用顺酐化EPDM增容的EPDM改性聚甲醛

以顺酐化三元乙丙橡胶（ＭＥＰＤＭ）为增容剂，研究了ＥＰＤＭ对聚甲醛（ＰＯＭ）的共混增韧生。结果表明，ＭＥＰＤＭ能明显改善ＰＯＭ与ＥＰＤＭ的相容性，使共混物分散相尺寸明显减少，分布更均匀，熔点和结晶度降低，缺口冲击强度提高。当ＰＯＭ／ＥＰＤＭ／ＭＥＰＤＭ（质量比）为８５／９／６时，共混物的缺口冲强度为１０．２ｋＪ／ｍ＾２。     

热塑性聚氨酯增韧改性聚甲醛的研究

本文对ＰＯＭ／ＴＰＰＵ／Ｚ－３共混体系进行了研究，结果表明，增容剂Ｚ－３可控制共混体系中分散相的颗粒尺寸及分布，起着聚集剂的作用。随着ＴＰＰＵ用量的增加，共混合金的结晶度和拉伸强度增降低，缺口冲击强度出现峰值，ＭＩ下降，当ＰＯＭ／ＴＰＰＵ／Ｚ－３＝１００／７／０．４９时，共混合金的缺口冲击强度达到最大值。     

聚甲醛/聚氨酯高韧合金的研究

通过机械共混法制备了ＰＯＭ／ＴＰＵ合金,考查了ＴＰＵ含量、增容剂以及开矿结构对共混物韧性的影响。结果表明,共混方法以及形态结构对共混物的性能有较大影响,增窝剂Ｇ是促进ＴＰＵ分散、使共混物实现高韧化的关键组分。     

POM／LDPE共混改性新品级的研究

本文对ＰＯＭ／ＬＤＰＥ／增容剂共混增容改性进行了研究，研究结果表明：增容剂的加入，使ＰＯＭ／ＬＤＰＥ体系中ＬＤＰＥ分散均匀，ＰＯＭ球晶细化，物理力学性能得到改善，且增容剂的用量控制在５－７％为最佳。所研制的新品级的主要性能指标为：拉伸强度５０－６０ＭＰａ，缺口冲击强度≥１２ｋＪ／ｍ＾２，制作的小模数齿轮精度等级达７级，摩擦系数为０．２０－０．３０。     

聚甲醛和高密度聚乙烯共混改性的研究

本文对ＰＯＭ／ＨＤＰＥ／增容剂Ｚ－２共混体系进行了研究．研究结果表明：随着ＨＤＰＥ用量的增加，共混体系的拉伸强度下降，缺口冲击强度出现峰值，流动性增大，密度降低，线膨胀系数增加．当ＰＯＭ／ＨＤＰＥ／Ｚ－２＝１００／３／７时，共混物的缺口冲击强度达最大值．     

PC／PE共混体系中增容剂最佳用量的确定

本文以聚碳酸酯（ＰＣ）／聚乙烯（ＰＥ）／聚乙烯蜡接技马来酸酐（ＰＥＷ－ｇ－ＭＡＨ）三元共混物为体系，研究了第三组份增容剂ＰＥＷ－ｇ－ＭＡＨ用量。共混物两相之间界面张力和共混物力学性能之间的相互关系。论证了通过测量高聚物之间界面张力来确定第三组份增容剂的最佳用量的技术途径。     

EPDM—g—MMA接枝率对POM／EPDM共混物增容作用的影响

本文介绍以ＢＰＯ为引发剂，合成接枝共聚物ＥＰＤＭ－ｇ－ＭＭＡ的方法，并对其进行红外表征，另外，借助ＳＥＭ和力学性能测试研究了接枝率时ＰＯＭ／ＥＰＤＭ共混物的增容作用的影响。     

EPDM－g－MMA接枝率对POM／EPDM共混物增容作用的影响

本文介绍以ＢＰＯ为引发剂，合成接枝共聚物ＥＰＤＭ－ｇ－ＭＭＡ的方法。并对其进行红外表征，另外，借助ＳＥＭ和力学性能测试研究了接枝率对ＰＯＷ／ＥＰＤＭ共混物的增容作用的影响。     

