无机粉体填充PBAT/PBS/PLA共混薄膜的制备与性能

将不同含量的聚丁二酸丁二酯(PBS)、碳酸钙(CaCO₃)/滑石粉(Talc)、聚乳酸(PLA)与聚对苯二甲酸-己二酸丁二酯(PBAT)进行熔融共混改性,研究各组分含量对PBAT/PBS/PLA共混材料加工性能、拉伸性能及其吹塑薄膜的拉伸性能、直角撕裂强度和热封强度的影响。采用熔体流动速率(MFR)仪、万能试验机、热封试验仪、差示扫描量热仪对PBAT共混薄膜的加工性能、力学性能和热封性能等进行测试。结合3因素3水平设计正交试验来优化试样配方,并对试验结果进行了正交试验极差分析。结果表明,PBAT/PBS/PLA共混材料的MFR值均在2.6～4.3 g/10 min范围内,薄膜吹塑成型加工稳定性良好。根据薄膜力学性能极差分析结果提出了最佳配方：PBAT含量为100质量份、PBS含量为10质量份、CaCO₃/Talc质量比为10/10和PLA含量为2质量份,验证试验结果表明,该配方制备的吹塑薄膜各项力学性能最高,横向、纵向拉伸强度分别为23.2 MPa和27.3 MPa,横向、纵向断裂伸长率分别为988%和1 137%,横向、纵向直角撕裂强度分别...     

PBAT/PLA/TPS生物降解薄膜的制备及性能研究

聚对苯二甲酸-己二酸-丁二醇酯(PBAT),聚乳酸(PLA)和热塑性淀粉(TPS)通过熔融共混并挤出吹膜。固定PBAT的质量分数为50%,改变PLA和TPS的比例。对PBAT/PLA/TPS薄膜的力学性能、热性能、结晶行为、撕裂断面形态、阻水性和氧气渗透性进行了研究。结果表明,PBAT/PLA/TPS薄膜中PLA的冷结晶温度降低了约40℃,PLA的冷结晶能力增强。随着TPS含量的增加,PBAT/PLA/TPS薄膜的拉伸强度降低、断裂伸长率增加。通过扫描电子显微镜观察,PBAT/PLA/TPS薄膜表现为明显的韧性断裂。水接触角和氧气渗透性测试表明薄膜具有良好的应用性能。     

交联改性PLA/PBAT吹塑薄膜性能的研究

将聚乳酸(PLA)、聚己二酸丁二酯-对苯二甲酸丁二酯(PBAT)和交联剂1,4-双叔丁基过氧化异丙基苯(BIBP)双螺杆共混挤出造粒并吹成薄膜,探讨了不同PBAT含量对共混薄膜的影响。DSC表明Tg增加,Tcc降低,Tm基本不变;相对于PLA/BIBP薄膜,PLA/PBAT/BIBP膜的断裂伸长率和撕裂强度增加,拉伸强度降低;Han点和Cole-Cole点表明,PLA/PBAT/BIBP(40/60/0.1)膜比其他比例的薄膜相容性更好;SEM表明,由于BIBP的交联作用,PLA/PBAT/BIBP(40/60/0.1)膜显示PLA与PBAT有更好的相容性。     

全生物降解聚乳酸(PLA)吹膜基础研究

采用熔融挤出吹塑的方法制备聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)薄膜,研究了加工温度,上牵引速率及吹胀比对PLA薄膜性能的影响力学性能结果表明:聚乳酸薄膜在吹胀比为1.8～2和上牵引速率6m/min的条件下,纵向与横向撕裂强度及其抗冲击强度分别可达132.4KN/m,166.4KN/m及0.27J。     

高含量PLA薄膜的制备及性能研究

以Joncryl ADR-4370F(ADR)为增容剂,超细滑石粉(Talc)为成核剂,聚乳酸(PLA)/聚对苯二甲酸-己二酸-丁二醇酯(PBAT)通过熔融共混,然后挤出吹膜。对PLA/PBAT薄膜的热性能、结晶行为、撕裂断面形态、力学性能和阻隔性能进行了研究。结果表明,PBAT的加入改善了PLA的柔韧性。随着PBAT含量(40%~70%)的增加,薄膜的拉伸强度和模量降低,断裂伸长率大幅增加了。薄膜的氧和水蒸气阻隔性能受PBAT影响不大。ADR的加入使得薄膜材料的相容性得到了提高。     

