Antioxidants and acid scavengers are fundamental additives for Ziegler-Natta (ZN) polyolefins. Although zinc stearate (ZnSt2) and calcium stearate (CaSt2) are widely used with conventional synthetic antioxidants, their applicability to the natural antioxidant vitamin E (VE) remains unclear. Here, the effects of ZnSt2 and CaSt2 on the processing stabilization efficiency of VE in a ZN polyethylene (ZN-PE) were investigated over a broad loading range of 50–2000 ppm. At low loading (e.g., 250 ppm), ZnSt2 improved the stabilization efficiency of VE, as evidenced by higher melt oxidative stability and better retention of melt viscosity, molecular weight, and chemical structure during repeated extrusion, whereas CaSt2 weakened VE stabilization. At high stearate loading (e.g., 2000 ppm), both stearates impaired the stabilization efficiency of VE, as reflected by lower melt oxidative stability, poorer retention of melt viscosity and molecular weight, and accelerated formation of degradation-related structures during repeated extrusion. Based on these results and the squalane model tests, we hypothesize that both stearates intrinsically weaken VE stabilization, whereas only ZnSt2 may partially protect VE by mitigating the more pronounced negative effect of catalyst residues. This balance may account for the beneficial effect of low-loading ZnSt2, the detrimental effect of excessive ZnSt2, and the consistently adverse effect of CaSt2 in the studied ZN-PE with low catalyst residue levels.

Cu-based catalysts play an important role in the hydrogenation of esters, however, their application at high temperatures is limited due to the low H & uuml;ttig temperature of Cu. Promoting the activity and stability of Cu catalysts at elevated temperatures remains a challenge. In this work, a highly stable Cu/MgO@SiO2 was calcined and reduced controllably from CuMg-MOF-74 modified with SiO2. This catalyst was then applied in the hydrogenation of poly(ethylene terephthalate)-degraded bis(2-hydroxyethyl)cyclohexane-1,4-dicarboxylate (BHCD) to 1,4-cyclohexanedimethanol (CHDM). Characterization results indicated that Cu/MgO@SiO2 exhibited an enlarged surface area and pore volume (104 m2 g-1 and 0.52 cm3 g-1), highly dispersed Cu (22.7%), and abundant basicity (480 mu mol g-1). It was confirmed that the conversion of BHCD and the selectivity of CHDM over Cu/MgO@SiO2 reached 99.2% and 97.1%, respectively, at 260 degrees C, 2.5 MPa H2, 0.8 gBHCD gcat.-1 h-1, and 155 molH2 molBHCD-1, which were superior to those over the reference Cu/MgO and other Cu-MgO-SiO2 catalysts. Furthermore, Cu/MgO@SiO2 maintained its activity even at 280 degrees C for 100 h, owing to the MgO-decorated Cu nanoparticles encapsulated by SiO2 hollow structures in the well-designed Cu/MgO@SiO2.

The introduction of nucleating agents is an important approach to improve product quality and production efficiency in the polymer industry. Interestingly, it has been observed that the addition of the nucleating agent Hyperform (R) HPN-20E into linear low-density polyethylene results in a decrease in the overall crystallization rate. Although this reduction is commonly explained by the decreased crystal growth rate at higher crystallization temperatures, it contradicts the general behavior observed in most nucleated polymer systems, where both crystallization temperature and crystallization rate increase. To further elucidate this unusual behavior, the active component of HPN-20E, calcium hexahydrophthalate (Ca-HHPA), was synthesized, and its influence on the crystallization behavior of a linear low-density polyethylene prepared by metallocene catalyst (mLLDPE) was systematically investigated. Our results reveal that Ca-HHPA promotes nucleation of these segments with high crystallization ability, while the increase in nucleation density contributes less to the crystallization rate than the reduction in growth rate caused by the elevated crystallization temperature. Meanwhile, the Ca-HHPA addition inhibits nucleation of segments with lower crystallization ability, leading to their crystallization at a greater undercooling. The combination of these two effects results in the observed decrease in the overall crystallization rate. [GRAPHICS]

