控制释放膜用聚乳酸的直接缩聚法合成

聚乳酸是一种控制释放膜用的新材料 ,以 L-乳酸为原料 ,研究了熔融聚合法直接合成聚乳酸的反应条件 ,即催化剂、反应温度、反应时间和压力等聚合条件对相对分子质量的影响。     

新型生物降解材料——含氢键聚乳酸的制备

采用熔融固相聚合制备了乳酸-氨基酸共聚物，并用HNMR IR DSC GPC对共聚物进行了袁征。结果表明：熔融聚合的最佳工艺条件为，催化剂辛酸亚锡用量为0．5％-1％、聚合时间为10h、氨基酸含量为0．5％-1％；固相聚合的工艺条件为，聚合时间20h、催化剂为辛酸亚锡。此工艺条件可制得分子量大于50000的共聚物。     

乳酸直接缩合法合成聚乳酸类生物降解材料

与传统的采用丙交酯单体开环聚合法相比 ,直接缩合法使合成流程缩短 ,工艺简化 ,有利于聚乳酸及其衍生物产品的开发和应用。其中 ,溶液聚合可以比熔融聚合获得相对较高的相对分子质量 ,但熔融聚合法较溶液聚合法的工艺更简单 ,适宜于制备扩链反应的预聚体。无催化剂的熔融聚合法还可以直接合成药物缓释材料     

新型生物降解材料--含氢键聚乳酸的制备

采用熔融固相聚合制备了乳酸-氨基酸共聚物。结果表明：熔融聚合的最佳工艺条件为，催化剂是实验室制备，用量为0．5％～1％、聚合时间为10h、氨基酸含量为0．5％～1％；固相聚合的工艺条件为，聚合时间20h、催化剂为实验室制备。此工艺条件可制得相对分子质量大于50000的共聚物。     

熔融聚合法直接合成聚乳酸的研究

以Ｌ一乳酸单体为原料,系统地研究了熔融聚合法直接合成聚乳酸的最佳工艺条件,即:选择氯化亚锡为催化剂,用量０．５ｗｔ%,在聚合温度１８０℃、绝对压力７０Ｐａ下反应１０ｈ,可获得较高分子量的聚乳酸。     

聚丙烯催化剂聚合性能的研究

采用磷酸酯类作内给电子体,MgCl2作载体合成球形聚丙烯催化剂,以三乙基铝为助催化剂,甲基环己基二甲氧基硅烷为外给电子体,研究液相本体法聚合条件对催化剂性能的影响,并对聚合物进行了分析.结果表明:该催化体系最佳聚合条件为搅拌转速150 r/min,反应温度75℃,n(Al)/(Ti)为600,n(Si)/n(Ti)为30.在此条件下,催化体系为长效型,催化剂活性高、氢调敏感性好,聚合物等规指数高、细粉少.     

生物降解材料聚乳酸的合成

系统地介绍了包括丙交酯二步法、乳酸溶液聚合法和乳酸熔融聚合法在内的各种聚乳酸合成方法；并从安全和经济的观点出发，对聚乳酸的合成研究方向进行了展望，指出使用安全无毒的催化剂进行乳酸直接熔融聚合生产聚乳酸尤其值得大力开发。     

D4的阳离子乳液聚合速率的研究

以八甲基环四硅氧烷为单体,十二烷基二甲基苄基溴化铵为阳离子型乳化剂,氢氧化钾为催化剂,进行环硅氧烷阳离子乳液聚合;采用凝胶色谱测定聚合产物的转化率.研究了温度、催化剂浓度、乳化剂浓度、搅拌速度及水油比等对聚合速度的影响.较佳的反应条件是:单体质量为整个聚合体系的34%,KOH用量为单体质量的1%,阳离子型乳化剂用量为单体质量的6.9%,反应温度70 ℃,搅拌速度250 r/min.     

溶液熔融法合成聚丁二酸丁二醇酯的工艺研究

该研究采用溶液熔融聚合法对聚丁二酸丁二醇酯(PBS)进行合成,采用控制变量法进行反复实验,以反应后的出水量及合成产物的颜色为实验指标分别讨论了合成聚丁二酸丁二醇酯的影响因素:即反应温度、时间及催化剂对合成条件的影响,分析得出了最优的合成工艺条件。     

成核剂对1-丁烯聚合及聚1-丁烯结晶性能的影响

采用齐格勒-纳塔催化剂,在2 L聚合釜中进行1-丁烯的本体聚合,聚合过程中加入成核剂,考察了成核剂种类对聚合性能和聚1-丁烯结晶性能的影响。结果表明:釜内添加成核剂使催化剂活性下降,对聚1-丁烯的相对分子质量造成一定影响;加入成核剂使聚1-丁烯的熔融温度及结晶度均提高,未加成核剂时熔融温度为126.8℃,加入成核剂后熔融温度最高达130.6℃,结晶度由49.0%提高到56.2%;加入酰胺类和磷酸酯盐类成核剂对加快聚1-丁烯晶型转变效果最佳。     