聚丙烯熔融接枝马来酸二丁酯增容聚丙烯／尼龙6的研究

研究了聚丙烯（ＰＰ）与马来酸二丁酯（ＤＢＭ）的接枝共聚物ＰＰｇＤＢＭ对聚丙烯／尼龙６（ＰＰ／ＰＡ６）共混物的增容作用。研究表明,ＰＰｇＤＢＭ是ＰＰ／ＰＡ６共混体系的有效增容剂,由于共混过程中就地生成ＰＰｇＰＡ６,改善了共混物的相容性,增加了两相界面的粘合,使分散相粒径减小,分散更均匀,提高了共混物的力学性能。增容剂接枝率的高低对增容效果有一定影响,接枝物中残留单体不影响增容效果     

EPDM/聚烯烃共混型热塑性弹性体的研究

制备ＥＰＤＭ／聚烯烃简单共混型热塑性弹性体。研究了聚合物种类、橡塑比、二元和三元共混对共混物力学性能的影响。结果表明，部分结晶性ＥＰＤＭ共混物的力学性能比无定形ＥＰＤＭ共混物好，部分结晶性ＥＰＤＭ与ＬＤＰＥ（低密度聚乙烯）共混物的拉伸强度大于两者的加和值，而其它二元共混物的拉伸强度均低于两共混单元的加和值；用ＬＤＰＥ部分替代ＰＰ，或用氯磺化聚乙烯（ＣＳＭ）部分替代结晶性ＥＰＤＭ进行三元共混，能改善部分结晶性ＥＰＤＭ／ＰＰ共混物的某些性能。     

On the compatibilization and dynamic vulcanization of polyacetal/ethylene propylene diene terpolymer blends

This study describes an attempt to improve the impact resistance of polyacetal (POM)/ethylene propylene diene terpolymer (EPDM) blends by means of compatibilization and dynamic vulcanization. A commerical copolymer, poly(acrylic acid)-grafted polypropylene (PGP), has been used as a compatibilizer to control the phase morphology of the blend system. Dicumyl peroxide is used to dynamically vulcanize the EPDM elastomer in the blend. At temperatures higher than 185°C, the compatibilizer decreases the viscosity of compatibilized and dynamically vulcanized (cdv) POM/EPDM blends. Impact strength of the cdv blend system increases considerably with a marginal decrease in tensile yield stress and heat deflection temperature as the PGP content increases. The significant increase in impact strength seems to be due to the role of PGP as a linking agent for the binary blends rather than as a third component. Though dynamic mechanical studies do not indicate any compatibility in cdv-POM/EPDM blends, scanning electron microscopy reveals the strong interpenetrating interphase in the compatibilized blend system. Dynamic vulcanization raises elastic recovery and tensile modulus of the blends. Hysteresis energies of the blends increase consistently with the addition of PGP. The crystalline structure of POM is not affected by compatibilization and vulcanization. © 1994 John Wiley & Sons, Inc.     

Studies on thermal stability and behaviour of polyacetal and thermoplastic polyurethane elastomer blends

The influence of thermoplastic polyurethane (TPU) elastomer on the rigidity of polyacetal (polyoxymethylene, POM) was studied by determining heat deflection temperature (HDT). The higher the content of TPU in the POM/TPU blend, the lower the HDT of the blend, as would be expected. A comparative study of the recycle capability of POM and the blends was carried out by measuring melt flow index (MFI) on each successive extrusion. Stress-strain behaviour of the virgin material and that obtained after fourth-time extrusion was analysed for POM and the blends. The effect of γ-radiation on the mechanical behaviour of the blends was investigated. The kinetics of thermal degradation of POM, TPU and their blends was studied. The kinetic parameters, viz. activation energy and the order of reaction, were established. The values of the activation energy of the blends were found to be higher than those of the POM and TPU, indicating improved stability of the resultant blends.     

