汽车密封条用乙丙橡胶的研究

以三氯氧钒-混合烷基铝为催化体系,以己烷为溶剂、氢气为相对分子质量调节剂研究了混合烷基铝对聚合物相对分子质量及其分布的影响,合成了门尼粘度、相对分子质量及其分布、乙烯含量、第三单体含量与国外同类产品4802基本相同的乙丙橡胶,应用性能研究结果表明,合成的样品性能与国外同类产品相当。     

新型相对分子质量调节剂在聚合物多元醇合成中的应用

采用连续法以新型相对分子质量调节剂合成聚合物聚醚多元醇(POP),研究其用量对POP产品性能的影响,并与硫醇为相对分子质量调节剂合成的POP进行对比。结果表明,用新型相对分子质量调节剂合成产品的固含量、粘度、过滤性都优于硫醇合成的POP,且POP颗粒圆滑,平均粒径相对较小;用其POP产品制备的聚氨酯泡沫的力学性能不低于硫醇合成的POP产品。     

耐热聚乙烯管材专用树脂的结构与性能

研究了3种耐热聚乙烯管材专用树脂的结构与性能。它们的共同特征为熔体流动速率低于0.7 g/10 min,密度为0.930~0.944 g/cm3,相对分子质量为(1.5~2.5)×105,可以为窄相对分子质量分布,也可以为中等相对分子质量分布。1-己烯共聚产品与1-辛烯共聚产品性质较为接近,都是窄相对分子质量分布,而1-丁烯共聚产品具有相对分子质量高(2.0×105以上),相对分子质量分布中等(10左右),熔体流动速率低(低于0.3 g/10min)、密度高(大于0.940 g/cm3)、拉伸屈服强度高、弯曲模量高、熔融峰温高、结晶峰温高的特点。相同条件下,1-丁烯共聚产品具有较高的黏度和模量。     

聚砜型油品抗静电剂的合成及性能评价

以α-烯烃、顺酐、SO2为原料合成聚砜型油品抗静电剂,用红外光谱对聚砜的结构进行了表征,考察了聚砜相对分子质量与其抗静电性能之间的关系,并对聚砜型油品抗静电剂的作用机理进行了探讨。结果表明,聚砜添加的质量浓度为3 mg/L时,加氢柴油电导率由17 pS/m增至170 pS/m,放置6天可继续增至428 pS/m,并且连续储存25天电导率稳定,没有下降趋势;相对分子质量大的聚砜产品初期抗静电效果不如相对分子质量小的,但相对分子质量大的聚砜产品后期作用效果优于相对分子质量小的产品;顺酐-烯烃聚砜分子链上羧基与砜基之间的强相互作用导致其抗静电效果明显优于烯烃聚砜。     

提高转化率对乳聚丁苯橡胶性能的影响

以吉林石化公司有机合成厂的乳聚丁苯橡胶(SBR)生产配方为标准配方,研究了聚合反应时间对转化率的影响,分析了提高转化率对SBR的生胶门尼黏度、结合苯乙烯含量、凝胶含量、相对分子质量及其分布、胶乳黏度等基本性能的影响。结果表明,在标准配方条件下,延长聚合反应时间,转化率可以达到70%。转化率为70%时所得SBR与转化率为62%时所得SBR相比,前者的生胶凝胶含量和胶乳黏度均增大了1倍,数均相对分子质量、重均相对分子质量和Z均相对分子质量均高于后者,相对分子质量分布变宽,且前者的生胶结合苯乙烯含量能够达到产品标准,而生胶门尼黏度和在50 m in时的300%定伸应力偏高于产品优级品要求。     

高相对分子质量亲水性聚醚合成工艺研究

以KOH为催化剂,环氧乙烷和环氧丙烷混合物为原料,采用2种工艺进行了高相对分子质量亲水性聚醚的合成。一种是由起始剂合成1 000相对分子质量中间体,然后直接合成产品(原生产工艺),再对其进行精制处理;另一种是由起始剂合成1 000相对分子质量中间体,然后当相对分子质量达到4 000时进行熟化脱气处理,再继续进环氧乙烷和环氧丙烷混合物合成产品(新生产工艺),接着对其进行精制处理。结果表明:采用新工艺的产品能达到设计相对分子质量,收率提高,品质得到提升,并使保水率提高到25%。     

