硅烷偶联剂改性酚醛泡沫塑料的制备和性能研究

以硅烷偶联剂KH–560作为增韧剂,制备了KH–560改性酚醛泡沫塑料,研究了KH–560含量对酚醛泡沫塑料性能的影响。结果表明,添加KH–560制备的改性酚醛泡沫塑料的性能得到明显提高,当KH–560质量分数(相对于参加反应苯酚的质量)为7%时,改性酚醛泡沫塑料的压缩强度、冲击强度和阻燃性均达到最大值,同纯酚醛泡沫塑料相比,分别提高了37%,68%和3.8%。当KH–560质量分数为5%时,改性酚醛泡沫塑料的粉化率最小,为1.6%。热失重分析结果表明,改性酚醛泡沫的热稳定性仅稍有降低,500℃时的质量保持率较纯酚醛泡沫塑料提高1%~3%,仍然保持优良的热稳定性。     

基于生物质单宁的低甲醛释放量酚醛泡沫制备与性能

利用生物质单宁取代部分苯酚,定量尿素作为甲醛捕捉剂,制备了单宁改性可发泡酚醛树脂,然后以硫酸与对甲苯磺酸混合酸作为固化剂,正戊烷为发泡剂,制备了单宁改性酚醛泡沫。利用傅里叶变换红外光谱和核磁共振氢谱对树脂结构进行了表征,依据GB/T 30694–2014检测了不同单宁用量对酚醛泡沫甲醛释放量的影响,使用电子万能试验机和极限氧指数(LOI)仪检测了不同单宁用量对酚醛泡沫力学性能和阻燃性能的影响。结果表明,改性酚醛泡沫pH为6;当加入的单宁用量为苯酚质量的3%时,改性酚醛泡沫甲醛释放量最低为1.1875 mg/L,达到了人造板E1标准,泡沫压缩强度为0.2166 MPa,冲击强度为2.81 kJ/m~2,粉化率低至2.01%,LOI达到37%,其综合性能最好。相对于纯酚醛泡沫,单宁改性酚醛泡沫的力学性能有所提升,脆性明显改善,阻燃性能显著提高。     

腰果酚改性焦油粗酚酚醛泡沫塑料的研究

为降低酚醛泡沫塑料的成本,改善其性能,以焦油粗酚、苯酚、多聚甲醛为原材料,腰果酚为改性剂,合成可发性腰果酚改性焦油粗酚酚醛树脂,发泡制备出腰果酚改性焦油粗酚酚醛泡沫塑料。研究了腰果酚用量对改性焦油粗酚酚醛泡沫塑料保温性能、阻燃性能、吸水率、力学性能和耐热稳定性等的影响,并通过傅立叶变换红外光谱仪对合成改性焦油粗酚酚醛树脂进行了表征,通过生物显微镜、热重分析仪对改性焦油粗酚酚醛泡沫塑料的微观结构和耐热稳定性进行表征。结果表明,腰果酚的加入使改性焦油粗酚酚醛泡沫塑料的综合性能有较大改善,当腰果酚占混合酚的质量分数为15%时,改性焦油粗酚酚醛泡沫塑料的综合性能最佳,吸水率为4.51%,压缩强度为0.31 MPa,弯曲强度为0.55 MPa,导热系数为0.036 W/(m·K),极限氧指数为35.2%。改性焦油粗酚酚醛泡沫塑料的保温、阻燃性能和耐热稳定性较好,泡孔致密均匀。     

氧化石墨改性酚醛泡沫材料的制备及其表征

采用原位聚合法制备了氧化石墨改性酚醛树脂,并以其为主要原料制备酚醛泡沫材料。通过红外光谱仪、万能试验机、热重分析仪、扫描电子显微镜等测试手段对改性酚醛泡沫材料的力学性能、热稳定性以及微观结构进行表征。结果表明,与未改性的酚醛泡沫塑料相比,添加1.0%氧化石墨改性酚醛泡沫材料泡孔尺寸更加均匀,压缩强度比未改性的酚醛泡沫塑料提高65.0%,表面粉化率显著降低,氧化石墨对酚醛泡沫材料的强度、韧性及热稳定性均有显著的提高。     

