PLA/BF/ATH阻燃复合材料的性能研究

将氢氧化铝(ATH)作为阻燃剂与聚乳酸(PLA)、竹粉(BF)共混,得到PLA/BF/ATH阻燃复合材料,并对该复合材料的性能进行了测试与表征。结果表明:随着ATH用量的增加,PLA/BF/ATH阻燃复合材料的力学性能有所降低,但复合材料的热稳定性和残炭率相对提高,而且ATH的引入对复合材料燃烧过程中热量和烟气的释放产生了一定的抑制作用;另外,当ATH用量为25 phr时,复合材料具有最佳综合性能。     

阻燃处理对聚乳酸/竹粉复合材料吸水性能的影响

利用氢氧化铝(ATH)、硅烷改性聚磷酸铵(APP)及APP/ATH复配阻燃剂与聚乳酸(PLA)、竹粉(BF)共混,制备阻燃型PLA/BF复合材料,并对其进行不同时间的浸水处理,测定阻燃型PLA/BF复合材料的吸水率和浸水处理前后的力学性能。结果表明,浸水处理后复合材料的拉伸强度和冲击强度均有不同幅度的降低,其中,APP/ATH复配阻燃剂阻燃型复合材料力学性能下降最显著,浸水4d后,其拉伸强度下降了近90%;APP和ATH单独阻燃的复合材料在浸水过程中的吸水率和吸水厚度膨胀率均较低,而APP/ATH复配阻燃剂阻燃型PLA/BF复合材料的吸水率最高,尺寸稳定性最差。     

聚乳酸/聚磷酸铵复合材料的阻燃性能和流变性能研究

采用共混的方法制备了聚乳酸/聚磷酸铵(PLA/APP)复合材料,并通过极限氧指数(LOI)和流变性能测试研究了APP的添加对PLA阻燃性能和流变性能的影响。结果表明:APP对PLA材料具有显著的阻燃作用,在其用量为10份时,PLA/APP复合材料的LOI值可达到36.2%;PLA/APP复合材料熔体的表观黏度随着剪切速率和温度的提升而逐渐减小,并且随着APP用量的增加呈先升后降趋势;复合材料的非牛顿指数随着温度的升高而增大,并且随着APP用量的增加呈先升后降趋势;复合材料熔体的黏流活化能随着剪切速率的增加而减小,并且随着APP用量的增加呈先减小后增大趋势。     

竹纤维质量分数对PCL/PLA/竹纤维复合材料性能的影响

将竹纤维(BF)与聚己内酯(PCL)、聚乳酸(PLA)熔融共混,通过模压工艺制备了PCL/PLA/BF增强复合材料。研究了BF质量分数对该复合材料力学性能、热稳定性以及熔融结晶行为的影响。结果表明:随着BF质量分数的增加,PCL/PLA/BF复合材料的冲击强度、拉伸强度和断裂伸长率均先增大后减小,并均在BF质量分数为40%时达到最大值,分别为11.26 k J/m2、12.68 MPa和5.2%;BF质量分数对PCL/PLA/BF复合材料的热稳定性无明显影响;BF的加入使得复合材料中PCL、PLA共混物的玻璃化转变温度降低,但不同BF质量分数的复合材料玻璃化转变温度变化不大;BF的加入使得复合材料结晶温度小幅提升,但结晶峰强度随着BF质量分数的增加而逐渐减弱。     

不同增塑剂对PLA/BF复合材料的性能影响

采用注塑工艺,探讨了乙酰柠檬酸三丁酯(ATBC)、聚乙二醇1500(PEG1500)、甘油(GY)和聚乙二醇200(PEG200)四种增塑剂及ATBC含量对聚乳酸/竹纤维(PLA/BF)复合材料的力学性能、吸水性、热稳定性、相容性的影响。结果表明,四种增塑剂都能使复合材料PLA/BF的相容性有所改善,但作用不同,少量ATBC的添加有利于PLA/BF复合体系相容性的提高。PEG1500和GY的添加有利于复合材料热稳定性的增加,而PEG200和ATBC则相反。PEG1500使复合材料的吸水率改变最大。力学性能分析可知,PEG1500对复合材料的韧性作用最显著,但同时拉伸强度的下降幅度也是最大,综合各因素得出ATBC最适合做该PLA/BF复合材料的增韧改性剂。随着ATBC含量的增加PLA/BF复合材料的热稳定性下降,吸水率提高,拉伸强度下降,韧性提高。     