离子液体/氯化亚锡催化合成聚乳酸的研究

以离子液体氯化1-丁基-3-甲基咪唑盐([Bmim]Cl)和氯化亚锡(SnCl_2)的复盐为催化剂,L-乳酸为原料,采用直接溶液缩聚法制备聚乳酸(PLA);探讨了催化剂用量、反应温度及反应时间对PLA相对分子质量的影响,借助红外光谱和核磁共振氢谱对聚合物进行了表征。结果表明:当反应体系真空度约1 kPa,[Bmim]Cl/SnCl_2催化剂质量分数为反应物的0.7%,[Bmim]Cl与SnCl_2的摩尔比为1:2,反应温度170℃,反应时间12 h时,制备的PLA的粘均相对分子质量为3.5×10~4。     

Solution-based synthesis of a four-arm star-shaped poly(L-lactide)

The mechanical properties of biocompatible poly(L-lactide) (PLA) could be dramatically enhanced by cross-linking and interesting network structures might be achieved via the formation of branched and star-shaped structures prior to such cross-linking. However, the synthesis of a four-armed star-shaped PLA is limited to bulk melt polymerization at relatively high temperatures that may degrade the monomer and render the reaction kinetics difficult to control. In this work, a solution-based polymerization approach is introduced with dimethylformamide as the solvent for the initiator and all other reactants. Varying the reactant concentrations and reaction temperature, four-arm PLA star structures were produced in solution and their properties were analyzed. The progress of the polymerization reaction was studied using the ¹H NMR and Fourier transform infrared spectroscopy. The quantitative evaluation of the monomer conversion was discussed on theoretical basis. The thermal properties and the crystallinity of the product polymers were evaluated using differential scanning calorimetry. Results indicate polymerization and cross-linking of the four-armed PLA were successful. The introduced solution-based method could open venues for better controlled and more economic reactions of star-shaped and cross-linked PLA.     

聚乳酸的直接合成研究(Ⅱ)

研究了以乳酸单体为原料的直接熔融缩聚的工艺条件,包括工艺路线、原料含水率、催化剂种类、温度及余压对合成的影响。结果表明:采用适当的工艺能通过熔融缩聚法制备出高分子质量的聚乳酸,且具有良好的生物降解性能。     

The synthesis of fulvic acid–thiourea amide derivates grafted polystyrene and its effect on the crystallization and performance of poly(lactic acid)

Fulvic acid–thiourea amide derivates (FA‐T) was synthesized via amidation with FA and thiourea, and its optimum reaction conditions were 7 h of reaction time, 1 wt% of sodium methylate, 130°C of reaction temperature, and 2 g of thiourea. Then, FA‐T grafted polystyrene (FA‐T‐PS) was synthesized by activators generated by electron transfer for atom transfer radical polymerization. Fourier transform infrared spectroscopy, static contact angle analysis, and X‐ray photoelectron spectroscopy confirmed that the synthesis of FA‐T‐PS. Then, poly(lactic acid)/FA‐T‐PS(PLA/FA‐T‐PS) composites were prepared by the melt blending with FA‐T‐PS as fillers. Mechanical test demonstrated that FA‐T‐PS increased the flexibility and ductility of PLA composites. Dynamic mechanical analysis revealed that FA‐T‐PS reduced friction and loss between PLA chain and filler, and further reformed had higher interfacial compatibility with PLA. Differential scanning calorimetric results and polarized optical microscopy analysis displayed that FA‐T‐PS had strong heterogeneous nucleation effect, which effectively enhanced the crystallization rate and the crystallinity of PLA. Friedman thermal decomposition kinetics presented that E _a of PLA/FA‐T‐PS (0.3 wt%) was increased by 52.94% compared with PLA, which demonstrated that FA‐T‐PS significantly enhanced the thermal stability of PLA. Therefore, FA‐T‐PS effectively improved the comprehensive performance of PLA. POLYM. ENG. SCI., 59:1787–1798, 2019. © 2019 Society of Plastics Engineers     

聚乳酸纤维的研究进展及应用

介绍了目前聚乳酸国内外的发展现状,阐述了聚乳酸的合成及纤维成形,并简要概括了其性能特征和应用领域。聚乳酸目前在国内外的发展呈现出多元化、多方向研究的状态,主要以美、德、日、中为主;其合成现阶段的研究集中在丙交酯开环聚合上;熔融纺聚乳酸纤维工业化生产技术比较成熟,溶液纺丝、静电纺丝等其他方式均处于研究阶段,而更多的关注点在于对聚乳酸的物理、化学、生物改性来扩展其应用。聚乳酸纤维具有优良的性能,因此被广泛应用于服装、生物医学、农林牧渔等行业,有巨大的应用前景和发展空间。     

