线型低密度聚乙烯溶液接枝聚甲基丙烯酸甲酯

用溶液接枝聚合的方法在线型低密度聚乙烯(LLDPE)上接枝聚合极性单体甲基丙烯酸甲酯(MMA)制备LLDPE-g-PMMA,研究了反应时间、单体用量和引发剂用量对接枝反应的影响。结果表明,随着引发剂和单体量的增加,聚合物的接枝率增加,当引发剂质量分数为0.48%,单体比率为150%时,接枝率将达到26.1%。利用红外光谱(FTIR)、核磁共振碳波谱仪(13C-NMR)对其进行结构表征,证明PMMA分子链被接枝聚合到LLDPE上。使用X射线衍射仪(XRD)、差示扫描量热仪(DSC)对接枝聚合物的结晶性能进行了分析,发现接枝聚合没有改变晶型,但结晶焓由61.39 J/g降低到47.18 J/g。     

硅烷交联聚乙烯电力电缆绝缘料的研制

采用两步法制备了硅烷交联聚乙烯（PE）电力电缆绝缘料。以双螺杆挤出机为反应器,以低密度聚乙烯（LDPE）和线型低密度聚乙烯（LLDPE）为基础树脂,考察了影响PE接枝交联的主要因素（如基础树脂的配比,交联剂的用量及种类,引发剂、抗氧剂的用量等）,得出了具有良好性能的硅烷交联PE电力电缆绝缘料的配方（质量份数）：LDPE为85．00phr,LLDPE为15．0H0phr,硅烷W为0．60phr,硅烷Q为1．40phr,引发剂为0．12phr,抗氧剂为0．20phr。     

聚烯烃离聚体原位增容PP/LLDPE共混物的研究!

用傅立叶红外光谱(FTIR)、力学性能测试等方法研究了聚烯烃离聚体原位增容聚丙烯/线性低密度聚乙烯(PP/LLDPE)共混物。结果表明:熔融状态下,在马来酸酐接枝聚丙烯/马来酸酐接枝线性低密度聚乙烯(PP-g-MAH/LLDPE-g-MAH)(质量比50/50)共混物中加入二水醋酸锌,共混物中的马来酸酐基团(羧酸基团)与Zn2+发生离子偶联反应,相界面就地产生的聚烯烃离聚体增加了两相界面黏合力,共混物力学性能提高;原位增容后共混物中的PP和LLDPE相熔点略微下降,LLDPE结晶温度向高温移动;在角频率为0.01～100.00s-1,原位增容后共混物的储能模量、损耗模量和复数黏度都高于简单共混物的,损耗正切(tanδ)低于简单共混物的;对于PP/PP-g-MAH/LLDPE/LLDPE-g-MAH四元体系,SEM显示原位增容后共混物的相界面变得模糊,相容性提高。     

硅烷接枝交联HDPE／LLDPE共混物性能研究

采用引发剂过氧化二异丙苯（DCP）、硅烷偶联剂乙烯基三乙氧基硅烷（VTEOS）和催化剂二月桂酸二丁基锡（DBTL）,通过双螺杆挤出机对高密度聚乙烯（HDPE）和线性低密度聚乙烯（LLDPE）的共混物进行硅烷接枝交联反应。通过力学测试和DSC研究产物不同凝胶含量对其性能影响。研究表明硅烷交联聚乙烯的拉伸和冲击强度随交联度的增大而提高,但产物结晶度和熔点有所下降,同时结晶均匀性变差。     

PEW-g-MAH的制备及其对PP/Talc的改性

由线型低密度聚乙烯裂解反应制备了低相对分子质量聚乙烯蜡，考察了工艺条件的影响因素。得出了反应温度、反应时间与相对分子质量、熔点、软化点之间的关系。在锅中用熔融接枝法制备马来酸酐接枝聚乙烯蜡，研究了反应时间、温度、引发剂和马来酸酐用量对产物接枝率、接枝效率的影响。结果表明在引发剂质量分数0．1％、马来酸酐质量分数4％、反应温度150℃、反应时间3h的条件下，聚乙烯蜡的接枝率达到1.49％。接枝的聚乙烯蜡可作为一种新型偶联剂用于改性聚丙烯与填料复合材料的力学性能，使改性后的聚丙烯复合材料的悬臂粱缺口冲击强度提高了50％。     

