基于正交实验法优化制备疏水聚丙烯及性能

以1,3,5-三甲基-1,3,5-(三氟丙基)环三硅氧烷(D₃F)、八甲基环四硅氧烷(D₄)、四甲基四乙烯基环四硅氧烷(D₄Vi)为原料,开环聚合得到乙烯基封端聚硅氧烷(FSI);随后,通过自由基聚合方式将全氟己基乙烯(TE-6)接枝到FSI上,合成了含氟聚硅氧烷(FSI-F)。采用NMR、GPC、FTIR表征了FSI-F的结构与相对分子质量。以FSI-F为疏水改性材料、注塑级聚丙烯(PP)为基材、正十六烷基三甲氧基硅烷(Dynasylan 9116)为相容性改性剂,通过熔融共混制得了FSI-F/PP复合材料。采用正交实验法优化了FSI-F质量分数、TE-6与D₄Vi物质的量比、Dynasylan9116质量分数对FSI-F/PP复合材料的疏水、疏油、力学性能的影响;通过SEM、AFM和TG-DSC揭示了FSI-F/PP复合材料形貌与热学性能与其综合性能的内在联系。结果表明,当n(D₄Vi)∶n(TE-6)=1∶2、FSI-F质量分数为6%、Dynasylan 9116质量分数...     

低粘度自交联氟氢乙烯基硅油的合成及应用

采用高活性强酸性阳离子交换树脂（HND-580）催化八甲基环四硅氧烷（D4）、四甲基四氢环四硅氧烷（D4H）和三氟丙基甲基环三硅氧烷（D3F）开环共聚,以四甲基二乙烯基二硅氧烷（D2Vi）为封端剂,制备了低粘度含氟含氢乙烯基硅油。探讨了聚合温度、聚合时间、催化剂用量、催化剂循环等因素对开环共聚反应的影响。通过核磁、红外测试分析共聚物的分子结构;通过热分析法测试共聚物热分解温度;研究结果表明,当聚合温度为60℃、反应时间为4h、催化剂用量为3%~5%时,得到的含氟含氢端乙烯基硅油产率为88.69%,粘度为31mpa?s。将硅油进行涂膜测试,所得水滴静态接触角可达115.2?。     

端乙烯基聚二甲基硅氧烷合成反应动力学的研究

以八甲基环四硅氧烷(D4)、四甲基四乙烯基环四硅氧烷为单体，端乙烯基硅油为封端剂，四甲基氢氧化铵[(CH3)4NOH]为催化剂，合成了端乙烯基聚二甲基硅氧烷(Vi—PDMs)和端乙烯基聚甲基乙烯基硅氧烷(Vi—PMVS)；并对其反应动力学进行了研究。结果表明，在以(CH3)4NOH为催化剂、D4和端乙烯基硅油为原料合成Vi-PDMS的反应中，110℃下反应速度较快，平均摩尔质量略低；在95℃和110℃下的单体转化率均为85％左右；产物的粘度与聚合物的数均摩尔质量的关系为lg17=4．351g-↑Mn-16．24。合成Vi—PMVS的反应在110℃时的反应动力学规律与Vi—PDMS基本一致，其摩尔质量随反应时间的延长出现更明显的峰值。     

含磷、氮聚硼硅氧烷的合成及其与膨胀型阻燃剂协同阻燃聚丙烯的研究

以9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)、四甲基四乙烯基环四硅氧烷(D4Vi)、N-β-胺乙基-γ-胺丙基甲基二甲氧基硅烷(NMDMS)以及硼酸(H3B O3)为原料合成了一种新型的含磷、氮聚硼硅氧烷(p PNBSi),通过傅里叶变换红外光谱(FT-IR)、热重分析(TGA)对其进行表征。将制备的p PNBSi与膨胀型阻燃剂协同阻燃聚丙烯(PP),研究其对阻燃PP材料阻燃性能及热稳定性能的影响。研究结果表明,当阻燃剂添加总量为20.0 wt%,p PNBSi用量为2.0 wt%时,阻燃PP材料的极限氧指数(LOI)从27.0%提高到31.5%,垂直燃烧级别从无级别变为UL-94V-0级,且热释放速率峰值(PHRR)和总热释放量(THR)均有降低,提高了PP的阻燃性能。     

