共混纺丝制聚苯硫醚超细纤维及其形态结构研究

以聚苯硫醚(PPS)和聚丙烯(PP)为原料,采用熔融共混纺丝法制备PPS/PP共混海岛纤维,经对二甲苯溶除剥离基体相PP,制得PPS超细纤维;研究了共混纺丝温度、共混比例、拉伸、溶解剥离对PPS超细纤维形态结构的影响。结果表明:PPS/PP最佳共混纺丝温度为290~300℃;随着PPS/PP质量比增大,PPS超细纤维直径逐渐变大,PPS/PP质量比从30/70增至60/40时,PPS超细纤维平均直径从228 nm增至408nm;当PPS/PP质量比大于60/40时,开始出现相转变现象;提高拉伸倍数有利于PPS超细纤维的细化,PPS/PP质量比为40/60时,3倍拉伸得到PPS超细纤维的直径分布范围为158~488 nm,平均直径为312 nm,大于3倍拉伸时,易出现毛丝断丝现象;当对二甲苯体积与共混纤维质量比为500∶1时,PPS超细纤维的最佳剥离温度为120℃、剥离时间2 h。     

纳米碳酸钙增强聚丙烯纤维的研究

将分散剂、纳米碳酸钙和聚丙烯(PP)切片按一定比例混合纺丝制得改性PP纤维。并研究了改性PP纤维的结构与性能。结果表明:当分散剂与纳米碳酸钙的质量比为1∶3,纳米碳酸钙质量分数为0．3%时,改性PP纤维的断裂强度和初始模量最大,分别为7．97,90．36 cN/dtex．纳米碳酸钙在改性PP纤维中分散均匀,且粒径为40～80 nm。与PP纤维相比,改性PP纤维的取向度变化不大,结晶度有所提高,但当纳米碳酸钙质量分数大于等于2%时,其结晶度下降明显。     

聚丙烯/亚麻纤维复合材料的成型工艺及力学性能研究

选取聚丙烯(PP)纤维为基体材料,亚麻纤维为增强材料。运用正交设计法,探讨了PP/亚麻纤维复合材料的模压成型工艺。研究分析了两种纤维的质量比、模压温度、热压保温时间对复合材料力学性能的影响。结果表明,两种纤维的质量比为50:50、模压温度为180℃、热压保温时间为60min时,PP/亚麻纤维复合材料的力学性能最佳。     

聚丙烯/分子筛共混纤维的结构与性能

用钛酸酯偶联剂对分子筛进行表面处理,按一定比例与聚丙烯(PP)切片共混纺丝,制得PP/分子筛共混纤维,研究PP/分子筛共混纤维的结构与性能。结果表明:当纤维中分子筛的质量分数为1%时,PP/分子筛共混纺丝纤维的可纺性好,断裂强度比纯PP纤维提高31.85%,上染率提高44.86%,初始模量、断裂功、回潮率均有所提高;与纯PP纤维相比,PP/分子筛共混纤维的结晶度略小、晶粒变大,取向度降低,纤维的染色性、吸湿性得到改善。分子筛与偶联剂发生化学反应,有利于分子筛和PP的结合,适当的分子筛含量时,纤维的力学性能有所提高。     

MPP无卤阻燃聚丙烯纤维的辐照改性研究

采用自制季戊四醇螺环磷酸酯双蜜胺盐(MPP)无卤阻燃剂与聚丙烯(PP)进行共混纺丝,制备了无卤阻燃PP纤维,采用低能电子辐照对无卤阻燃PP纤维进行改性,并对MPP的结构、PP纤维的力学性能及阻燃性能进行了表征。结果表明:自制MPP为预期结构;随着MPP含量的增加,PP纤维的极限氧指数(LOI)增大,但其断裂强度有所下降;MPP质量分数为8%时,纤维断裂强度为6.02 cN/dtex,LOI为24.5%;随低能电子辐照量的增大,MPP质量分数8%的阻燃PP纤维的LOI大幅度增加;当电子辐照量为200 kGy时,阻燃PP纤维的LOI为33.8%,断裂强度为3.08 cN/dtex,起始分解温度和残炭率比纯PP纤维均有较大幅度增加,燃烧形成连续致密的炭层。     