回收PE/PET共混物的原位微纤化和反应增容研究

通过原位微纤化技术和反应增容,制备了含回收聚对苯二甲酸乙二醇酯(PET)、低密度聚乙烯(LDPE)和线性低密度聚乙烯(LLDPE)以及高密度聚乙烯(HDPE)的原位微纤化共混物(MRB).探讨了原位成纤作用下,相容剂马来酸酐接枝聚乙烯(PE-g-MAH)用量对共混物力学性能的影响,同时利用差示扫描量热仪(DSC)和扫描电镜(SEM)研究了含4份PE-g-MAH共混物的非等温结晶特性和共混物形态.结果表明,成纤和增容双重作用对共混物的拉伸强度、断裂伸长率、弯曲模量和弯曲强度都有提高,而冲击强度有所下降;微纤对基体聚乙烯结晶有促进作用且注塑共混物比拉伸共混物更明显.HDPE与LLDPE发生了共结晶;拉伸共混物中的微纤比注塑共混物中的微纤长.     

胶粉/LLDPE弹性体合金的研制

系统研究了废胶粉（GRT）／线型低密度聚乙烯（LLDPE）弹性体合金（GRT／LLDPE）的配方，以及粒径，GRT含量，相容剂和硫化剂（DCP）用量对共混物力学性能的影响，结果表明，采用两阶共混法，当GRT／LLDPE共混比为：60：40，DCP用量为2份，相容剂马来酸酐三单体接枝物用量为3－5份时，所得弹性体合金力学性能最佳，弹性体合金的拉伸强度从简单共混物的5．8Mpa上升到11．1MPa，撕裂强度从39．4kN/m，上升到63．4kN/m，断裂伸长率从180％增加到260％。     

反应挤出法制备LLDPE-g-(GMA-co-St)的研究

以甲基丙烯酸缩水甘油酯(GMA)为接枝单体,苯乙烯(St)为接枝共单体,在双螺杆挤出机上对线型低密度聚乙烯(LLDPE)进行熔融接枝,制备了LLDPE-g-(GMA-co-St).研究了引发剂用量、单体用量、共单体用量和抑交联剂亚磷酸三苯酯等对LLDPE接枝物接枝率和熔体质量流动速率的影响,利用红外光谱对接枝物进行了表征.研究表明,St的加入能有效提高GMA的接枝率,亚磷酸三苯酯有效抑制了LLDPE的交联.最佳配方为:过氧化二异丙苯(DCP)为0.15份,GMA为3份,St为3份,亚磷酸三苯酯为1份.     

LLDPE/LLDPE-g-AA共混物的接触角及红外光谱表征

利用溶融共混的方法制备了线性低密度聚乙烯/线性低密度聚乙烯接枝丙烯酸（LLDPE/LLDPE-g-AA)共混物。用傅里叶红外光谱（FT-IR）和测定接触角的方法对不同LLDPE-g-AA含量的LLDPE/LLDPE-g-AA共混物膜的表面进行了表征。结果表明,随着共混物中LLDPE-g-AA含量的增加,水和甘油等极性液体与共混物表面的接触角下降。依据共混物的FT-IR计算了其羧基峰强度。发现极性液体与LLDPE/LLDPE-g-AA共混物膜表面的接触角越小,羧基峰强度越大。     

偶联剂对HDPE基竹塑复合材料力学性能的影响

采用硅烷、钛酸酯和马来酸酐接枝聚乙烯制备竹塑复合材料,研究偶联剂的种类和含量对竹塑复合材料性能的影响.结果表明:采用硅烷和马来酸酐接枝聚乙烯两种偶联剂制备的复合材料,具有较高的拉伸强度、冲击强度和弯曲强度.马来酸酐接枝聚乙烯的加入量达到竹粉质量含量的9％左右时,材料的冲击强度最高.     

Characterization of radiation-grafted polymer films using CP/MAS NMR spectroscopy and confocal Raman microscopy

Preirradiated poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) base film were grafted with different amounts of an α-methylstyrene (AMS) and methacrylonitrile (MAN) copolymer. The molar ratio of AMS and MAN in the grafted polymer was determined using ¹³C- CP/MAS NMR spectroscopy and compared with the molar ratio determined with FTIR spectroscopy. The distribution of the components across the thickness of the grafted films was determined using confocal Raman microscopy. The validation of the confocal Raman microscopy was performed with FEP films grafted with MAN only, where pronounced grafting fronts were observed. The local degree of grafting for AMS/MAN co-grafted FEP films was calculated for each sample based on the intensity profiles, taking the mass of the grafted polymer and its molar ratio into account. The grafting of the AMS/MAN co-grafted films was found to be homogeneous over the thickness, even in case of small amounts of the copolymer (15 mass%). The homogeneity of the grafting across the film thickness is a prerequisite to obtain sufficient proton conductivity after sulfonation of the radiation-grafted films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Photodegradation of Azathioprine in the Presence of Sodium Thiosulfate