丙酸聚醚中间体的合成及其对相对分子质量分布和PEG含量的影响

研究了低沸点酸起始剂酯醚的合成工艺 ,即先合成中间体 ,再合成目标产品 ,讨论了不同环氧乙烷 (EO)、环氧丙烷 (PO)加成数的中间体对聚醚相对分子质量分布以及质量指标的影响。该法所得聚醚产品相对分子质量分布系数 (重均相对分子质量 /数均相对分子质量 )低于 1 0 5 ,副产物聚乙二醇含量为零。     

聚酯连续生产过程微观质量控制系统问世

天津石化公司化纤厂与北京大学共同研制成功聚酯连续生产过程微观质量控制系统，已通过鉴定。 该控制系统给出以聚酯产品相对分子质量分布及各阶段为目标的数学模型，并以聚酯相对分子质量分布微观质量为监控指标，实现了计算机闭环控制和在线瞬时控制、工艺控制的优选。聚酯连续生产过程微观质量控制系统问世     

抗氧剂425的合成与结构表征

研究了以对乙基苯酚、叔丁醇为原料,在酸性条件下,进行烷基化反应,合成2 叔丁基 4 乙基苯酚,再进一步缩合成抗氧剂425的工艺条件。并对产品进行了熔点,相对分子质量,高效液相色谱(HPLC)及核磁共振谱(NMR)的测定。结果表明,两步反应的收率分别为85%～90%和50%～60%。产品熔程为121～123℃,相对分子质量为368 3,均与文献相符。HPLC分析在5 272min出峰,NMR谱图证明所得到产品为抗氧剂425。     

小中空容器用HDPE产品气味问题分析

针对国产小中空容器用高密度聚乙烯(HDPE)产品在加工时存在气味的问题,分别对国产HDPE和进口HDPE产品进行升温淋洗分级分析、不同相对分子质量聚合物含量分析、庚烷提取物含量分析。结果表明:气味大小与产品中低相对分子质量聚合物的含量多少有关,气味由低相对分子质量聚合物引起,通过控制低相对分子质量聚合物的产生可有效解决产品气味问题。     

Dynamic simulation and experimental evaluation of EPDM synthesis with ET(IND)2ZRCL2/MAO catalyst system

A mathematical model for the homogeneous terpolymerization of ethylene–propylene–diene (EPDM) in a semibatch reactor using Et(Ind)₂ZrCl₂/MAO as a catalyst system was developed and reported herein. In this study, we developed a kinetic model in order to explain the catalyst and EPDM properties such as catalyst activity, weight‐average molecular weight, and terpolymer composition, which were experimentally and theoretically obtained. For this system, a lower E/P feed ratio leads to a lower molecular weight and a broader initial molecular weight distribution, while the increase in diene concentration leads to a decrease in the catalyst activity without broadening the MWD of the resulting polymers. The proposed model accounts for these experimental trends and for some data in the literature.     

Effect of mastication on molecular weight and molecular weight distribution of EPDM polymer and SBR

EPDM and SBR were masticated on an open mill. The temperature range of mastication for EPDM was 68–480°F. SBR was milled at 170–200°F. The gel-permeation chromatography analyses were made on the masticated samples. For EPDM at 68°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is nonrandom. At constant mastication time between 182 and 315°F, there is little change in molecular weight. Mastication for 18 min at 480°F broadens the molecular weight distribution; the degradation is random. For SBR at 170–200°F, molecular weight decreases and molecular weight distribution narrows with mastication time; the degradation process is also nonrandom. Nonrandom degradation for both EPDM and SBR results in a narrowing of the molecular weight distribution, without build-up of low molecular weight molecules, and without a shift in the peak molecular weight. This is contrary to nonrandom degradation of natural rubber where a shift in the peak molecular weight occurs with mastication time.     

