液晶嵌段共聚物PET/60PHB-b-PC的合成及结构与性能

采用ＰＥＴ齐聚物的原位乙酰化法通过加入少量乙二醇（ＥＧ）合成了端羟基液晶聚合物ＰＥＴ／６０ＰＨＢ，并将其作为大单体，与双酚Ａ及碳酸二苯酯通过熔融酯交换法，进一步制得了液晶嵌段共聚物ＰＥＴ／６０ＰＨＢ ｂ ＰＣ．研究了合成规律，并借助粘度测定、ＤＳＣ、偏光显微镜、Ｘ 光衍射和红外光谱分析等手段对合成的液晶嵌段共聚物进行了表征．研究表明，当ＰＥＴ齐聚物的ηｉｎｈ＝００５～００７ｄＬ／ｇ，Ａｃ２Ｏ／ＰＨＢ（ｍｏｌ／ｍｏｌ）＝１３，ＥＧ／ＰＥＴ（ｍｏｌ／ｍｏｌ）＝００６时能获得颜色、液晶性、溶解性均很好的端羟基液晶聚合物ＰＥＴ／６０ＰＨＢ，以此液晶聚合物为原料，采用合适的配方与工艺，能获得粘度较高、液晶性较好，并且熔体流动性很好的液晶嵌段共聚物ＰＥＴ／６０ＰＨＢ ｂ ＰＣ．通过偏光显微镜与Ｘ 光衍射观察，证明此嵌段共聚物呈现向列型液晶织构，但其液晶态织构与纯ＰＥＴ／６０ＰＨＢ、ＰＥＴ／６０ＰＨＢ和ＰＣ的混合物明显不同．此外，还初步建立了用红外的分析手段鉴定液晶聚合物ＰＥＴ／６０ＰＨＢ端基的方法．     

乙烯系自由基聚合阻聚效应（ⅩⅧ）：哌啶氮氧自由基氨基硫…

本文研究了３种１－（芳酰基）－４［４＇－（２，２，６，６－四甲基哌啶）－１－氧自由基］氨基硫脲化合物（ＡＴＳＣＰＯ）分别同通用阻聚剂（ＣＩＨ），如对苯二酚（ＨＱ），苯醌（ＢＱ），吩噻嗪（ＰＴ）及二乙羟胺（ＤＥＨＡ）组成的混合阻聚剂对ＡＩＢＮ引发的ＭＭＡ自由基聚合的影响，研究结果表明：当［ＡＴＳＣＰＰ］／ＣＩＨ＝５：１时，除ＡＴＳＣＰＯ－ＢＱ外，其余阻聚效果均较ＡＴＳＣＰＯ和ＣＩＨ单独用作阻聚剂时高     

含二烯丙基双酚A醚相容剂对HDPE/PC共混体系的影响

用低密度聚乙烯接枝二烯丙基双酚Ａ醚（ＬＤＰＥ ｇ ＤＢＡＥ）作为高密度聚乙烯／聚碳酸酯（ＨＤＰＥ／ＰＣ）共混体系的增容剂,研究了其对ＨＤＰＥ／ＰＣ共混体系的影响．通过共混物形态观察、热力学性能测试和结晶性分析,发现ＬＤＰＥ ｇ ＤＢＡＥ对ＨＤＰＥ／ＰＣ共混体系有良好的增容效果．并发现了增容剂在共混物中的最佳用量为１０ｐｈｒ,提高增容剂的接枝率更有利于改善共混物的性能     

双■唑啉化合物偶联聚酯的研究Ⅱ.聚对苯二甲酸乙二酯的偶联反应

用特性粘度（［η］）和羧值为参数，研究了双唑啉化合物（ＢＯＺ）对聚对苯二甲酸乙二酯（ＰＥＴ）的扩链反应动力学过程，表明ＢＯＺ是与ＰＥＴ中羧基反应，考察了不同工艺生产的ＰＥＴ的扩链效果，结果说明达到的［η］极大值取决于原始ＰＥＴ的［η］与羧值之比     

双恶唑啉化合物偶联聚酯的研究：II.聚对苯二甲酸乙二酯的偶联反应

用特性粘度（［η］）和羧值为参数，研究了双恶唑啉化合物（ＢＯＺ）对聚对苯二甲酸乙二酯（ＰＥＴ）的扩链反应动力学过程，表明ＢＯＺ是与ＰＥＴ中羧基反应，考察了不同工艺生产的ＰＥＴ的扩链效果，结果说明达到的［η］极大值取决于原始ＰＥＴ的［η］与羧值之比。     

