Enhanced mechanical properties and flame retardancy of short jute fiber/poly(lactic acid) composites with phosphorus-based compound

In this work, a phosphorous-based compound(DOPO-ICN) was obtained by a two-step process. 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO) reacted with formaldehyde firstly, followed with reacting with 1,6-hexane diisocyanate(HDI). The chemical structure of DOPO-ICN was confirmed by Fourier transform infrared spectroscopy(FTIR) and 1 H NMR.The influence of DOPO-ICN on the mechanical and flammability properties of jute/PLA composites was studied. Compared to DOPO, DOPO-ICN improved the tensile, flexural and impact strength of the flame retardant jute/PLA composites. Moreover,the flammability of jute/PLA composites with different DOPO and DOPO-MA loading was investigated by thermogravimetric analysis(TGA), UL 94 test and limiting oxygen index(LOI) measurements. The results showed that DOPO-ICN imparted the flame retardancy to the jute/PLA composites.     

聚乳酸/聚乙二醇共混材料的性能研究

通过溶液共混法制备了PLA/PEG共混材料,对其力学性能、热性能和生物降解性能等进行测试.结果表明,随着PEG添加量的逐渐增加,PLA/PEG共混材料的断裂伸长率均大幅度提高, 但拉伸强度逐渐降低,弹性模量也呈下降趋势;同时,PLA/PEG共混材料的Tg逐渐下降,聚乳酸分子链间作用力减弱,常温塑性增强,而PEG添加量对其熔点Tm影响不大,熔融焓却随之增大;添加PEG能提高聚乳酸在土壤中的水解速率,从而加快其降解速率.     

Biodegradation and mechanical property of polylactic acid/thermoplastic starch blends with poly (ethylene glycol)

The effects of adding poly (ethylene glycol) (PEG) into polylactic acid/thermoplastic starch blends (PLA/TPS) on the properties were investigated by DSC, SEM and mechanical property-testing. The blends of PLA/TPS blended with increasing content PEG exhibited lower temperature of glass transition (Tg) and lower temperature of melting (Tm) as well as higher melt flow index (MFI), which indicates the plasticization and processability of the composites were dramatically improved. The tensile strength, flexural strength and izod impact strength of PLA/TPS (80/20) increased at first and then decreased with increasing content of PEG due to stronger interfacial adhesion. The optimized mechanical property can be obtained for the blend with 3 wt% PEG. The samples containing PEG after soil burial for 5 months showed quicker degradation being accompanied with large weight loss and mechanical properties loss.     

黄麻纤维/环氧树脂复合材料的力学性能

探讨了黄麻/环氧树脂复合材料板的制作方法,并对不同质量分数与长度的黄麻纤维增强的板材进行了拉伸及弯曲性能测试,采用扫描电镜观察了拉伸断面的微观形貌.讨论了纤维质量分数与长度对复合材料拉伸强度、拉伸模量、弯曲强度和弯曲模量的影响.实验结果表明,加入黄麻纤维有利于提升环氧树脂的拉伸和弯曲,纤维质量分数与长度对复合材料力学性...     

Creep behaviour of wood flour/poly(vinyl chloride) composites

The experimental creep data were focused on wood-flour (WF) /poly vinyl chloride (PVC) composites with the variations in additive concentrations of wood flour, silane coupling agent, organomodified montmorillonite (OMMT) and nano-cacium carbonate (nano-CaCO₃). Their effects were analyzed using the Four-element Burger Model incorporating microscopic mechanisms. Total creep strain was low with increasing WF while elastic strain was high and plastic flow strain was low in modeling. Modification of WF with silane was beneficial to creep resistance, so did adding low ratio of OMMT (1.5 wt%) and nano-CaCO₃ in composites. Thus, it was effective in reducing creep either by stiffening the PVC matrix using rigid nano-particles or by improving their adhesion with resin. However, superfluous quantity of any additament did not benefit the improvement owing to either earlier destruction of their agglomerates or stress-concentrated cracks in the over-incrassated interface.     

黄麻毡/PP膜复合汽车内饰材料的制备及工艺优化

黄麻毡/PP膜制备的复合材料用于汽车内饰,具有质轻、强力高及绿色环保等优点。探讨了黄麻毡/PP膜通过层压法制备汽车内饰材料的工艺方法。采用正交和单因素分析法优选了黄麻毡与PP膜复合制备的工艺参数.结果表明,当PP膜与黄麻毡质量比为40∶60时,所制备复合材料的拉伸强度和弯曲强度在工艺条件为热压温度180℃、热压压力10 MPa、热压时间9 min时最优。     

黄麻毡/PP膜复合汽车内饰材料的制备及工艺优化

黄麻毡/PP膜制备的复合材料用于汽车内饰,具有质轻、强力高及绿色环保等优点.探讨了黄麻毡/PP膜通过层压法制备汽车内饰材料的工艺方法.采用正交和单因素分析法优选了黄麻毡与PP膜复合制备的工艺参数.结果表明,当PP膜与黄麻毡质量比为40:60时,所制备复合材料的拉伸强度和弯曲强度在工艺条件为热压温度180℃、热压压力10...     