水滑石与聚磷酸铵协同阻燃辐射交联型聚烯烃

为了开发更安全可靠的工程材料，将水滑石(LDH)和聚磷酸铵(APP)复配加入聚烯烃复合材料，通过熔融共混方式制备阻燃聚烯烃复合材料，通过电子束辐射交联的方式提升聚烯烃复合材料的力学性能。结果表明：APP的加入可以有效增加聚烯烃复合材料热分解残留物质量，但过量添加APP对复合材料热延伸性能产生明显负面作用。当APP的添加量为20份，聚烯烃复合材料的热释放速率峰值(pHRR)降至192 kW/m²，有效延缓聚烯烃复合材料燃烧早期热量释放速度。电子束辐照后样品的力学性能提升，APP的添加量为20份，聚烯烃复合材料的拉伸强度和断裂伸长率分别达到9.8 MPa和248%。选择合适的配比进行复配并辐射交联，可以制备具有优异阻燃性能和良好力学性能的聚烯烃复合材料。     

竹质纤维形态对聚乳酸基竹塑复合材料性能的影响

为高值化利用竹材加工剩余物资源,以聚乳酸(PLA)为基体,竹粉纤维(BF)、竹屑纤维(BS)、竹原纤维(BN)与竹浆纤维(BP)为填料,采用密炼-注塑工艺制备了四种竹塑复合材料,研究了竹质纤维种类对其结构与性能的影响。研究结果显示,BP与BN纤维长径比更大,BS中颗粒形态较多,BF与BS质地较刚硬。BF、BN与PLA共混熔体的混炼扭矩更大,PLA/BP复合材料吸水率最大。BF,BS,BN与PLA的界面相容性较好,其添加改善了复合材料的力学性能,而BP添加降低了复合材料的力学性能。与PLA相比,在纤维质量分数为30%时,PLA/BF,PLA/BS与PLA/BN复合材料拉伸强度分别提高了17.85%,13.6%,11.89%,冲击强度分别提高24.33%,18.70%,35.57%,弯曲强度分别提高19.45%,21.45%,4.99%。PLA/BF复合材料的综合力学性能最优,其次为PLA/BS复合材料,PLA/BP复合材料最差。研究可为竹塑复合材料的开发与应用提供有益参考。     

PLA/BF复合材料的增塑研究

以聚乙二醇400(PEG400)为增塑剂,采用注塑成型的方法制备了聚乳酸/竹纤维(PLA/BF)复合材料,探讨了PEG400用量对PLA/BF复合材料增塑性能的影响。结果表明,PEG400的引入虽在一定程度上有利于PLA/BF复合材料两相相容性的提高,但会使复合材料的热稳定性下降、吸水性提高。力学性能测试表明,随着PEG400用量的增加,PLA/BF复合材料的拉伸强度逐渐下降,冲击强度则基本呈上升趋势,即PEG400对复合材料可起到一定的增韧作用。     

APP/BF–KH550协同阻燃热塑性聚氨酯的性能

以竹纤维(BF)为协同阻燃剂,将聚磷酸铵(APP)引入热塑性聚氨酯(PUR-T)中,制备了膨胀型阻燃复合材料。为了提高PUR-T的分散性,将硅烷偶联剂KH550接枝到BF上。对PUR-T基膨胀型阻燃复合材料进行了燃烧性能、力学性能测试,结果表明:与纯PUR-T相比,PUR-T/APP/BF KH550样品在UL94测试中达到了V 0等级;通过添加8%的APP和2%的BF-KH550,复合材料样品的极限氧指数达到了30.3%;同时,最大热释放速率值下降了86.6%;90%PUR-T/8%APP/2%BF KH550试样的拉伸强度为23.9 MPa,高于90%PUR-T/8%APP/2%BF样品。     