For Zieglar-Natta (Z-N) polypropylene (PP) to which a nucleating agent (NA) was added to regulate the properties, selecting an appropriate acid scavenger, a necessary additive for Z-N PP, is important for optimizing the effectiveness of the NA. However, the impact of various acid scavengers on the performance of NAs has not been systematically studied. In this work, the effect of two most widely used acid scavengers, calcium stearate (CaSt2) and zinc stearate (ZnSt2), on PP crystallization promotion performance of a commonly used NAs, NX8000 (a typical representative of sorbitol-type NAs family) was systematically investigated. It was found that CaSt2 did not significantly alter the crystallization temperature (T c) of PP containing NX8000, while ZnSt2 was detrimental to the nucleation benefit of NX8000, especially in the NA concentration range, where effective nucleation began but remained below the "critical saturation concentration". The mechanism study showed that CaSt2 added to PP almost remains chemically unchanged during heating and exhibits no significant impact on the NA. Differently, ZnSt2 undergoes chemical reactions in a matrix at elevated temperature, producing stearic anhydride, which reacts with NX8000. As a result, a portion of the NA is consumed, leading to a reduction in its efficacy. Our work not only contributes to a comprehensive understanding of mechanisms when multiple additives are used simultaneously but also helps optimize additive formulations to maximize the performance of each component.

Due to the mechanical stability of PP layer,the PP/HDPE double-layer microporous membrane could be prepared at a higher heat-set-ting temperature than that of PE monolayer membrane.In this work,the effects of heat-setting temperature on the pore structure and properties of PP/HDPE double-layer membrane were studied.With the increase of heat-setting temperature from 120 ℃ to 130 ℃,the length of connecting bridge crystal and crystallinity in the PE layer increase due to the melting of thin lamellae and the stability of connecting bridge structure during heat-setting.The corresponding air permeability,porosity,wettability of liquid electrolyte and mechanical property of the heat-set microporous membrane increase,exhibiting better electrochemical performance.However,when the heat-setting temperature is further increased to 140 ℃,higher than the melting point of PE resin,some pores are closed since the lamellae and connecting bridges melt and shrink during heat-setting,resulting in a decrease of air permeability and porosity.In contrast,there is negligible change in the PP layer within the above heat-setting tem-perature region.This study successfully builds the relationship between the stable pore structure and property of microporous membrane dur-ing heat-setting,which is helpful to guide the production of high-performance PP/PE/PP lithium batteries separator.

Porous organic polymers (POPs) are attracting attention for their easy functionalization and potential as catalyst supports in olefin polymerization. In this study, sulfonated POP (s-POP) supported Ziegler-Natta catalysts were used for ethylene polymerization, producing ultra-high molecular weight polyethylene, with M ν reaching up to 6.83 × 106 g mol-1. The maximum M ν of polyethylene was achieved by Cat-3 with DIBP as the internal donor, albeit with a partial loss of catalytic activity. Polymerization conditions also play a pivotal role in determining the molecular weight of polyethylene. Hydrogen, being the most efficient chain transfer agent, can decrease the molecular weight to 9.68 × 104 g mol-1 at higher hydrogen concentrations ([H2] : [C2H4] = 0.83), and the s-POP-supported ethylene polymerization catalysts were observed to exhibit high sensitivity to hydrogen response. The effects of polymerization temperature, [Al] : [Ti] molar ratio, and ethylene pressure on ethylene polymerization were thoroughly investigated.

