CM与乙烯甲基丙烯酸酯弹性体共混硫化胶性能研究

本文研究了不同共混比对氯化聚乙烯橡胶（CM）/乙烯甲基丙烯酸酯弹性体（EMA）共混硫化胶在热空气老化前后的物理机械性能、耐油等性能的影响规律。结果表明,随着共混硫化胶中EMA含量的增大,硫化时间延长;随着EMA橡胶含量的增大,共混硫化胶的撕裂强度、扯断伸长率基本保持不变,硬度、100%定伸应力增大,拉伸强度降低,老化前后共混硫化胶的各项性能变化趋势跟老化之前大体相同,并且变化不大,所以EMA硫化胶的热空气老化性能好。耐热油老化后,拉伸强度和扯断伸长率是降低的,并且低于耐油之前,100%定伸应力逐渐增大,小于耐油之前相同并用比的值;体积变化率和质量变化率增大。     

改善三元乙丙橡胶耐油性能的研究

研究氯化聚乙烯(CPE)、丁腈橡胶(NBR)与三元乙丙橡胶(EPDM)并用对共混胶力学性能和耐油性能的影响。结果表明,在EPDM/CPE共混胶中随CPE用量的增加,硫化胶的硬度、拉伸强度、撕裂强度和定伸应力呈现上升趋势、在ASTM3号油中浸泡后体积变化率变化不明显;在EPDM/NBR共混胶中随NBR用量的增加,硫化胶的拉伸强度、撕裂强度和定伸应力呈现下降趋势、在油中体积变化率明显减小;在EPDM/NBR/CPE共混胶中随NBR和CPE用量的增加,硫化胶的力学性能变化不明显,但在油中浸泡体积变化率明显降低,通过电镜照片对共混胶断面分析得知CPE的加入明显改善了EPDM和NBR之间的相容性。     

HDPE/LDPE复合交联物的热降解研究

采用热重分析仪（TG）考察了高密度聚乙烯（HDPE）／低密度聚乙烯（LDPE）复合交联物的热稳定性。结果显示，HDPE／LDPE复合交联物的热稳定性低于HDPE／LDPE共混物。FTIR分析证实，交联反应使聚乙烯（PE）的支化程度提高，取代基的位阻效应在一定程度上影响了PE的热降解过程。在N2气氛下，HDPE／LDPE共混物及交联物的热降解过程均为一步降解反应。Kissinger法求解HDPE／LDPE共混物及其复合交联物的热降解活化能发现，LDPE质量分数在20％～30％之间变化时，HDPE／LDPE交联物的热降解过程对温度的敏感性发生了突变。     

防老剂MB用量对CM／EVM共混胶性能的影响

研究了共混比为70／30的氯化聚乙烯（CM）／乙烯一醋酸乙烯酯橡胶（EVM）共混胶中不同MB的用量下,共混胶的硫化特性,热空气老化前后共混胶的力学性能、两相交联密度和动态力学性能。研究表明：随着MB用量的增加,共混胶的硫化特性稍有变化;老化前后,1#共混胶的力学性能及交联密度变化率较高,玻璃化转变温度的变化程度较大;老化前后,5#共混胶的力学性能变化率较低,交联密度变化率较低,玻璃化转变温度的变化程度较小。     

茂金属聚乙烯蜡对PE共混体系流变行为的影响

用毛细管流变仪研究了茂金属聚乙烯蜡改性聚乙烯共混体系的流变行为，探讨了茂金属聚乙烯蜡用量对共混体系熔体流变行为、熔体黏度、非牛顿指数和流动活化能的影响。结果表明：茂金属聚乙烯蜡对LLDPE／LDPE流动黏度降低明显，增加用量可使黏度逐渐降低；而对MPE／LLDPE／LDPE共混体系流动行为的影响比较复杂，在低剪切应力下黏度随茂金属聚乙烯蜡用量增加而逐渐降低，而在高剪切应力下黏度先增后减；茂金属聚乙烯蜡与MPE／LLDPE／LPDPE的相容性好于LLDPE／LDPE共混体系。     

