蒙脱土填充环氧化天然橡胶/PVC热塑性弹性体的制备与性能研究

采用熔融插层法制备蒙脱土(MMT)/聚氯乙烯(PVC)插层产物,再将该产物与环氧化天然橡胶(ENR)在密炼机中进行动态硫化制备ENR/PVC/MMT共混型热塑性弹性体(TPE),研究了蒙脱土的填充量对共混物力学性能、热稳定性以及动态机械性能的影响。实验结果表明:随着蒙脱土填充量的增加,ENR/PVC/MMT共混型热塑性弹性体的拉伸强度、撕裂强度和邵氏硬度增大,断裂伸长率略有下降;蒙脱土会促进TPV中PVC的降解,使得复合材料的热稳定性降低,动态热机械分析测得的复合材料的tanδ曲线峰峰强降低,峰宽变宽。     

不同改性蒙脱土对ENR/PVC共混型TPV填充效果的研究

采用熔融插层法制备了聚氯乙烯/蒙脱土(PVC/MMT)插层产物,再将该产物与环氧化天然橡胶(ENR)在密炼机中进行熔融共混制备ENR/PVC/MMT共混型热塑性弹性体(TPV),研究了不同改性MMT对共混物力学性能、热稳定性以及动态力学性能的影响。结果表明:二甲基双十八烷基铵改性蒙脱土(MMT-2C18)能显著提高ENR/PVC共混型TPV的拉伸强度,无机MMT能显著提高ENR/PVC的断裂伸长率,十八烷基铵改性蒙脱土(MMT-C18)会降低TPV的拉伸强度和断裂伸长率;有机改性MMT会促进TPV中PVC的降解,使得复合材料的热稳定性降低;动态热力学分析显示,MMT可使复合材料的储能模量增加,其中有机改性MMT使材料的损耗因数(tanδ)曲线峰强降低,峰宽变宽。     

聚氯乙烯/蒙脱土纳米复合材料的研究

采用熔融插层法制备了聚氯乙烯(PVC) /蒙脱土(MMT)纳米复合材料并进行了表征,研究了PVC/MMT纳米复合材料的力学性能。结果表明:PVC进入到有机MMT的片层间形成了纳米复合材料,但PVC不能进入钠基MMT的片层间,形成纳米复合材料;蒙脱土的加入提高了PVC的力学性能,而且PVC/有机MMT纳米复合材料的拉伸和冲击强度总是优于PVC/钠基MMT复合材料;对PVC/有机MMT纳米复合材料而言,复合材料的V型缺口冲击比U型缺口冲击敏感,其力学性能随热处理时间延长而降低,但PVC/有机MMT复合材料比PVC/钠基MMT的抗热性好。     

PVC-U/蒙脱土复合材料的制备与力学性能研究

采用聚氧乙烯-聚氧丙烯(EP)嵌段共聚物对钠基蒙脱土进行有机化处理改性,XRD测试结果表明嵌段共聚物插层进入了蒙脱土层间.用熔融共混法制备了聚氯乙烯/蒙脱土复合材料,并研究了钠基蒙脱土和EP改性的有机蒙脱土对复合材料力学性能的影响.研究结果表明,采用EP对MMT进行改性能够提高MMT与PVC之间的相容性,PVC-U/MMT-EP复合材料的力学性能得到明显提高,EP对MMT改性是制备有机改性蒙脱土的有效方法之一.     

蒙脱土改善PVC／PS共混物相容性的研究

利用扫描电子显微镜、广角X射线衍射仪和示差扫描量热分析仪对蒙脱土(MMT)改善PVC/PS共混体系相容性研究发现,PVC/PS为不相容的共混体系,但通过物理和化学两种方法将MMT引入PVC/PS共混体系后,分散相PS在PVC连续相中的分布变均匀,两相的相容性有了明显的改善;MMT加入PVC/PS共混体系后,两种聚合物的玻璃化转变温度之间的差值由22℃左右最低减小到7℃,说明MMT能明显改善PVC/PS共混物的相容性,但对力学性能的改善并不是十分明显。     

甲苯-2,4-二异氰酸酯改性蒙脱土制备方法及结构表征的研究

研究了甲苯-2,4-二异氰酸酯(TDI)分子结构中的异氰酸酯基团(─NCO)与蒙脱土(MMT)表面羟基的修饰反应,以反应程度P(TDI)为指标,考察了反应时间、反应温度、TDI的用量以及蒙脱土活化条件对改性反应程度的影响。结果表明,TDI改性蒙脱土的最佳条件为:反应时间80 min,反应温度80℃,MMT与TDI质量比为1∶0.3,蒙脱土活化条件为250℃、反应2 h,反应程度可达到34.28%。IR,XRD测试改性物TDI/MMT,结果表明,TDI与蒙脱土片层表面的羟基发生反应,引入了─NCO基团,改性后的蒙脱土的层间距较原土有所增大,从而实现了蒙脱土的有机化改性。     

