粉复合材料制备与性能

以棕榈酰氯为酯化剂改性秸秆粉,探究了不同酯化反应条件下秸秆粉取代度的变化,并对改性前后秸秆粉进行了傅里叶变换红外光谱测试及接触角测试,进一步验证了酯化反应的成功.制备了基于聚己二酸/对苯二甲酸丁二酯(PBAT)和改性前后秸秆粉的复合材料,考察了秸秆粉的不同酯化处理条件对复合材料拉伸、冲击性能的影响,通过对比可得,当反应...     

聚氯乙烯/稻壳粉木塑发泡制品的研究

通过模压成型方法对聚氯乙烯/稻壳粉木塑发泡制品进行了研究,分析了稻壳粉的不同填充量、不同处理方法、不同增塑剂用量以及工艺条件对复合材料性能的影响。由研究结果可知:稻壳粉含量为40份时,制品的综合性能较好;稻壳粉以硅烷偶联剂处理效果较好;随DOP的用量加大,制品的拉伸强度降低,冲击性能和发泡性能提高;实验中,工艺条件的控制是一个极为重要的因素,它直接影响制品的性能。     

PVB／纳米TiO2复合材料的制备和表征

制备了不同聚乙烯醇浓度的聚乙烯醇缩丁醛（PVB），利用偶联剂和超声波分散法对纳米二氧化钛（TiO2）进行了表面处理，用共混法制备了PVB／纳米TiO2复合材料。采用红外光谱、X射线衍射、扫描电镜等表征了复合材料的红外吸收性能、光学性能、结构和微观形貌，测试了复合材料的力学性能。结果表明：由于纳米TiO2粒子的加入，复合材料的韧性得到明显提高，其断裂伸长率为纯PVB的6-8倍左右，同时使PVB／纳米TiO2复合材料具有良好的紫外线屏蔽性能。     

Stereocomplex formation between enantiomeric PLA–PEG–PLA triblock copolymers: Characterization and use as protein‐delivery microparticulate carriers

Two enantiomeric triblock ABA copolymers composed of poly(L ‐lactide)–poly(ethylene glycol)–poly(L ‐lactide) (PLLA–PEG–PLLA) and poly(D ‐lactide)–poly(ethylene glycol)–poly(D ‐lactide) (PDLA–PEG–PDLA) were synthesized with two different middle‐block PEG chain lengths by ring‐opening polymerization of L ‐lactide and D ‐lactide in the presence of PEG, respectively. A pair of enantiomeric triblock copolymers were combined to form a stereocomplex by a solvent‐casting method. The triblock copolymers and their stereocomplexes were characterized by ¹H‐ and ¹³C‐NMR spectroscopy and gel permeation chromatography. Their crystalline structures and crystalline melting behaviors were analyzed by the wide‐angle X‐ray diffraction method and differential scanning calorimetry. The stereocomplex formed between a pair of enantiomeric triblock copolymers exhibited a higher crystalline melting temperature with a distinctive 3/1 helical crystalline structure. PLLA–PEG–PLLA and its stereocomplex with PDLA–PEG–PDLA were used to fabricate a series of microspheres encapsulating a model protein drug, bovine serum albumin (BSA). They were prepared by a double‐emulsion solvent‐evaporation method. The morphological aspects of the microspheres were characterized and BSA release profiles from them were investigated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1615–1623, 2000     

PLA/PBAT共混物的降解性能研究

通过双螺杆挤出机和吹膜机组制备不同比例的聚乳酸/聚对苯二甲酸己二酸丁二酯（PLA/PBAT）共混物薄膜,测量共混物的热性能、力学性能,并观察其相形貌,计算共混物在堆肥条件下的生物降解率,研究共混物降解前后的结构、热力学行为和元素的变化。结果表明,PLA与PBAT是不相容体系,加入PBAT后PLA的韧性得到改善;PLA的生物降解率高于PBAT,共混物的生物降解率随着PBAT含量的增加而降低,且在降解初期,PLA的降解产物会促进PBAT的水解;PLA、PBAT及其共混物在堆肥降解前期只是大分子链水解为小分子链的过程,不发生分子链的结构变化;PLA及PBAT的降解会先发生在无定形区,共混物中PLA在无定形区的降解速度受到PBAT的影响而变慢,且共混物中PLA、PBAT的降解行为发生变化,无定形区与结晶区的降解同时发生;共混物在堆肥试验初期的降解以水解为主。     

Synthesis,Characterization, and Release Dynamic of Acetylsalicylic Acid From Acetylsalicylic Acid/Poly(vinylalcohol-co-ethylene) Membrane

A series of poly(vinylalcohol-co-ethylene)/acetylsalicylic acid blends (PEVA/AcSa) of different AcSa contents were prepared and characterized by the solubility test, differential scanning calorimetry, and scanning electron microscopic analyses. The results revealed that AcSa was perfectly soluble in PEVA at certain composition and uniformly distributed throughout the polymer matrix. The release dynamic of AcSa from PEVA/AcSa material was studied at body temperature during 92 h in which the influence of AcSa initially incorporated in PEVA, the pH of media, the membrane thickness, and the stability of AcSa release rate on the release dynamic were detailed.     

