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以聚乳酸(PLA)为原料,添加不同含量的麦秸秆纤维(WF),热压成型制备WF/PLA复合材料。通过傅立叶变换红外吸收光谱仪(FTIR)分析了木聚糖酶、果胶酶、淀粉酶处理前后WF化学官能团变化,研究了WF添加量以及不同生物酶处理WF对WF/PLA复合材料力学性能、吸湿吸水性能的影响,观察其断面微观结构。结果表明:FTIR显示生物酶可溶解WF中纤维素、表面脂类物质等。随着WF添加量的增加,未处理WF/PLA复合材料的拉伸强度呈下降趋势,当WF质量分数为7%时,WF/PLA复合材料的冲击强度最高为6.961 kJ/m2,平衡吸湿率最低为1.29%。当WF添加量为7%时,经果胶酶处理的WF/PLA复合材料力学性能最好,其拉伸强度、冲击强度分别为16.89、8.456 MPa;平衡吸湿率最低为0.56%,24 h吸水率最低为1.18%。断面微观结构显示,相比于未处理,经酶处理后的WF与PLA界面结合较好,其中经果胶酶处理后两者界面结合性最好。 相似文献
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采用熔融沉积法(FDM)3D打印工艺制作木粉(WF)与聚乳酸(PLA)质量比为3:100的WF/PLA复合材料,研究了打印工艺参数对WF/PLA复合材料力学性能的影响,确定了最佳打印工艺条件,然后,在最佳条件下,打印WF与PLA质量比为11:100的WF/PLA复合材料,并且,将该材料的性能与FDM 3D打印PLA试样进行了对比。结果表明,当打印层厚度为0.1 mm、打印温度为220℃、打印速度为50 mm/s、填充密度为100%、沉积角度为0时,WF/PLA复合材料的力学性能最佳。在该工艺条件下,WF与PLA质量比为11:100的WF/PLA复合材料的拉伸强度、拉伸模量、弯曲强度、弯曲模量和冲击强度分别为纯PLA的89.61%、97.56%、82.86%、92.40%和95.04%,与纯PLA相比,复合材料的表面润湿性能较好,吸水率显著增大。 相似文献
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在聚乳酸(PLA)/自制抗菌母料(AMB)纳米复合材料中添加扩链剂甲苯二异氰酸酯(TDI),研究了TDI含量对纳米复合材料抗菌性能和力学性能的影响。结果表明,TDI质量分数在0~2.5%范围内,随着TDI含量的增加,复合材料对大肠杆菌的抗菌性能逐渐轻微减弱,但仍为强抗菌材料;拉伸强度、缺口冲击强度和弯曲强度逐渐增加,断裂伸长率先增加后减小。当TDI质量分数为2.5%时,复合材料的综合性能最好,与PLA/AMB相比,其拉伸强度、断裂伸长率、缺口冲击强度和弯曲强度分别提高了7.9%,147.6%,29.4%和22.0%,抗菌率为99.1%,仍为强抗菌材料。 相似文献
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将环氧系扩链剂ADR添加到聚乳酸(PLA)/Nano-ZnO/叶绿素铜酸(CCA)纳米复合抗菌材料中,研究了ADR添加量对复合材料抗菌性能和力学性能的影响。结果表明,在ADR质量分数为0%~1.0%范围内,随ADR含量的增多,复合材料对大肠杆菌的抗菌性能略有减弱,其缺口冲击强度有较大幅度的增加,弯曲强度、拉伸强度略有增加,断裂伸长率先增大后减小,ADR质量分数小于1.0%时仍属强抗菌材料。当ADR质量分数为1.0%时复合材料的综合性能较好,其抗菌率为99.4%,拉伸强度、断裂伸长率、缺口冲击强度、弯曲强度分别比PLA/Nano-ZnO/CCA复合材料提高了4.6%,11.6倍、71.4%,4.8%。 相似文献
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采用熔融共混法制备了聚乳酸(PLA)/纳米碳酸钙(nano-CaCO3)复合材料,利用X射线衍射仪、差示扫描量热仪(DSC)、万能拉力机和摆锤冲击试验机等研究了PLA/nano-CaCO3复合材料的结晶性能和力学性能。结果表明:nano-CaCO3粒径及用量、表面处理剂种类及用量均会对PLA/nano-CaCO3复合材料的结晶行为产生一定影响。当硬脂酸钠用量为3.5%(质量分数)时,与纯PLA相比,随着nano-CaCO3用量的增加,PLA/nano-CaCO3复合材料的拉伸强度逐渐下降,断裂伸长率和缺口冲击强度均逐渐升高。 相似文献
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以聚乳酸(PLA)和聚己二酸/对苯二甲酸丁二酯(PBAT)为基体,杨木粉(WF)为填充增强材料,使用混炼机熔融共混制备PLA/PBAT/WF复合材料,采用熔融沉积成型(FDM)技术制备标准实验试样,通过扫描电子显微镜、红外光谱分析、旋转流变测试以及力学试验等方法,研究不同含量的硅烷偶联剂KH550对PLA/PBAT共混物以及PLA/PBAT/WF的相容性、流变性及力学性能的影响。结果表明,在偶联剂用量为3 %(质量分数,下同)时,拉伸强度提高了136 %;偶联剂KH550与 PLA和PBAT共价键偶联生成接枝聚合物,二者相容性得到提高;同时偶联剂与WF表面羟基发生缩聚反应有效的改善了其与PLA/PBAT的基体相容性,PLA/PBAT/WF复合材料的FDM的制件力学性能得到较大提升;复合材料的黏度随偶联剂含量的增加呈下降的趋势,含量为3 %时线材的综合打印性能及制品质量最佳。 相似文献