Zinc stearate (ZnSt2) and calcium stearate (CaSt2) are two kinds of extensively used additives in polymer in-dustry. However, the selection principle of the two soaps in different polyolefins is still unclear. To establish the action mechanism of these soaps in polyolefins application, the understanding of the exact structures when they play roles is prerequisite. In this work, considering that these additives play their roles during the melt processing of polyolefin, in which the structure may be different with their as-received states, the structures and evolution behavior of the two soaps in a polyolefin melt upon heating and cooling were systematically explored. It was found that the two soaps exhibited different dispersed structures and evolution behavior in the polypropylene random copolymer (PPR). The ZnSt2 in PPR presented microcrystal at low temperatures and dissociated into ionic clusters during heating, and then gradually aggregated and recrystallized upon cooling; while the CaSt2 in PPR exhibited vitreous agglomerates with lamella ordered structure at low temperatures and transformed to diverse colloidal liquid crystal aggregates during heating, and then gradually reassembled to vitreous agglom-erates in cooling process. At concentration closed to practical application (about 1000 ppm or less), ZnSt2 in molten PPR dispersed in form of ionic clusters like closed small molecules, whereas CaSt2 in PPR melt presented weakly ordered aggregates. These findings provided an important foundation for building up the well-defined relationship between the structure and performance of these soaps in polyolefins.

Transparent impact resistant polypropylene（EP08T） was prepared by a pilot-scale Spheripol Ⅱ process. Using EP08T as base material, the effects of three transparent nucleating agents Millad NX8000（NX8000）, Millad 3988（3988）and NA-21 on the optical properties, mechanical properties and crystallization behavior of EP08T were studied. The results show that with the increase of the amount of nucleating agent, the optical properties, impact strength and crystallization temperature（Tc） of the samples are greatly improved, and the tensile strength, flexural strength and flexural modulus are slightly improved, among which NX8000 has the best improvement effect. When the addition amount of NX8000 reaches 0.3%, the optical properties and impact strength of EP08T are the best. The haze of NX8000-0.3 can be reduced to 12.8%, with a decrease of more than 60%. The impact strength of NX8000-0.3 can reach 24.6 kJ/m~2, which is 3.5 times that of EP08T. The nucleating agent of NX8000-0.3 can significantly increase the T c of EP08T and shorten the forming cycle. When the addition amount of nucleating agent is 0.3%, NX8000, 3988 and NA-21 can increase the Tc of EP08T by 13.8, 11.7 and 11.5 ℃ respectively, shorten forming cycle of the sample and improve the processing efficiency.

超高分子量聚乙烯(ultrahigh molecular weight polyethylene,UHMWPE)以其优异的耐磨性、耐冲击性、耐腐蚀性等物理化学性能,被广泛应用于国防军事、航空航天、海洋工程以及体育用品等领域.大量研究致力于通过催化剂体系的设计与开发,实现UHMWPE形貌形态、分子量及其分布、支化度等结构的调控.本文综述了近年来用于制备UHMWPE的齐格勒-纳塔催化剂体系,茂金属催化剂体系,FI催化剂体系以及后过渡金属催化剂体系等的研究进展.

While nanoparticles were considered to be the most promising compatibilizers for immiscible polymer blends, high-efficient nanoparticle-based compatibilizers were still under development. Herein, a high-reactive silica nanosheet (HRN) compatibilizer with excellent compatibilization effect was synthesized and its compatibiliza-tion effect was investigated. The HRN compatibilizer was fabricated by skillfully melt-blending amino func-tionalized silica hollow spheres (AHS) and the poly(styrene-co-glycidyl methacrylate) (PSGMA) with average ten reactive epoxy groups per chain. During the mixing, the AHS were crushed to nanosheets upon the strong shearing and simultaneously grafted PSGMA chains on nanosheets via the reaction of epoxy and amino groups. The PSGMA with high epoxy groups content endowed the HRN with high reactivity. To demonstrate the com-patibilization efficiency of our high-reactive compatibilizer, different amounts of HRN were incorporated into the immiscible polylactic (l-acid)/polybutylene adipate terephthalate (PLLA/PBAT) blend, a blend system widely applied in packing and agricultural films, to investigate and compare the changes in morphologies and me-chanical properties. Only 3 wt% addition of HRN compatibilizer could significantly decrease the droplets size and dramatically improve the tensile strength and elongation at break of the blend by 1.4 and 23 times. The present work provided a new idea for the development of nanoparticle-based compatibilizer with high compa-tibilization efficiency.