四元配合物吸光光度法测定铝的研究

提出了在乙酸钠－乙酸介质中,利用Ａｌ－ＥＧＴＡ－ＰＲ－ＣＰＢ四元体系测定铝的新方法。试验表明乙二醇二乙醚二氨基四乙酸（ＥＧＴＡ）,铝,邻苯三酚红（ＰＲ）,溴化十六烷基吡啶（ＣＰＢ）可迅速反应生成四元蓝色配合物Ａｌ·ＥＧＴＡ·ＰＲ３·ＣＰＢ１２,可用于痕量铝的测定,ε＝１．１×１０＾５Ｌ·ｍｏｌ＾－１·ｃｍ＾－１,ＲＳＤ为５．８％（ｎ＝６）。加标回收率１０１．７％￣１０５．０％,实测水和化学试剂中痕     

聚环氧丙烷聚氨酯／聚（甲基丙烯酸甲酯—苯惭烯）IPN的研究

改变聚（甲基丙烯酸甲酯－苯乙烯（Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）中 甲基丙烯酸甲酯的含量（ＷＭＭＡ），通过一步法合成出聚环氧氯丙烷聚氨酯（ＰＵ（ＰＥＣＨ）／Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）ＩＰＮ．ＤＳＣ、ＴＥＭ和动态粘弹谱研究结果表明：当Ｐ（ＭＭＡ＿ｃｏ－Ｓｔ）中ＷＭＭＡ大于０．６时，ＩＢＮ仅有一个Ｔｇ；当ＷＭＭＡ小于０．４时，ＩＰＮ有２个Ｔｇ，ＴＥＭ上出现相区，Ｐ（ＭＭＡ－ｃｏ－Ｓｔ）深度参数（δ）及δ的氢键作     

以混合模板剂合成TS-1分子筛及其性能研究

以四丁基溴化铵（ＴＢＡＢｒ）＋四乙基氢氧化铵（ＴＥＡＯＨ，ｎ（ＴＢＡ＋）／ｎ（ＴＥＡ＋）＝１）或以四丙基溴化铵（ＴＰＡＢｒ）＋ＴＥＡＯＨ为模板剂，钛酸四丁酯和正硅酸乙酯为原料，于１７０℃水热合成出ＴＳ１分子筛．对合成的ＴＳ１样品进行了ＸＲＤ，ＦＴＩＲ，ＳＥＭ和ＢＥＴ比表面积分析，证实了样品中钛已进入Ｓｉｌｉｃａｌｉｔｅ１骨架．选择戊烷氧化为探针反应，考察了ＴＳ１的催化活性．结果表明以ＴＥＡＯＨ为碱，合成的样品晶粒较大，达到４～１０μｍ，用氨水和ＴＥＡＯＨ调节反应液的碱度，对晶体的生长和形貌的影响各不相同．文中还就ＴＥＡＯＨ引入的作用进行了讨论．     

聚酯酰胺的合成及表征

用两种方法合成了聚酯酰胺（ＰＥＡ）共聚物．一种是两步法，即先合成对苯二甲酸乙醇酰胺（ＢＡＥＴ）单体，然后与对苯二甲酸乙二酯（ＢＨＥＴ）共缩聚；另一种是一步法．即在酯交换反应中直接添加乙醇胺（ＥＡ）．两种方法制得的聚酯酰胺（ＰＥＡ）共聚物测试证明了为产物，并分析了合成中的化学反应．     

乙烯系单体自由基聚合的阻聚效应──XIX．取代哌啶羟胺和二叔丁基羟胺及其稳定自由基对苯乙烯－丙烯腈共聚合的影响

研究了二叔丁基羟胺（ＤＴＢＨＡ），二叔丁基氮氧自由基（ＤＴＢＮＯ·），２，２，６，６－四甲基－４－羟基哌啶羟胺（ＴＭＨＰＨＡ）和２，２，６，６－四甲基－４－羟基哌啶－１－氧自由基（ＴＭＨＰＯ·）对过氧化苯甲酰（ＢＰＯ）６０℃引发的苯乙烯（Ｍ１）－丙烯腈（Ｍ２）共聚合的阻聚行为．结果表明，这些阻聚剂对Ｓｔ－ＡＮ共聚均表现良好的阻聚行为，其中氮氧自由基优于相应羟胺．同时观察到Ｓｔ—ＡＮ竞聚率的改变，羟胺使ｒ１有所降低，ｒ２略有增大．但相应的氮氧自由基是相反结果．阻聚剂为２００ｐｐｍ时，共聚物中的恒比共聚点由对照实验的０．６１９变化为０．５３３，０．６４５，０．５８９和０．６９８相对于ＤＴＢＨＡ，ＤＴＢＮＯ·，ＴＭＨＰＨＡ和ＴＭＨＰＯ·．     

Polymer crystalline orientation resulting from melt deformation and solidification of talc and mica filled polyethylene compounds

An experimental study is presented of orientation of polymer crystallographic axes in talc and mica filled polyethylene which has been extruded from various dies, melt spun and compression molded. The data is interpreted in terms of uniaxial crystalline orientation factors. It is observed that in all cases theb crystallographic axis of the polyethylene seems to be oriented normal to the surfaces of the mica and talc flakes.     

