Improvements of properties of asphalt by poly(methyl methacrylate) additives

This article presents the effect of adding poly(methyl methacrylate) (PMMA) with different molecular weights on the mechanical properties of asphalt in terms of durability, strength, and resistance to rutting. By controlling the time of reaction we obtained PMMA of two different molecular weights: PMMA1 and PMMA2. The ageing properties of polymer modified asphalts were studied using the thin film over (oven) a test. A hot storage stability test was carried out for polymer modified binder. The physical properties of asphalt modified with PMMA including penetration value and softening point were examined at two different temperatures. Resilient modulus test was evaluated by a Universal Testing Machine. Results showed that an incorporation of PMMA into asphalt binder has significantly improved its properties under studies. Indirect tensile strength test and durability performance of the modified asphalts was evaluated as well. The resulted modification was found to be dependent on the polymer molecular weight. The PMMA1 exhibited effective and cheerful results.     

Influence of ZnSt2 on structure of acrylate-based ionomers with different lanthanide (La(III)) ion and acid contents

A series of acrylate processing aid（ACR）-based ionomers with different lanthanide（La（Ⅲ）） ion and acid contents were synthesized,and the interaction between ionomer and zinc stearate（ZnSt₂） was investigated immediately after thermally annealing the ionomer/ZnSt₂（3/1 in weight） mixtures at 180℃.The results revealed that the ion groups in ionomer have a strong interaction with ZnSt₂.The annealed mixtures contained hot alcohol extractable and unextractable ZnSt₂.The melting of ZnSt₂ and the thermal behavior of the ionomer in the annealed mixtures were seriously influenced by the contents of La（Ⅲ） and acid in the ionomers.The ionomer containing 0.25 mmol/g acid and 0.37 mmol/g La（Ⅲ） has a detectable cluster phase.Annealing its ZnSt₂ mixture could break down the cluster phase and lower glass transition temperature of the ionomer matrix.However,washing away the extractable ZnSt₂ led to the reappearance of the cluster transition temperature and return of the glass transition temperature of matrix to the original position.     

Mechanical and thermal properties of nanosized titanium dioxide filled rigid poly(vinyl chloride)

Nano-sized rod-like titanium dioxide (TiO2) filled rigid poly(vinyl chloride) (PVC) nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr (parts per hundreds of resin) could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness.     

部分水解聚甲基丙烯酸甲酯/氢氧化钙复合物对硬质聚氯乙烯热稳定性与透明性及塑化行为的影响

采用溶液沉淀法制备了部分水解的聚甲基丙烯酸甲酯(h-PMMA)/氢氧化钙(Ca(OH)2)复合物.采用X-射线衍射(XRD)、红外光谱(FTIR)、等离子体发射光谱和差示扫描量热表征了h-PMMA/Ca(OH)2复合物的组成与结构;采用刚果红测试、动态热稳定测试和热失重分析(TGA)研究了复合物对聚氯乙烯(PVC)的热稳定效果;通过紫外-可见(UV-Vis)光谱、扫描电镜(SEM)照片和熔融塑化曲线研究了复合物对PVC透明性和塑化行为的影响.结果表明,在Ca(OH)2晶体生长过程中,h-PMMA通过—COO-/Ca2+离子配位作用吸附于Ca(OH)2表面,不仅限制了Ca(OH)2粒子尺寸,且有助于Ca(OH)2在PVC中均匀分散.所得h-PMMA/Ca(OH)2复合物在显著提高PVC热稳定性和塑化能力的同时,还使PVC保持透明性.     

