二月桂酸硫代二甘醇酯的合成及其在聚丙烯中抗氧化性能研究（英文）

以硫代二甘醇和月桂酸为原料,选用对甲苯磺酸为催化剂、二甲苯为带水剂,合成了抗氧剂二月桂酸硫代二甘醇酯。适宜工艺条件为:反应温度140℃,醇酸摩尔比为2∶1.5,催化剂用量为月桂酸质量的2.0%。将产物应用于聚丙烯中,与商品化的抗氧化剂相比具有良好的抗氧化性能。结果表明,添加二月桂酸硫代二甘醇酯后,聚丙烯的熔体流动速率从5.36g·10min-1降低到3.59g·10min~(-1);断裂伸长率和冲击强度分别达到112.2%和121.0k J·m~(-2)。当与商品化抗氧化剂168或1010混合使用时,抗氧化性能显著增加:与168混合时,熔体流动速度、拉伸强度、断裂伸长率和冲击强度分别达3.28g·10min~(-1)、40.2MPa、140.8%和124.2k J·m~(-2);与1010混合时,熔体流动速度达3.56g·10min~(-1)。     

PP/EPDM共混体系的辐射效应

聚丙烯和三元乙丙橡胶(EPDM)的γ辐射效应及辐射后的聚丙烯熔体流动速率的测定表明,在限定空气中聚丙烯随着辐照剂量的增加,熔体流动速率急剧下降,而三元乙丙橡胶随辐射剂量的增加,凝胶含量逐渐增加。在20kGy的剂量辐照下,凝胶含量为22．7％,加入2％的三聚异氰酸三烯丙酯,在相同的剂量辐照下,凝胶含量达到68％。在低剂量下辐照对共混物的拉伸强度影响不大,对冲击强度有很大的影响。在20kGy的剂量辐照下,加入50％EPDM的聚丙烯的缺口冲击强度由1．95kJ／m^2提高到30kJ／m^2,维卡软化温度由85．9℃提高到97．0℃。     

反相高效液相色谱法测定抗氧化剂硫代二丙酸双十二醇酯

提出了用反相高效液相色谱法测定抗氧化剂硫代二丙酸双十二醇酯(DLTDP)含量的方法。采用Symmetry C18色谱柱,甲醇-水(98+2)为流动相,示差折光检测器,外标法定量,抗氧化剂DLTDP的质量浓度在0.20~20.0 g·L-1范围内与峰面积呈线性关系,测定下限(10S/N)为0.10 g·L-1。应用此方法分析了5批DLTDP样品,测得其DLTDP的质量分数在95.6%~99.3%之间,测定值的相对标准偏差(n=5)均小于1.1%。     

结合分子模拟探讨不同醚键PBS基共聚物的性能与酶催化降解

以硫二甘醇取代二甘醇,在聚(丁二酸丁二醇酯)(PBS)分子主链上分别引入硫醚和氧醚基团,得到聚(丁二酸丁二醇酯-丁二酸硫代二乙二醇酯)[P(BS-co-TDGS)]和聚(丁二酸丁二醇酯-丁二酸二乙二醇酯)[P(BS-co-DEGS)],通过热重分析(TG)和X射线衍射(XRD)测试比较了二者的结晶性能和热性能.采用南极假丝酵母脂肪酶N435(CALB)为催化剂,在水相中研究了P(BS-co-TDGS)和P(BS-co-DEGS)的降解规律及差异性.采用分子模拟方法研究了共聚物可能存在的聚集态以及N435酶与底物的结合,模拟结果验证了共聚物P(BS-co-TDGS)的结晶度下降及热稳定性降低的结论.分子对接模拟结果表明,N435酶与DEGSDEG单元的结合能更大,即含有丁二酸硫代二乙二醇酯键型底物P(BS-co-DEGS)与N435酶活性位点的对接更为稳定.     