Effects of the ethylene–propylene–diene monomer microstructural parameters and interfacial compatibilizer upon the EPDM/montmorillonite nanocomposites microstructure: Rheology/permeability correlation

Attempts have been made to investigate the effects of ethylene–propylene–diene monomer (EPDM) rubber structural parameters on the developed microstructure, mechanical properties, rheology, and oxygen gas permeability of EPDM/organically modified montmorillonite (O‐MMT) nanocomposite samples prepared via melt mixing. Maleic anhydride grafted EPDM (EPDM‐g‐MAH) has been employed as an interfacial compatibilizer. The influence of the EPDM melt viscosity and chain linearity on the extent of exfoliation of the clay nanolayers has been evaluated through the calculation of the nanolayer aspect ratio (length/thickness) with the Halpin–Tsai model. The results are consistent with the X‐ray diffraction patterns of the samples. The flocculation of the clay nanolayers has been found to be more probable when O‐MMT is mixed with highly branched, low‐molecular‐weight EPDM. More exfoliation occurs when EPDM rubber with a high molecular weight but low branching is used. This has been confirmed by more nonlinear melt rheology behavior and broadening of the retardation time spectra. Maleated EPDM has been shown to be effective in enhancing the molecular intercalation of the clay nanolayers and the prevention of flocculation in both low‐molecular‐weight and high‐molecular‐weight EPDM matrices. Dynamic melt rheology measurements have revealed nonterminal behavior within the low‐frequency range by interfacially compatibilized molten samples with an EPDM‐g‐MAH/clay ratio of 3, regardless of the matrix molecular weight and chain linearity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

不同牌号三元乙丙橡胶的结构与性能对比

对8个牌号三元乙丙橡胶(EPDM)的微观结构、硫化特性、物理机械性能、耐磨性能及耐老化性能进行了对比.结果表明,EPDM中第3单体亚乙烯基降冰片烯(ENB)质量分数影响了EPDM的硫化速率.8个牌号中EPDM 9950 C的硫化速率最快,EPDM 3722的硫化速率最慢;充油胶EPDM 3666的硫化速率与结构类似的E...     

Structured polymer blends: 2. Processing of polypropylene/EDPM blends: controlled rheology and morphology fixation via electron beam irradiation

Electron beam irradiation has been used to improve the processability of polypropylene/ethylene-propylenediene monomer (PP/EPDM) blends (controlled rheology) in combination with fixation of morphology by inducing crosslinks in the dispersed EPDM phase. An optimum morphology for impact toughening has been obtained via extrusion-blending high molecular weight PP with EPDM. Upon irradiation before subsequent processing (injection moulding) this morphology is fixated, whereas the viscosity of the blend decreases as a result of chain scission of the PP matrix. Impact strength and elongation at break of these irradiated blends are better than those of blends of low molecular weight PP with EPDM, which possess comparable overall viscosity.     

Solution properties and molecular structures of EPM and EPDM

The solution properties of EPDM were investigated based on EPM as a model compound of linear molecules. The glass transition temperature and the propylene content in EPDM were measured as a function of the molecular weight. Good agreement between the solution behaviors of EPM and EPDM was observed. This was correlated to change not only in the propylene composition but also in the monomer sequence distribution.     

Effects of the compatibilizer structural parameters on microstructural formation in ethylene–propylene–diene monomer rubber/ethylene–propylene–diene monomer rubber‐g‐maleic anhydride/organoclay nanocomposites