过氧化物硫化体系对CM／XNBR共混物性能的影响研究

研究了不同用量过氧化物硫化体系对氯化聚乙烯橡胶（CM）／羧基丁腈橡胶（XNBR）共混硫化胶各相交联密度及热空气老化前后的物理机械性能、耐油性能等的影响规律。结果表明,随硫化体系用量的增加,共混硫化胶两相的交联密度都明显增加,交联密度差值变大;焦烧时间逐渐降低;硬度、拉伸强度、100％定伸应力、体积磨耗量呈上升趋势,永久变形、扯断伸长率明显降低,撕裂强度整体变化不大,常温下体积和质量变化率均很小,高温下体积和质量变化率明显降低后趋于平稳;热空气老化后,硬度、拉伸强度、100％定伸应力、撕裂强度整体上升,扯断伸长率整体下降,体积磨耗量整体变化不大;热油老化后,拉伸强度、100％定伸应力变化不大,扯断伸长率明显降低。     

SBS/LDPE共混型热塑性弹性体的性能研究(Ⅰ)

选用热塑性丁苯橡胶（SBS）和低密度聚乙烯（LDPE）为主体材料，采用部分动态硫化法制备了一类性能良好的材料-热塑性丁苯橡胶/低密度聚乙烯共混型热塑性弹性体，具有力学强度高，断裂伸长率大，可重复加工等特点，并研究了聚烯烃的品种，橡塑比，硫化体系等因素对动态硫化SBS/LDPE热塑性弹性体力学性能的影响。     

NBR/PVC共混物耐溶剂性能的研究

考察了NBR／PVC共混比和NBR／PVC与EPDM,IIR或PU三元硫化共混物在天那水中的体积变化和物理性能变化。结果表明,当NBR／PVC以70／30共混时,二元共混物的耐溶剂性能最好;NBR／PVC／PU共混比为50／20／30时,三元共混物耐天那水性能最好,经天那水浸泡后的性能变化很小。     

氯丁橡胶/氯化聚乙烯橡胶共混胶的过氧化二异丙苯共硫化性能

研究了以过氧化二异丙苯（DCP）作共硫化剂的氯丁橡胶（CR）与氯化聚乙烯橡胶（CM）共混胶的性能,并用橡胶加工分析仪和动态热机械分析仪进行了表征。结果表明,与纯CR和CM相比,CR/CM共混胶的加工性能明显改善,焦烧时间缩短,正硫化时间变长,力学性能介于纯CR和纯CM之间。共混胶的储能模量（G＇）大于纯CR和CM,损耗因子（tanδ）介于两者之间。CR与CM具有一定的相容性。当DCP/Zn O/亚乙基硫脲（质量比）为1.80/4.25/0.35时,CR/CM共混胶的G＇更大,tanδ略小,两相的玻璃化转变温度更为靠近,交联程度、相容性、共硫化程度高于三者质量比为0.80/4.25/0.50时的CR/CM共混胶。     

动态硫化PSBR/PE共混型热塑性弹性体的研究

采用动态硫化法制备了粉末丁苯橡胶（PSBR）／聚乙烯（PE）共混型热塑性弹性体（TPO），研究了共混比、硫化体系、填料种类及用量、加工工艺对共混胶力学性能的影响。结果表明，当PSBR／PE共混比为60／40并采用传统硫化体系、白炭黑作补强剂时，TPO综合性能较好。     

聚烯烃包覆石蜡相变材料的结构和初步热性能

分别以低密度聚乙烯（LDPE）和乙烯-辛烯共聚物（POE）为包覆材料,以石蜡为相变材料,制备了定形相变材料,采用SEM、DSC和流变性能对其进行分析表征。SEM电镜显示了两种不同的表面形貌;DSC测试表明石蜡加入量越多,潜热越大,POE/石蜡体系的潜热高于LDPE/石蜡体系;流变性能研究表明,石蜡的加入在固态时提高了基体的储能模量,对于LDPE/石蜡体系,LDPE为连续相;对于POE/石蜡体系,由于POE和石蜡熔融温度非常接近,分辨不出谁是连续相谁是分散相。     

Thermal and mechanical properties of LDPE/sisal fiber composites compatibilized with functionalized paraffin waxes