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以聚乳酸(PLA)为基体树脂,nano-ZnO和叶绿素酮酸(CCA)为复合抗菌剂,通过溶液共混制得抗菌母料(AMB),用PLA与AMB、柠檬酸三丁酯(TBC)热机械共混制得PLA/AMB/TBC纳米复合材料。研究了母料中nano-ZnO/CCA质量配比对纳米复合材料抗菌性能和力学性能的影响。结果表明,少量CCA的加入使纳米复合材料对大肠杆菌的抗菌性能大幅度提高;当纳米复合材料中TBC和nano-ZnO质量分数分别为10%和0.9%,AMB中nano-ZnO/CCA质量配比为18/8时,纳米复合材料的抗菌性能最好,其抗菌率达到99.6%,断裂伸长率是纯PLA的2.17倍,拉伸强度、弯曲强度和冲击强度保留率分别为75%,65%,70%。 相似文献
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A new ampholytic homopolypeptide, , 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 () 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. 相似文献
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Silvia Schicker Daniel E. García Igor Gorlov Rolf Janssen Nils Claussen 《Journal of the American Ceramic Society》1999,82(10):2607-2612
Wet milling of Al2 O3 -aluminide alloy (3A) precursor powders in acetone has been investigated by milling Fe/Al/Al2 O3 and Fe2 O3 /Al/Al2 O3 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 Fe2 O3 /Al/Al2 O3 powder mixtures were observed, the formation of a nanocrystalline, ordered intermetallic FeAl phase in Fe/Al/Al2 O3 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. 相似文献
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Sintering kinetics of the system Si3 N4-Y2O3 -Al2 O3 were determined from measurements of the linear shrinkage of pressed disks sintered isothermally at 1500° to 1700°C. Amorphous and crystalline Si3 N4 were studied with additions of 4 to 17 wt% Y2 O3 and 4 wt% A12 O3 . 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 ' -Si3 N4 and glass or β '-Si3 N4 , α '-Si3 N4 , and glass. The compositions and amounts of the residual glassy phases are estimated. 相似文献
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Akira Akimoto 《Polymer》1974,15(4):216-218
The polymerization of vinyl chloride has been investigated using an 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. 相似文献
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Mats Carlsson Mats Johnsson Mats Nygren 《Journal of the American Ceramic Society》1999,82(8):1969-1976
Ta0.33 Ti0.33 Nb0.33 C and Ta0.33 Ti0.33 Nb0.33 C x N1− 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 , Ta2 O5 , Nb2 O5 , 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. 相似文献