Blends of polyacetal and ethylene-octene elastomer: Mechanical,dynamic mechanical and morphological properties

Polyacetal (POM) and ethylene octene copolymer(EOC) elastomers form immiscible blends with extremely low compatibility. In order to improve the dispersion, stability and properties of these blends, dynamic vulcanization was carried out in a twin screw extruder using dicumyl peroxide. The tensile strength decreased with increase in % elongation at break for both blend systems. There was a drastic decrease in impact strength for unvulcanized blends as the elastomer content increased and this was attributed to the coalescence of the elastomer particles as their content increased. In the case of dynamically vulcanized blends there was a significant increase in impact strength as the levels of elastomer increased. Dynamic mechanical analysis has been carried out to investigate the effect of blend composition and dynamic vulcanization on dynamic mechanical parameters such as storage modulus, loss modulus and loss factor. The results indicate gross incompatibility of POM and EOC blends. However, dynamically vulcanized blends show better adhesion between component polymers. The morphological studies reveal that the particle size and coalescence of elastomer was significantly reduced in comparison to unvulcanized bends. The phase adhesion was improved by dynamic vulcanization. Hence, it was observed that dynamic vulcanization effectively improves the morphology of the blend system and enhances the properties of polyacetal.     

Morphology and nonisothermal crystallization of a polyacetal/poly(ε‐caprolactone) reactive blend prepared via a chain‐transfer reaction

A polyacetal (POM)/poly(ε‐caprolactone) (PCL) reactive blend prepared via a chain‐transfer reaction was investigated with respect to its morphology and nonisothermal crystallization, and the results were compared with those of a simple POM/PCL blend. The reactive blend had a microscopically phase‐separated morphology in which the diameter of the PCL microphase was below 100 nm, and it clearly yielded ring‐banded spherulites, whereas between the two blends, there were no significant differences in the diameters and polygonal edges of the spherulites and in the long period of the POM phases. The PCL part of the reactive blend crystallized within the confined microspace with about 10% lower crystallinity than that of the corresponding simple blend. A lower Avrami exponent and crystallization rate parameter of the PCL part were observed in the primary crystallization process of the reactive blend. In contrast, the crystallinity of the POM component and the nonisothermal crystallization kinetic parameters of the POM part showed no noticeable differences between the two blends at any given cooling rate. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology,thermal, and mechanical properties of polyacetal/ionomer blends

This study is directed towards the development of modifiers for and the understanding of their role in improving the impact properties of an engineering polymer, polyacetal (POM). It is demonstrated that modifiers that induce ion-dipole interactions can lead to substantial enhancements in the room temperature impact performance of POM without sacrificing its unique balance of mechanical, thermal, and chemical resistance properties. The mechanical and physical properties of blends of a commercial copolymer type polyacetal (POM) with terpolymers of ethylene, methylacrylate and acrylic acid (EAAT) and its zinc ionomer form (EAAT-Zn), are reported. Substantial differences both in the mechanical and impact performance were found in these two modified POM systems. DSC and optical microscopy studies of such blends demonstrates only minor differences in the microcrystalline structure of the two blend systems. A nearly three fold reduction in the spherulite size of POM was found from addition of as little 5% of either modifier, thus ruling out this mechanism for the observed increased toughness of the blends. Dynamic mechanical measurements and cryofractured surface microscopy observations indicate that enhancements in the physical properties of POM modified with zinc ionomers of EAAT are due to enhanced interfacial adhesion and to the (inherent) mechanical rigidity (due to ionic interactions), of the modifier. In these blends the tensile and impact strength are found to be a function of the degree of neutralization of the terpolymer acid content. In particular, an optimum balance of impact and tensile properties is obtained with partial neutralization (in the range of 25 to 50% of the terpolymer acid content) and at modifier addition levels in POM in the range of 5 to 10%. The EAAT modifier for POM was found to be ineffective even up to 20% addition as compared to EAAT-Zn modifier. Ion-dipole interactions are thus shown to be more influential than the hydrogen bonding that occurs in EAAT-POM blends. The study suggests a new approach to modify polar engineering polymers via such interactions.     