Thermal degradation of poly(vinyl bromide), vinyl bromide-methyl methacrylate copolymers,and poly(vinyl bromide)-poly(methyl methacrylate) blends

Degradation behavior has been compared for PVB, five VB-MMA copolymers which span the composition range, PMMA, and PVC by using thermogravimetry in dynamic nitrogen and thermal volatilization analysis (TVA) under vacuum for programmed heating at 10°C/min. Volatile products have been separated by subambient TVA and identified. PVB is substantially less stable than PVC but shows inmost respects analogous degradation behavior. The introduction of VB into the PMMA chain leads to intramolecular lactonization with release of methyl bromide at temperatures a little above 100°C; after this reaction is complete, however, the polymer is more stable toward volatilization than PMMA. Copolymers with moderate and high VB contents also lose hydrogen bromide. Carbon dioxide is a significant product at intermediate compositions. The variation of product distribution with copolymer composition is discussed in relation to the several reactions involved and comparisons are made with VC-MMA copolymers. PVB-PMMA blends snow some features of degradation behavior in common with the PVC-PMMA system but also very important differences. The effect of PVB is only to stabilize the PMMA; the mechanism is discussed. The role of PVB as an additive and VB as a comonomer for fire-retardant PMMA compositions is briefly considered in relation to earlier studies.     

Thermal degradation studies in poly(vinyl chloride)/poly(methyl methacrylate) blends

The miscibility, morphology, and thermal properties of poly(vinyl chloride) (PVC) blends with different concentrations of poly(methyl methacylate) (PMMA) have been studied. The interaction between the phases was studied by FTIR and by measuring the glass transition temperature (T_g) of the blends using differential scanning calorimetry. Distribution of the phases at different compositions was studied through scanning electron microscopy. The FTIR and SEM results show little interaction and gross phase separation. The thermogravimetric studies on these blends were carried out under inert atmosphere from ambient to 800 °C at different heating rates varying from 2.5 to 20 °C/min. The thermal decomposition temperatures of the first and second stage of degradation in PVC in the presence of PMMA were higher than the pure. The stabilization effect on PVC was found most significant with 10 wt% PMMA content in the PVC matrix. These results agree with the isothermal degradation studies using dehydrochlorination and UV-vis spectroscopic results carried out on these blends. Using multiple heating rate kinetics the activation energies of the degradation process in PVC and its blends have been reported.     

Proton conducting membranes based on poly(vinyl chloride) graft copolymer electrolytes

The direct preparation of proton conducting poly(vinyl chloride) (PVC) graft copolymer electrolyte membranes using atom transfer radical polymerization (ATRP) is demonstrated. Here, direct initiation of the secondary chlorines of PVC facilitates grafting of a sulfonated monomer. A series of proton conducting graft copolymer electrolyte membranes, i.e. poly(vinyl chloride)‐g‐poly(styrene sulfonic acid) (PVC‐g‐PSSA) were prepared by ATRP using direct initiation of the secondary chlorines of PVC. The successful syntheses of graft copolymers were confirmed by ¹H‐NMR and FT‐IR spectroscopy. The images of transmission electron microscopy (TEM) presented the well‐defined microphase‐separated structure of the graft copolymer electrolyte membranes. All the properties of ion exchange capacity (IEC), water uptake, and proton conductivity for the membranes continuously increased with increasing PSSA contents. The characterization of the membranes by thermal gravimetric analysis (TGA) also demonstrated their high thermal stability up to 200°C. The membranes were further crosslinked using UV irradiation after converting chlorine atoms to azide groups, as revealed by FT‐IR spectroscopy. After crosslinking, water uptake significantly decreased from 207% to 84% and the tensile strength increased from 45.2 to 71.5 MPa with a marginal change of proton conductivity from 0.093 to 0.083 S cm^?1, which indicates that the crosslinked PVC‐g‐PSSA membranes are promising candidates for proton conducting materials for fuel cell applications. Copyright © 2008 John Wiley & Sons, Ltd.     

Study on the interaction of lanthanum(III) with adrenaline

Lanthanum(III) equilibria in the presence of adrenaline have been investigated by potentiometric titration under physiological conditions (37°C and an ionic strength of 0.15?M NaCl). The interaction of lanthanum(III) with adrenaline has also been studied using an ab initio method. The complex species in the lanthanum(III)–adrenaline system have been ascertained and the protonation constants for adrenaline and the stability constants for lanthanum(III) complexes with adrenaline have been obtained. Adrenaline can form stable lanthanum(III) complexes with the phenolic hydroxyl group of adrenaline as the binding site of lanthanum(III).     

