矿渣微粉填充PA6复合材料的力学性能研究

以矿渣微粉为填料,经共混、挤出造粒、注塑成型工序制备出矿渣微粉/尼龙6(PA6)复合材料,采用扫描电镜(SEM)观察断口形貌,通过检测样品的拉伸强度、断裂伸长率和冲击强度,研究了矿渣微粉对尼龙6复合材料的力学性能影响。结果表明,矿渣微粉在PA6复合材料中主要起到承受部分荷载,阻挡裂纹扩展的作用。当用矿渣微粉质量分数为25%填充PA6时,与纯PA6相比,拉伸强度能提高13%。此时拉伸强度为52 MPa,冲击强度为5.794 k J/m2。     

3D打印PLA/PCL复合材料的力学性能

以聚己内酯(PCL)和聚乳酸(PLA)为实验原料,分别配比PCL质量分数在10%,20%和30%的PLA/PCL混合料,再经双螺杆挤出机挤出造粒后得到PLA/PCL复合材料。分别以纯PLA和3种不同配比的PLA/PCL复合材料为实验原料,使用粒料3D打印机制备拉伸、弯曲和冲击试件,并进行力学性能测试。结果表明,纯PLA试件的拉伸强度最大,为50.64 MPa,随着PCL含量的增加,试件的拉伸强度逐渐下降;试件的断裂伸长率随着PCL的含量的增加先增高后降低,当PCL质量分数为20%时,断裂伸长率达到最大值为25%;试件的弯曲强度随PCL含量的增加逐渐下降;试件的冲击强度随PCL含量的增加逐渐增大,当PCL质量分数为30%时,试件的冲击强度达到最大值,为15.80 kJ/m~2。     

PA6/POE-g-MAH/PE–UHMW材料的制备及性能

以耐热改性组分尼龙6(PA6)为基体材料,超高分子量聚乙烯(PE-UHMW)为综合性能平衡组分,增韧剂马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)为相容剂,制得PA6/PE-UHMW/POE-g-MAH三元复合材料。研究结果表明,POE-g-MAH的加入可改善PA6的韧性,但降低了PA6的拉伸强度,随着POE-g-MAH加入量增加,PA6断裂伸长率逐渐增加,当添加量为30%时,断裂伸长率达到最大值397%,拉伸强度为39 MPa。PE-UHMW组分不仅提高了复合材料的拉伸强度和韧性,同时改善了其耐水解性能。当PA6∶POE-g-MAH∶PE-UHMW=70∶30∶10时,断裂伸长率提高至477%,拉伸强度为42 MPa。通过扫描电子显微镜分析观察复合材料的微观形态,发现在PA6基体中POE-g-MAH和PE-UHMW形成"核–壳"结构,对PA6韧性的提高起到了协同作用。     

挤出工艺对长碳链尼龙管断裂伸长率的影响

通过挤出工艺生产长碳链尼龙(PA)11管,并采用火焰热处理方式对PA11管进行后处理,借助拉伸试验设备对PA11管的断裂伸长率进行评价。研究了不同的挤出模具温度(模温)、挤出速度、冷却水温和火焰热处理强度等工艺参数对PA11管断裂伸长率的影响。结果表明,PA11管的断裂伸长率随着模温和火焰热处理强度的升高呈现先升高后降低的趋势,随着挤出速度和冷却水温的降低而升高。生产PA11管最佳的工艺参数为模温235℃、挤出速度25 m/min、冷却水温20℃、火焰热处理强度40%,此时PA11管的断裂伸长率达到219%,拉伸后试样表面的“橘皮状”缺陷消失。     

含磷超支化聚合物共混改性PA6的性能研究

以尼龙(PA)6为基体树脂,含磷超支化聚酰胺(HBPA)为改性剂,通过熔融挤出制备了PA6/HBPA共混物。采用毛细管流变仪、力学性能测试、极限氧指数(LOI)测试及热重(TG)分析研究了HBPA含量对共混物流变性能、力学性能和阻燃性能的影响。结果表明,随HBPA含量的增加,共混物熔体的非牛顿指数逐渐接近于1,熔体向牛顿流体转变;熔体表观黏度下降,加工性能得到改善;熔体黏流活化能增大,对温度的敏感性变强。加入少量的HBPA能够提高PA6的力学性能,当HBPA质量分数为0.5%时共混物拉伸强度最大,由纯PA6的62.6 MPa增加到72.4 MPa,当HBPA质量分数为1%时,断裂伸长率和缺口冲击强度最大,分别由纯PA6的228.3%和19.8 kJ/m2提高到284.7%和24.5 kJ/m2。LOI测试和TG分析表明,HBPA可通过促进凝聚相成炭,提高PA6的阻燃性,当HBPA质量分数为1.5%时,共混物的LOI最大,达到28.4%。     