The effect of maleic anhydride‐grafted hard paraffin wax (MA‐g‐wax) and oxidized hard paraffin wax (OxWax), as possible compatibilizers, on the morphology, thermal and mechanical properties of LDPE/sisal fiber composites were examined. The differential scanning calorimetry (DSC) results show that sisal alone did not change the crystallization behavior of LDPE, while the two waxes influenced the crystallization behavior of LDPE in different ways, whether mixed with LDPE alone or in the presence of sisal. The thermal properties seem to be influenced by the fact that the waxes preferably crystallize around the short sisal fibers, and by the fact that the two waxes have different compatibilities with LDPE. The TGA results show an increase in the thermal stability of the blends in the presence of the two waxes, with LDPE/OxWax showing a more significant improvement. The presence of wax, however, reduced the thermal stability of the LDPE/sisal/wax composites. The presence of OxWax and MA‐g‐wax similarly influenced the tensile properties of the composites. Both waxes similarly improved the modulus of the compatibilized composites, but in both cases the tensile strengths were worse, probably because of a fairly weak interaction between LDPE and the respective waxes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

PE膜用填充母料的研制

以CaCO_3为填料核,低密度聚乙烯(LDPE)为载体制得填充母料并应用于聚乙烯(PE)膜中.研究了不同种类偶联剂活化CaCO_3、CaCO_3与LDPE共混比和PE蜡的加入对填充母料的熔体流动速率(MFR)的影响,考察了填充母料在PE膜中的应用效果.结果表明,DL-411-D型铝酸酯偶联剂的活化效果较好;CaCO_3与LDPE为2∶1～3∶1时母料的MFR适于薄膜的挤出流延;母料应用于PE膜中可达到作为卫生材料的要求.     

Effect of EVA copolymer on properties of different polyethylenes in silane crosslinking process

Abstract

The effect of molecular structure of polyethylene (PE) [low density PE (LDPE), linear LDPE and high density PE] and silane/peroxide concentration on the grafting level and gel content in silane crosslinking process has been studied. The effect of incorporation of ethylene vinyl acetate (EVA) copolymer on the rate of crosslinking and thermal properties of PEs has been reported. The order of gel content was LDPE>linear LDPE>high density PE. With the incorporation of EVA, the rate of crosslinking increased. The degree of crystallinity did not change with crosslinking significantly. However, the shape of melting and crystallisation peaks changed, and two regions due to gel and sol parts were formed. In EVA/PE blends, two melting points were observed for both crosslinked and uncrosslinked samples. The SEM images showed the droplet matrix morphology with the EVA as the dispersed phase, especially for EVA/LDPE blend. The EVA/PE blends failed in hot set test, while the origin of PEs passed the hot set test successfully.     

Thermoplastic elastomers from rubber and recycled polyethylene: chemical reactions at interphases for property enhancement

Recycled low density polyethylene (R‐LDPE) has been reactively compatibilized with butadiene rubber (BR) by using small additions of reactive polyethylene copolymers and reactive BRs to produce thermoplastic elastomers (TPEs). TPEs were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), rheology measurements, wide‐angle X‐ray scattering (WAXS) and mechanical testing. WAXS results show that the presence of BR and reactive modifiers does not completely prevent the crystallization of R‐LDPE during the TPE formation. Depression of the melting point has been found in all cases. Also in all cases, compatibility is provided by formation of interfacial layers. The best mechanical characteristics are obtained for R‐LDPE + BR blends compatibilized with poly(ethylene‐co‐acrylic acid) (PE‐co‐AA) and polybutadiene terminated with isocyanate groups (PB‐NCO) for PB‐NCO = 7.5 wt% per PB and COOH/NCO ratio = 1/1. The stress at break and elongation at break are respectively improved by 31 % and 63 %. The PB‐NCO modifier participates in co‐vulcanization with BR in the rubber phase and reacts at the interface with the PE‐co‐AA dissolved in the polyolefin phase. As a result, the amorphous phase of R‐LDPE is dissolved by the rubber phase and a morphology with dual phase continuity is formed, assuring an improvement of mechanical properties of TPEs. Copyright © 2004 Society of Chemical Industry     

Effects of glycerol and PE‐g‐MA on morphology,thermal and tensile properties of LDPE and rice starch blends