Biodegradation of Absorbable Hydroxyapatite／Poly—DL—lactide COmposites in Different Environment

To develop a new generation of absorbable fracture fixation devices with enhanced biocompatibility,the biodegradation mechanism and its influence on the cellular response at the tissue/implant interfoce of hydroxyapatite/poly-DL-lactide(HA/PDLLA) composites were investigated in vitro and in vivo.HA/PDLLA rods were immersed in phosphate-buffered saline,or implanted in muscle and bony tissue for 52 weeks.Scanning electron microscopic and histological studies were done.The degradation rate was the slowest in vitro,slower in muscle tissue and fast in bone.In vitro,the composites degraded heterogeneously and a hollow structure was formed.In bone,the limited clearing capacity leads to the accumulation of oligomeric debris,which contribute totally to the autocatalytic effect.So,the fastest degradation and intense tissue response were seen.In muscle tissue,oligomeric debris migratred into vicinal fibers over a long distance from the original implant cavity and the tissue reactions were,however,quite moderate.For the same size organic/inorganic composite,the environment where it was placed is the major factor in determining its biodegradation process and cellular reaction.In living tissue,tactors such as cells,enzymes and mechanical stress have an obvious influentce on the biodegradation and biological process at the tissue/implant interface,The biocompatibility of the HA/PDLLA composistes is enhanced with the incorporating of the resorbable HA microparticles.     

L-乳酸的熔融缩聚及反应动力学研究

采用熔融缩聚法直接合成聚乳酸(PLLA),探讨了催化剂种类、反应时间、反应温度对聚合反应的影响. 实验结果表明:较适宜的催化剂为对甲苯磺酸,反应温度180℃,反应压力小于100Pa. 研究了170℃、180℃下的缩聚反应动力学,发现在此实验条件下乳酸熔融缩聚属二级反应.     

Synthesis and characterization of poly/organo-montmorillonite composites

The incorporation of clay nanoplatelets into biodegradable polymers is considered to be one of the best combinations for developing environmentally-benign high-performance materials. We utilized organo-montmorillonite （OMMT） in ring-opening polymerization of bisphenol A diglycidyl ether and adipic acid to prepare biodegradable linear poly （ bisphenol A diglycidyl adipate ） / organomontmorillonite （PBA/OMMT） nanocomposites. The products were analyzed by XRD, TEM, 1H NMR, GPC, DSC and TGA. The results demonstrated that PBA/OMMT nanocomposites were successfully formed and sufficient for the ordinary heating process. OMMT was beneficial for the modification of PBA hydroxyl polyesters on branched rate and polydispersity.     

聚乳酸基生物降解共混物的制备及性能表征

用聚丁酸丁二醇酯作为改性剂制备了聚乳酸基生物降解共混物,并对其热稳定性、韧性、机械性能及形态进行了表征.结果表明,添加改性剂可显著提高聚乳酸的韧性.扫描电子显微镜照片显示,共混物通过引发大量的裂纹吸收外部能量,从而提高其韧性.     

聚(乳酸-羟基乙酸-L-赖氨酸)的制备与表征

制备了一种新型的聚(乳酸-羟基乙酸-L-赖氨酸)共聚物,以改善聚乳酸材料的神经细胞亲和性. 以Nε-苄氧羰基-L-赖氨酸和溴乙酰溴为起始原料,合成了单体3S-[4-(苄氧羰基氨基)丁基]-吗啉-2,5-二酮,将该单体与丙交酯聚合生成聚(乳酸-羟基乙酸-Nε-苄氧羰基-L-赖氨酸),再经催化氢解脱苄氧羰基制得聚(乳酸-羟基乙酸-L-赖氨酸).采用核磁共振氢谱、接触角测试、MTT实验和扫描电镜对其结构和性能进行了表征.结果表明,聚(乳酸-羟基乙酸-L-赖氨酸)较聚乳酸具有更好的亲水性和神经细胞亲和性,聚(乳酸-羟基乙酸-L-赖氨酸)有望成为一种更理想的神经修复材料.     

