Rayleigh散射研究非相容聚苯乙烯／顺丁橡胶合金相结构

用光散射在线采集与分析方法完成了熔融混炼过程中非相容高分子共混物的形态结构分析。选择了聚苯乙烯／顺丁橡胶合金体系。使用了小角前向光散射和小角背散射（在线）技术，用Debye-Bueche光散射理论的结构参数如相关蹁ac、平均弦长l、平均旋转半径Rg和积分不变量Q表征了共混物中分散相尺度和均匀性。用扫描电子显微镜（SEM）测定了共混物中分散相尺寸，并与光散射的结果进行了比较。ac,l和Rg的变化规律与显微镜的结果是一致的。用积分不变量Q研究了共混物的均匀性。     

聚苯乙烯／顺丁橡胶合金相结构的X光小角散射研究

采用X光小角散射法研究了聚苯乙烯/顺丁橡胶合金体系的相结构及相容性。用Debye-Bueche光散射理论的结构参数，如相关距离ac．平均弦长l、旋转半径Rg和积分不变量Q等表征了合金中分散相的尺度及其分布在连续相中的均匀性，用扫描电子显微镜(SEM)定量测定了合金中分散相尺寸的大小和尺寸分布。结果表明：上述各光散射结构参数均可以在纳米尺度范围内表征合金体系的相结构，积分不变量Q可以表征合金体系相结构的均匀性。聚苯乙烯(PS)/颐丁橡胶(PB)合金是典型的不相容体系，无论PB还是PS处于稀相时均不呈现分子分散。     

小角光散射研究PP／EOC增韧体系

以乙烯 -1-辛烯共聚物 (EOC)对聚丙烯 (PP)进行增韧改性 ,通过小角光散射测取到不同配比的共混物的相关距离 αc、积分不变量Q ,进一步求得分散相粒子表面间距 τ和过渡层厚度d ,研究 τ与材料冲击性能之间的关系 ,发现存在一个临界值 τc与材料的脆韧转变点相对应。当 τ≤τc 时 ,材料是韧性的 ;当 τ>τc 时 ,材料呈脆性。在共混过程中 ,τ随共混时间增加逐渐减小 ,在共混的中后期趋于稳定 ;随 τ值的减小 ,材料冲击强度增加。过渡层厚度d随EOC含量的递增逐渐增大 ,对应材料的冲击强度增加。     

高聚物共混改性后的透明性

本文阐述了影响聚合物共混两相体系透明性的因素。从复杂的两相聚合物混合体系的光散射中,通过一定的简化假设得到单分散非相干单散射的理想体系。该体系光散射理论表明,散射程度(浊度)受分散相数量、分散相颗粒尺寸、两相相对折光指数及入射光波长的影响。得出提高聚合物混合体系透明度的关键是使两相折光指数相匹配,即 m→l,这一结论对真实体系仍适用。并指出共混的透明度还受到成型加工工艺的制约。本文还介绍了提高共混物透明性的几种途径。     

相差显微镜研究PP/POE共混体系的相分散行为

采用密炼机在线取样，相差显微镜拍照研究乙烯-1-辛烯共聚物（POE）在聚丙烯（PP）中的相分散行为。由于相差显微镜图样经过傅里叶变换得到的图样与小角光散射图样有很好的对应关系，本文引入光散射试验中的结构参数-分散相平均粒径αc2以表征PP／POE共混体系的相分散行为。根据αc2值随时间的变化，把PP／POE共混的相分散过程分为分散初期，分散中期，分散后期3个阶段。按照αc2值与组成的关系，可以看出PP／POE（POE质量分数为30％），体系开始出现双连续相结构．与扫描电镜结果相一致。     

高分子共混物的相结构对力学性能的影响

本文以聚丙烯 尼龙1010(PP PA1010)共混体系为模型研究了高分子共混物的微观相结构对宏观力学性能的影响,并通过微观力学模型来预测共混物的拉伸强度。通过光散射试验和扫描电镜结果讨论了两相平均弦长比(L1 L2)以及分散相的质心相关距(D)与拉伸性能的关系。结果表明,当分散相一定时,拉伸强度随两相相对尺寸的增大和分散相颗粒相关性的减弱而减小。理论计算的分散相最小体积分数与相形貌观察的结果非常接近,添加增容剂的体系,由于改善了界面粘合,使理论预测值与试验结果很好的吻合。     

PA／PP—g—MAH／PP共混物的界面和形态研究

用小角X光衍射和偏光显微镜等方法研究了具有相容区的PA101／PP-g-MAH/PP熔融共混物的界面和结晶开态，PA101和PP－g-MAH在熔融共混过程中生成新的基团，在相间存有界面，体系中两相的结晶形态均匀，共混物的拉伸屈服强度随着界面层厚度的增大而提高。     