碳酸酯基阳离子Gemini表面活性剂的相转移催化性能研究

采用二月桂酸二丁基锡为催化剂,N,N-二甲基乙醇胺与碳酸二甲酯酯交换反应制得二(N,N-二甲基胺基乙基)碳酸酯(Ⅰ),产率92％(以碳酸二甲酯计);再与1-溴代十六烷反应得到一种含碳酸酯基阳离子Gemini表面活性剂(Ⅱ),产率68.5％[以(Ⅰ)计],用IR、1 HNMR、元素分析表征了其结构.采用(Ⅱ)为固-液相转...     

聚丙烯中硫酯类抗氧剂的质谱分析

采用齐格勒-钠塔催化剂使丙烯催化聚合得到聚丙烯。聚丙烯树脂本身具有优良的性能,如机械强度好,易加工成型,质量轻,成本低等,但也存在一些缺陷,如由于聚丙烯结构中存在叔碳原子,在造粒加工、贮存和使用过程中,易受热、光、氧等的作用而降解,导致材料的性能降低。为了抑制和延缓聚丙烯的氧化降解,需要在造粒阶段加入抗氧剂。本文以一种聚丙烯树脂样品为研究对象,采用溶剂抽提法提取有机添加剂,并用柱层析法对添加剂进行了分离;利用EI-MS分析了添加剂的组成,其中通过谱图解析,鉴定出添加剂中含有硫酯类抗氧剂-硫代二丙酸二(十四)酯(DMTP),并用此类常用化合物进行了验证,分析结果对树脂牌号的开发具有指导意义。     

微波辅助酶促月桂酸淀粉酯的合成

以天然玉米淀粉和月桂酸为原料,脂肪酶Novozym 435为催化剂,研究了微波辐照下月桂酸淀粉酯的酶促合成。通过对淀粉进行预处理活化来提高淀粉的酯化反应活性,并主要考察了微波功率、月桂酸用量、脂肪酶Novozym 435用量及反应时间等参数对酶促月桂酸淀粉酯合成的影响。采用气相色谱法进行取代度的测定,并以取代度为考察指标,确定了最佳的反应条件。结果表明,淀粉的最佳预处理方法为NaOH/尿素混合溶液法,经该法处理后淀粉的酯化反应活性大大提高;微波辐照技术的应用大大缩短了反应时间,并提高了月桂酸淀粉酯的取代度。适宜的工艺条件为：微波功率为240W,月桂酸用量为30%,酶加入量为7%,反应时间26min。在上述反应条件下可以制得取代度为 0.0311的月桂酸玉米淀粉酯。     

聚有机硅氧烷的研究——Ⅶ.硅橡胶的室温熟化和高温降解

用原硅酸乙酯为交联剂和二月桂酸二丁基锡酯为催化剂使聚二甲基硅氧烷在室温下进行熟化变为三向结构的弹性体(硅橡皮)时,在有水的情况下,原硅酸乙酯用量越多,熟化越快,无水时,结果相反。我们认为在空气中,原硅酸乙酯会经水解缩合变为聚硅酸乙酯,因此室温熟化的真正的交联剂不是象文献所说的原硅酸乙酯而是聚硅酸乙酯。 室温熟化所得的硅橡皮在高温下,机械强度会迅速下降然后逐渐恢复。将硅橡皮分别在空气及氮气中进行高温处理,并测定其溶胀度的变化的结果,证明这现象是由于硅橡皮在高温下发生降解及氧化所致。降解是由于水在二月桂酸二丁基锡酯或它的水解产物月桂酸催化下使聚二甲基硅氧烷主链的Si—O—Si键水解所引起的。     

微波辅助酶促月桂酸淀粉酯的合成

以天然玉米淀粉和月桂酸为原料,脂肪酶Novozym 435为催化剂,研究了微波辐照下月桂酸淀粉酯的酶促合成.通过对淀粉进行预处理活化来提高淀粉的酯化反应活性,并主要考察了微波功率、月桂酸用量、脂肪酶Novozym 435用量及反应时间等参数对酶促月桂酸淀粉酯合成的影响.采用气相色谱法进行取代度的测定,并以取代度为考察指标,确定了最佳的反应条件.结果表明,淀粉的最佳预处理方法为NaOH/尿素混合溶液法,经该法处理后淀粉的酯化反应活性大大提高;微波辐照技术的应用大大缩短了反应时间,并提高了月桂酸淀粉酯的取代度.适宜的工艺条件为:微波功率为240 W,月桂酸用量为30%,酶加入量为7%,反应时间26 min.     