磷酸三苯酯改性酚醛纤维的制备及其性能研究

以磷酸三苯酯改性酚醛树脂为原料,采用熔融纺丝法制备出改性酚醛纤维,并对改性酚醛纤维的结构和性能进行了研究。结果表明:与纯酚醛纤维相比,磷酸三苯酯改性后的酚醛纤维韧性增加,其阻燃性和热稳定性明显提高;当磷酸三苯酯质量分数为7%时,改性酚醛纤维拉伸强度为114.2 MPa,弹性模量为3217 MPa,极限氧指数提高至41.86%,在空气气氛下600℃的残炭率增至75.0%,在氮气气氛下800℃的残炭率增至69.4%。     

新型增韧阻燃酚醛树脂泡沫塑料的研制

以聚磷酸铵(APP)、三聚氰胺(MEL)和季戊四醇(PER)为阻燃剂,聚乙二醇和玻璃纤维改性酚醛树脂为基体,制备改性阻燃酚醛泡沫塑料。通过对改性基体材料进行红外分析,对改性阻燃泡沫塑料进行扫描电镜、冲击强度、热稳定性以及阻燃性能测试,确定了聚乙二醇与复合阻燃剂用量对泡沫塑料性能的影响。结果表明:酚醛树脂100份,聚乙二醇12份,复合阻燃剂15份,制备的改性阻燃酚醛泡沫塑料具有优异的韧性和阻燃性能,其冲击强度为5.54 kJ/m2,达到B1难燃材料的标准。     

E-PDMS增韧酚醛树脂泡沫材料的制备

对低聚环氧封端聚硅氧烷改性酚醛树脂进行了发泡工艺研究,考察了发泡温度及各种发泡助剂包括表面活性剂、发泡剂、酸固化剂的用量对材料泡沫性能影响的规律,并确定了改性酚醛树脂发泡的最佳工艺条件。实验用电子万能材料试验机和氧指数仪测试泡沫体的压缩强度和氧指数;用生物显微镜比较了酚醛树脂改性前后发泡体的形貌。实验结果表明:E-PDMS增韧改性酚醛泡沫的力学性能和耐水性均较普通酚醛泡沫有明显改观,其泡沫压缩强度达到396 k Pa,是改性前的2.2倍;吸水率是改性前的71%;材料的泡孔均匀;材料的氧指数虽有所下降,但也达到40.1%。     

酚化腐植酸改性酚醛泡沫材料的制备与性能的分析

以特定工艺制备酚化改性腐植酸（PHA）,选择并优化工艺参数从而制成PHA改性酚醛泡沫材料。采用傅里叶红外分析、热失重分析、氮吸附和冲击强度测试等方法对PHA改性酚醛泡沫材料结构和性能进行了分析。结果表明,当PHA质量分数为40 %时, PHA改性酚醛泡沫材料的冲击强度为5.7 kJ/m2,压缩强度为0.33 MPa,极限氧指数为47 %,热导率为0.038 W/（m·K）,在400 ℃时的质量保留率为79.1 %。其各项性能良好,可以替代部分苯酚制备PHA改性酚醛泡沫材料。     

酸固化剂对酚醛泡沫材料性能的影响

以多聚甲醛代替部分甲醛溶液制备高固体含量可发性酚醛树脂,在70℃发泡制备酚醛泡沫塑料。研究了酸固化剂的种类对酚醛泡沫塑料的密度、固化速度、力学性能、易碎性能、阻燃性能、热稳定性和微观结构的影响。结果表明,以盐酸、磷酸、对甲苯磺酸、水复配的酸固化剂基本符合酸固化剂的选择标准,制备的酚醛泡沫塑料性能较优,密度为51.82 kg/m3,初始分解温度为155℃,900℃时的质量保持率为52.6%,弯曲及压缩强度分别为0.2,0.355 MPa,掉渣率为25.7%,氧指数为48.5%,孔径分布在100～200μm的范围内。     

复合增韧酚醛泡沫塑料及其热稳定性能的研究

采用异氰酸酯(MDI)和聚乙二醇(PEG)协同增韧酚醛树脂发泡材料,通过对酚醛泡沫塑料进行红外分析(IR spectra),拉伸强度测试和冲击强度测试,研究了异氰酸酯和聚乙二醇的结构和用量等因素对增韧效果的影响,同时分析增韧酚醛泡沫的热稳定性和阻燃性。结果表明,酚醛树脂100份,改性剂的总量15份,异氰酸酯和聚乙二醇的质量比为1∶3时,冲击强度最大,达到6.224 kJ/m2,拉伸强度为1.26 MPa,泡沫粉化率降低了5.11%。热稳定性和阻燃性有都所下降,平均燃烧时间增加了4 s。     

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。