Impact modification of polyacetal by thermoplastic elastomer polyurethane

The main goal of this study was impact modification of polyacetal [polyoxymethylene (POM)] with thermoplastic elastomer polyurethane (TPU). We modified the impact strength of POM 10‐fold. The mechanical properties, thermal behavior, and morphology of POM/TPU blends consisting of 5 to 50% of TPU were studied. It was found that the best impact modification of the blends was at 15% concentration of TPU and the maximum elongation at break was at 30% concentration of TPU. The impact strength of POM/TPU blends can be improved by using diphenylmethane diisocyanate (MDI) as compatibilizer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2573–2582, 2002     

Polyacetal/poly(tetrafluoroethylene) blends,I. The effect of Na-treated poly(tetrafluoroethylene) on polyacetal

The various properties of the blends of polyacetal (POM) with up to 20 wt.-% chemically surface-treated poly(tetrafluoroethylene) (CPTFE) were investigated and compared with those of POM/PTFE blends. The PTFE is added to POM to improve the wear properties, however, the mechanical properties of POM/PTFE blends decrease with increasing PTFE content, but tensile strength and Young's modulus of POM/CPTFE blends are more than 2 times higher than that of the POM/PTFE blends. SEM shows that the size of inherent agglomerative PTFE is in the range of 30 to 100 μm. The particle size of major CPTFE dispersed in POM is smaller than 1 μm.     

POM共混增韧改性研究

研究了POM COPA、POM LDPE和POM HDPE三种共混体系,测试了不同配比共混物的冲击强度,对POM COPA及紫外线辐射的HDPE进行了红外光谱(FT IR)分析。结果表明:(1)在三种共混体系中,COPA对POM的增韧效果最佳,且COPA与POM分子间有氢键作用;(2)EVA在POM LDPE及POM HDPE共混体系中起相容剂的作用;(3)HDPE经紫外线辐射后,由于在其分子链上引入了极性羰基,从而大大提高了对POM的增韧效果。     

Polyoxymethylene/thermoplastic polyurethane blends compatibilized with multifunctional chain extender

Novel compatibilized polyoxymethylene/thermoplastic polyurethane (POM/TPU) blends are successfully developed using multifunctional chain extender, Joncryl ADR‐4368, as the compatibilizer. The outstanding compatibilization efficiency of Joncryl on POM/TPU blend was demonstrated by its even higher mechanical properties with only 0.5 wt % of Joncryl than those with 5 wt % of three commonly used compatibilizers. Addition of only 0.5 wt % Joncryl can double the impact strength and significantly improve its tensile strength and flexural strength for POM/TPU (75/25) blend. SEM images show that Joncryl can reduce TPU particle size and enhance the interfacial interactions between POM and TPU. The interparticle distance of TPU in POM/TPU/Joncryl blends was calculated as 0.2 μm, quite close to the critical matrix ligament thickness of POM/TPU blends (0.18 μm). The impact force profile vividly shows that the addition of Joncyl in POM/TPU blends can dramatically increase the total impact energy absorbed by this blend system and enhance the interfacial interactions between POM and TPU. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Blends of poly(propylene) and polyacetal compatibilized by ethylene vinyl alcohol copolymers

Polymer blends of poly(propylene) (PP) and polyacetal (polyoxymethylene, POM) with ethylene vinyl alcohol (EVOH) copolymers were investigated by differential scanning calorimetry (DSC), rheological, tensile, and impact measurements, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The PP–POM–EVOH blends were extruded with a co‐rotating twin‐screw extruder. The ethylene group in the EVOH is partially miscible with PP, whereas the hydroxyl group in the EVOH can form hydrogen bonding with POM. The EVOH tends to reside along the interface, acting as a surfactant to reduce the interfacial tension and to increase the interfacial adhesion between the blends. Results from SEM and mechanical tests indicate that a small quantity of the EVOH copolymer or a smaller vinyl alcohol content in the EVOH copolymer results in a better compatibilized blend in terms of finer phase domains and better mechanical properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1471–1477, 2003