食品接触聚丙烯塑料中抗氧化剂迁移模型研究

在聚丙烯(PP)树脂中加入不同浓度梯度的抗氧化剂2,6-二叔丁基对甲酚(BHT)、四(3,5-二叔丁基-4-羟基)苯丙酸季戊四醇酯(抗氧化剂1010),通过双螺杆塑料挤出机在190℃混合挤出造粒并热压成膜,自制了食品包装用PP塑料膜(膜厚0.1 mm)。通过高效液相色谱仪(HPLC)配二极管阵列(PDA)检测器(检测波长为282 nm)测定PP样品中的两种抗氧化剂在食品模拟液(95%乙醇溶液)中的迁移量,其中BHT迁移出,而抗氧化剂1010未迁移出。在实验数据基础上,利用软件对迁移数据进行迁移模型拟合,建立了抗氧化剂BHT的Weibull迁移模型和Piringer迁移模型,比较了所建立的两种模型的适用性,结果表明, Weibull模型对实际测试结果的拟合优度( R2)能达到0.99以上,Weibull模型比Piringer模型更接近于实际迁移结果,同时,Weibull模型和Piringer模型的参数间存在一定的数学关系,符合关系式τ≈12.2(L2/D)。     

有机硅改性双酚A型环氧树脂研究

采用二氯二甲基硅烷 (DMS) ,或DMS与α ,ω 二氯聚二甲基硅氧烷 (DPS)的混合物来改性双酚A型环氧树脂 ,通过对固化物的冲击强度、拉伸强度、断裂伸长率和玻璃化转变温度 (Tg)的测定 ,探讨了改性方法、有机硅组成与含量等对材料性能的影响 .结果表明 ,用 5 7phr的DMS改性时 ,树脂固化物的冲击强度达2 0 2kJ m2 ,拉伸强度达 6 7 0MPa ,断裂伸长率达 11 2 9% ,Tg 达 16 8 0℃ ;分别比未改性时提高了 9 4kJ m2 ,2 1 1MPa ,5 4 %以及 32 6℃ .而用 0 7phrDMS +10phrDPS共同改性时 ,除Tg 和拉伸强度略有上升外 ,冲击强度达到了 31 6kJ m2 ,断裂伸长率达到 81 6 % ,分别比纯环氧提高了 2 0 8kJ m2 和 75 7% .     

Effects of the compatibilizer PE‐g‐GMA on the mechanical,thermal and morphological properties of virgin and reprocessed LDPE/corn starch blends

The effects of the compatibilizer polyethylene grafted with glycidyl methacrylate (PE‐g‐GMA) on the properties of low‐density polyethylene (LDPE) (virgin and reprocessed)/corn starch blends were studied. LDPE (virgin and reprocessed)/corn starch blends containing 30, 40 and 50 wt% starch, with or without compatibilizer, were prepared by extrusion and characterized by the melt flow index (MFI), tensile test, dynamic mechanical analysis (DMTA) and light microscopy. The addition of starch to LDPE reduced the MFI values, the tensile strength and the elongation at break, whereas the modulus increased. The decreases in the MFI and tensile properties were most evident when 40 and 50 wt% starch were added. Blends containing 3 wt% PE‐g‐GMA had higher tensile strength values and lower MFI values than blends without compatibilizer. Light microscopy showed that increasing the starch content resulted in a continuous phase of starch. Copyright © 2005 John Wiley & Sons, Ltd.     

