Phase morphology and mechanical properties of a poly(ether sulfone)‐modified bismaleimide resin

The polymerization‐induced phase‐separation behavior of a thermoplastic [poly(ether sulfone) (PES)]‐ modified thermosetting bismaleimide resin during isothermal curing was investigated with differential scanning calorimetry, time‐resolved light scattering, and scanning electron microscopy with various contents and molecular weights of PES. The results suggested that the phase structure changed from a dispersed structure to a bicontinuous structure to phase inversion with an increase in the PES content. Three kinds of PES with different molecular weights were used to study the effects of the molecular weight on the phase structure and mechanical properties of modified systems. With higher molecular weight PES, a phase‐inversion morphology could be obtained at lower PES contents. The curing conversion of bismaleimide was affected by the composition of the blend. The curing rate decreased with an increase in the PES content. A blend with 15 wt % PES of a suitable molecular weight had a higher tensile strength and elongation at break than that without PES. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

PPC/PDAP共混膜的制备和性能

将过氧化二异丙苯(DCP)置于特定温度下,引发邻苯二甲酸二烯丙酯(DAP)在聚碳酸亚丙酯(PPC)溶液中聚合,制备得到聚碳酸亚丙酯/聚邻苯二甲酸二烯丙酯(PPC/PDAP)共混膜。采用红外光谱仪(FTIR)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)、热重分析仪(TGA)、万能试验机和水蒸气透过率测试仪对共混膜的红外吸收、结晶性、热、力学和阻隔性能进行了表征。结果表明,通过DAP的聚合,提高了PPC的结晶性,使PDAP在PPC基体中形成交联网络,提高了共混膜的热、力学和阻隔性能。相比纯PPC,当DAP含量为20%时,共混膜的玻璃化转变温度和拉伸强度分别提高了5.3℃和266%;当DAP含量为40%时,共混膜的失重5%热分解温度提高了50.9℃,透湿系数下降了25%,因此,阻隔性能得到了提升。     

TPU/硅橡胶弹性体动态硫化过程相态结构控制研究

将硅橡胶加氢硫化,采用动态硫化方法制备了聚氨酯/硅橡胶热塑性弹性体,并与简单二元共混体系进行了比较.在简单共混体系中,硅橡胶用量为55%和60%时,体系分别形成两相连续和聚氨酯分散相结构,而在动态硫化后均实现了硫化硅橡胶均匀分散在聚氨酯基体中的相态结构.在动态硫化过程中,催化剂加入1 min内已经实现了相反转,但此时分散相分散不均匀;动态硫化5 min产物相比简单二元共混体系,拉伸强度提高了1 277%,断裂伸长率提高了546%.     

完全生物降解塑料PLA/PPC合金的结构与性能研究

利用机械共混法,将聚乳酸(PLA)与聚丙撑碳酸亚丙酯(PPC)熔融共混,制备了完全生物降解塑料PLA/PPC合金,并用FTIR、流变仪等手段研究了其结构、力学性能和流变性能。结果表明该共混体系具有良好的相容性、力学性能和熔体流动性,PLA与PPC之间存在着较强的相互作用,PPC的加入使体系拉伸强度下降幅度不大,断裂伸长率升高到23.8%,比纯PLA提高近20倍。共混体系的黏度亦随着PPC的加入逐渐增大,PLA/PPC(50/50)体系的黏流活化能为37.1kJ/mol,同时在一定的温度范围内,提高切应力也会使体系黏度下降。     

Compatibility study in natural rubber and maize starch blends

Blends containing various ratios of natural rubber (NR) and maize starch (MS) were prepared on a two roll mill. The effect of starch contents on physico-mechanical properties and curing characteristics of the prepared blend vulcanizates was investigated. The data indicate poor mechanical properties, delayed cure rate index, and decreased maximum torque with increasing starch content in the blend formulation. This indicates that the interfacial interaction between the blend components was poor. Various contents of the compatibilizers, maleic acid anhydride (MAH) and glycidyl methacrylate (GMA), were mixed with the blend NR/MS (90/10). The effect of the compatibilizer contents on the physico-mechanical properties and curing characteristics of the binary blend was investigated. Compatibilized blends with GMA (1 phr) showed an improvement in the physico-mechanical properties in comparison with uncompatibilized blend samples. Blends with MAH exhibited higher modulus and hardness values with respect to GMA blends. The efficiency of the compatibilizers was also evaluated by studies of phase morphology (scanning electron microscope), Fourier transform infrared spectroscopy, and thermal stability (thermogravimetric analysis). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

