Solvothermal process for grafting maleic anhydride onto poly(ethylene 1-octene)

Solvothermal process was developed to graft maleic anhydride (MAH) onto poly(ethylene 1-octene) (POE). Fourier transform infrared spectra (FT-IR) and ¹H NMR spectra confirmed that maleic anhydride was successfully grafted onto the POE. The influences of MAH content, initiator concentration, POE concentration, reaction temperature, reaction time and solvents on the graft copolymerization were investigated through both of the grafting degree (GD) and gel content (GC). The results demonstrated that high grafting degree (up to 10.85%) could be obtained while the gel content was still low. Further studies revealed that POE-g-MAH could also be achieved in poor solvents of POE through this method.     

Initiation of Radical Chain Reactions of Thiol Compounds and Alkenes without any Added Initiator: Thiol‐Catalyzed cis/trans Isomerization of Methyl Oleate

A kinetic study of the dodecanethiol‐catalyzed cis/trans isomerization of methyl oleate (cis‐ 2 ) without added initiator was performed by focusing on the initiation of the radical chain reaction. The reaction orders of the rate of isomerization were 2 and 0.5 for 1 and cis‐ 2 , respectively, and an overall kinetic isotope effect k_H/k_D of 2.8 was found. The initiation was shown to be a complex reaction. The electron‐donor/‐acceptor (EDA) complex of dodecanethiol ( 1 ) and cis‐ 2 formed in a pre‐equilibrium reacts with thiol 1 to give a stearyl and a sulfuranyl radical through molecule‐assisted homolysis (MAH) of the sulfur–hydrogen bond. Fragmentation of the latter gives the thiyl radical, which catalyzes the cis/trans isomerization. A computational study of the EDA complex, MAH reaction, and the sulfuranyl radical calculated that the activation energy of the isomerization was in good agreement with the experimental result of E_A=82 kJ M ^?1. Overall, the results may explain that the thermal generation of thiyl radicals without any initiator is responsible for many well‐known thermally initiated addition reactions of thiol compounds to alkenes and their respective polymerizations and for the low shelf‐life stability of cis‐unsaturated thiol compounds and of mixtures of alkenes and thiol compounds.     

Preparation and Compatibility of EVM/TPU Blend

The preparation of EVM (ethylene‐vinyl acetate copolymer rubber)/TPU (thermoplastic polyurethane) blends with various ratios and their compatibility were investigated. The influence of mixing technology, filler type and content, the VA content in EVM (40 and 70 wt.%) and the addition of compatibilizers on the mechanical properties and the compatibility of the EVM/TPU blends were systematically studied.

The test results showed that in preparation of the blend, fillers should be added to the blend to improve the processability and that among the fillers used, silica showed the best reinforcing effect on the blends. The best parameters for blending EVM and TPU in a HAAKE rheometer was: mixing temperature 160°C, rotor speed 45 rpm and mixing time 15 min. The test results also showed that the compatibility of EVM 700 (VA=70%) with TPU was better than that of EVM400 (VA=40%). The addition of a compatibilizer EVM‐g‐MAH and EVM‐g‐FME improved the processability of the blends. The addition of EVM‐g‐MAH also improved the compatibility of EVM 700/TPU blend; both the mechanical properties and hot‐air aging properties of the blends were improved. However, the addition of EVM‐g‐FME did not improve the compatibility of EVM/TPU blends.     

不同引发剂引发SBS接枝马来酸酐的机理研究

采用FTIR和1 H NMR研究了引发剂过氧化二苯甲酰 (BPO)和偶氮二异丁腈 (AIBN)对聚苯乙烯 聚丁二烯 聚苯乙烯 (SBS)接枝马来酸酐 (MAH)的影响 ,讨论了相应的接枝机理 ,通过丁二烯 (PB)段碳碳双键(CC)随接枝率变化的规律进一步验证了机理 .结果表明 ,BPO与AIBN引发接枝的机理不同 ,BPO可引发PB的双键和烯丙位碳氢键 ,但引发烯丙位的速率比引发双键大 ;当BPO浓度达到一定量时 ,大量烯丙位的引发保护了碳碳双键 ,随BPO浓度的增大 ,碳碳双键的含量先减少后增加 .AIBN不能引发PB段烯丙位的碳氢键 ,只能引发双键接枝     

几种反应型相容剂及其在聚合物共混改性中的应用

反应型增容已经成为提高聚合物相容的一个重要手段。甲基丙烯酸缩水甘油配(GMA)、马来酸酐(MAH)和丙烯酸(AA)作为主要的接枝单体己得到广泛应用。本文从GMA、MAH和AA官能化聚合物的作用机理，以及他们作为反应型相容剂，通过“原位”反应增容聚合物共混体系，提高聚合物合金的相容性两个方面，介绍了国内外在反应型增容这一领域内所取得的进展。     