PEN／MMT纳米复合材料结晶动力学的研究

采用熔融插层法制备聚2,6-萘二甲酸乙二酯(PEN)/蒙脱土(MMT) 纳米复合材料,用Avrami方程和张志英方法对所得数据进行了等温结晶和非等温结晶动力学的研究.结果表明,在PEN/MMT共混物中由于MMT的加入,降低了PEN/MMT的结晶活化能,导致共混物的结晶速率提高;MMT含量影响共混物的结晶速度,加入少量的MMT可以明显提高共混物的结晶速率;共混物的表面活化能的变化与Avrami方程得出的n值变化相似,MMT的含量影响共混物成核结晶速度.     

改性矿物填料增强橡胶/聚氯乙烯共混体系

研究了橡胶、增塑剂、矿物填料和表面处理剂对橡胶／聚氯乙烯(PVC)共混物力学性能的影响,用扫描电镜分析了有机胺类表面处理剂改性高岭土／丁腈橡胶(NBR)／PVC的界面结合状况。结果表明,当NBR用量为30份,邻苯二甲酸二辛酯用量为60份,有机胺类表面处理剂质量分数为3％,填充60份的超细碳酸钙或高岭土或牌号为SMF的蒙脱土时,可得到力学性能较佳的NBR／PVC共混物;不同矿物填料对NBR／PVC共混物的增强作用不同,经有机胺类表面处理剂改性后,以超细碳酸钙、高岭土和蒙脱土SMF的增强效果最为明显。     

聚苯乙烯-丙烯酸酯/蒙脱土纳米复合材料的制备和热性能研究

采用原位乳液聚合法和乳液共混法分别制备聚苯乙烯-丙烯酸酯/蒙脱土(PSB/MMT)复合材料,研究不同类型的蒙脱土对插层结构类型的影响,用X射线衍射(XRD)对其插层结构进行表征,不同方法制备出的复合胶膜具有不同的插层结构,利用TG-DSC分析法分析其热降解性能。结果表明,添加了蒙脱土的PSB/MMT的复合体系热稳定性提高,其中插层型的要优于剥离型。     

ABS/MMT纳米复合材料的制备及性能的研究

文章采用丙烯腈-丁二烯-苯乙烯(ABS)/氨基蒙脱土(MMT)进行熔融共混得到不同含量MMT的ABS/MMT纳米复合材料。用扫描电子显微镜、拉伸试验机、冲击试验机研究ABS/MMT的力学性能及断面结构。结果得出:在ABS/MMT纳米复合材料中,随着MMT含量的增加,ABS/MMT复合材料的拉伸强度呈先上升后下降,且当MMT含量在3份时性能较好,缺口冲击强度呈线性下降趋势。ABS/MMT冲击断面中,出现了许多网孔结构,橡胶粒子被蒙脱土的的片层包裹着,不能发生塑性变形,其为ABS/MMT复合材料缺口冲击强度降低的主要原因之一。     

Synthesis of PBA/PMSAN core-shell graft copolymer and its application as a processing aid for PVC

The core—shell graft copolymer of α-methyl styrene with acrylonitrile on poly(butyl acrylate) was synthesized. The graft polymerization was investigated as a function of reaction temperature, initiator concentration used in the secondary polymerization, monomer to polymer ratio and emulsifier concentration. The compatibility of this core—shell graft copolymer with poly(vinyl chloride) (PVC) was determined by the solubility parameter method and scanning electron microscopy. The mechanical and rheological behaviour of the blend show that this core—shell graft copolymer can be used as a processing aid for PVC.     

Preparation and properties of poly(vinyl alcohol)-clay nanocomposite materials

A series of polymer-clay nanocomposite (PCN) materials that consist of poly(vinyl alcohol) (PVA) and layered montmorillonite (MMT) clay are prepared by effectively dispersing the inorganic nanolayers of MMT clay in organic PVA matrix via an in situ free radical polymerization with AIBN as initiator. Organic vinyl acetate monomers are first intercalated into the interlayer regions of organophilic clay hosts and followed by a one-step free radical polymerization. The prepared poly(vinyl acetate)-clay (PVAc-clay) solution are then saponified via direct-hydrolysis with NaOH solution to form PVA-clay nanocomposite materials. The as-synthesized PCN materials are typically characterized by Fourier-Transformation infrared (FTIR) spectroscopy, wide-angle X-ray diffraction and transmission electron microscopy.The molecular weights of poly(vinyl alcohol) (PVA) extracted from polymer-clay nanocomposite (PCN) materials and bulk PVA are determined by gel permeation chromatography (GPC) analysis with THF as eluant. The viscosity property of PCN materials with different feeding amount of MMT clay is studied by an ubbelohode capillary viscometer. The morphological image of as-synthesized materials is studied by scanning electron microscopy (SEM) and optical polarizing microscope (OPM). Effects of the material composition on the thermal stability, mechanical strength, optical clarity of PVA along with a series of PCN materials, in the form of fine powder and free-standing film, are also studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analyzer (DMA) and UV-visible transmission spectra, respectively.     