氯化聚乙烯/废旧轮胎胶粉共混发泡性能研究

采用模压法进行发泡,以氯化聚乙烯（CM）为基体,研究了胶粉用量、硫化温度、硫化助剂对CM发泡体的泡体性能、泡孔结构的影响。结果表明,CM发泡体随着胶粉用量的增加,发泡密度逐渐增加,泡孔体积及发泡倍率逐渐减少。综合CM发泡体的泡体性能及泡孔结构,当胶粉用量为10份,170℃下硫化7min,使用TCHC作硫化助剂时,可得到发泡效果好,断面均匀分布,泡孔结构明显的CM发泡体。     

动态硫化EPDM/PP热塑性弹性体制备工艺研究

研究了不同硫化体系 ,硫化时间 ,硫化剂的用量 ,共混温度 ,橡塑比 ,填充炭黑和软化剂的用量对动态硫化 EPDM/ PP共混物性能的影响。研究结果表明 :酚醛硫化体系制得的 EPDM/ PP共混物加工性能和力学性较佳 ,硫化时间在 10～ 15 min,硫化剂的用量以完全交联 EPDM为宜 ,共混温度控制在 170℃～ 190℃ ,橡塑比 70 / 3 0～ 5 0 / 5 0 ,填充炭黑在 40份以内 ,软化剂在 2 0份以内较为理想     

Structure development via reaction-induced phase separation in tetrafunctional epoxy/polysulfone blends

For the cure process of tetrafunctional epoxy resin/polysulfone(EP/PSF) blends, we investigated the effect of cure temperature and blend composition on the phase separation behavior by light scattering and the structure development during cure by an optical microscope. The EP/PSF blend without the curing agent was shown to exhibit an LCST-type phase behavior (LCST = 241°C). At the early stage of curing, the EP/PSF blend was homogeneous at the cure temperature. As the cure reaction proceeded, the blend was thrust into a two-phase regime by the LCST depression caused by the increase in a molecular weight of the epoxy-rich phase, and the phase separation took place via a spinodal decomposition (SD) or nucleation and growth (NG) mode, depending on the blend composition and the cure temperature. When cured isothermally at 220°C, the blend exhibited a sea-island morphology formed via the NG mode below 5 wt % PSF content, while the SD mode prevailed above 20 wt % PSF content. At the intermediate composition range, combined morphology with both sea-island and cocontinuous structure was observed. On the other hand, by lowering the cure temperature and/or increasing the content of PSF component, a two-phase structure with a shorter periodic distance was obtained. It seems that the rate of the phase separation is considerable reduced, while that of the cure reaction is not as much. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2233–2242, 1997     

Effect of different curing systems on heat shrinkability and mechanical properties of ethylene vinyl acetate/epoxidized natural rubber blends

Ethylene vinyl acetate (EVA)/epoxidized natural rubber (ENR) blends containing 10 and 30 wt % ENR were prepared by using an internal mixer. Five different types of curing systems were employed: dicumyl peroxide (DCP), sulfur (S), phenolic resin (Ph), DCP + S, and DCP + Ph. DCP could crosslink with both EVA and ENR while S and Ph were curing agents for ENR. The DCP system provided the lowest tensile properties and tear strength because of low crosslinking in ENR phase. Addition of sulfur or phenolic resin increased the mechanical properties due to a better vulcanization of the rubber phase. The mechanical properties of the blends decreased with increasing ENR content. The rubber particle size in the blends containing 30% ENR played a more important role in the mechanical properties than the blends containing 10% ENR. ENR particle size did not affect heat shrinkability of EVA and a well vulcanized rubber phase was not required for high heat shrinkage. Furthermore, heat shrinkage of the blends slightly changed as the ENR content increased for all curing systems. With regard to the mechanical properties and heat shrinkability, the most appropriate curing system was DCP + Ph and in the case the 10 wt % ENR content produced a more favorable blend. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication of poly(ε‐caprolactone) (PCL)/poly(propylene carbonate) (PPC)/ethylene‐α‐octene block copolymer (OBC) triple shape memory blends with cycling performance by constructing a co‐continuous phase morphology

In this paper, a triple shape memory material was prepared by ultra‐simple melt blending from poly(ε‐caprolactone) (PCL), poly(propylene carbonate) (PPC) and ethylene‐α‐octene block copolymer (OBC). The obtained material possessed a co‐continuous phase morphology and presented an excellent triple shape memory effect (triple‐SME). Theoretical prediction demonstrated that a special continuous phase morphology could be constructed by adjusting the proportions of the blend. Moreover, the results indicated that a close relationship existed between the phase morphology and the triple‐SME of PCL/PPC/OBC. The sample with 35 vol% PPC content contributed to the formation of a continuous phase morphology and exhibited the optimal triple‐SME. Additionally, the sample PCL/PPC/OBC (32.5/35/32.5) showed outstanding structure and performance stability during cycle loading–unloading tests, which evidenced the prominent cycling shape memory property (nearly 100% shape fixing and recovery of temporary shape). Overall, this work could provide an efficient, convenient and recyclable method to obtain high‐performance shape memory materials. © 2020 Society of Chemical Industry     