淀粉/PVA/木糖醇改性材料制备及其黏附性能研究

以淀粉为基材,添加聚乙烯醇(PVA)、木糖醇为改性剂,研究木糖醇用量对材料力学性能、黏附性能与柔软程度的影响。结果表明,随着木糖醇含量增加,材料的拉伸强度先减小后略有增加,断后伸长率和撕裂强度总体呈现先增大后减小的变化趋势,硬度逐渐降低,柔性逐渐提高,黏附所需时间先减小后增大。当木糖醇质量分数为5%时,断后伸长率和撕裂强度达到最大值,黏附所需时间达到最小值。最优配方为：去离子水75%、淀粉15%、PVA 5%和木糖醇5%,此时材料的拉伸强度为7.5MPa,后伸长率为141.1%,撕裂强度为7.6N/mm,硬度为17.2HA,黏附所需时间为1.1s。材料柔性良好,在生物医用黏附领域具有良好的应用前景。     

微纳层叠共挤PP/PA6/CNTs原位微纤复合膜的制备及性能研究

采用双转子连续混炼挤出机与微纳层叠共挤出成型设备制备了聚丙烯/聚酰胺6/碳纳米管（PP/PA6/CNTs）复合材料和原位微纤复合膜,通过扫描电子显微镜（SEM）、流变仪、差示扫描量热仪（DSC）、万能拉伸试验机及电阻测试仪对其微观结构、流变性能、结晶性能、力学性能和导电性能进行了表征。结果表明,与共混相比,微纳层叠共挤出法使得分散相PA6/CNTs形成了微纤,微纤的形成不仅提升了复合膜的动态流变性能,并且增加了基体PP相的结晶度,提高了PA6相的结晶温度,提升了复合膜的结晶性能;当CNTs含量为0.5 %（质量分数,下同）时,复合膜的拉伸强度和断裂伸长率均达到最大值,分别为42.17 MPa和857.82 %,体积电阻率（R）下降到10⁴ Ω·cm,综合力学性能和导电性能达到最佳。     

无机颗粒/碳纤维共增强聚酰胺6复合材料的制备与力学性能研究

采用熔融挤出法制备出无机颗粒(IP)增强聚酰胺6(PA6)复合材料,使用叠层模压法制备了IP/碳纤维(CF)共增强PA6复合材料(PA6/IP/CF)。利用场发射扫描电子显微镜、万能试验机等研究了IP的形貌和含量对复合材料性能的影响。结果表明,当滑石粉(TALC)的添加量达到10%(质量分数,下同)时,PA6/CF/TALC复合材料的各项力学性能达到最大值,弯曲强度为374.6 MPa、剪切强度为58.7 MPa、冲击强度为76.9 kJ/m~2;当玻璃微珠(GB)的添加量达到15%时,PA6/CF/GB复合材料的各项力学性能达到最大值,弯曲强度为404.4 MPa、剪切强度为66.7 MPa、冲击强度为86.5 kJ/m~2;GB相较于TALC对复合材料的增强效果更好,使复合材料的综合力学性能得到进一步提高。     

园林绿化打草绳用尼龙6的耐热性和耐磨性的辐照改性

针对尼龙6(PA6)打草绳的耐磨性和高温粘连性问题，采用电子束辐照的方法对其进行改性。对取向前后的PA6进行不同剂量的电子束辐照，并采用X射线衍射(XRD)、电子拉力机、红外光谱(FTIR)、差示扫描量热仪(DSC)等对不同吸收剂量的样品进行测试和表征。力学性能测试结果表明，未取向样品随着吸收剂量增加，断裂伸长率下降，从270%下降到145%,拉伸断裂强度先上升再下降，取向性PA6随着吸收剂量增加，断裂伸长率从118%下降到43%,拉伸断裂强度从110 MPa下降到90 MPa;凝胶含量测试结果表明，未取向PA6在辐照剂量达到100 kGy后其凝胶含量可达54%,继续增加辐照剂量，凝胶含量增加缓慢，而取向性PA6在150 kGy后凝胶含量达到最大值，随后略微降低；DSC测试结果表明，未取向的样品的结晶度随着辐照剂量的增加先由23.2%上升到25.9%后下降到24.7%,而取向的样品的结晶度与未取向样品相比显著提升，但是取向性PA6样品随着辐照剂量的增加，结晶度不断下降，从27.4%下降到24.8%;FTIR分析表明，取向性样品的羰基指数显著高于未取向性样品的，且增长速率也明显快于未取向...     

回收PET/PA66复合材料的研究

采用OZ作为反应相容剂,通过反应挤出制备了回收聚对苯二甲酸乙二酯(PET)/聚酰胺66(PA66)复合材料。研究了相容剂用量对复合材料的拉伸强度、冲击强度、流变性能和形态结构等的影响。结果表明,PA66质量分数为60%、相容剂OZ质量分数为5%时,可以得到综合性能与PA66相当的复合材料,降低了PA66的成本,同时使PET得到了回收。     

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.     

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.     

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.     

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.