侧基为苯环的改性环硅氧烷的合成及其对硅橡胶性能的影响

通过甲基二苯基硅烷(Me Ph_2Si H)改性四甲基四乙烯基环四硅氧烷(D_4~(Vi))制得了2种含有不同苯环侧基浓度的改性环硅氧烷,采用核磁共振表征了改性环硅氧烷,并研究了改性环硅氧烷对硅橡胶阻尼性能及物理机械性能的影响。结果表明,2种改性环硅氧烷分别为D_4~(Vi)分子中3个乙烯基基团与Me Ph_2Si H发生硅氢化反应的产物和D4Vi与Me Ph_2Si H完全硅氢加成反应的产物; 添加改性环硅氧烷能够提高硅橡胶的阻尼性能,且侧基浓度越大,硅橡胶的阻尼性能越佳; 添加含有活性乙烯基的改性环硅氧烷能够提高硅橡胶的物理机械性能,而无乙烯基、含有大空间位阻基团的改性环硅氧烷则会降低物理机械性能。     

低黏度自交联氟氢乙烯基硅油的合成及应用

采用阳离子交换树脂催化八甲基环四硅氧烷(D4)、四甲基四氢环四硅氧烷(D4H)和三氟丙基三甲基环三硅氧烷(D3F)开环共聚,以四甲基二乙烯基二硅氧烷(D2Vi)为封端剂,制备了低黏度自交联氟氢乙烯基硅油(F-PMHS).探讨了聚合温度、聚合时间、催化剂用量、催化剂循环等因素对聚合反应的影响.通过FTIR、1HNMR、TGA对共聚物进行分析.结果表明,当聚合温度为60℃、反应时间为6 h、催化剂用量为总单体质量5％时,得到的F-PMHS产率为88.69％,黏度为32.7 mPa·s.将硅油进行涂膜测试,所得涂膜固化性好,剥离力低至7 g/25 mm,水滴静态接触角达114.9°.     

含氢氟硅油对加成型氟硅橡胶性能的影响

以四甲基环四硅氧烷(DH4)、三氟丙基甲基环三硅氧烷(DF3)、四甲基二硅氧烷为原料,磺酸树脂球为催化剂,合成了不同活性氢质量分数的含氢氟硅油,再将其与端乙烯基或侧乙烯基氟硅液体胶进行加成反应,考察了含氢氟硅油活性氢质量分数和用量对加成型氟硅橡胶性能的影响。结果表明,当含氢氟硅油用量一定时,随着活性氢质量分数的提高,端乙烯基氟硅橡胶硬度升高,拉伸强度先增后减,拉断伸长率减小;当活性氢质量分数一定时,随着含氢氟硅油用量的增加,端乙烯基氟硅橡胶硬度和拉伸强度降低,拉断伸长率提高;当活性氢质量分数为0.3%,n(Si—H)∶n(Si—Vi)=3.5时,端乙烯基氟硅橡胶邵尔A硬度为40度,拉伸强度为6.4 MPa,拉断伸长率为589%。     

高相对分子质量氟硅生胶的制备与热性能研究

以γ-三氟丙基甲基环三硅氧烷(D3F)、三甲基三乙烯基环四硅氧烷(D3Vi)为原料,碱为催化剂制得了乙烯基质量分数为0.25%、不同相对分子质量的氟硅橡胶。采用D3Vi作为共聚单体可以将乙烯基引入到共聚物中,实验中D3F的聚合速率非常高,10 min后的转化率均为90%以上。优化了聚合反应条件,通过FTIR、1H-NMR、GPC表征了氟硅生胶的结构组成和相对分子质量,通过DSC和TG研究了其热性能。结果表明,氟硅生胶的玻璃化转变温度为-69℃,在300℃以下未出现明显的热降解现象,耐高温性能低于普通的甲基乙烯基硅橡胶。     