可生物降解PLA/St/BF复合材料的制备

以甘油为增塑剂,采用挤出注塑工艺制备了可生物降解聚乳酸(PLA)/淀粉(St)/蔗渣(BF)复合材料,研究了原料配比对复合材料力学性能、吸水性能、热稳定性及流变性能的影响,并利用扫描电子显微镜对复合材料断面进行了观察。结果表明:BF与St用量较大时,制备的PLA/St/BF复合材料仍能保持一定的力学性能,能满足实际加工要求;BF对PLA/St复合材料具有一定的增强作用;增大极性组分St和BF用量会大幅提高PLA/St/BF复合材料的吸水性,且组分间界面间隙变大。     

Synthesis of dysprosium/Mn–Cu ferrite binary nanocomposite: Analysis of structural,morphological, dielectric,and optomagnetic properties

Manganese–copper ferrite (MCFO) and dysprosium (Dy)-doped manganese–copper ferrite nanocomposites (Mn_0.5Cu_0.5Dy_xFe_2−xO₄) (x = 0, 0.05, 0.10, and 0.15) were synthesized by sonochemical method. Crystal structure and the structural parameters of the MCFO were analyzed based on the doping concentration of Dy ion. It was observed that the average crystalline size of the synthesized nanocomposite decreases when the concentration of Dy increases. The existing spherical surface morphology of the MCFO and Dy-doped MCFO nanocomposites were obtained through scanning electron microscopy. In the UV spectrum, the pristine MCFO sample showed an absorbance peak at 743 nm whereas the absorbance values of Dy-doped ferrite nanocomposite considerably shifted (blue) toward a lower wavelength (231–222 nm). The dielectric parameters of all ferrite nanocomposites were studied in the frequency range of 100 Hz to 5 MHz. The dielectric spectrum revealed that dielectric constant and loss tangent decreased with increased doping concentration of Dy ion. The saturation magnetization also changed with Dy doping in MCFO. The impact of Dy on manganese–copper ferrite changed the optical, dielectric and magnetic properties of the prepared binary ferrite nanocomposite, which can be used for microwave-absorbing material applications.     

Mechanical Properties of Compression Molded Banana Pseudo-stem Filled Unplasticized Polyvinyl Chloride (UPVC) Composites

Mechanical strengths of a banana pseudo-stem (BPS) fiber and unplasticized polyvinyl chloride (UPVC) composite were evaluated to assess the possibility of using it as a new material in engineering applications. Samples were fabricated by the compression molding process with reference to the effect of filler loading. The samples were submitted to mechanical tests to measure tensile, flexural, and impact properties of the composites. The nature of adhesion between the matrix and the reinforcement and information relating the structure of mechanical properties can be obtained by scanning electron microscopy (SEM) assessment of the composite fracture surface. The mechanical properties show that the composites did not have good adhesion between filler and matrix; on the other hand, the filler insertion improved the flexural modulus and the material rigidity.     

核壳型纳米粒子合成方法及其性能的研究进展

核壳纳米粒子作为复合纳米粒子一个重要的分支,由于其光、磁和催化等方面的优异性能,近年来引起了人们广泛的关注.本文主要介绍了核壳纳米粒子的制备方法及诸多性能,并对核壳纳米粒子的发展进行了展望.     