Studies on Poly(Methyl Methacrylate) (PMMA) and Thermoplastic Polyurethane (TPU) Blends

Blends of poly(methyl methacrylate) (PMMA) and thermoplastic polyurethane (TPU) in different compositions viz., 95/5, 90/10, 85/15 and 80/20 (by wt/wt, % of PMMA/TPU) were blended by melt mixing using a twin‐screw extruder. All the PMMA/TPU blends have been characterized for physico‐mechanical properties such as density, melt flow index, tensile behavior and izod impact strength. The impact strength of the PMMA/TPU blends were found to increase significantly with an increase in the percentage of TPU up to 20%, by retaining the tensile strength of PMMA. The effect of chemical aging on the performance of blends has been studied.     

Nitron tetrachloroaurate(III) electrodes with poly(vinyl chloride) and liquid membranes for the selective determination of gold

PVC matrix and liquid membrane electrodes have been developed for direct potentiometric determination of gold(III). The membranes incorporate nitron tetrachloroaurate(III) as electroactive material. Fast response for gold(III) over the concentration range 10(-5)-0.1M, with response slopes of 52.8-55.2 mV/decade is obtained. The electrodes show good selectivity for gold(III) at pH 2-5 in the presence of many anions and cations. The PVC membrane electrode offers the advantages of greater selectivity (except for Cr(3+), Mn(2+) and ClO(-)(4)) and higher thermal stability. The liquid membrane electrode gives a higher response slope and faster time of response than the PVC membrane electrode. Determination of AuCl(-)(4) over the range 2 mug/ml-2 mg/ml shows an average recovery of 98.5% and a mean standard deviation of 1.0%. Determination of gold in some gold alloys (58.3-99.9% Au) and pharmaceutical preparations gave an average recovery of 99.4% and a mean standard deviation of 0.7%, which are comparable with the performance obtained with the spectrophotometric Malachite Green and gravimetric U.S. Pharmacopeia methods.     

Synthesis,characterization of layered double hydroxide‐poly(methylmethacrylate) graft copolymers via activators regenerated by electron transfer for atom transfer radical polymerization and its effect on the performance of poly(lactic acid)

Layered double hydroxide‐poly(methylmethacrylate) (LDH‐PMMA) graft copolymers were prepared via activators regenerated by electron transfer for atom transfer radical polymerization. The results showed that the hydrophobicity of LDH‐PMMA was improved by the incorporation of hydrophilic groups. Moreover, poly(lactic acid) (PLA)/LDH‐PMMA nanocomposites were prepared by melt blending to enhance the performances of PLA. The crystallization and mechanical properties of the PLA/LDH‐PMMA nanocomposites were studied by differential scanning calorimetry, tensile testing, and polarized optical microscopy, respectively. Results of mechanical testing showed that the tensile strength, elongation at break, and impact strength of PLA/LDH‐PMMA nanocomposites were increased by 5.64%, 37.95%, and 49.70%, respectively, compared with PLA. The differential scanning calorimetry results indicated that LDH‐PMMA eliminated the cold crystallization of PLA matrix and improved the crystallinity of PLA by 37.26%. The polarized optical microscopy of PLA/LDH‐PMMA nanocomposites demonstrated that LDH‐PMMA increased the crystallization rate of PLA. It was also found that the rheological behaviors of the PLA nanocomposites were significantly enhanced. Based on these results, a new choice for modified LDHs was provided and used as a nucleating agent to improve the properties of PLA.     

The influence of core-shell structured modifiers on the toughness of poly (vinyl chloride)

The core-shell structured grafted copolymer particles of polybutadiene grafted polymethyl methacrylate (PB-g-PMMA, MB) were prepared by emulsion polymerization. The MB particles were used to modify poly (vinyl chloride) (PVC) by melt blending. The mechanical properties of the PVC blends were investigated. The micro-morphology of the PVC blends was observed by scanning electron microscopy (SEM). The results indicated that the samples with the best impact strength could be obtained when the core-shell weight ratio of PB to PMMA is lower than 93:7, the mechanical properties correlated well with SEM morphologies, the addition of modifier with the ratio core to shell of 93:7 could reduce the domain size of the dispersed phase. Furthermore, the compatibility and properties of the blends were greatly enhanced and improved. The modifier particles could be well dispersed in the PVC matrix.     