Influence of the Addition of Lauric Acid to Films Made from Gelatin,Triacetin and a Blend of Stearic and Palmitic Acids

Summary: The objective of this research was to verify the influence of adding increasing amounts of lauric acid on the functional properties of homogenized films made from gelatin, triacetin and a blend of palmitic and stearic acids. The films were characterised with respect to their visual aspect, water vapour permeability (WVP), water solubility, mechanical properties (tensile strength and percent elongation), oxygen permeability (O₂P), opacity (OP) and melting and glass transitions temperatures. The films produced were malleable and macroscopically homogeneous. The addition of 1% of lauric acid to the film of gelatin, triacetin and blend of palmitic and stearic acids (5.84 ± 0.31 gmm · m⁻² dkPa) caused a slight decrease in WVP. The additions of 2.5% (5.70 ± 0.76 gmm · m⁻² dkPa), 5% (5.38 ± 0.64 gmm · m⁻² dkPa) and 10% (4.50 ± 0.55 gmm · m⁻² dkPa) of lauric acid were sufficient to make a significant difference in the WVP at the higher levels used. As compared to the gelatin and triacetin film, the addition of lauric acid at all the concentrations studied resulted in a slight increase in the film solubility. The addition of hydrophobic substances to gelatin/triacetin films (15.26 ± 0.28 cm³ · µm · m⁻² dkPa) favoured an increase in O₂P permeability, this effect being greater in the films made from gelatin, triacetin, blend of palmitic and stearic acids and 10% lauric acid (24.48 ± 0.07 cm³ · µm · m⁻² dkPa). The increasing addition of lauric acid significantly reduced the tensile strength and increased elongation of the films composed of gelatin, triacetin and blend that being more evident at the concentrations of 5% (67.58 ± 1.23 MPa and 11.45 ± 0.57%) and 10% (63.50 ± 1.56 MPa and 12.90 ± 0.57%). The addition of 1% (OP, 27%) and 10% (OP, 28%) of lauric acid induced no visible effect on the opacity of the films. The thermogrammes showed three transitions for the gelatin/triacetin/stearic-palmitic blend/1% lauric acid films (−57.42 °C, 23.74 °C and 44.11 °C) and two for the gelatin/triacetin/stearic-palmitic acids blend/10% lauric acid films (−56.22 °C and 17.35 °C). As observed by DSC, the addition of fatty acids resulted in the appearance of more than one melting peak for all films in relation to the gelatin and triacetin film.     

Foam/Film Alternating Multilayer Structure with High Toughness and Low Thermal Conductivity Prepared via Microlayer Coextrusion

Multilayer membranes prepared via microlayer coextrusion have attracted wide attention due to their unique properties and broad applications. In present study, the foam/film alternating multilayer sheets based on ethylene-vinyl acetate copolymer(EVA) and high-density polyethylene are successfully prepared via microlayer coextrusion. The cells in the sheets are single-cell-array along the foamed EVA layers with uniform cell size. In addition, the effects of layer number and foam relative thickness on morphology, mechanical properties, damping and heat insulation properties are investigated. The cell size decreases significantly with increasing layer number due to the enhanced confine effects. The tensile strength, elongation at break, and heat insulation also increase significantly. However, the mechanical damping properties change little in the observed frequency. Meanwhile, with higher relative thickness of EVA foam, the sheets have lower tensile strength and lower thermal conductivity, while the damping properties are enhanced in a specific frequency scope. The elongation at break of the optimized sample comes to 800% and the thermal conductivity decreases to 61 mW·m~(-1)·K~(-1), which shows high toughness and low thermal conductivity, indicating a possible method for preparing materials with high toughness and heat-insulating properties.     

Solvent Free Lipase Catalysed Synthesis of Ethyl Laurate: Optimization and Kinetic Studies

The current research work represents solvent free enzymatic synthesis of fatty acid ethyl ester; ethyl laurate. Immobilized lipase Fermase CALB?10,000 was used for the synthesis of ethyl laurate from ethanol and lauric acid. The influence of process parameters such as catalyst loading, speed of agitation, mole ratio, molecular sieves and temperature were studied. Fermase CALB?10,000 offered a conversion of 92.46 % at 60 °C in 4 h at optimized condition. The experimental data was best fitted by the Random Bi-Bi model with inhibition of both the substrates i.e. lauric acid and ethanol. The following kinetic parameters were retrieved from the model: V_max = 1.243 × 10³ mmol/min/g enzyme; K_A = 0.1283 mmol; K_B = 8.51 mmol; K_iA = 5.098 mmol; and SSE = 0.0142. The activation energy for the enzymatic esterification was also determined and calculated to be 28.49 kJ/mol. A maximum conversion of 71 % was obtained after 5 successive reuse of Fermase CALB?10,000 lipase.     