三嵌段共聚有机硅氧烷的合成与性能研究

以氢氧化锂为引发剂,二甲基甲酰胺为促进剂,采用分步投料法合成出聚二甲基（甲基乙烯基）硅氧烷－聚二甲基二苯基（甲基乙烯基）硅氧烷－聚二甲基（甲基乙烯基）硅氧烷三嵌段共聚物;研究了四甲基四乙烯基环四硅氧烷（D4^Vi)用量对嵌段共聚物的摩尔质量及所制硅橡胶物理机械性能的影响。结果表明,D4^Vi用量对嵌段共聚物的摩尔质量影响不大,但对硅橡胶的物理机械性能影响很大。当D4^Vi质量分数为0.1%、0．2％时,硅橡胶的物理机械性能较好,拉伸强度可达10．70MPa,撕裂强度最大为21．61kN/m,拉伸永久变形为2％－4％。     

加成型固化氟硅橡胶的制备及性能

以三氟丙基甲基环三硅氧烷(D_3F)、八甲基环四硅氧烷(D_4)、四甲基四乙烯基环四硅氧烷(D_4Vi)作为单体,以短链乙烯基硅油作为封端剂,通过阴离子开环聚合的方式合成氟含量不同的乙烯基氟硅液体胶;通过阳离子开环聚合的方式分别合成了交联剂含氢氟硅油及Karstedt铂金催化剂,考察氟含量、乙烯基含量、填料含量等因素对加成型固化氟硅橡胶物理性能的影响。结果表明,当端乙烯氟硅液体胶含氟基团摩尔分数为30%、填料DM-30S的用量为31.5份时,固化后氟硅橡胶的邵尔A硬度可以达到44,拉伸强度达到8 MPa,断裂伸长率达到689%,撕裂强度达到38.9 kN/m。     

芳纶浆粕增强聚丙烯复合材料的结构与性能

利用双螺杆挤出机制备了聚丙烯(PP) /芳纶浆粕(PPTA-pulp)以及聚丙烯(PP)/芳纶浆粕(PPTA-pulp)/马来酸酐接枝聚丙烯(MAH-g-PP)复合材料。采用力学性能测试、差示扫描量热仪（DSC）、扫描电子显微镜(SEM)、平板流变仪,研究了PP/ PPTA-pulp复合材料的力学性能、结晶行为、断面形态结构及流变行为。结果表明：随着PPTA-pulp含量的增加,复合材料的拉伸强度和弯曲模量增加,缺口冲击强度和断裂伸长率下降,芳纶浆粕对聚丙烯结晶起了成核剂的作用。马来酸酐接枝聚丙烯(MAH-g-PP)作为相容剂,改善了PPTA-pulp与基体PP分子之间的亲和性,提高了界面作用力,并使复合材料的储存模量、损耗模量和力学性能进一步改善。     

One-step synthesis of hydrophobic magnesium hydroxide nanoparticles and their application in flame-retardant polypropylene composites

Hydrophobic magnesium hydroxide (MH) nanoparticles were prepared by a one-step synthesis method in a high-gravity environment generated by a novel impinging stream-rotating packed bed (IS-RPB) reactor. The reactant solutions were simultaneously and continuously pumped into the IS-RPB reactor, and then Tween 80 was added as a surface modifier. The morphology, structure, and properties of blank and hydrophobic MH were characterized. The effects of MH nanoparticles on the flame retardancy, thermal stability, and mechanical properties of PP/MH composites were also studied. We found that the obtained MH nanoparticles exhibited hexagonal lamella with a mean size of 30 nm, excellent hydrophobic properties (e.g., high water contact angle of 112°), and improved thermal stability of MH. The limiting oxygen index (LOI) further showed that increased MH loading can significantly improve flame-retardant performance, which reached 29.3% for PP/MH composites with 30 wt% hydrophobic samples. The thermal stability and mechanical properties of the PP/MH composites with hydrophobic samples were also much higher than those of PP/MH composites with blank MH. Results showed that the one-step synthesis had high potential application in the large-scale production of hydrophobic MH nanoparticles.     