Biodegradable PPC/(PVA-TPU) ternary blend blown films with enhanced mechanical properties

Biodegradable films of poly(propylene carbonate)/poly(vinyl alcohol)-thermoplastic polyurethane [PPC/(PVA-TPU)] ternary blends were successfully prepared by melting blending method. The mechanical properties of poly(propylene carbonate) blown film were greatly improved by blending PPC with PVA-TPU. In order to afford the melt processing of PVA, the PVA-TPU binary blend was firstly prepared using thermoplastic polyurethane as a polymeric plasticizer. The rheological behavior, mechanical properties and morphology of these blends were studied. Considering its melt viscosity and thermally processing temperature, the PVA-50%TPU, as a modifier, was blended with PPC to prepare PPC/(PVA-TPU) ternary blend. SEM observation revealed a basic one-phase morphological structure with very good interfacial adhesion between the extremely blurred PPC and PVA-TPU two components. Meanwhile, the miscibility of the ternary components was verified by only one glass-transition temperature obtained from DMA tests. The tensile strength and tear strength of PPC/(PVA-TPU) blown films were determined at different temperatures. The results demonstrate that the mechanical properties of PPC/(PVA-TPU) films were enhanced dramatically at low temperature when compared with neat PPC. At room temperature, PPC/30 %(PVA-50%TPU) blown film exhibited a tensile strength of 26 MPa, and an elongation at break of 484.0 %. Its tear strength in the take-up direction is 124.1 kN/m, and the one in machine direction is 141.9 kN/m. At a low temperature of 0 °C, PPC/30 %(PVA-50%TPU) exhibited a tensile strength of 40.7 MPa and tear strength of 107 kN/m, which are 153 % and 142 % of those of neat PPC respectively. The blending of PPC with the PVA plasticized with TPU provides a practical way to extend the application of the new biodegradable polymer of PPC in the area of blown films.     

The effect of mercapto‐modified ethylene–vinyl acetate (EVA) on curing parameters,mechanical properties,and thermal properties of vulcanized styrene–butadiene rubber (SBR)/EVA blends

The effect of EVA functionalized with mercapto groups (EVALSH) on the compatibilization of SBR and EVA copolymer blends was investigated in vulcanized systems based on sulfur or dicumyl peroxide (DCP). The presence of EVALSH resulted in an improvement of the tensile properties, indicating the reactive compatibilizing effect of this compound. The best mechanical performance was achieved with the sulfur‐curing system for both compatibilized and noncompatibilized blends. The blend systems were also analyzed by scanning electron microscopy, differential scanning calorimetry, and dynamic‐mechanical analysis. The crystallinity of the EVA phase was significantly affected by the presence of the EVALSH, whereas no substantial change was detected on the damping properties or the glass transition temperature of the SBR phase. Considering the aging properties, the presence of EVALSH increases the thermal stability of the blends vulcanized with DCP. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 239–249, 2002     

Dynamic vulcanization of polyethylene‐based thermoplastic elastomer blends

In this investigation, the effects of blending with ethylene–propylene–diene terpolymer and subsequent dynamic curing with sulfur on the macromolecular structure and properties of pure low‐density polyethylene and high‐density polyethylene were studied. The crosslinking efficiency of polyethylene‐based ethylene–propylene–diene terpolymer blends upon dynamic curing was assessed with torque and gel content measurements. The curing of dispersed ethylene–propylene–diene terpolymer in a polyethylene matrix improved both the mechanical and thermomechanical properties as a result of the formation of a crosslink structure in the rubber phase. In view of the electrical applications of this cured blend material, the volume resistivity was measured. The thermal stability of vulcanized polyethylene/ethylene–propylene–diene terpolymer blends was found to be superior to that of unvulcanized blends. In scanning electron microscopy analysis, good interface bonding between the polyethylene matrix and dispersed ethylene–propylene–diene terpolymer was observed for the cured blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚丙撑碳酸酯与壳聚糖共混物的研究

以聚丙撑碳酸酯(PPC)和壳聚糖(CS)为主要原料,在其他添加剂的作用下制备可生物降解性塑料聚丙撑碳酸酯/壳聚糖共混物,通过加入不同量的壳聚糖来研究壳聚糖对共混物的力学性能和微观形态的影响.结果表明:共混物熔体流动速率在CS为5份时有最大值,共混物的加工流动性得到提高,面当CS为10份时共混物断裂伸长率有最大值,所以加入CS及其他助剂使共混物的力学性能得到显著提高,共混物的韧性和加工性能得到提高.     