聚乳酸/聚丁二酸丁二醇酯/二氧化碳基热塑性聚氨酯三元薄膜的制备与性能研究

用熔融共混法和挤出吹膜工艺制备了聚乳酸(PLA)/聚丁二酸丁二醇酯(PBS)/二氧化碳基热塑性聚氨酯(PPCU)薄膜。用差示扫描量热仪(DSC)、力学测试、流变测试和接触角分别详细研究了PLA/PBS/PPCU共混体系的结晶性能、力学性能、流变学特性和亲水性。DSC结果分析表明PLA与PBS的结晶可互相抑制,共混体系总结晶度下降,有利于薄膜的韧性提高。力学结果表明PPCU对PLA改性效果好,显著提高其力学性能。而PBS的加入进一步改善了PLA的柔韧性,断裂伸长率更高,杨氏模量下降显著。PBS的加入使体系黏度降低,增加流动性。PBS对改善共混薄膜亲水性有一定作用。     

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。     

PLA/PPA共混材料的相容性和热力学性能

采用熔融共混的方法制备了聚己二酸丙二醇酯(PPA)增塑改性聚乳酸(PLA)材料,采用动态力学热分析(DMA)测试仪、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)等手段研究了聚乳酸/聚己二酸丙二醇酯(PLA/PPA)共混材料的相容性、热性能和力学性能。结果表明,在PPA组分质量分数低(5%)的时候,共混物是完全相容体系;随着PPA组分含量的增加,共混物的玻璃化转变温度及冷结晶温度降低,断裂伸长率大幅度增加,当PPA质量分数为20%时,共混材料的断裂伸长率达到248%,获得了良好的增塑聚乳酸的效果。     

PBS/PLA/滑石粉3D打印线材制备及熔融沉积成型工艺研究

以聚丁二酸丁二醇酯(PBS)为基体,滑石粉和聚乳酸(PLA)为改性剂,采用熔融挤出法制备了PBS/PLA/滑石粉三维 （3D）打印线材,并对其进行了熔融成型研究。通过分析结晶性能、流变性能、力学性能、断面形貌和打印效果对PBS/PLA/滑石粉体系进行了探究。结果表明,PLA的加入使PBS的结晶温度下降了5 ℃;随着PLA含量的增加,材料的复数黏度、储能模量和损耗模量均得到提高;而拉伸强度则随PLA含量的增加下降了1.71 MPa,缺口冲击强度下降了2.63 kJ/m2;PLA含量的增加使断面逐渐粗糙;在打印效果上复合材料的打印模型随PLA含量的增加而变得美观规整,当底板温度高于110 ℃时,打印制件的翘曲度较低,同时拉伸强度随着打印温度的升高而增加。     

PLA/PBAT薄膜的制备及其降解性能研究

以过氧化二苯甲酰(BPO)为界面相容剂,采用熔融挤出、吹塑成型的方法制备了聚乳酸/己二酸-对苯二甲酸-丁二酯共聚物(PLA/PBAT)薄膜。通过力学性能检测和碱液加速降解试验研究了PBAT含量对PLA/PBAT薄膜力学性能及降解速率的影响;并运用红外光谱(FTIR)及动态力学分析(DMA)探究了降解机理。结果表明:随着PBAT含量的增加,PLA/PBAT复合薄膜的拉伸强度、拉伸模量及直角撕裂强度减小,断裂伸长率增大。PLA/PBAT复合薄膜的降解实质是酯键的水解。与降解前相比,降解后薄膜的储能模量大幅度降低,玻璃化转变温度略微下降。     

Preparation and properties of poly(Nε,Nε-dicarboxymethyl-l-lysine)

A new ampholytic homopolypeptide, $\text{poly}\text{(N}{}^{\mathrm{\epsilon }}\text{,N}{}^{\mathrm{\epsilon }}\text{-}\text{dicarboxy-methyl-}\text{l}\text{-lysine}\text{)}$, which has one tertiary amino and two carboxyl groups in the side chain has been derived from a hydrochloride salt of poly(L-lysine). The polymer in aqueous solution seems to be in the coil form with locally extended structure (LES) at neutral pH. In both the acidic and alkaline regions, the molar ellipticity of the polymer changes as a result of change in net charge on the side chain. The conformational changes may be from the coil with LES to other coiled forms. 5–7 M NaClO₄ and 80% aqueous methanol induce the α-helix in the polymer at neutral pH. Divalent cations, Cu²⁺ and Ca²⁺, do not induce any remarkably ordered structures such as α-helix or β-structure in the polymer in aqueous solution at any pH. Ultraviolet absorption studies show an absorption peak of the polymer-Cu²⁺ complex near 240 nm. Dependence of the peak intensity on pH at various q values ($\text{q =}\text{[}\text{Cu}{}^{\mathrm{2+}}\text{]}\text{[}\text{residue}\text{]}$) indicates the two steps of the complex formation. At q less than 0.64, the formation is described only with the first step. An average coordination number for Cu²⁺ at the first step was calculated to be about 2 by the method of Mandel and Leyte. The association constant of Cu²⁺ with the residue at the step was determined from the absorption data to be far smaller than that for the Cu²⁺-EDTA complex. The second step of the formation occurs in the case of large q but the absorption data for the second step cannot be obtained exactly due to precipitation.     

