Thermally stable antimicrobial polyvinylchloride/maleimido aromatic hydrazide composites

Antimicrobial novel substituted maleimido aromatic hydrazides were synthesized from N‐[4‐(chlorocarbonyl) phenyl] maleimide with salicylhydrazide, p‐aminobenzohydrazide, or p‐aminosalicylhydrazide. They were characterized by Fourier transform infrared (FTIR), hydrogen‐1 nuclear magnetic resonance (¹H‐NMR), mass spectra, elemental analyses, and antimicrobial activities. These derivatives were investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC) at 180°C in air by measuring the rate of dehydrochlorination, the extent of discoloration, and the changes that occurred in the molecular masses of the degraded PVC samples. The previously reported stabilizing efficiency data of a nonsubstituted derivative, which was synthesized from N‐[4‐(chlorocarbonyl) phenyl] maleimide with benzohydrazide, is also given for comparison. The results reveal the greater stabilizing efficiency of the investigated derivatives as shown by their longer thermal stability (Ts) periods and lower dehydrochlorination rates in relation to dibasic lead carbonate, cadmium‐barium‐zinc stearate, and n‐octyltin mercaptide industrial stabilizers. The stabilizing efficiency increases with the introduction of electron donating substituent groups in the aromatic ring of the stabilizer molecules. Moreover, the investigated stabilizers impart better color stability for the degraded samples as compared with the reference stabilizers. A synergistic effect is achieved when the materials under investigation were mixed in various weight ratios with any of the reference stabilizers, reaching its maximum at equivalent weight ratio of the investigated stabilizer to the reference one. J. VINYL ADDIT. TECHNOL., 22:247–258, 2016. © 2014 Society of Plastics Engineers     

Thermally stable ion conductive polymer composites containing imide-anion-type zwitterions

Summary Zwitterion bearing highly dissociable imide anion (EIm5csI) was used as major component for stable polymer electrolytes. A polymerization of methyl acrylate in the presence of EIm5csI/LiTFSI mixture gave a flexible film with the ionic conductivity of 9.3×10^-6 Scm^-1 at 50 °C. Mixing of poly(lithium acrylate) and EIm5csI/LiTFSI mixture improved ionic conductivity (3.3×10^-5 Scm^-1 at room temperature), lithium transference number (0.44), and thermal stability.     

PVC/碳纳米管复合材料的制备

采用原子转移自由基聚合(ATRP)在多壁碳纳米管(MWNTs)表面接枝聚丙烯酸丁酯(PBA)得到MWNTs-PBA,并以此对聚氯乙烯(PVC)改性,采用熔融共混法制备了PVC/MWNTs-PBA复合材料。傅里叶变换红外光谱分析及透射电子显微镜观察结果表明:采用ATRP法成功地将PBA接枝到MWNTs的表面。接枝了聚合物的碳纳米管可以提高复合材料的结晶温度(5 oC左右)、耐热温度(20 oC左右);复合材料的流变性能、导电性能也同时得以提高。     

Thermally stable photoresist polymer

A new photoresist stable to 500°C has been developed. The addition of potassium dichromate to a polyamic acid, believed to be the condensation product of pyromellitic dianhydride and 4,4′-diaminodiphenylether, results in a photosensitive polymer which can be cast or spun. The resultant film after exposure, development and post-bake is a crosslinked aromatic polyimide. An efficient developing solution consisting of a 5:1 mixture of hexamethylphosphoramide and dimethylsulfoxide has been discovered. The system has been fully characterized in terms of composition, film formation, exposure, development, hardening and removal. This material has already proven useful as an area-controlled, thermally stable dielectric and as a sputter-etch resist. It has been demonstrated that under the conditions of sputter-etching (bombardment of substrate with Ar, Ar⁺ species with energies from 1–300 eV) commercial photoresists, of the polyisoprene variety, char to the extent of being ineffective as a masking material. Under these same conditions, the thermally stable resist retains its film integrity and uniform sputter-etch rate. An exemplary processing sequence is included as an appendix.     

Thermally stable phosphonium-montmorillonite organoclays

Sodium montmorillonite (MMT) was modified with several organic phosphonium salts. Organoclays with water soluble surfactants were prepared by the traditional cation exchange reaction. An alternative procedure was used to prepare organoclays with water insoluble salts. The effect of chemical composition and molecular weight of the salts on the thermal stability and basal spacing were evaluated. The phosphonium montmorillonites exhibit higher thermal stability than conventional ammonium organoclays. The basal spacing is generally larger for the phosphonium montmorillonites. These properties provide a good potential for the use of phosphonium organoclays for the synthesis of polymer/clay nanocomposites by melt processing.     