Radiation effects on the immiscible polymer blend of nylon1010 and high-impact strength polystyrene (II): mechanical properties and morphology

The paper studies the morphology and mechanical properties of immiscible binary blends of the nylon 1010 and HIPS through the radiation crosslinking method. In this blend, the HIPS particles were the dispersed phases in the nylon1010 matrix. With increasing of dose, the elastic modulus increased. However, the tensile strength, elongation at break and the energy of fracture increased to a maximum at a dose of 0.34 MGy, then reduced with the increasing of dose. SEM photographs show that the hole sizes are not changed obviously at low dose and at high dose, remnants that cannot be dissolved in formic acid and THF can be observed in the holes and on the surface. TEM photographs showed that radiation destroys the rubber phases in the polymer blend.     

Synergistic Effect of Phosphite with FuUerene C60 and Fullerenol C60（OH）24 as Antioxidants in Polypropylene

Polypropylene samples with fullerene C60, fullerenol C60（OH）24, 1010, C60/168, C60-OH/168 and 1010/168 as antioxidants were prepared by extrusions. MFR, YI, TGA and OIT of all the samples were tested. According to the results of MFR, during the melt extrusion, fullerene showed excellent stability effect on PP. The antioxidative ability of fullerene was comparable to the traditional antioxidant 1010. The antioxidative ability of fullerenol was not significant in the first extrusion and it accelerated the degradation of PP in the second and the third extrusions. TGA and OIT tests showed that the stability effects of fullerene and fullerenol were slightly lower than antioxidant 1010. In the first time, antioxidant 168 was reported to show great synergistic effects with fullerene and fullerenol as antioxidants, which sussested a simple way to enhance the antioxidative abilities of fullerene and fullerenol.     

一种含树枝单元的高流动性尼龙6的原位聚合及性能测试

将低代数的树枝状大分子聚酰胺胺(polyamidomine,即PAMAM)分别与对苯二甲酸配制成母盐溶液,再以母盐溶液,己内酰胺,封端剂一起投入高压釜进行原位聚合,通过调节PAMAM在己内酰胺中的比例及改变不同的PAMAM代数得到新型高流动性尼龙6.FTIR显示,与线性尼龙相比较,高流动性尼龙6的γ(N—H)和2δ(N—H)两处对应峰都发生了明显的蓝移.对于树枝单元含量较低(0.3 wt%~0.5 wt%)的新型尼龙6,拉伸性能没有下降,缺口冲击强度增加,而熔体流动却显著得到改善.DSC显示,新型尼龙6的结晶曲线的结晶峰温度有不同程度的降低,晶体生长速率明显减慢.     

TGA application for optimising the accelerated aging conditions and predictions of thermal aging of rubber

Changes in the residual compression set, tensile strength and elongation at break, as well as the oxygen absorption and mass change, are evaluated during the thermal oxidation of butadiene-nitrile-based carbon black-filled rubber. Activation energies for the processes are determined. Using TGA, the activation energy of the first thermal degradation stage (87-88 kJ/mol) corresponded to the increase in compression set. The activation energy of the second stage (116-117 kJ/mol) corresponded to the decrease in the elongation at break and oxygen absorption. These correlations confirm that TGA can be used to predict the thermal stability of rubber.     

松香基聚醚酯弹性体的制备及表征

通过松香与聚醚丙烯酸酯的Diels Alder加成产物与聚乙二醇、柠檬酸的缩聚反应,合成出松香基聚醚酯弹性体,产物采用红外、拉伸、DSC和TGA进行了表征。 TGA测试表明,松香基聚醚酯弹性体的10%热失重温度在300 ℃以上,拉伸测试表明,拉伸强度为0.26～0.62 MPa,断裂伸长率为338%～458%。