Aiming at obtaining high toughness polypropylene (PP) products, in this work, using high density polyethylene (HDPE) and styrene-ethylene-butylene-stryrene (SEBS) as toughening agents, PP/SEBS/HDPE blends were successfully fabricated by melt-blending method, and the microstructure, mechanical, thermodynamics, and rheological properties of the blends were investigated. The results revealed the core-shell structure particles with HDPE as the core and SEBS as the shell were dispersed in PP in the PP/SEBS/HDPE blends. The core-shell structure particles played good roles in toughening PP matrix, and the PP/SEBS/HDPE blends underwent brittle-tough transition at 15 wt% SEBS and 5 wt% HDPE. The impact toughness of PP/SEBS/HDPE blends with 15 wt% SEBS and 15 wt% HDPE reached 60.1 kJ/m(2), which was almost 1441.0% that of pure PP. The formation of core-shell particles in the system led to an increase in the degree of chain entanglement between the dispersed phase and PP, which enhanced the interfacial adhesion. In addition, based on the experimental results, the relationship between the viscosity and the material toughness was proposed, revealing the brittle-ductile transition behavior and the toughening mechanism.

以聚丙烯(PP)为基体、高密度聚乙烯(HDPE)为增韧剂,采用熔融共混的方式制备了PP/HDPE共混物,研究了HDPE的添加量对PP的增韧效果并探究了其增韧机理.结果表明,随着HDPE添加量的增加,所制备的PP/HDPE共混物的缺口冲击强度逐渐增大,当HDPE的添加量达到20％后,缺口冲击强度达到6.2 kJ/m2,较纯PP的3.9 kJ/m2提高了59.0％,后继续提高HDPE含量,共混物的缺口冲击强度保持不变.增韧机理为PP/HDPE共混物在受到外力作用时,HDPE与PP的界面脱黏并形成空洞,空洞吸收能量.同时,HDPE充当应力集中点,产生"拉丝"现象,HDPE颗粒边缘向垂直于受力的方向延伸,应力从PP传递到HDPE,吸收能量.

选用高效、热稳定良好的有机类抗菌剂(KJ-1)与纤维级聚丙烯(PP)粉料混炼挤出,制备非织造布用抗菌PP树脂及抗菌PP纤维,研究了抗菌剂及其添加量对PP抗菌性能、力学性能及加工性能的影响,并对非织造布用抗菌PP纤维的抗菌性能和力学性能进行表征.结果表明:抗菌剂KJ-1分解温度为260℃,可满足与PP混炼挤出加工要求;添加KJ-1质量分数为0.02％时,抗菌PP树脂对大肠杆菌和金黄色葡萄球菌的抗菌率均大于99％,灰分质量分数为0.019％,230℃时其加工性能与纯PP树脂非常接近;添加KJ-1质量分数0.02％制备2.22 dtex×40 mm非织造布用抗菌PP纤维,纺丝过程中工艺参数波动较小,喷丝板使用时间为22.8 h,纤维断裂强度为1.9 cN/dtex,断裂伸长率为325.4％,对大肠杆菌和金黄色葡萄球菌的抗菌率均大于99％,抗菌长效性达250 d以上.