共混条件对原位法制备的PS—MMA／PA6合金形态结构的影响

用原位聚合／原位增容的方法，在密炼机上将PSMMA／CL共混并引发CL阴离子聚合制备PS-g-PA6/PA6的共混物。试验发现，分散相颗粒直径随共混时间的延长而增大。调节大分子活化剂和小分子活化剂的用量，可以获得含有大量纳米级分散相的聚合物合金。提高密炼机的转子转速，有利于分散相颗粒的细化和均匀化。     

聚乙烯-聚丙烯共混体系聚集态结构的研究——Ⅱ、小角激光散射法

聚乙烯(PE)和聚丙烯(PP)都是典型的结晶性高聚物,二者共混后形成了复杂的多相体系,研究和表征其聚集态结构是十分困难的。而小角激光散射法具有仪器设备简单、散射图形明显、测试结果直观性强、可以进行定量计算等优越性,因此是研究该共混体系聚集态结构的一种很好的方法,可以给出良好的结构信息。为此本文用小角激光散射仪(SALS)对聚乙烯-聚丙烯共混体系的聚集态结构进行了探讨和分析。     

新型液晶PVDF合金的研究

本文系统地研究了液晶聚合物(LCP)与PVDF合金共混体系的组成及加工工艺条件对共混物制件性能的影响。并用SEM观察了合金的形态结构。结果表明:在液晶含量10%左右时,加工温度为210℃,合金的拉伸强度最高,磨耗量最低,体系分散均匀并形成了较多的微纤结构。     

Structural characterization of semicrystalline polymer blends by small-angle neutron scattering

A series of phase-separated polyethylene-polypropylene blends, which have undergone different thermal treatments, have been analysed by small-angle neutron scattering (SANS). The coherent scattering from normal hydrogenated blends is virtually zero, but strong contrast may be induced by partial or complete deuteration (labelling) of either phase. Here, the scattering from blends with complete labelling of the polyethylene phase was analysed to provide the domain dimensions by means of a theory due to Debye using an exponential correlation function. By this means the mean chord intercept lengths of both phases were shown to be in the range 1000–10000Å. The scattering from blends with partial labelling of the polyethylene was analysed to give the radius of gyration of the molecules in the polyethylene domains, which was found to be close to that measured in the homopolymer. For melt-quenched blends the deuterated polyethylene was shown to be statistically distributed in the polyethylene phase, whereas for slow-cooled blends, partial segregation of the labelled molecules occurred.     

Relation of chain constitution with phase structure in blends: compatibility of two phases in blends of polyamide with low‐density polyethylene and its ionomers

Pressed films of binary blends (polyamide with low‐density polyethylene or Surlyn) and ternary (polyamide with low‐density polyethylene and Surlyn or a graft‐copolymer of acrylic acid onto low‐density polyethylene) were examined by dynamic mechanical analysis, thermally stimulated current, and small‐angle X‐ray scattering. The variation of the glass transition temperature for two phases in the blends was studied by dynamic mechanical analysis and thermally stimulated current. X‐ray scattering from the relation of the phases was analyzed using Porod's law and led to values of the interface layer in the blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 488–494, 2000     

Blends of polypropylene with poly(cis‐butadiene) rubber. II. Small‐angle X‐ray scattering studies of the phase structure of immiscible blends of polypropylene with poly(cis‐butadiene) rubber

Pressed films of the blends of polypropylene (PP) with poly(cis‐butadiene) rubber (PcBR) were studied by IR spectra, small‐angle X‐ray scattering, and scanning electron microscopy. The problem of the interaction between different macromolecules in the blends of PP/PcBR is discussed by melt‐mixing at a temperature of 210°C using IR. X‐ray scattering from the relation of the phase was analyzed using Porod's law, and the interface layer thickness was calculated. The immiscibility of the blends of PP/PcBR was proved. The structure parameters, the correlation distance a_c, average chord lengths l?, and radius of gyration R?_g were obtained by the Debye–Buech statistical theory of scattering. Porod's index was calculated and the shape of the dispersed phase is discussed in relation to Porod's index in the blends. The morphology and structure of the blends were investigated by scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2088–2094, 2002     

Crystalline structure and phase structure of mLLDPE/LDPE blends

The crystalline structure and phase structure of metallocene linear low density polyethylene (mLLDPE) and low density polyethylene (LDPE) blends were investigated, using a combination of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS) techniques. The samples displayed cocrystallization phenomenon for LDPE of 80 wt% in the blends, indicating good compatibility between the two components under this circumstance; as LDPE content decreased, phase separation arose whereas partial cocrystallization still existed in the blends. Over the whole range of weight fractions, the intrinsic crystal structure of mLLDPE does not change with the addition of LDPE, while enhanced orthorhombic crystalline phase were observed as LDPE content increased. The changes in the thickness of interface layer σ_b, dispersed phase size a_c and integral invariant Q further indicate the existence of partial compatibility between the two phases. Irrespective of the phase inversion, the morphology of the dispersed phase is deduced to be in a transitional state from rod-like shape to flakes within the whole proportional range investigated.     