Thermally stable conducting composites based on a carbon black‐filled polyoxadiazole matrix

New thermally stable conducting materials can be obtained by dispersing conducting carbon black into poly(4,4′‐diphenylether‐1,3,4‐oxadiazole) (POD–DPE) solution in NMP. The blend preparation process resulted in quite good dispersed composite and a relatively low percolation threshold (around 5 wt % of CB). The effect of the compressive stress on the resistivity of composite has been evaluated. The resistivity decreases continuously as the applied pressure is increased. In addition to the electrical conductivity, the presence of carbon black resulted in higher thermally stable materials. The thermal stability, electrical conductivity, and pressure‐sensible characteristics make this conducting material a good candidate for application in manufacture of pressure sensors for high temperature ambient. This material shows a typical semiconductor behavior, characterized by an increase of conductivity with the temperature. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1631–1637, 2004     

Thermally stable and amorphous polyfluorene

Two‐dimensional ladder‐type polyfluorenes, which consist of polystyrene as the polymer backbone and polyfluorene as the light emitting component, were prepared through three synthetic pathways A, B, and C. In path A, the precursor polymer IP1 was obtained from the graft reaction of fluorene to units of poly(vinylbenzyl chloride) and then the ladder‐type polymer P1 was prepared by coupling at the 2,7‐position of fluorene with FeCl₃ as an oxidizing agent in chloroform. In path B, IP2 was obtained from the graft reaction of lithiated 2,7‐dibromofluorene and units of poly(vinylbenzyl chloride), and then P2 was prepared by the aryl‐coupling of IP2 with a Ni‐catalyst through the reductive polymerization. In path C, 4‐(fluorenylmethyl)styrene was prepared by the reaction of 4‐chloromethylstyrene and lithiated fluorene. Fluorene‐attached syndiotatic polystyrene, IP3, was obtained in the polymerization of 4‐(fluorenylmethyl)styrene with CpTiCl₃‐MAO catalyst, and for P3 oxidative coupling was further carried out. The polymers exhibited glass transition temperatures (T_g) of 422°C for P1, 404°C for P2, and 311°C for P3, and no melting endotherms were found. Syndiotaticity contributes the high glass temperature of P3 despite low molecular weight. Thermal decomposition temperatures at 5 wt % loss (T_d) of 475°C for P1, 448°C for P2, and 365°C for P3 were observed. The fluorescence peaks of P1, P2, and P3 were observed at 401, 416, and 415 nm, respectively. For the emission spectrum of P3, no shoulder or peak regarding of aggregation of polyfluorene was observed. Syndiotacticity, due to the alternative configuration of fluorene, prevents a large Stoke's shift of the luminescence spectrum. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1335–1340, 2005     

Polypyromellitimides. Thermally stable materials

The effect of backbone flexibility on the thermal behaviour of the polyimides was investigated by synthesizing copolyimides based on pyromellitic dianhydride (PMDA) and benzidine (B), p-phenylene diamine (P), and p,p′-diamino diphenyl methane (D). Soluble polyamic acids were obtained by carrying the reaction in dimethyl formamide (DMF) at 0°C. The cyclodehydration of amic acid to polyimides was carried out by chemical means (acetic anhydride : pyridine). Several copolyimides were prepared by changing the molar ratios of diamines in initial monomer feed. These were characterized by evaluation of intrinsic viscosity of polyamic acid in DMF at 30°C. The presence of amic acid and imide structures in the backbone was confirmed by IR spectra. Thermal behaviour of the polymers in air and nitrogen atmosphere was evaluated by dynamic thermogravimetry. The integral procedural decomposition temperature and activation energy of thermal degradation has been evaluated.     