PP/PP-g-MAH/PA6共混物结构与可纺性研究

运用DSC、SEM、纺丝成形等手段研究了增容剂聚丙烯接枝马来酸酐 (PP g MAH)对聚丙烯 聚酰胺 6(PP PA6 )共混物结构和性能的影响 .结果表明 ,共混物呈典型海岛型两相结构 ;增容剂PP g MAH与PA6之间的在位反应改善了PP PA6共混体系的相容性 ,使共混物中PA6的热结晶峰消失 ,PP的结晶生长速率和成核速率降低 ,可纺性提高     

化学位移张量的测量

对于刚性晶格中的分子,化学位移是与外加磁场空间取向相关的张量,这个张量有6个独立的分量. 化学位移张量也可以利用其主轴分量及主轴与晶体坐标系的方向余弦来表示. 很显然,知道了固体分子中各不等价位置处的化学位移张量,就可以推测出分子中电子分布的图象,具有重要意义. 本文首先描述了化学位移张量测量的理论,对测量化学位移 各 向异性的各种方法作了介绍和比较,并详细论述了一些常用的方法,如二维魔角跳旋转(M a gic Angle Hopping, MAH)、二维魔角慢旋转(Magic Angle Turning, MAT)和二维变相旋转边带分离（2D phase-adjusted spinning sidebands, 2D-PASS）技术等. 最后,还介绍了单晶化学位移张量的常规测量方法.     

Structure and properties of chlorinated polyvinyl chloride graft copolymer with higher property

In this work, maleic anhydride (MAH) was grafted onto chlorinated polyvinyl chloride (CPVC) with high chlorine content (66 wt%) via in‐situ chlorinating graft copolymerization (ISCGC) to obtain the material with improved mechanical strength, softening point, and thermal stability of the material. The structure of the graft product (CPVC‐cg‐MAH) was characterized by FTIR, ¹H NMR, GPC, and UV. CPVC‐cg‐MAH contains less vinylidene chloride (CCl₂) units and double bond than corresponding CPVC. Meanwhile, the number–average molecular weight (M_n) and weight–average molecular weight (M_w) of CPVC‐cg‐MAH are increased, but distribution of molecular weight (M_w/M_n) is decreased. Then, the tensile strength and notched impact strength of CPVC‐cg‐MAH increased by 14.5 and 34.6%, respectively. Furthermore, the results of DMA, DSC, TG, and Vicat softening point showed that the loss peak of CPVC‐cg‐MAH was higher evidently than CPVC and moved to high temperature, the glass transition temperature (T_g) of CPVC‐cg‐MAH was consistent with CPVC, initial weight loss temperature, and maximum weight loss rate temperature of CPVC‐cg‐MAH increased by 7.2°C and 6.1°C, respectively, and the Vicat softening temperature of CPVC‐cg‐MAH increased by 15°C and up to 130°C. Copyright © 2011 John Wiley & Sons, Ltd.     

Chemical initiation mechanism of maleic anhydride grafted onto styrene-butadiene-styrene block copolymer

The mechanism of grafting styrene-butadiene-styrene (SBS) tri-block copolymer with maleic anhydride (MAH) initiated by benzoperoxide (BPO) or 2,2^′-azo-bis-isobutyronitrile (AIBN) was studied by FTIR and ¹H NMR spectroscopies. The variation of CC (double bond) content in SBS-g-MAH was used to verify the different graft mechanisms of BPO and AIBN, indicating that the chemical initiation mechanisms of MAH grafted onto SBS of AIBN is different from that of BPO. The graft reaction occurs by addition on CC for AIBN, while by removal of an allylic hydrogen atom from SBS and by addition on CC at the same time for BPO. The graft efficiency of AIBN is higher than that of BPO in this system.     

马来酸酐(MAH)表面改性纳米碳酸钙粉体的制备及表面性能

通过在两相法制备纳米碳酸钙的过程中添加一定量的马来酸酐(MAH)的方法，在纳米碳酸钙的表面引入羧基、羟基、双键等活性基团对纳米碳酸钙进行表面改性，并通过调节马来酸酐的用量，有效地控制纳米碳酸钙的极性和表面能。接触角实验结果表明，当马来酸酐的加入量为2%时可以获得界面性能最理想的改性纳米碳酸钙。还在此基础上提出了马来酸酐(MAH)对纳米碳酸钙进行表面改性的过程机理，并以SEM，ATR-FTIR和TGA等手段对上述过程机理进行了验证。