生物可降解聚丁二酸乙二醇酯的合成与降解性能研究

以丁二酸和乙二醇为原料,直接熔融聚合,合成了高相对分子量的聚丁二酸乙二醇酯(PES),用FTIR,1H-NMR表征其结构;考察了不同聚酯反应催化剂对其聚合反应的影响,结果表明:三氧化二锑的催化效果是最佳的。同时,利用酶降解和体外水解的方法,对聚合物降解性能进行研究,结果表明:PES是一种可生物降解的聚合物,且在体外具有一定的降解性。     

原位聚合法制备PVB/纳米Ti02复合材料及其性能与表征

利用韶声波分散法将纳米_氧化认(TiO2)均匀分散到聚乙烯醇(PVA)水溶液中,通过原位法制备了一系列不同TiO2含量的聚乙烯醇缩丁醛(PVB)纳米TiO2复合材料。采用FT-IR, UV-VIS, DSC和TG,AFM等平段对所制得的原位复合材料的结构、微观形貌和性能讲行了研究。结果表明,在合成PVB讨程中引入纳米Ti( )>粒子,能更均匀地分散在PVB笨质中,PVB对TiU粒子具有很奸的位理效果,形成了以纳米TiO2粒子为核心的网络结构。该原位复合材料的力学性能尤其是韧性得到了明显捍高,在TiO2相对PVB含量较低时其断裂伸长率就达到纯PVB的6倍左右,同时该复合材料具有良奸的紫外屏蔽性能及耐热性能,而且材料溶解后的诱明度良奸。     

微囊藻毒素-RR的提取与生物降解

对采集的微囊藻毒素-RR(microcystin-RR,MC-RR)提取并在其含量达到0.1 mg/g(湿重)的基础上,采用鞘氨醇单胞菌降解菌株对提取的MC-RR的生物降解进行了研究。结果表明在温度为30℃、pH=7.0并且有氧条件下,反应体系中初始浓度为42.3 mg/L的MC-RR在36 h内被完全降解。利用高效液相色谱(HPLC)分析发现,在MC-RR生物降解过程中相继出现两个降解产物,其中第一个降解产物的紫外扫描图谱与MC-RR相似度高达95%。     

聚乳酸/酯化纤维素/纳米CaCO_3复合材料的制备与表征

采用熔融共混法制备了聚乳酸(PLA)/酯化纤维素/纳米CaCO3复合材料,并通过力学性能测试、差示扫描量热仪、热重分析和扫描电镜等测试手段对复合材料的性能进行了表征。结果表明,当酯化纤维素和纳米CaCO3的总含量小于5%时,能够起到较好的增强作用,复合材料的力学性能明显优于纯PLA;酯化纤维素和纳米CaCO3的加入起到了异相成核作用,但会降低复合材料的热稳定性;酯化纤维素在复合材料中分散充分,无聚集现象;但当填料总含量大于10%时,纳米CaCO3发生明显发生聚集。     

聚酯/聚醚型聚氨酯互换膜材的制备与应用

为了优化聚氨酯(PUR)包膜尿素控释性能,采用多亚甲基多苯基异氰酸酯分别与聚酯和聚醚多元醇按不同配比混合,依照不同次序先后喷涂在尿素颗粒表面制备聚酯型和聚醚型PUR互换层包膜尿素并利用分光光度法研究其控释性能。通过接触角、热重分析和扫描电子显微镜对膜材的润湿性、热稳定性和形貌进行了表征,并采用傅立叶变换红外光谱分析了尿素释放过程中膜层的结构变化。结果表明,聚酯型PUR的疏水性弱于聚醚型PUR,但热稳定性高于后者;两者的包覆次序影响PUR包膜尿素的控释效果,聚酯型PUR为外层、聚醚型PUR为内层时控释性能优良,当两者包覆比例(质量比)为1.5∶1.5时,释放期最长可达84 d。     

吹膜级PBS/PLA复合材料的制备与性能研究

利用熔融共混法制备了综合性能优良的吹膜级聚丁二酸丁二酯/聚乳酸(PBS/PLA)复合材料,并通过万能试验机、差示扫描量热分析仪、热重分析仪、透气透湿分析仪分别测试了PBS/PLA复合材料及其薄膜的力学性能、热性能、阻隔性能。结果表明,制备的PBS/PLA复合材料较纯PBS树脂具有更好的刚性,且所吹塑的薄膜与包装用低密度聚乙烯膜各项性能相当。     

Dwarf Cavendish as a Source of Natural Fibers in Poly(propylene)‐Based Composites

Summary: Composite materials were prepared by compounding and hot‐pressing PP or MAPP and lignocellulosic fibers extracted from the rachis of Musa acuminate Colla var. Dwarf Cavendish banana tree. The fibers were used as raw filler or after a chemical treatment expected to remove most of the extractible compounds. The resulting materials were characterized using SEM, DSC, DMA, tensile tests and water sorption experiments. All results show that the main aspect involved in the interfacial adhesion between the polar filler and the non‐polar matrix is the extraction of lignin and fatty substances. This results in higher values of the degree of crystallinity and crystallization temperature of the matrix, higher mechanical properties and lower water sensitivity.

Scanning electron micrograph showing the cross section of the lignocellulosic filler obtained from rachis of banana tree: (a) raw, and (b) extracted fibers.     

细菌纤维素/聚乙烯醇复合材料的制备及性能

采用浸渍法向细菌纤维素(BC)中引入聚乙烯醇(PVA),对BC/PVA复合材料的结构、光学性能及力学性能进行研究。当浸渍液中PVA浓度为20 g/L时,力学性能及光学性能测试表明,复合材料在保持BC超高力学强度的同时光学性能较纯BC显著提高,透光率最高可达90.74%,可见光区最多提高24.26%。扫描电子显微镜及X射线衍射表明,大量自由PVA渗入BC网络结构,复合材料层状结构淡化,结晶度下降。