Rheology and Physical Properties of Polyethylene/Polyethylene‐Ionomer Blends and their Clay Nanocomposites

Rheological and solid‐state physical properties of blends containing high‐density polyethylene (HDPE) and a polyampholyte derivative (PE‐g‐PA) are assessed along with their onium ion‐exchanged montmorillonite clay (NR‐MM) nanocomposites. Strong deviations from the log‐additivity rule of zero‐shear viscosity, combined with synergistic behavior in tensile moduli, are consistent with a multi‐phase blend morphology. While this affects clay dispersion in filled blends, PE‐g‐PA/HDPE based nanocomposites are shown to exhibit a favorable balance between material stiffness and ductility.

     

Nonisothermal crystallization and melting behavior of mPE/LLDPE/LDPE ternary blends

Nonisothermal crystallization kinetics of ternary blends of the metallocence polyethylene (mPE), low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE) were studied using DSC at various scanning rates. The Ozawa theory and a method developed by Mo were employed to describe the nonisothermal crystallization process of the two selected ternary blends. The results speak that Mo method is successful in describing the nonisothermal crystallization process of mPE/LLDPE/LDPE ternary blends, while Ozawa theory is not accurate to interpret the whole process of nonisothermal crystallization. Each ternary blend in this study shows different crystallization and melting behavior due to its different mPE content. The crystallinity of the ternary blends rises with increasing mPE content, and mPE improve the crystallization of the blends at low temperature. The crystallization activation energy of the five ternary blends that had been calculated from Vyazovkin method was increased with mPE content, indicating that the more mPE in the blends, the easier the nucleus or microcrystallites form at the primary stage of nonisothermal crystallization. LLDPE and mPE may form mixed crystals due to none separated-peaks were observed around the main melting or crystallization peak when the ternary blends were heating or cooling. The fixed small content of LDPE made little influence on the main crystallization behavior of the ternary blends and the crystallization behavior was mainly determined by the content of mPE and LLDPE.     

Advances and approaches for chemical recycling of plastic waste

The global production and consumption of plastics has increased at an alarming rate over the last few decades. The accumulation of pervasive and persistent waste plastic has concomitantly increased in landfills and the environment. The societal, ecological, and economic problems of plastic waste/pollution demand immediate and decisive action. In 2015, only 9% of plastic waste was successfully recycled in the United States. The major current recycling processes focus on the mechanical recycling of plastic waste; however, even this process is limited by the sorting/pretreatment of plastic waste and degradation of plastics during the process. An alternative to mechanical processes is chemical recycling of plastic waste. Efficient chemical recycling would allow for the production of feedstocks for various uses including fuels and chemical feedstocks to replace petrochemicals. This review focuses on the most recent advances for the chemical recycling of three major polymers found in plastic waste: PET, PE, and PP. Commercial processes for recycling hydrolysable polymers like polyesters or polyamides, polyolefins, or mixed waste streams are also discussed.     

Structural effects on thermal properties and morphology in XLPE

This study investigated the morphological, thermal and mechanical changes with increasing crosslink density for two low density polyethylenes (LDPE). A reference LDPE was compared with an LDPE containing a higher number of vinyl groups that was introduced via a copolymerisation with a diene. During crosslinking, two reactions simultaneously occur in the copolymer, i.e. a reaction of the vinyl groups and combination crosslinking. After crosslinking with a low amount of peroxide, the majority of the crosslinks originate from reacted vinyl groups in the LDPE containing the higher number of vinyl groups, whereas the crosslinks in the reference LDPE originate from combination crosslinking, thus leading to different crosslinked structures for the two polymers. The melt temperature, crystallisation temperature, and degree of crystallinity were measured using a Differential Scanning Calorimeter. Thermal fractionation studies and morphology studies were also made. The Differential Scanning Calorimetry results show a decrease in those properties for both materials along with a concurrent change in the morphology when the crosslink density increased. The results deviate slightly between the materials.     

Abiotic and biotic degradation of oxo-biodegradable polyethylenes

Conventional polymeric materials accumulate in the environment due to their low biodegradability. However, an increase in the biodegradation rate of these polymers may be obtained with the addition of pro-degrading substances. This study aimed to evaluate abiotic and biotic degradation of polyethylenes (PEs) using plastic bags of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) formulated with pro-oxidant additives as test materials. These packaging materials were exposed to natural weathering and periodically analyzed with respect to changes in mechanical and structural properties. After a year of exposure, residue samples of the bags were incubated in substrates (compost of urban solid waste, perlite and soil) at 58 °C and at 50% humidity. The biodegradation of the materials was estimated by their mineralization to CO₂. The molar mass of the pro-oxidant-activated PE decreased and oxygen incorporation into the chains increased significantly during natural weathering. These samples showed a mineralization level of 12.4% after three months of incubation with compost. Higher extents of mineralization were obtained for saturated humidity than for natural humidity. The growth of fungi of the genera Aspergillus and Penicillium was observed on PE films containing pro-oxidant additives exposed to natural weathering for one year or longer. Conventional PE films exposed to natural weathering showed small biodegradation.     