生物可降解聚乳酸的制备及其性能研究

以L-乳酸(LLA)为原料合成L-丙交酯,通过L丙交酯开环聚合制备高分子量的聚乳酸(PLA)。考察反应温度、反应时间以及催化剂用量对PLA的影响,获得优化的聚合工艺条件。GPC测得PLA的重均分子量可达21.9×104g/mol。FTIR和旋光度测试表明产物为聚L-乳酸(PLLA)。DSC和XRD测试证明:PLLA为结晶性材料,熔点为170℃,属于α'-和α-相共存的混合晶型。拉伸测试表明:高分子量的PLLA具有良好的力学性能。     

Synthesis and chain extension of hydroxyl‐terminated poly(lactic acid) oligomers and application in the blends

Hydroxyl‐terminated poly(lactic acid) prepolymer (LA prepolymer) were prepared via L ‐lactic acid as monomer, 1,4‐butanediol as blocking agent and Sn(II) octoate as catalyst by direct melt polymerization. Then the LA prepolymer was blended with starch followed by in situ chain extending reaction using different content of TDI as chain extender, producing the high molecular weight of poly(ester urethane) in the blends. The LA prepolymer/starch‐TDI blends were characterized by GPC, ¹H‐NMR, SEM, DSC, tensile strength testing, and water resistance. The SEM results of cross‐section show that, compared with the simple PLA/starch blends, almost the starch granules were completely covered by ploy(ester urethane) in the LA prepolymer/starch‐TDI blends system. In comparison to the simple PLA/starch blends, the mechanical properties of LA prepolymer/starch‐TDI blends were increased, such as tensile strength increasing from 18.6 ± 3.8 to 44.2 ± 6.2 Mpa, tensile modulus increasing from 510 ± 62 to 1,850 ± 125 Mpa and elongation at break increasing from 1.8 ± 0.4 to 4.0 ± 0.5 %, respectively. This is attributed to high weight of poly (ester urethane) was formed via in situ reaction of the end of hydroxyl (LA prepolymer) and isocyanate groups and the starch granules were easily covered by ploy(ether urethane) via in situ polymerization in the blends. Moreover, covalent linkage was formed between the two phases interfaces. As a result, the interfacial adhesion was enhance and improved the mechanical property. In addition, the water resistance of LA prepolymer/starch‐TDI blends was much better that of the simple PLA/starch blends. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

新型环保材料——聚乳酸的合成及改性研究进展

聚乳酸是一种优良的可生物降解聚合物,是世界公认的环保、可持续发展材料。对聚乳酸的合成方法进行了综述,包括间接法和直接法。直接法作为一种新兴的方法被广泛采用,又可分为溶液缩聚法、熔融缩聚法等。同时聚乳酸通过改性,其相应的性能会得到很大的改善,其应用领域会更加广阔。对聚乳酸的改性研究进展进行了介绍,其改性方法有物理改性、化学改性和复合改性等。物理改性又分为共混改性和增塑改性等;化学改性可分为共聚改性和交联改性等;复合改性包括与各种纤维复合改性和与无机纳米材料复合改性等。     

In situ intercalation green polymerization,characterization, and kinetics of poly(lactic acid)/zinc oxide pillared saponite nanocomposites

Poly(lactic acid) (PLA)/Zinc oxide (ZnO) pillared saponite nanocomposites were prepared with ZnO pillared saponite as the green catalyst and lactic acid as monomer through in situ intercalation polymerization method. The optimum polymerization parameters were as follows the addition content of ZnO pillared saponite was 1% (wt) and the reaction was running at 180°C for 7 h. The Fourier transform infrared and ¹H NMR results showed that the polymerization sample was PLA; Gel permeation chromatography result showed the PLA had a narrow molecular weight distribution, which arranged from 3,000 to 5,000 and the polydispersity index of PLA was 1.2. Differential scanning calorimetry showed ZnO pillared saponite improved the crystallinity of PLA. Thermogravimetric analysis showed the thermal stability of PLA‐based nanocomposites were improved by ZnO pillared saponite. It was shown that in situ intercalative polymerization kinetics model of PLA/ZnO pillared saponite nanocomposites accorded with third order, and the activation energy of polymerization reaction was 49.3 kJ/mol under the polymerization reaction conditions as follows: the vacuum degree was 0.085 MPa, the temperature was 130°C, and the reaction extent was 2.35∼47.69%, the content of ZnO pillared saponite catalyst was 1 wt%. POLYM. COMPOS., 35:1023–1030, 2014. © 2013 Society of Plastics Engineers     

聚乳酸/酯化纤维素复合材料的制备与表征

通过气固反应利用马来酸酐（MA）对纤维素进行酯化改性,采用熔融共混工艺制备了聚乳酸（PLA）/酯化纤维素复合材料。红外分析表明纤维素与MA发生了酯化反应。力学性能测试、热重分析、差示扫描量热仪（DSC）、扫描电镜（SEM）等分析表明,PLA/酯化纤维素复合材料的拉伸模量和弯曲模量随酯化纤维素含量的增加而升高,拉伸强度、弯曲强度和热稳定性随酯化纤维素含量的增加而降低;复合材料的Tc相对纯PLA较高,说明酯化纤维素的加入起到了异相成核作用,使结晶速率提高。酯化纤维素在复合材料中分散充分,但两者的界面黏结力较弱。