二—(2,2''''—联吡啶)—三—(硝酸)合镧(Ⅲ)La(C_(10)H_8N_2)_2(NO_3)_3的电子结构和化学键

引 言 希土化合物由于涉及f轨道,用分子轨道方法有一定困难,前人曾采用过多种处理方法。文献[8]报导了希土-2,2’-联吡啶配位方法和性质研究。文献[8],[9]对镧与2,2—联吡啶,硝酸配合物的合成,性质和结构亦作过研究。本文采用适用于镧系元素化合物电子结构计算的自旋非限制的INDO方法来研究La(C_(10)H_8N_2)_2(NO_3)_3的电子结构和化学键。     

Investigation of polymer miscibility by spectroscopic methods. III. Labeling of poly(vinyl chloride), poly(methyl methacrylate) and poly(styrene-co-acrylonitrile) with fluorescent chromophores for nonradiative energy transfer studies

Poly(vinyl chloride) (PVC) is generally recognized as miscible with s.poly(methyl methacrylate) (s.PMMA), poly(?-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) copolymer (SAN) containing 27 wt % AN. Nonradiative energy transfer (NRET) is a very sensitive technique in the investigation of the polymer miscibility. To compare by NRET the actual degree of miscibility of the PVC/s.PMMA, PVC/PCL, and PVC/SAN polymer pairs, each polymer is to be labeled with a fluorescent chromophore to an extent of 1 or 2 mol %. This paper reports efficient pathways to attach anthracene (acceptor) or naphthalene (donor) onto preformed PVC, s.PMMA, and SAN samples. All the attempts for grafting carbazole (donor) moieties have failed, as well as any labeling of PCL whatever the nature of the chromophore.     

Thermal stability, smoke emission and mechanical properties of poly(vinyl chloride)/hydrotalcite nanocomposites

Poly(vinyl chloride)/hydrotalcite (PVC/HT) nanocomposites were prepared through vinyl chloride suspension polymerization in the presence of HT nanoparticles surface modified with alkyl phosphate (AP). The thermal stability, smoke emission and mechanical properties of PVC/HT nanocomposites were investigated. It was found that AP molecules were effectively absorbed by HT particles with no intercalation into the interlayer of HT. The dispersion morphologies of PVC/HT nanocomposites were observed by transmission electron microscopy showing that the majority of HT particles were dispersed in the PVC matrix in the nanoscale. The Congo Red measurement and thermogravimetric analysis showed that the thermal stability time, and the temperatures at 10% weight loss and at the maximum weight loss rate of PVC resins increased as the weight fraction of HT in the composite resins increased. The well-dispersed nano-sized HT showed an obvious smoke suppression effect on PVC. The maximum smoke density decreased about 1/3 and 1/2 when 2.5 wt% and 5.3 wt% nano-sized HT were incorporated into PVC, respectively. Furthermore, PVC/HT nanocomposites exhibited greater tensile strength and impact strength than the pristine PVC.     

Modification of poly(vinyl chloride). X. Crosslinking of poly(vinyl chloride) with a soft segment of an elastomer containing thiol groups