Wet Milling of Fe/Al/Al2O3 and Fe2O3/Al/Al2O3 Powder Mixtures

Wet milling of Al₂O₃-aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al₂O₃ and Fe₂O₃/Al/Al₂O₃ powder mixtures. The influence of the milling process on the physical and chemical properties of the milled powders has been studied. Particle refinement and homogenization were found not to play a dominant role, whereas plastic deformation of the metal particles leads to the formation of dislocations and a highly disarranged polycrystalline structure. Although no chemical reactions among the powder components in Fe₂O₃/Al/Al₂O₃ powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al₂O₃ powder mixtures caused by mechanical alloying was detected. Chemical reactions of Fe and Al particle surfaces with the atmosphere and the milling media lead to the formation of highly porous hydroxides on the particle surfaces. Hence the specific surface area of the powders increases, while the powder density decreases during milling. The fraction of Fe oxidized during milling was determined to be 0.13. The fraction of Al oxidized during milling strongly depends on the metal content of the powder mixture. It ranges between 0.4 and 0.8.     

Participation of lewis base on vinyl chloride polymerization with Al(C2H5)3CCl4 catalyst system

The polymerization of vinyl chloride has been investigated using an $\text{Al}\text{(}\text{C}{}_2\text{H}{}_5\text{)}{}_3\text{CCl}{}_4$ catalyst system in the presence of various Lewis bases. Effective Lewis bases are γ-butyrolactone, diglyme and diethylenetriamine which are multidentate. The rate of polymerization is dependent not only on the basicity of the Lewis base used but also on a coordination number of one. The latter is the predominant factor. For the effect of polymeric amines, a tentative hypothesis is discussed.     

Sintering of Si3N4-Y2O3-Al2O3

Sintering kinetics of the system Si₃N4-Y2O₃-Al₂O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si₃N₄ were studied with additions of 4 to 17 wt% Y₂O₃ and 4 wt% A1₂O₃. Sintering occurs by a liquid-phase mechanism in which the kinetics exhibit the three stages predicted by Kingery's model. However, the rates during the second stage of the process are higher for all compositions than predicted by the model. X-ray data show the presence of several transient phases which, with sufficient heating, disappear leaving mixtures of β ' -Si₃N₄ and glass or β '-Si₃N₄, α '-Si₃N₄, and glass. The compositions and amounts of the residual glassy phases are estimated.     

Synthesis and Characterization of Ti0.33Ta0.33Nb0.33C and Ti0.33Ta0.33Nb0.33CxN1-x Whiskers

Ta_0.33Ti_0.33Nb_0.33C and Ta_0.33Ti_0.33Nb_0.33C _x N_{1− x} whiskers were synthesized via a carbothermal vapor-liquid-solid growth mechanism in the temperature range 900°-1450°C in Ar or N₂. The optimum temperature was 1250°C. Whiskers were obtained in a yield of 70-90 vol%. The whiskers were 0.5–1 µm in diameter and 10–30 µm in length. The starting materials that produced the highest whisker yield were: TiO₂, Ta₂O₅, Nb₂O₅, C, Ni, and NaCl. C was added to reduce the oxides, and Ni to catalyze whisker growth. NaCl was used as a source of Cl for vapor-phase transportation of Ta and Nb oxochlorides and Ti chlorides to the catalyst. The catalyst metal was recycled several times during the synthesis and was transported as NiCl₂( g ) according to thermodynamic calculations. The rate of formation and the chemical composition of the whiskers depended on the synthesis temperature, the choice of catalyst, and the atmosphere. At low temperatures, the whiskers were enriched in Nb and Ta, whereas the Ti content increased with increased synthesis temperature.