The study of polystyrene blends: The relationship of phases and structure in blends of polystyrene with ethylene–propylene diene monomer rubber and its grafted copolymer

Pressed films of blends of polystyrene (PS) with ethylene–propylene diene monomer rubber (EPDM) or grafted copolymer of styrene (St) onto EPDM (EPDM-g-St) rubber were examined by small-angle X-ray scattering (SAXS), and scanning electron microscope (SEM). Small-angle X-ray scattering from the relation of phase was analyzed using Porod's Law and led to value of interface layer on blends. The thickness of interface layer (σ_b) had a maximum value at 50/50 (PS–EPDM-g-St) on blends. The radius of gyration of dispersed phase (domain) and correlation distances a_c in blends of PS–EPDM-g-St were calculated using the data of SAXS. The morphology and structure of blends were investigated by SEM. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 805–810, 1998     

Miscibility and crystallization of biodegradable poly(butylene succinate-co-butylene adipate)/poly(vinyl phenol) blends

Miscibility, crystallization kinetics, crystal structure, and microstructure of biodegradable poly(butylene succinate-co-butylene adipate) (PBSA)/poly(vinyl phenol) (PVPh) blends were studied by differential scanning calorimetry, optical microscopy, wide angle X-ray diffraction, and small angle X-ray scattering in detail in this work. PBSA and PVPh are miscible as evidenced by the single composition dependent glass transition temperature and the negative polymer-polymer interaction parameter. Isothermal crystallization kinetics of PBSA/PVPh blends was investigated and analyzed by the Avrami equation. The overall crystallization rates of PBSA decrease with increasing crystallization temperature and the PVPh content in the PBSA/PVPh blends; however, the crystallization mechanism of PBSA does not change in the blends. Furthermore, blending with PVPh does not modify the crystal structure of PBSA. The microstructural parameters, including the long period, thickness of crystalline phase and thickness of amorphous phase, all become larger with increasing the PVPh content, indicating that PVPh mainly resides in the interlamellar region of PBSA spherulites in the blends.     

Structure and thermodynamics in polymer blends. Neutron scattering measurements on blends of poly(methyl methacrylate) and poly(styrene-co-acrylonitrile)

Neutron scattering on polymer blends of deutero-poly(methyl methacrylate) (D-PMMA) and poly(styrene-co-acrylonitrile) with 19 wt% acrylonitrile (PSAN-19) exhibits excess scattering for scattering vectors Q0.2 nm⁻¹ if the volume fraction of D-PMMA is less than 0.5 and greater than 0.05. The range of occurrence and the amount of excess scattering depends to a certain degree on the procedure of sample preparation. If the excess scattering is eliminated by linear extrapolation from large to small Q in the Zimm representation, the residual scattering intensity in the small and intermediate Q-range can be interpreted by the mean field approach of de Gennes with a concentration-dependent effective interaction parameter. The scattering intensity in the intermediate Q-range can be described with the coil scattering function of Debye using effective radii of gyration and interaction parameters obtained from Q → 0 extrapolated scattering data. In the intermediate Q-range the scattering curves of D-PMMA in the bulk and in the investigated blends show small differences outside the limits of experimental error. These differences are interpreted as an environmental influence of the conformation of the PMMA chain.     

Comparison of the phase behaviour of the liquid-crystalline polymer/poly(methyl methacrylate) and poly(vinyl acetate)/poly(methyl methacrylate) blends

The phase behaviour of blends of a liquid-crystalline polymer (LCP) and poly(methyl methacrylate) (PMMA), as well as the phase state of blends of PMMA and poly(vinyl acetate) (PVA) has been investigated using light scattering and phase-contrast optical microscopy. The blends of LCP and PMMA have been obtained by coagulation from ternary solutions. The cloud point curves were determined. It was established that both pairs demix upon heating, ie have an LCST. In the region of intermediate composition, the phase separation proceeds according to a spinodal mechanism; however for LCP/PMMA blends, the decomposition proceeds according to a non-linear regime from the very onset. In the region of small amounts of LCP, the phase separation follows a mechanism of nucleation and growth. For PMMA/PVA blends, the spinodal decomposition proceeds according to a linear regime, in spite of the molecular mobility that PVA chains develop at lower temperatures. Only after prolonged heat treatment does the process transit to a non-linear regime. The data show a similarity between the phase behaviour of blends of liquid-crystalline and of flexible amorphous polymers. The distinction consists of the absence of a linear regime of decomposition for LCP-PMMA blends. © 1999 Society of Chemical Industry