并列型聚丙烯复合纤维织物的开纤工艺与吸湿性能研究

以聚对苯二甲酸乙二醇酯(PET)、聚己内酰胺(PA 6)分别与聚丙烯(PP)复合的并列型PP/PET、PP/PA 6复合纤维为原料,制成织物后分别采用氢氧化钠(NaOH)、盐酸(HCl)溶液对织物进行开纤处理,研究开纤工艺对织物的减量率和纤维表面形态的影响,确定较佳开纤工艺条件,并对开纤后织物的吸湿性能进行表征。结果表明:增加开纤溶液浓度及开纤时间均会大幅度提高复合纤维织物的减量率,纤维表面发生侵蚀;PP/PET复合纤维织物的较佳开纤工艺为开纤溶液NaOH质量分数1.5%、开纤时间30 mim,PP/PA 6复合纤维织物的较佳开纤工艺为开纤溶液HCl质量分数15%、开纤时间30 mim;开纤处理后,PP/PA 6复合纤维织物的吸湿性能显著优于PP/PET复合纤维织物,组分质量比为5:5的PP/PA 6复合纤维织物的吸水率达347.9%、芯吸高度达81 mm。     

聚丙烯离子交换纤维研究

利用超声波分散原理将苯乙烯（St）分散到聚丙烯纤维（PP）中，以过氧化苯甲酰（BPO）作为引发剂，使苯乙烯接枝到PP纤维表面，得到PP－g-St纤维；然后用浓硫酸将PP－g-St纤维磺化，制成强酸型离子交换纤维。研究了反应时间、反应温度等对离子交换纤维的质量摩尔浓度的影响，并用红外光谱加以表征。结果表明：温度90℃下磺化反应2h，可得到离子交换质量摩尔浓度为0.95mmol/g的强酸型离子交换纤维。     

新型核壳纤维增韧聚丙烯的研究

采用同轴静电纺丝技术制备聚碳酸酯为壳层,三元乙丙橡胶为核层的直径为300～600 nm的同轴纤维.将不同份数的核壳纤维与聚丙烯经过单螺杆混合,注塑后得到PP/核壳纤维复合材料.研究发现,核壳纤维用量在3份以下时,其在PP基体中的分散均匀,界面良好;核壳纤维的加入使PP的结晶速率提高,β晶含量先增大后减少;核壳纤维的用量为3份时,冲击性能较纯PP相比提高了22.17%.     

活性粉末混凝土高温后强度退化规律试验研究

为研究活性粉末混凝土(RPC)高温后强度退化规律,对高温后RPC试件的质量损失、抗压性能和劈裂抗拉性能进行测试,并分析温度和纤维掺量对RPC强度的影响。结果表明:随着温度的升高,RPC试件的表观颜色由深逐渐变浅,质量损失率逐渐增大;而强度损失率均随着温度升高呈先减小后增大的趋势,但临界温度不同,立方体抗压强度和劈裂抗拉强度的临界温度为300 ℃,而轴心抗压强度的临界温度为200 ℃,此外,300 ℃后轴心抗压强度损失率高于立方体抗压强度,800 ℃后强度损失率均超80%,宏观强度退化的根本原因是基体微观形貌的劣化;掺有聚丙烯(PP)纤维的RPC试件高温后强度损失率相对较小,且当钢纤维掺量为2%(体积分数)时,PP纤维的最佳掺量为0.15%(体积分数)。通过回归分析,建立了RPC强度损失率与温度和PP纤维掺量间的计算公式。     