The effect of sodium thiosulfate (ST) on the photodegradation of azathioprine (AZA) was analyzed by UV-VIS spectroscopy, photoluminescence (PL), FTIR spectroscopy, Raman scattering, X-ray photoelectron (XPS) spectroscopy, thermogravimetry (TG) and mass spectrometry (MS). The PL studies highlighted that as the ST concentration increased from 25 wt.% to 75 wt.% in the AZA:ST mixture, the emission band of AZA gradual downshifted to 553, 542 and 530 nm. The photodegradation process of AZA:ST induced: (i) the emergence of a new band in the 320–400 nm range in the UV-VIS spectra of AZA and (ii) a change in the intensity ratio of the photoluminescence excitation (PLE) bands in the 280–335 and 335–430 nm spectral ranges. These changes suggest the emergence of new compounds during the photo-oxidation reaction of AZA with ST. The invoked photodegradation compounds were confirmed by studies of the Raman scattering, the FTIR spectroscopy and XPS spectroscopy through: (i) the downshift of the IR band of AZA from 1336 cm⁻¹ to 1331 cm⁻¹, attributed to N-C-N deformation in the purine ring; (ii) the change in the intensity ratio of the Raman lines peaking at 1305 cm⁻¹ and 1330 cm⁻¹ from 3.45 to 4.57, as the weight of ST in the AZA:ST mixture mass increased; and (iii) the emergence of a new band in the XPS O1s spectrum peaking at 531 eV, which was associated with the C=O bond. Through correlated studies of TG-MS, the main key fragments of ST-reacted AZA are reported.     

硅烷接枝交联HDPE、LLDPE及其共混物的结构研究

利用红外光谱、差示扫描量热法等方法研究了高密度聚乙烯(HDPE)、线性低密度聚乙烯(LLDPE)及其共混物的乙烯基三乙氧基硅烷(VTEOS)接枝及交联产物的分子结构、熔融行为。结果表明,VTEOS接枝交联PE能力为:LLDPE>HDPE/LLDPE共混物>HDPE;接枝和交联使HDPE、LLDPE及其共混物的结晶度和熔点降低,晶粒变得不均匀。     

Structure and adhesion properties of linear low‐density polyethylene powders grafted with acrylic acid via ultraviolet light

The structure and adhesion properties of linear low‐density polyethylene (LLDPE) powder grafted with acrylic acid (AA) via ultraviolet light (UV) were studied by Fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), and water contact angle, peel strength, and graft degree measurements. The results show that the chemically inert LLDPE powder can be graft‐copolymerized with AA via this photografting method. The graft degree increases with the ultraviolet irradiation time. The hydrophilicity of the grafted LLDPE powder and the peel strength of high‐density polyethylene (HDPE)/steel joint with the grafted LLDPE powder used as hot‐melt adhesive are improved considerably, as compared to that with the ungrafted LLDPE powder. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2549–2553, 2006     

Thermal degradation of flame‐retarded polyethylene/magnesium hydroxide/poly(ethylene‐co‐propylene) elastomer composites

Magnesium hydroxide‐based halogen‐free flame retarded linear low‐density polyethylene (LLDPE) composites containing poly(ethylene‐co‐propylene) (EP) elastomer were prepared by a melt process and subsequently vulcanized thermally. The thermal degradation of the composites was studied using thermogravimetric (TG) analysis and real‐time Fourier transform infrared (RT‐FTIR) spectroscopy. The combustion residues from the composites were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS). The results from TG and RT‐FTIR tests show that the incorporation of a suitable amount of the elastomer into polyethylene/magnesium hydroxide composites after vulcanization increases the thermal stability. A graphite‐like char was found for the composites with EP elastomer, from Raman spectroscopy studies. XPS results indicate that there are several forms of carbon present in the combustion residues of the composites with EP elastomer, compared with only one form of carbon in the residues of the composites without the elastomer. Copyright © 2003 Society of Chemical Industry     