To obtain poly(vinyl chloride) (PVC) of excellent toughness, a new method of crosslinking PVC is proposed in which PVC is crosslinked with the soft segment in an elastomer such as liquid Thiokol. The reaction can be accomplished by immersing PVC–Thiokol blends in liquid ammonia at 20–30°C. A similar reaction occurs in aqueous ammonia when hexamethylphosphoramide is used as an activator. Characteristics of the crosslinked PVC thus obtained and of the controls of a similar uncrosslinked composition (PVC–Thiokol LP-8, 100:5 by weight) were as follows: tensile strength, 7.3 and 4.8 kg/mm²; elongation at break, 30 and 2.5%; Young's modulus, 3.5 × 10⁴ and 2.9 × 10⁴ kg/cm²; tensile impact, 88 and 15 kg-cm/cm³, respectively. The crosslinked PVC as plasticized with dioctyl phthalate (DOP) and the control blend (PVC–Thiokol LP-8–DOP, 100:10:10 by weight), respectively, showed tensile strengths of 5.9 and 4.8 kg/mm², elongations at break of 44 and 24%, Young's moduli of 2.5 × 10⁴ and 1.6 × 10⁴ kg/cm², and tensile impact strengths of 62 and 120 kg-cm/cm³. As the crosslinkage through the soft segments increases up to about 5%, the elongation at break, Young's modulus, and tensile impact, in addition to the tensile strength, are improved. This is different from the results so far observed with the crosslinked amorphous polymers and is characteristic of the products of crosslinking through the soft segment. The experimental results are discussed in this paper.     

MMA接枝改性PVC/CaCO3纳米复合材料的力学性能

采用熔融共混法制备PMMA接枝改性纳米CaCO3增韧PVC（PVC/CaCO3）复合材料,并研究了复合材料的力学性能.结果表明,通过表面PMMA的接枝改性,可以显著提高纳米CaCO3增韧聚氯乙烯复合材料的拉伸强度和拉伸模量,在纳米CaCO3颗粒表面PMMA包覆层厚度为2nm时,复合材料的拉伸强度和拉伸模量达到极大值.对比于未处理纳米CaCO3和钛酸酯偶联剂处理纳米CaCO3,PMMA接枝改性纳米CaCO3增韧PVC复合材料的拉伸强度得到较大幅度提高.SEM显示,经过PMMA接枝改性后的碳酸钙在PVC基体中分散均匀,与基体界面结合良好.     

Graft polymers from poly(vinyl chloride) and chlorinated rubber

Graft polymers from poly(vinyl chloride) (PVC) and chlorinated rubber (CIR) with side chains of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), or poly(ethyl methacrylate) (PEMA) were synthesized. For this purpose, a vinyl monomer was polymerized in the presence of small quantities of PVC or CIR with benzoyl peroxide as catalyst. The graft polymers were separated from both homopolymers by precipitation with methanol from methyl ethyl ketone solutions of the reaction products and the grafting efficiency was calculated. The graft polymers were characterized by infrared spectra, elemental analysis, NMR, and osmometric or light-scattering determinations. From the results it is concluded that the PVC or CIR molecules contain side chains of PMMA, PMA, or PEMA. The graft polymers showed higher molecular weights, and the values of second virial coefficient for these polymers were much different from those of the starting polymers.     

Separation of gadolinium(III) and lanthanum(III) by nanofiltration-complexation in aqueous medium

A new method is proposed for the separation of gadolinium(III) and lanthanum(III) in aqueous medium by nanofiltration combined with a complexation step. First DTPA was chosen as ligand for a selective Gd(III)/La(III) complexation. Having investigated the influence of three factors (pH, temperature and amount of ligand) for the selective complexation of DTPA towards Gd(III) and La(III), the system is then combined with a nanofiltration separation process to remove 92% of initial Gd(III) and only 12% of initial La.     

Investigation of polymer miscibility by spectroscopic methods V. Effect of molecular weight and block copolymerization of syndiotactic poly(methyl methacrylate) on its miscibility with poly(vinyl chloride)

Investigated by nonradiative energy transfer (NRET), the state of mixing of PVC and s.PMMA which is on the dimensional scale of a few nanometers is significantly affected by the chain length. When PVC is blended with s.PMMA of increasing molecular weight (MW), the longest chains of s.PMMA are likely to segregate from a homogeneous blend formed by PVC and low-MW s.PMMA. The phase separation should therefore be of purely entropic origin and strongly dependent on both the relative percentage and the chain length of each component. These results are in qualitative agreement with conclusions previously drawn from DSC and transmission electron microscopy. NRET is a more powerful tool in probing heterogeneities compared to DSC and the thermally stimulated depolarization current method; it provides evidence against the previously suggested model of a 1:1 PVC/s.PMMA aggregate.