Poly(methyl methacrylate)/clay nanocomposites by photoinitiated free radical polymerization using intercalated monomer

A series of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposite were prepared by successfully dispersing the inorganic nanolayers of MMT clay in an organic PMMA matrix via in situ photoinitiated free radical polymerization. Methyl methacrylate monomer was first intercalated into the interlayer regions of organophilic clay hosts by “click” chemistry followed by a typical photoinitiated free radical polymerization. The intercalated monomer was characterized by FT-IR spectroscopy, elemental analysis and thermogravimetric analysis methods. The intercalation ability of the modified monomer and exfoliated nanocomposite structure were confirmed by X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Thermal stability of PMMA/MMT nanocomposites was also studied by both differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

The modification of lanthanum‐exchanged montmorillonite with anionic surfactants to enhance the thermal stability of polyvinyl chloride

A series of thermally stable lanthanum organic montmorillonites (La‐OMMTs) were successfully prepared by modifying Na‐MMT with anionic surfactants and lanthanum chloride. Fourier transform infrared spectroscopy and X‐ray diffraction indicated that the anionic surfactants resided in the interlayer spaces and expanded the MMT basal spacing from 1.23 nm to 3.3 nm. Thermogravimetric and differential thermal analysis (TG/DTA) results showed that the intercalation of sodium dodecyl sulfonate into the lanthanum organic MMT resulted in its excellent thermal stability. The use of the La‐OMMT samples in polyvinyl chloride (PVC) resins was tested, and the TG/DTG results revealed that the three La‐OMMTs could significantly enhance the thermal stability of PVC. The modified La‐OMMT with the highest thermal stability is expected to be useful in polymer/layered silicate nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41535.     

Preparation and characterization of poly(butyl acrylate‐co‐2‐ethylhexyl acrylate) grafting of vinyl chloride resin with good impact resistance

Crosslinked poly(butyl acrylate‐co‐2‐ethylhexyl acrylate) [P(BA–EHA)] latex was synthesized by seeded emulsion polymerization. P(BA–EHA)/poly(vinyl chloride) (PVC) composite latex was prepared using P(BA–EHA) latex as the seed. The effects of the amount of P(BA–EHA) on the latex particle diameters and mechanical properties of the materials are discussed. The grafting efficiency (GE) of P(BA–EHA)‐grafted vinyl chloride (VC) in the synthesized resin was investigated, and the GE increased with an increasing P(BA–EHA)/VC ratio. The morphology of P(BA–EHA)/PVC was characterized using TEM, SEM, and DMA. TEM indicated that the particles of the P(BA–EHA)/PVC composite latex have a clear core–shell structure. DMA illustrated that the compatibility between P(BA–EHA) and PVC was well improved. With an increasing P(BA–EHA) content, the loss peak in the low‐temperature range became stronger than that of pure PVC, and the maximum values of the loss peaks gradually shifted to higher temperature. SEM showed that the fractured surface of the composite sample exhibited better toughness of the material. The notched impact strength of the material with 4.2 wt % P(BA–EHA) was 11 times that of PVC. TEM showed that P(BA–EHA) was uniformly dispersed in the PVC matrix and that the interface between the two phases was indistinct. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 643–649, 2003     

Core–shell particles designed for toughening poly(vinyl chloride)

A novel core–shell modifier (MOD) made up of polystyrene and poly(butyl acrylate) (PBA) grafted on a crosslinked styrene‐co‐butadiene core was synthesized by emulsion polymerization. This modifier was used for enhancing effectively the impact ductility of poly(vinyl chloride) (PVC) without losing its transparency. The effects of the MOD on the properties of PVC/MOD blends were explored. It was found that the butyl acrylate (BA) content of the MOD was an important factor affecting the properties of PVC/MOD blends. The Izod impact strength of these blends reached 1200 J m^?1 when the MOD contained 40 wt% BA. The dispersion morphology of the MOD in the PVC matrix was investigated using transmission electron microscopy, with a uniform dispersion of the MOD with higher BA content being obtained. The toughening mechanism of PVC/MOD blends was also investigated. The presence of BA in the MOD enhanced the ductility of the PVC blends due to the increased amount of soft phase (PBA). The dispersion morphology indicated that the interfacial interaction between MOD particles and PVC matrix was improved due to the presence of PBA graft chain in the MOD. TEM of impact fracture samples showed that shear yielding of the PVC matrix and debonding of MOD particles were the major toughening mechanisms for the PVC/MOD blends. Copyright © 2010 Society of Chemical Industry     