Porous organic polymers (POPs) have attracted much attention in numerous areas, including catalysis, adsorption and separation. Herein, POP supported Ziegler–Natta catalysts were designed for preparation of isotactic polypropylene (iPP). The POPs-based Ziegler–Natta catalysts exhibited the characteristic of broad molecular weight distribution (MWD > 11) with or without adding an extra internal electron donor. The added internal electron donor 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate (ID-2) used in cat-2 showed good propylene polymerization activity of 15.3 × 106 g·PP/mol·Ti·h, high stereoregularity with 98.2% of isotacticity index and broad molecular weight distribution (MWD) of 12.3. Compared to the MgCl2-supported Ziegler–Natta catalysts (cat-4) with the same ID-2, cat-2 showed higher chain stereoregularity for propylene polymerization. As seen in the TREF results, the elution peak of PP-2 (124.0 °C, 91.7%) is 1.5 °C higher than the isotactic fraction from PP-4 (122.5 °C, 87.2%), and even 1.2 °C higher than PP-5 prepared from ID-3 with the characteristics of high stereoregularity. Moreover, the pentad methyl sequence mmmm of PP-2 (93.0%) from cat-2 is 0.5% higher than that of PP-4 from cat-4. XPS analysis revealed that the minute difference in binding energy of Ti, Mg, C and O atoms exist between the inorganic MgCl2 and the organic polymer based Z–N catalysts. The plausible interaction mechanism of active sites of Mg and Ti with the functional groups in the POP support and the added ID was proposed, which could be explained by their high stereoregularity and the broad molecular weight distribution of the POP-based Z–N catalysts.

Isobutylene polymerization was studied with the rare-earth metal scandium cationic com-plexes as catalysts and molecular weight and its dis-tribution,and glass transition temperature of poly-isobutylene were investigated by screening the cata-lyst system,adjusting the ratio of monomer to catalyst and regulating the reaction temperature and time.The results showed that the constrained-geometry-configuration scandium dialkyl catalyst which had relatively smaller steric hindrance had the highest catalytic activity for isobutylene polymerization among 5 kinds of rare-earth metal scandium cationic catalysts.The higher mole ratio of monomer isobuty-lene to catalyst was,the higher number-average rela-tive molecular weight the resulting polymer had.The lower reaction temperature was,the higher numbe-average relative molecular weight of the polymer was,however,when the reaction temperature was below-60℃,the number-average relative molecular weight of the polymer decreased significantly.The reaction time had little effect on the change of the number-average relative molecular weight of the polymer.In addition,the polymerization reaction temperature and time had no significant effect on the glass transition temperature of polyisobutylene.

聚丙烯(PP)作为一种热塑性树脂,具有质量轻、无毒和易加工成型等特点,被广泛应用于车辆、航天和建筑等领域.但PP材料的韧性较差,大大限制了其进一步的应用.因此,对其韧性的改善一直受到研究人员的广泛关注.本文主要综述了当前研究最广泛的橡胶或弹性体、刚性粒子和核-壳结构粒子物理增韧PP的增韧机理、研究进展,同时也介绍了其他物理增韧方法(β成核剂、纤维、超声辅助)的研究进展,并对将来增韧改性PP的研究方向进行了展望.

Porous organic polymers (POPs) have received increasing attentions in a wide range of areas including adsorption, separation and catalysis. In this paper, a kind of sulfonated POP was designed, synthesized and used as Zeigler-Natta catalyst support for propylene polymerization. The prepared s-POP obtained highly porous structure with specific surface area of 542 m2/g (BET) and pore volume of 0.433 g/ml. The prepared s-POP based Zeigler-Natta catalysts with diisobutyl phthalate (ID-1) and 3-methyl-5-tert-butyl-1,2-phenylene dibenzoate (ID2) exhibit good propylene polymerization activity, high stereoregularity and broad molecular weight distribution. The polymerization activity of Cat-2 with (ID-2) is 32.6 x 106 g.PP/mol.Ti. h with Mw/Mn of 13.8 and isotacticity index of 98.3%. The stereoregularity or isotactic sequence distribution of the prepared polypropylene (PP) was characterized by DSC?13CNMR and TREF techniques, and the results showed that the s-POP based catalyst (cat-2) with ID-2 obtained particularly higher isotatic sequence than the MgCl2-based Ziegler-Natta catalyst (cat-4) with the same internal donor. Pentad methyl sequence mmmm of PP-2 (94.1%) from cat-2 is 1.6% higher than that of PP-4 from cat-4, and the elution temperature of PP-2 (123.5 degrees C, 91%) is 1 degrees C higher than the isotactic fraction from PP-4 (122.5 degrees C, 87.2%). This characteristics of broad molecular weight and peculiar high stereoregularity of s-POP based catalyst could be attributed the modulation of chemical environment around Ti and Mg elements, and XPS analysis exhibited the minute difference of binding energy of Ti?Mg?C and O atoms. Furthermore, the plausible formation mechanism of active sites for the s-POP based Z-N catalyst was proposed.