Effects of nanosilica filler surface modification and compatibilization on the mechanical,thermal and microstructure of PP/EPR blends

Polypropylene/ethylene-propylene rubber/nanosilica (PP/EPR/nano-SiO₂) composites were prepared by a melt blending masterbatch process using a Brabender mixer. In order to improve the interfacial adhesion and achieve diverse desired properties of the composites, nanosilica surface silylation by means of two silane coupling agents: N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (AEAPTMS) and 3-methacryloxypropyltrimethoxysilane (MPTMS) was explored. The composites were also compatibilized using three compatibilizers: methyl methacrylate grafted PP (MMA-g-PP), glycidylmethacrylate grafted PP (GMA-g-PP) and maleic anhydride grafted PP (MAH-g-PP). The properties of the blends and the composites were examined using tensile and Izod impact tests, differential scanning calorimetry (DSC), thermogravimetric analysis (ATG) and scanning electron microscopy (SEM). According to the mechanical property evaluations, the incorporation of nano-SiO₂ particles into PP/EPR blend improved the tensile strength and Young’s modulus of the composites. The elongation and Izod impact strength were adversely affected. A significant improvement in the mechanical properties was obtained for the composites with AEAPTMS-SiO₂ and MAH-g-PP. The DSC results indicated that the incorporation of the modified silica and MAH-g-PP increased the crystallinity of the composites. However, no significant variation in the crystallinity was observed as a result of the addition of MMA-g-PP and GMA-g-PP. The TGA results revealed that the composites exhibit a higher thermal stability than that of the neat matrix. SEM micrographs of the fractured surfaces revealed a two-phase morphology with EPR nodules being dispersed in the PP matrix. SEM also indicated that the incorporation of MAH-g-PP into PP/EPR composites contributes to a better dispersion of the EPR phase and nano-SiO₂ particles in the polymer matrix.     

Water absorption and mechanical properties of PP/HIPS hybrid composites filled with wood flour

Water absorption and mechanical performance of the injection‐molded hybrid composites prepared from different ratios of two polymer blends (57 wt%), two compatibilizers (3 wt%), and two wood species (40 wt%) were investigated. The ratio of polypropylene and high‐impact polystyrene (HIPS) gradually increased in the blend (from 10 to 30 wt%). Styrene–ethylene–butylene–styreneblock copolymer and maleic anhydride‐grafted PP (MAPP) were used as compatibilizer (3 wt%). The shore D hardness of the PP/wood composites was improved by the incorporation of the HIPS. The HIPS/wood flour composites showed higher tensile modulus but lower tensile strength than the PP/wood composites. The water resistance of the PP/wood composites decreased with increasing HIPS content. POLYM. COMPOS., 38:863–869, 2017. © 2015 Society of Plastics Engineers     

Compatibilizing effect of maleated polypropylene on the mechanical properties and morphology of injection molded polyamide 6/polypropylene/organoclay nanocomposites

Polyamide 6/polypropylene (PA6/PP=70/30 parts) blends containing 4 phr (parts per hundred resin) of organophilic modified montmorillonite (organoclay) were prepared using twin screw extruder followed by injection molding. Maleated polypropylene (MAH-g-PP) was used to compatibilize the blend system. The mechanical properties of PA6/PP nanocomposites were studied through tensile and flexural tests. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to assess the fracture surface morphology and the dispersion of the organoclay, respectively. X-ray diffraction (XRD) was used to characterize the formation of nanocomposites. The thermal properties were characterized by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The dynamic mechanical properties of PA6/PP nanocomposites were analyzed by using dynamic mechanical thermal analyzer (DMTA). The strength and stiffness of PA6/PP nanocomposites were improved significantly in the presence of MAH-g-PP. This has been attributed to the synergistic effect of organoclay and MAH-g-PP. The MAH-g-PP compatibilized PA6/PP nanocomposites showed a homogeneous morphology supporting the compatibility improvement between PA6, PP and organoclay. TEM and XRD results revealed the formation of nanocomposites as the organoclay was intercalated and exfoliated. A possible chemical interaction between PA6, PP, organophilic modified montmorillonite and MAH-g-PP was proposed based on the experimental work.     