聚碳酸亚丙酯-聚乳酸共混熔纺纤维的制备与性能

以乙烯-马来酸酐共聚物(ZeMac)作为反应性相容剂,利用熔融纺丝法制备了聚碳酸亚丙酯(PPC)-聚乳酸(PLA)共混纤维。通过傅里叶变换红外光谱仪、热重分析仪、差示扫描量热分析仪、纤维强伸度仪等分别研究了共混纤维的分子结构、热稳定性、相容性及力学性能。结果表明:PLA的引入较大地提高了PPC的力学性能,加入少量的ZeMac可以有效地改善PPC的热稳定性,同时也能够提高共混体系的相容性。当PPC-PLA与PPC-PLA-ZeMac体系组分质量比分别为70/30和70/30/0.7时,其抗拉强度分别为11.23 MPa和20.83 MPa,较未改性的PPC分别提高了6.5倍和12.1倍,同时还能保持较高的断裂伸长率。该项研究为完全可生物降解PPC熔融共混纤维的工业化提供了可能性。     

Studies on the blends of carbon dioxide copolymer. III. NBR/PPC systems

In this paper, the blends of the carbon dioxide copolymer, poly(propylene carbonate) (PPC), with nitrile rubber (NBR) were studied by DSC, DMA, TEM and TG. PPC can enhance the mechanical properties of NBR, while oil resistance and tensile set at break of NBR/PPC systems were as good as that of NBR. The coagent of triallylisocyanurate or maleic anhydride with carbon black can much improve the curing efficiency of dicumyl peroxide in NBR/PPC systems. © 1996 John Wiley & Sons, Inc.     

Dynamic vulcanization of recycled milk pouches (LDPE–LLDPE) and EPDM blends using dicumyl peroxide

The viability of thermomechanical recycling of post‐consumer milk pouches (blend of low‐density polyethylene (LDPE) and linear low‐density polyethylene (LLDPE)) and its scope for suitable engineering applications were investigated. The effects of blending with ethylene‐propylene‐diene monomer (EPDM) rubber and subsequent curing using dicumyl peroxide (DCP) on the macromolecular structure and properties of recycled polyethylene (PE) blends were studied. The crosslinking efficiency of recycled PE/EPDM blends and possible thermooxidative degradation of recycled polymer upon peroxide curing was assessed using torque and gel content measurements along with infrared spectroscopic analysis. Both the torque and gel content of the blends varied with DCP crosslinking reactions and also were affected by oxidative degradation. In view of the electrical application area of this recycled blend material, the dielectric breakdown strength and volume resistivity were measured. The mechanical performance and thermal stability of recycled PE/EPDM blends improved with progressive crosslinking by DCP but deteriorated somewhat at higher DCP dose. Scanning electron microscopy showed good interface bonding between recycled polymer and dispersed EPDM phase in the cured blends compared to the non‐cured blends. Copyright © 2007 Society of Chemical Industry     

Curing behavior of liquid crystalline epoxy/DGEBA blend

The effect of liquid crystalline epoxy (LCE) resin on the curing behavior and thermomechanical properties of diglycidylether of bisphenol A (DGEBA) was investigated. LCE was blended with DGEBA and curing behavior of the blend was studied according to LCE content in the blend. Curing of DGEBA was accelerated and thermomechanical properties of DGEBA were considerably improved by the addition of LCE, which acted as a molecular reinforcement. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of the cure cycle and thermoplastic content on the final properties of dicyanate ester/polysulfone Semi‐IPNS

A bisphenol A dicyanate resin, BADCy, was toughened by incorporating polysulfone, PSU, at various compositions. The catalyst system used was a mixture of copper acetylacetonate and nonylphenol. Phase separation and rheokinetics were studied through curing. The blends seemed to have a LCST behavior, and the presence of PSU did not affect the polycyclotrimerization kinetics. The phase structure, thermal, and mechanical properties of the final network were investigated as a function of the PSU content and cure temperature. The toughness of the BADCy/PSU blends was closely related to their final morphology, increasing with the amount of phase inversion. The mechanical properties were not affected by the addition of the thermoplastic. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1799–1809, 2002     

Preparation and characterization of blend membranes of polyurethane and superfine chitosan powder

A novel kind of asymmetric blend membranes with superfine chitosan powder (SCP) and biomedical polyurethane was prepared by immersion precipitation phase inversion method. Effects of different SCP content on the morphology and properties of the blend membranes were investigated. The result showed that SCP content had little influence on the cross-section structure of the blend membranes, and the cross-section presented a cellular structure. WAXD results revealed that the aggregated structure of SCP remained. With an increment of SCP content, the pore diameter and porosities of blend membranes increased firstly, and then decreased. While, the water absorption rate and water vapor transmission rate were improved remarkably with increasing SCP content. The mechanical testing results indicated that with an increment of SCP ratio, mechanical properties presented a descending trend, whereas all blend membranes exhibited the good elasticity.