Porous organic polymers (POPs) are widely used in various areas such as adsorption, separation and catalysis. In the present work, ionic liquid-modified porous organic polymers (IL-POPs) synthesized by dispersion polymerization were applied to immobilize metallocene catalysts for olefin polymerization. The prepared IL-POPs were characterized by Fourier transform infrared spectrometer (FT-IR), nitrogen sorption porosimetry, X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometer (ICP) and scanning electron microscope (SEM) analysis. The IL-POPs obtained pores with surface specific area (SSA) ranging from 16.9 m2/g to 561.8 m2/g, and total pore volume (TPV) ranging from 0.08 cm3/g to 0.71 cm3/g. The supported catalysts Zr/MAO@IL-POPs exhibit great activity (3700 kg PE/mol·Zr·bar·h) in ethylene polymerization, and the GPC-IR results show that the polyethylene has narrow molecular weight distribution (2.2 to 2.8). The DSC results show that the melting point of prepared polyethylene was as high as 138 °C, and the TREF analysis results indicate that they have similar chemical composition distribution with elution temperature at 100.5–100.7 °C.

研究了热处理的温度和时间对2种抗冲共聚聚丙烯(IPC)(EP533N-1,EP533N-2)分散相结构和力学性能的影响.结果表明:当热处理温度低于IPC熔融温度(167℃)时,橡胶相相对分子质量较小的EP533N-1分散相分布均匀性好于橡胶相相对分子质量较大的EP533N-2;当热处理温度高于167℃,EP533N-2分散相分布均匀性好于EP533N-1.热处理温度高于167℃时,EP533N-1中的乙烯丙烯嵌段共聚物(EbP)逐渐汇集成一个网络结构.2种IPC的常温抗冲击性能和弯曲模量均随热处理温度升高而增加,其中,热处理温度为100～130℃时,EP533N-1的低温抗冲击性能最佳,热处理温度为160℃时,EP533N-2的低温抗冲击性能最佳.

Abstract The effect of Joncryl ADR®-4368 (abbreviated ADR) and dicumyl peroxide (DCP) on poly(butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) blend was investigated. Two different blending procedures were adopted: (1) one-step blending of all components for 8 min; (2) premixing of PBAT and ADR (or DCP) for 4 min followed by addition of PLA blending for 4 min. ADR and DCP were effective compatibilizers for the PBAT/PLA blend by one-step blending which were confirmed by improving the phase interface between PBAT and PLA, decreasing the dispersed phase size, increasing the elasticity, viscosity and tensile strength. Moreover, the addition of ADR into PBAT/PLA blend by two-step blending was more efficient than the one-step blending based on refined morphology and further increased tensile properties. The two-step blending was beneficial to produce a larger amount of PBAT-graft-PLA (PBAT-g-PLA) copolymers at the phase interface. However, DCP was added to the PBAT/PLA blend by the two-step blending which showed lower properties than one-step blending. DCP triggered free branching reactions in a fast way. Based on the character of compatibilizers, choosing properly blending procedures can enlarge the tensile properties. These results would be interesting for industrial polymer materials, and may be importance to the wider practical application of PBAT/PLA blends.