EAA增容LLDPE/PEO共混物及其增容机理

以乙烯-丙烯酸共聚物(EAA)为增容剂, 研究了它在线性低密度聚乙烯(LLDPE)/聚环氧乙烷(PEO)共混物中的增容作用及其增容机理。采用电子显微镜(SEM)、动态力学分析(DMA)、DSC和红外光谱(IR)对共混物形态及其微观结构进行了表征。结果表明, EAA对LLDPE/PEO共混物有一定的增容作用; 其增容机理为: EAA和LLDPE两者的非晶区部分相容, 而EAA分子中的羧基与PEO分子中的醚氧基相互作用形成了分子间氢键。     

Nonisothermal crystallization kinetics and melting behavior of bimodal medium density polyethylene/low density polyethylene blends

Nonisothermal crystallization kinetics and melting behavior of bimodal-medium-density- polyethylene (BMDPE) and the blends of BMDPE/LDPE were studied using differential scanning calorimetry (DSC) at various scanning rates. The Avrami analysis modified by Jeziorny and a method developed by Mo were employed to describe the nonisothermal crystallization process of BMDPE. The BMDPE DSC data were analyzed by the theory of Ozawa. Kinetic parameters such as the Avrami exponent (n), the kinetic crystallization rate constant (Z_c), the peak temperatures (T_p) and the half-time of crystallization (t_1/2) etc. were determined at various scanning rates. The appearance of double melting peaks and the double crystallization peaks in the heating and cooling DSC curves of BMDPE/LDPE blends indicated that the BMDPE and LDPE could crystallize respectively.     

茂金属聚乙烯和低密度聚乙烯共混物的流变行为

研究了茂金属催化乙烯丁烯1共聚物mPE和LDPE共混物的流变行为.测定了一系列共混物的稳态剪切粘度和动态粘弹性,用改进Cross模型拟合实验数据.mPE的零切粘度η₀较小,从牛顿型转变为非牛顿型所需的剪切速率较大,转变应力较高,在挤出加工剪切速率范围内熔体粘度高,对剪切敏感性差,这是由于它有较低的重均分子量、窄的分子量分布(M_w/M_n=21)所致.对于对数加和规律,共混物η₀在mPE/LDPE为50/50和25/75时有强烈的正偏差,这是由于共混物自由体积减小所致.共混物的转变应力τ^*和非牛顿指数n随LDPE加入量增大而降低,表明共混物对剪切的敏感性提高,加工性得到改善.G'和G”的一致性说明mPE和LDPE共混是相容的.     

Substantially enhancing the catalytic performance of bis(imino)pyridylcobaltous chloride pre‐catalysts adorned with benzhydryl and nitro groups for ethylene polymerization

Variations in the ligand structure of homogeneous late transition metal catalysts through judicious choice and location of substituent is the foremost strategy in improving their catalytic performance for ethylene polymerization. In this contribution, symmetrical and unsymmetrical bis(imino)pyridylcobaltous chloride complexes adorned with nitro and benzhydryl groups {2‐[1‐(2,6‐dibenzhydryl‐4‐nitrophenylimino)ethyl]‐6‐[1‐(alkylphenylimino)ethyl]pyridylcobaltous chloride (alkyl: R¹ = Me and R² = H, Co1 ; R¹ = Et and R² = H, Co2 ; R¹ = ⁱPr and R² = H, Co3 ; R¹ and R² = Me, Co4 ; R¹ = Et and R² = Me, Co5 ; R¹ = benzhydryl and R² = NO₂, Co6 )} have been prepared and applied as catalysts for ethylene polymerization. The molecular structure of Co1 and Co2 revealed the unequal steric protection of the cobalt center induced by bis(imino)pyridine chelate. In the presence of methylaluminoxane (MAO) or modified methylaluminoxane (MMAO) activators at different ethylene feeding rates (1 and 10 atm), catalysts Co1 – Co5 displayed high activities at 10 atm ethylene and produced strictly linear polyethylene (PE) with high molecular weight, Co2 /MMAO being the most highly active catalytic system showing the highest activity of 9.41 × 10⁶ g of PE (mol of Co)^?1 h^?1 which is three times higher than that of prototypal cobalt catalyst ( Co0 ) under identical conditions. Moreover, high melt temperature and unimodal molecular weight distribution are the characteristics of the resulting polyethylene.