单向玻璃纤维-铝合金层板的几种力学性能研究

本文用实验方法研究了单向玻璃纤维-铝合金层板的拉伸性能、疲劳性能和冲击性能。利用金属体积分数理论验证了这类层板的拉伸性能。通过对其疲劳性能的实验研究，发现裂纹扩展速率的大小及刚度的下降与加载的最大循环应力密切相关的规律。实验发现该层板具有比铝合金好得多的冲击性能。     

TMPTMA在硅橡胶中的应用研究

研究了助交联剂三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)对硅橡胶硫化性能、力学性能、低温性能和粘接性能的影响。结果表明,加入少量TMPTMA能改善硅橡胶的硫化特性和工艺性,提高硫化胶的硬度,降低硅橡胶的结晶温度,并有效提高硅橡胶与金属的粘接强度;但TMPTMA用量超过一定数值后,由于TMPTMA部分自聚合,在硅橡胶内形成一定的交联网络,造成两相界面粘接力变差,致使硅橡胶的拉伸强度降低。当TMPTMA用量为1份时,硅橡胶具有最佳的综合性能。     

聚氨酯种类对机械性能以及阻尼性能影响研究

分别以聚四氢呋喃醚二醇(PTMEG)、聚氧化丙烯二醇(PPG-1000)为软段,以二苯基甲烷二异氰酸酯(MDI-50、MDI-100LL),以及扩链剂1,4-丁二醇(BDO)、三羟甲基丙烷(TMP)为硬段,采用预聚体法制备了聚氨酯弹性体。并系统研究了聚氨酯体系中各组分的种类对材料机械性能和阻尼性能的影响。     

A new precursor to lightweight porous Si–Al–O–B ceramics with enhanced microwave transmissivity

Nowadays, complicated preparation processes and harsh sintering conditions wave transparent ceramics limit its further development. To solve this problem, we explore a promising precursor by adopting a polymerization-pyrolysis method to prepare porous Si–Al–O–B ceramics at a mild sintering condition (1000 °C). The porous Si–Al–O–B ceramics exhibits enhanced wave transparency at 10–16 GHz with a low dielectric constant (<3), a low loss angle tangent value (<0.01), and simultaneously, a relative high flexible strength of 82 MPa. According to the results of the XRD and FTIR analysis, porous Al₄B₂O₉ crystallization dispersed in the amorphous SiO₂ matrix constructs the main phases of the products. The changes of Al and B elements are confirmed to have an effect on the phase compositions and micro structure of the composite ceramics, which obviously affect the mechanical and dielectric properties of the derived ceramics. The as-prepared porous Si–Al–O–B ceramics could be a potential candidate for next generation electronic window materials due to its low dielectric constant and loss angle tangent value, as well as high flexible strength.     

Effects of support and additive on oxidation state and activity of Pt catalyst in propane combustion

The effects of support and additive on the oxidation state and catalytic activity of Pt catalyst in the low temperature propane combustion were systematically investigated on Pt/MgO, Pt/Al₂O₃ and Pt/SiO₂–Al₂O₃. The catalytic activity varied much with both support materials and additives. The catalyst on the more acidic support showed higher activity, and the catalytic activity on every support materials increased as the electronegativity of additives increased, while some additives decreased the activity. The oxidation state of platinum, estimated by white line intensity of Pt L_III-edge XANES spectrum, also varied with the support and additives, and additives with higher electronegativity greatly prevented the platinum from its oxidation under oxidising atmosphere. Among almost all the catalysts with various supports and various additives, a clear relationship was observed between the oxidation state of platinum and the catalytic activity; the more metallic platinum showed higher activity. Thus, it was concluded that the total electrophilic/electrophobic property derived from those of the support and additive controls the oxidation state of platinum, which intensively affects the catalytic activity; i.e. higher electrophilic property provides less oxidised platinum, resulting in high catalytic activity. The mechanism of this effect was also discussed on the basis of thermochemical data, and it was proposed that the electrophobic materials promote the noble metal oxidation since the noble metal oxo-anion such as PtO^δ− is more stabilised with electrophobic cation.     

阻隔性PET/PEN共聚酯的性能研究

对共聚型阻隔聚酯PETNx(x为共聚酯中NDA占羧酸总质量的百分比)的热性能、流变性能和阻隔性能进行了研究。结果表明,PETNx体系属于假塑性流体。PETNx的CO2气体阻隔性优于常规PET;随着PETNx中NDA含量的增加,共聚物的玻璃化温度呈线性增高。