Nanocomposite vulcanizates based on ethylene–propylene–diene monomer rubber (EPDM) and organically modified montmorillonite with improved mechanical and barrier properties were prepared via a melt‐mixing process in the presence of maleic anhydride grafted ethylene–propylene–diene monomer rubber (EPDM‐g‐MAH) as an interfacial compatibilizer. The effects of the EPDM Mooney viscosity as the matrix and also the compatibilizer molecular weight and its maleation degree on the developed microstructure were also studied. The annealing of the vulcanized nanocomposites based on a low‐Mooney‐viscosity EPDM matrix and low‐Mooney‐viscosity EPDM‐g‐MAH enhanced the flocculation of the dispersed clay platelets; this implied that the flocculated structure for the clay nanolayers was more thermodynamically preferred in these nanocomposites. This was verified by the decrease in the oxygen permeability of the nanocomposite vulcanizates with increasing annealing time. The tendency of the clay nanosilicate layers to flocculate within the matrix of EPDM was found to be influenced by the clay volume fraction, the maleation degree, and also, the Mooney viscosity of the compatibilizer. Interfacially compatibilized nanocomposites based on high‐molecular‐weight EPDM exhibited a more disordered dispersion of the clay nanolayers, with a broadened relaxation time spectra; this was attributed to the higher shearing subjected to the mix during the melt‐blending process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rheology and properties of EPDM/BR blends with or without a homogenizing agent or a coupling agent

Rheology, dynamic mechanical properties, mechanical properties, and morphology of ethylene–propylene–diene rubber/butadiene rubber (EPDM/BR) blends with or without a homogenizing agent or a coupling agent were investigated. AAHR (a mixture of aliphatic and aromatic hydrocarbon resins) was used as a coupling agent. The dynamic mechanical analysis and the morphological studies revealed that EPDM and BR were incompatible and the addition of AAHR was very effective to plasticize the EPDM/BR blend and enhance the compatibility between EPDM and BR. It was found that the addition of an AAHR increased the amounts of bound rubbers and, hence, the vulcanizate properties such as tear strength and fatigue resistance of the EPDM/BR blends were improved. The blends of maleic anhydride-grafted EPDM and BR were also prepared and the properties were compared. The dynamic mechanical analysis and the morphological studies revealed that the addition of TESPT increased the weight of bound rubbers and provided better dispersion of carbon black, resulting in good mechanical properties such as tear strength and fatigue resistance of the vulcanized EPDM/BR blends. © 1996 John Wiley & Sons, Inc.     

Surface segregation of polyethylene in low‐density polyethylene/ethylene–propylene–diene rubber blends: Aspects of component structure

Aspects of the molecular weight and its distribution, the branching of low‐density polyethylene (LDPE), and the molecular composition of the ethylene–propylene–diene rubber (EPDM) matrix are presented in this article in terms of their influence on the surface segregation of polyethylene (PE) in elastomer/plastomer blends. All of the PEs studied, despite different weight‐average molecular weights and degrees of branching, segregated to the surface of the LDPE/EPDM blends. Atomic force microscopy pictures demonstrated defective crystalline structures on the surface of the blends, which together with a decrease in the degrees of their bulk crystallinity and a simultaneous increase in their melting temperatures, pointed to a low molecular weight and a defective fraction of PE taking part in the surface segregation. The extent of segregation depended on the molecular structure of the EPDM matrix, which determined the miscibility of the components on a segmental level. The higher the ethylene monomer content in EPDM was, the lower was the PE content in the surface layer of the blends. The composition and structure of the surface layer was responsible for its lower hardness in comparison with the bulk of the blends studied. The surface gradient of the mechanical properties depended on the physicochemical characteristics of the components and the blend composition, which created the possibility of tailoring the LDPE/EPDM blends to dedicated applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 625–633, 2006     

Synthesis and properties of vinyltrimethoxysilane–EPDM–styrene graft terpolymer

The graft copolymerizations of vinyltrimethoxysilane (VTMO) and styrene (St) onto ethylene–propylene–diene terpolymer (EPDM) were carried out with benzoyl peroxide (BPO) as an initiator in toluene. The effects of EPDM concentration, mole ratio of VTMO to St, reaction time, reaction temperature, and initiator concentration on the graft copolymerizations were examined. The synthesized VTMO–EPDM–St graft terpolymers (VES) were confirmed by infrared and ¹H-NMR spectroscopies. The molecular weight, thermal stability, light resistance, and weatherability of the graft terpolymer were investigated by gel permeation chromatography, thermogravimetric analysis, and Fade-o-Meter. The number-average molecular weight was 109,000. It was found that the heat resistance and light resistance as well as weatherability of VES are considerably better than those of acrylonitrile–butadiene–styrene terpolymer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1345–1352, 1998