Structural effects of type of intercalant in poly (4‐vinylpyridine) nanocomposites: compatible homopolymer or block copolymer

4‐vinylpyridine monomer was mixed with organophilic montmorillonite (MMT) clay and polymerized in the presence of free‐radical initiator. MMT clay was rendered organophilic by means of ion‐exchanging sodium cations for low‐molecular‐weight quaternized poly(4‐vinylpyridine) (P4VP) homopolymer and diblock copolymers of styrene and quaternized 4‐vinylpyridine (SVP) with different sequence lengths. The swelling behaviour of the MMT clay was studied by X‐ray diffraction (XRD). After the cation exchange, the resulting organophilic clays showed an expansion of interlayer distance indicating the nanoscale ordering of intercalant polymer and MMT layers. The nanocomposite materials, when moulded, exhibited improved thermal stability and dynamic mechanical properties compared with neat P4VP. The composite, having longer ionic segments in its organophilic MMT, showed exfoliated nanocomposite structure as well as higher stiffness and damping properties at higher temperatures even for MMT loading as low as 2 wt%. Copyright © 2006 Society of Chemical Industry     

Morphology and properties of PVC/clay nanocomposites via in situ emulsion polymerization

PVC/Na⁺–montmorillonite (MMT) nanocomposites were prepared via a simple technique of emulsion polymerization at several different MMT clay concentrations. X‐ray diffraction and transmission electron microscopy studies revealed the formation of a mixture of intercalated and exfoliated nanostructure. Tensile testing results showed that the tensile modulus of the nanocomposites increased with the addition of clay, while the tensile strength decreased little. The notched impact strength of the nanocomposites was also improved. For systems containing clay in the range of 2.1 to 3.5 wt %, the impact strength was almost two times as large as that of pure PVC. However, those mechanical properties began to decrease with the continuously increasing amount of clay. The fracture surface of pure PVC and the nanocomposites was observed by scanning electron microscope. Thermal properties of the nanocomposites were found to increase as a result of clay incorporation. The glass transition temperatures of the PVC/clay nanocomposites were nearly identical to that of pure PVC. The Vicat softening points exhibited a progressively increasing trend with the clay content added. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 277–286, 2004     

Effects of the nature and combinations of solvents in the intercalation of clay with block copolymers on the properties of polymer nanocomposites

Polystyrene (PS) nanocomposites were prepared by the free‐radical polymerization of styrene in the presence of organically modified montmorillonite (MMT) clays. MMT clay was modified with a low‐molecular‐weight and quarternized block copolymer of styrene and 4‐vinylpyridine [poly(styrene‐b‐4‐vinylpyridine) (SVP)] with 36.4 wt % PS and 63.6 wt % poly(4‐vinylpyridine) (P4VP). Special attention was paid to the modification, which was carried out in different compositions of a solvent mixture of tetrahydrofuran (THF) and water. The swelling behavior of the MMT clay was studied by an X‐ray diffraction technique. The diffraction peak shifted to lower 2θ angles for all of the modified clays, which indicated the intercalation of the quarternized SVP copolymer into the MMT layers in different degrees. Higher interlayer distances, which showed a high degree of block copolymer insertion, were obtained for solvent compositions with THF in water. The resultant nanocomposites were characterized by X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, and dynamic mechanical analysis. The desired exfoliated nanocomposite structure was achieved when the MMT modification was conducted in 50 or 66 wt % THF, whereas the other modifications all resulted in intercalated structures. The resulting exfoliated nanocomposite was found to have better thermal stability and dynamic mechanical performance compared to the others, even with 2% clay loading. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Acrylonitrile-styrene-acrylate particles with different acrylonitrile contents for improving the toughness of poly(vinyl chloride) resin

Poly(butyl acrylate) grafted styrene and acrylonitrile copolymer (PBA-g-SAN, ASA) with core–shell structures were prepared by emulsion polymerization technology to improve the toughness of the poly(vinyl chloride) (PVC). The mechanical properties of the PVC/ASA blends were investigated. The notch impact strength of the PVC/ASA blend could reach 1200 J/m when the 13 phr ASA was added to the PVC. This was several times more than pure PVC resin. Scanning electron microscopy analysis results indicated that the improvement in impact strength of the PVC/ASA blend was attributed to shear yielding induced by ASA particles. Additionally, subtle changes in the ratio of monomers in the shell layer led to significant fluctuations in the mechanical properties of the composites. Dynamic mechanical analysis showed that the intermolecular interaction forces between ASA particles and PVC resins played a key role in improving the toughness of PVC/ASA blend.