The effects of glycerol and polyethylene‐grafted maleic anhydride (PE‐g‐MA) on the morphology, thermal properties, and tensile properties of low‐density polyethylene (LDPE) and rice starch blends were studied by scanning electron microscopy (SEM), differential scanning calorimetry, and the Instron Universal Testing Machine, respectively. Blends of LDPE/rice starch, LDPE/rice starch/glycerol, and LDPE/rice starch/glycerol/PE‐g‐MA with different starch contents were prepared by using a laboratory scale twin‐screw extruder. The distribution of rice starch in LDPE matrix became homogenous after the addition of glycerol. The interfacial adhesion between rice starch and LDPE was improved by the addition of PE‐g‐MA as demonstrated by SEM. The crystallization temperatures of LDPE/rice starch/glycerol blends and LDPE/rice starch/glycerol/PE‐g‐MA blends were similar to that of pure LDPE but higher than that of LDPE/rice starch blends. Both the tensile strength and the elongation at break followed the order of rice starch/LDPE/glycerol/PE‐g‐MA blends > rice starch/LDPE/glycerol > LDPE/rice starch blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 344–350, 2004     

Preparation of PLA-Coated Energy Storage Microcapsules and Its Application in Polyethylene Composites

With polylactic acid (PLA) resin as walls and paraffin wax as core substances, phase change microcapsules were prepared based on solvent evaporation method. The energy storage microcapsules (ESM) agents had a mean diameter of about 5 ～ 10 µm. Moreover, the thermal properties of the ESM agents were measured by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Different types of PE composites were prepared with different amounts of these additives. The energy storage properties of PE/ESM composites were improved compared with that of pure PE and PE/paraffin wax composites. However, the tensile properties of these composites showed remarkable decrease.     

Photobiodegradation of low‐density polyethylene/banana starch films

The effects of the starch content, photosensitizer content, and compatibilizer on the photobiodegradability of low‐density polyethylene (LDPE) and banana starch polymer blend films were investigated. The compatibilizer and photosensitizer used in the films were PE‐graft‐maleic anhydride (PE‐g‐MA) and benzophenone, respectively. Dried banana starch at 0–20% (w/w) of LDPE, benzophenone at 0–1% (w/w) of LDPE, and PE‐g‐MA at 10% (w/w) of banana starch were added to LDPE. The photodegradation of the blend films was performed with outdoor exposure. The progress of the photodegradation was followed by determining the carbonyl index derived from Fourier transform IR measurements and the changes in tensile properties. Biodegradation of the blend films was investigated by a soil burial test. The biodegradation process was followed by measuring the changes in the physical appearance, weight loss, and tensile properties of the films. The results showed that both photo‐ and biodegradation rates increased with increasing amounts of banana starch, whereas the tensile properties of the films decreased. The blends with higher amounts of benzophenone showed higher rates of photodegradation, although their biodegradation rates were reduced with an increase in benzophenone content. The addition of PE‐g‐MA into polymer blends led to an increase in the tensile properties whereas the photobiodegradation was slightly decreased compared to the films without PE‐g‐MA. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2725–2736, 2006     

Effect of Morphology on the Biodegradation of Thermoplastic Starch in LDPE/TPS Blends

In this study, thermoplastic starch (TPS) was mixed with low density polyethylene with different melt flow indexes in a one-step extrusion process to produce LDPE/TPS blends varied from 32% to 62% by weight of TPS. The influence of starch content and LDPE viscosity on morphology, biodegradation and tensile properties of LDPE/TPS blends were evaluated. Starch continuity and biodegradability were studied by hydrolytic, enzymatic and bacterial degradation. The LDPE viscosity had a considerable effect on the morphology and the connectivity of the starch particles. Evaluation of hydrolytic extraction showed that blends having TPS content above 50 wt% possessed a full connectivity. Studies of biodegradation indicated that the bacterial attack on starch resulted in weight loss of TPS of 92%, 39% and 22%, for PE1/TPS having 62% and 32% TPS, and PE2/TPS (31% TPS), respectively. Comparatively, the weight loss was more significant at 100%, 66% and 31% by hydrolytic extraction. Differences between these two techniques were discussed in terms of the accessibility of starch domains to microorganisms. Tensile properties (ε_b and E) decreased with increasing exposure time to activated sludge. Changes in tensile properties were highly dependent on the biodegradation rate. PE1/TPS blends having 32% starch remained ductile after 45 days of exposure to bacterial attack.