一种嗜碱菌微生物发酵法生产乳酸的条件优化

从14株嗜碱菌中筛选到一株LP3-3产乳酸能力较强,经16S rRNA序列测定初步鉴定为Exig-uobacterium aurantiacum(金橙黄微小杆菌)。对筛选出菌株的发酵培养基进行了优化,研究了不同碳、氮源种类和碳氮比对乳酸产量的影响,确定了最佳发酵培养基组成;经发酵实验,确定了摇瓶发酵最佳条件。在优化过程中,采用毛细管电泳检测发酵液中乳酸的含量。经过优化后,乳酸产量由初始的10.02 g/L,提高到最佳发酵条件下的16.27 g/L,比原来提高了62.4%,达到了较好的效果。     

一种嗜碱菌微生物发酵法生产乳酸的条件优化

从14株嗜碱菌中筛选到一株LP3-3产乳酸能力较强,经16S rRNA序列测定初步鉴定为Exig-uobacterium aurantiacum(金橙黄微小杆菌)。对筛选出菌株的发酵培养基进行了优化,研究了不同碳、氮源种类和碳氮比对乳酸产量的影响,确定了最佳发酵培养基组成;经发酵实验,确定了摇瓶发酵最佳条件。在优化过程中,采用毛细管电泳检测发酵液中乳酸的含量。经过优化后,乳酸产量由初始的10.02 g/L,提高到最佳发酵条件下的16.27 g/L,比原来提高了62.4%,达到了较好的效果。     

Melt synthesis and characterization of poly(L-lactic acid) chain linked by multifunctional epoxy compound

High molecular weight(Mw) poly(L-lactic acid)s(PLLAs) were synthesized using multifunctional epoxy compound(Joncryl-ADR4370) as chain extender. The products were characterized by gel permeation chromatography(GPC) and spectroscopy(¹HNMR and FTIR). The results indicated that the Mw of PLLA increased with the increasing of the ratio of epoxy compound and the extending of reaction time. The highest M _w of PLLA reached 360 000 g/mol when the ratio of epoxy compound was 1.5 wt%. However, the reactants turned to cross-linking when the ratio of epoxy compound was over 1.5 wt%. Differential scanning calorimetry(DSC) measurements demonstrated that the glass transition(T _g) and melting temperatures(T _m ) of products increased slightly as the increase of the molecular weight. Analysis of the hydrolytic degradation in vitro showed that the branched PLLA possessed the quicker degradability than that of the linear PLLA.     

聚乳酸纤维的合成加工与应用

阐述了聚乳酸的合成方法、聚乳酸纤维的纺丝成型方法、聚乳酸纤维的结构性能及主要应用范围.合成高分子量聚乳酸的主要方法有开环聚合、扩链聚合、溶液聚合及熔融固相聚合等.采用适当高分子量的聚乳酸树脂经干法纺丝或熔融纺丝可以制备聚乳酸纤维,聚乳酸具有高结晶和取向性,除具有特有的生物降解性外,聚乳酸纤维在强度、模量、断裂伸长率等方面可以与聚酯、尼龙等合成纤维相媲美.聚乳酸纤维广泛应用于纺织、卫生医疗、建筑、农林等行业.     

乳酸菌对人参皂苷Rb1的生物转化研究

从酸奶、酸菜汁、辣白菜、水果中分离得到5种乳酸菌(L1-L5),并利用分离得到的乳酸菌进行人参皂苷Rb1的生物转化.结果表明,除了菌株L2外,其他4种乳酸菌均能将人参皂苷Rb1转化为稀有人参皂苷F2或C-K.经鉴定,菌株L1为发酵乳杆菌(Lactobacillus fermentum),菌株L5为植物乳球菌(Lactococcus plantarum),其他3种均为植物乳杆菌(Lactobacillus plantarum).     

聚醚氨酯/聚甲基丙烯酸甲酯IPN阻尼性能研究

以甲苯二异氰酸酯预体与聚醚反应,合成了一系列高温固化的聚醚氨酯,用于与体型聚甲基丙烯酸甲酯的互穿聚合物网络化研究,并对所获得的ＩＰＮ体系阻尼性能进行了测试。动态力学性能检测表明：聚氨酯软段中－ＯＨ与－ＮＣＯ的比例、软硬的相对含量以及交联密度。甲基丙烯酸     

乙烯/乙酸乙烯酯/甲基丙烯酸嵌段聚合物离聚体的合成及性能研究

以乙烯／乙酸乙烯酯／甲基丙烯酸三元嵌段聚合物为基体合成了它的钠、锌盐离聚体，通过FT-IR谱图以及DSC、TGA曲线证明了钠、锌离子与甲基丙烯酸发生了反应，玻璃化温度、熔点有提高；同时经过力学性能测试表明，合成的离聚体在力学性能方面有改进，硬脂酸锌是离聚体的有效增塑、增强剂，离聚体的拉伸强度随着硬脂酸锌用量的增加而增加，其最大用量为30％。     

聚酯纤维与丙烯酸接枝共聚研究

用过氧化氢作引发剂，以水为介质，在不同的单体浓度、引发剂浓度及温度条件下，使丙烯酸与ＰＥＴ纤维进行接枝共聚，结果表明，随着单体浓度的增加，反应时间的延长，反应温度的提高，接枝率不断提高，而引发剂过氧化氢对接枝聚合则存在一个较适宜的浓度，接枝后纤维的吸湿率及阳离子染料上染率均得到了改善。