PP/甘蔗皮纤维复合材料的拉伸性能

采用热压工艺制造聚丙烯(PP)/甘蔗皮纤维复合材料,并研究其拉伸性能。研究热压温度为175℃、压力为2 MPa、时间15 min工艺条件下纤维粒径大小和质量分数对复合材料拉伸强度和拉伸弹性模量的影响。结果表明:在甘蔗皮纤维质量分数为40%条件下,复合材料拉伸性能随着粒径减小呈现先增加后减少的趋势,当纤维粒径为40~60目(0.45~0.3 mm)时材料拉伸强度最大,为8.58 MPa,此时弹性模量为2.44 GPa;在相同纤维粒径40~60目条件下,纤维质量分数为40%时PP复合材料拉伸强度最大,纤维质量分数为50%时PP复合材料拉伸弹性模量最大,达到2.65 GPa。根据实验结果,甘蔗皮纤维增强PP复合材料在纤维粒径为40~60目、质量分数在40%时综合拉伸性能最佳。     

焦油一次汽化温度计算方法的探讨

利用相平衡原理得出的焦油蒸馏时一次汽化温度的计算方法,其结果与按经验公式的计算结果进行了比较,同时讨论了一次汽化温度与焦油馏分产率及二段蒸发器过热蒸汽用量的关系。     

Techniques for screening adhesives for structural applications

—Due to its chemistry, no structural adhesive system (epoxies, acrylics, etc.) is likely to offer an ideal combination of toughness, strength, moisture resistance, and ambient-temperature curing. Therefore, for effective use of adhesives in primary structures, an engineer must be able to identify adhesives that represent an optimum compromise among the different properties. In this paper, we present techniques for screening high-strength, ambient-temperature-curing adhesives for (1) moisture resistance under sustained loading and (2) fracture resistance in a way that is directly related to joint performance.     

Efficacy for Whitlockite for Augmenting Spinal Fusion

Whitlockite (WH) is the second most abundant inorganic component of human bone, accounting for approximately 25% of bone tissue. This study investigated the role of WH in bone remodeling and formation in a mouse spinal fusion model. Specifically, morphology and composition analysis, tests of porosity and surface area, thermogravimetric analysis, an ion-release test, and a cell viability test were conducted to analyze the properties of bone substitutes. The MagOss group received WH, Group A received 100% beta-tricalcium phosphate (β-TCP), Group B received 100% hydroxyapatite (HAp), Group C received 30% HAp/70% β-TCP, and Group D received 60% HAp/40% β-TCP (n = 10 each). All mice were sacrificed 6 weeks after implantation, and micro-CT, hematoxylin and eosin (HE) staining, and Masson trichome (MT) staining and immunohistochemistry were performed. The MagOss group showed more homogeneous and smaller grains, and nanopores (<500 nm) were found in only the MagOss group. On micro-CT, the MagOss group showed larger fusion mass and better graft incorporation into the decorticate mouse spine than other groups. In the in vivo experiment with HE staining, the MagOss group showed the highest new bone area (mean: decortication group, 9.50%; A, 15.08%; B, 15.70%; C, 14.76%; D, 14.70%; MagOss, 22.69%; p < 0.0001). In MT staining, the MagOss group demonstrated the highest new bone area (mean: decortication group, 15.62%; A, 21.41%; B, 22.86%; C, 23.07%; D, 22.47%; MagOss, 26.29%; p < 0.0001). In an immunohistochemical analysis for osteocalcin, osteopontin, and CD31, the MagOss group showed a higher positive area than other groups. WH showed comparable bone conductivity to HAp and β-TCP and increased new bone formation. WH is likely to be used as an improved bone substitute with better bone conductivity than HAp and β-TCP.     

Demand Increases for New Fungicides for Rice

<正> After June this year China's regions growingmiddle and late rice had widespread blastand sheath/culm blight.Such diseasesplagued 19.2 million hectares.Starting fromJuly the market for new fungicides that cancontrol blast and sheath/culm blight for ricewas more and more active.Makers of traditional pesticides for thecontrol of blast have to contend with fiercecompetition from new pesticides in marketthis year.Kitazine,iprobenfos,isoprothiolane and tricyclazole,oftenused by farmers in the past,are graduallybeing replaced by new varieties with high