Study on the grafting of PET onto the glass fiber surface during in situ solid‐state polycondensation

An in situ solid‐state polymerization process was developed to produce long glass fiber reinforced poly(ethylene terephthalate) (PET) composites. As reported in our last article, one advantage of this new process is that the good wetting of reinforcing fiber can be obtained for using low‐viscosity oligomer as raw materials. In this article, the grafting of PET macromolecular chain onto the surface of reinforcing glass fiber during in situ solid‐state polycondensation (SSP) will be investigated, which was believed to be another advantage for this new process and should be very important for thermoplastic composite. The reinforcing glass fiber after removing ungrafted PET from a long glass fiber reinforced PET composite by solvent extraction was investigated by SEM, pyrolysis‐gas chromatography mass spectrometry (Py‐GC/MS), DSC, and FTIR. The information from morphology of SEM photos of glass fiber surface, the spectrum of Py‐GC/MS, the melt peak at differential scanning calorimetric (DSC) curve, and the spectrum of Fourier transform infrared Raman spectroscopy (FTIR) gave a series evidence to prove the presence of grafted PET layer on the surface of silane‐coupling‐treated glass fiber. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 775–781, 2006     

聚乙烯溶液构成对控释肥料释放性能的影响

以聚乙烯为主要膜材料,采用喷雾相转化法和流化床设备制备控释肥料。系统研究聚合物溶液质量分数、低密聚乙烯(LDPE)与线性低密聚乙烯(LLDPE)配比、溶剂对制备包膜尿素释放期的影响。结果表明,包膜液质量分数从5%增加到8%,包膜尿素释放期由20 d增加到173 d,说明包膜液质量分数增加对释放期延长有显著影响;LDPE/LLDPE质量比从1增加到3,控释尿素释放期从98 d减少到32 d,说明聚乙烯分子的线性结构对释放期影响显著;质量分数控制在7%时,使用四氯乙烯、正辛烷、十氢化萘和环己烷4种溶剂处理的包膜肥养分释放期在87—108 d之间,4种不同溶剂对释放性能没有显著影响。为了制备释放期适宜的包膜肥料,包膜液质量分数宜控制为7%,不同线性聚乙烯混用能改变包膜控释肥料的控释性能,上述4种溶剂均可以用来配制包膜液。     

Chemical modification of hemp fibers by silane coupling agents

Natural hemp fibers were chemically modified using silane coupling agents to reduce their hydrophilic character. The existence of a chemical bond between coupling agents and hemp fibers was confirmed by ATR‐FTIR spectroscopy, ²⁹Si Nuclear Magnetic Resonance (NMR), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), and BET surface area measurements. It was shown that the initial concentration and the chemical structure of the organosilane coupling agent have an effect on the grafted quantity on the hemp fiber surfaces. The grafted quantity increased proportionally to the initial concentration of silane molecules. The presence of polar amino end group (NH₂) in silane structure can cause an increase in the grafted quantity, compared with results obtained in the case of silane molecules containing methacryloxy groups. This effect is attributed to the formation of hydrogen bonds between NH₂ and unreacted hydroxyl groups of hemp fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

铝塑复合管硅烷交联聚乙烯专用料的研究

研究了高密度聚乙烯（HDPE）／线性低密度聚乙烯（LLDPE）硅烷接枝交联体系。分析了过氧化二异丙苯（DCP），乙烯基三乙氧基硅烷（VTES），加工设备及工艺条件（温度，螺杆转速）对体系熔体流动速率（MFR）和凝胶含量的影响。并用Buss混炼设备制备出高流动性的铝塑复合管硅烷接枝交联PE专用料。     

Characterization of PET/LLDPE blends compatibilized with DEM-grafted-polyethylene

Summary Polyethylene terephtalate (PET)/linear low density polyethylene (LLDPE) blend compatibilized with diethylmaleate grafted polyethylene (DEM-g-LLDPE) were characterized by FTIR spectroscopy, thermogravimetrical analysis (TGA) and scanning electron microscopy (SEM). FTIR and TGA results indicate that there are interactions between the components of the blends, which produced variations in the infrared bands associated with the conformational changes (from gauche to trans) within the glycolic sequences of the polyester and a sinergistic effect on the thermal-oxidative stability of the compatibilized blends. Morphological analysis showed a dispersed particle size reduction and a better adhesion between the matrix and the disperse phase. Received: 3 March 1998/Revised version: 28 May 1998/Accepted: 10 June 1998