Cellulose nanofibril‐reinforced polypropylene composites for material extrusion: Rheological properties

Polypropylene (PP) is not typically utilized in 3D printing material extrusion because PP shrinks and warps during the printing process. Cellulose nanofibrils (CNF) have the potential to make PP 3D printer processable and also enhance mechanical properties of PP printed parts. The rheological behavior of CNF‐PP composites during material extrusion requires study because it is different from injection molding and compression molding processes. This study revealed the effects of CNF contents (3 and 10 wt%) and maleic anhydride polypropylene (MAPP) coupling agent on the rheological properties of CNF–PP composites. Morphological analysis showed that CNF agglomerated during spray drying and a spherical structure was formed. Rheological tests showed that the elastic modulus, complex viscosity, viscosity, and transient flow shear stress of PP were increased by the addition of 10 wt% CNF, while the creep strain of PP was reduced. The damping factor and stress relaxation time remained the same when 10 wt% CNF was added to the PP. Incorporation of MAPP into the CNF–PP composites impacted the rheological properties of the CNF–PP composites. Flexural strength and modulus of PP were improved by 5.9% and 26.8% by adding 10 wt% CNF compared to the control. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

功能化聚丙烯的制备及对聚丙烯与尼龙66共混体系的增容作用

讨论了马来酸酐含量、反应时间、引发剂用量、抗氧剂用量等对马来酸酐功能化聚丙烯的影响,及马来酸酐功能化聚丙烯对聚丙烯与尼龙６６共混体系的增容作用。     

Structure and properties of high melt strength polypropylene prepared by combined method of blending and crosslinking

High melt strength polypropylene (HMSPP) was prepared by in situ heat induction reaction, in which pure polypropylene (PP) powders without any additives was used as basic resin, and low density polyethylene (LDPE) and trimethylolpropane triacrylate (TMPTA) were added as blending resin and as crosslinking agent, respectively. Microstructure of the obtained HMSPP (PP/LDPE/TMPTA blends) was characterized by FTIR, Wide‐angle X‐ray diffraction (WAXD), and testing of gel content. The effect of LDPE content on melt strength and melt flow rate of HMSPP were investigated. When the content of LDPE was 40 wt %, the melt strength of the HMSPP was above 16 CN, which was much higher than those of pure PP powder (2.6 CN) and PP/LDPE blends without TMPTA (6.1 CN). Moreover, thermal behavior and mechanical properties of the HMSPP were also investigated. The results showed that the thermal stability and impact strength of HMSPP were greatly improved. In addition, HMSPP possessed good processing performance and good foaming properties. The foams produced by HMSPP showed uniform, closed, and independent cells. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and evaluation of composites containing polypropylene and cotton gin trash

Composites of polypropylene (PP) and cotton gin trash (GT) were prepared to enhance the utilization of agro-based materials in industrial products. GT was modified by two methods: toluene washed only, and toluene washed and treated with maleic anhydride-grafted polypropylene (MAPP). These GT samples were extruded with PP, including MAPP and ethylene/vinyl acetate copolymer in various weight ratios (32 composites total). The PP composites displayed tensile strengths close to that of the neat PP, and exhibited higher values of tensile modulus and lower elongation at break than the neat PP. Based on DSC measurements, the PP composites containing 10 wt% GT exhibited two crystalline regimes, while those containing 20 wt% GT were similar in crystallinity to that of the neat PP. The composites were also characterized using SEM, TGA, water absorption tests, and contact angle measurements. These composites represent a more sustainable alternative to neat, fossil fuel-based PP.     

Vinyl polysiloxane microencapsulated ammonium polyphosphate and its application in flame retardant polypropylene

Vinyl polysiloxane microencapsulated ammonium polyphosphate (MAPP) was prepared by a sol-gel method using vinyltrimethoxysilane as a precursor to improve its thermal stability and hydrophobicity. The MAPP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and thermogravimetric analyzer (TGA). The results showed that ammonium polyphosphate (APP) was successfully coated with vinyl polysiloxane. MAPP and pentaerythritol (PER) were used together to improve the flame retardancy of polypropylene (PP). The flame retardant properties of PP composites were investigated by limiting oxygen index (LOI), UL-94 test, TGA and SEM. When the MAPP was added as a flame retardant, with PER as a char forming agent, the LOI of PP/MAPP/PER composites was 33.1%, and it reached the UL-94 V-0 level. The results also demonstrated that the flame retardant properties of PP/MAPP/PER composites were better than those of PP/APP/PER composites at the same loading. Moreover, the addition of flame retardant and carbon forming agent could promote the crystallization behavior of PP.