PVC/高岭土复合材料的制备及其力学性能研究

针对PVC加工过程中韧性差、冲击强度低、热不稳定等问题,制备了PVC/N-十六烷基马来酰胺酸镧(Ⅲ)-高岭土复合材料。通过刚果红实验、傅里叶红外光谱(FTIR)、X-射线衍射(XRD)、热重分析(TGA)等表征了其结构与热性能;通过扫描电镜(SEM)观察复合材料表观形貌;研究了插层后的高岭土对PVC材料抗冲击强度的影响。结果表明,插层改性后的高岭土层间距增大;PVC复合材料圆形度得到了提高,外形变得更加规整;获得的复合材料断裂伸长率和冲击强度都有所增强,复合材料的热稳定性能也得到了提高。     

Friction and wear properties of NBR/PVC composites

Acrylonitrial butadiene rubber (NBR)/Polyvinyl chloride (PVC) composites with different PVC content were prepared. The effect of PVC content on the mechanical strength and tribological properties of the NBR/PVC composites was investigated. The morphologies of the worn traces and debris of NBR/PVC composites and worn traces of mating ball were observed using a scanning electron microscope (SEM). It was found that the friction and wear of NBR/PVC was lower than that of NBR without PVC. The NBR/PVC composite with 30% PVC content showed the best synthetic mechanical and tribological properties. The inferior elastic properties and the lesser deformation under the applied load of composites with PVC resulted in hysteric force and adhesion force decrease, which leading to a lower friction and wear of NBR/PVC composites. The frictional failure unit of NBR70/PVC30 composite being smaller should be an important reason of the wear of the composite being lowest. The lubricating effect of PVC played an important role in decreasing the friction coefficient and wear of NBR/PVC composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Thermally stable solar-blind diamond UV photodetector

Thermally stable, deep-ultraviolet (DUV) photodetectors are developed by fabricating a semi-transparent tungsten carbide (WC) or hafnium nitride (HfN) Schottky contact and an annealed Ti/WC Ohmic contact on a boron-doped homoepitaxial p-type diamond layer. Thermal annealing at 500 °C improves the rectifying current–voltage characteristics of the photodiode, resulting in a dramatic enhancement (by a factor of 10³) of DUV responsivity at 220 nm. The discrimination ratio between DUV and visible light is measured to be as large as 10⁶ at a reverse bias voltage as small as 2 V, and it remains almost constant after annealing at 500 °C for 5 h. The short-circuit photocurrent of the HfN Schottky photodiode gradually decreases as the annealing temperature increases, which is well explained by the dependence of the depletion layer width beneath the contact interface on the annealing temperature. In contrast, the short-circuit photocurrent of the WC photodiode is rapidly reduced as the temperature increases. The B doping is found to affect the time response property and reducing the B concentration significantly reduces the response time. Metal carbide and nitride contacts for diamond are thus useful for developing a thermally stable diamond UV photodetector.     

Mechanical and morphological properties for sandwich composites of wood/PVC and glass fiber/PVC layers

This work manufactured sandwich composites from glass fiber/poly(vinyl chloride) (GF/PVC) and wood/PVC layers, and their mechanical and morphological properties of the composites in three GF orientation angles were assessed. The effects of K value (or viscosity index) of PVC and Dioctyl phthalate (DOP) loading were of our interests. The GF/PVC was used as core layer whereas wood/PVC was the cover layers. The experimental results indicated that PVC with low K value was recommended for the GF/PVC core layer for fabrication of GF/WPVC sandwich composites. The improvement of PVC diffusion at the interface between the GF and the PVC core layer was obtained when using PVC with K value of 58. This was because it could prevent de‐lamination between composite layers which would lead to higher mechanical properties of the sandwich composites, except for the tensile modulus. The sandwich composites with 0° GF orientation possessed relatively much higher mechanical properties as compared with those with 45° and 90° GF orientations, especially for the impact strength. Low mechanical properties of the sandwich composites with 45° and 90° GF orientation angles could be overcome by incorporation of DOP plasticizer into the GF/PVC core layer with the recommended DOP loadings of 5–10 parts per hundred by weight of PVC components. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚氯乙烯的离子型热可逆交联研究

通过二胺的烷基化反应，制备了不同链长的二叔胺，利用二叔胺与聚氯乙烯(PVC)链上的活性氯形成季铵盐离子键的反应，制备了具有离子型热可逆交联特性的PVC。在研究中发现，对于硬聚氯乙烯(PVC-U)，适当份数的交联剂能够提高材料的杨氏模量、屈服强度、断裂强度和断裂伸长率；应用于软聚氯乙烯(PVC-S)时，断裂强度、断裂伸长率均得到提高，而永久变形量明显降低，并且交联时间的延长对力学性能影响显著。     

Ultraviolet light aging properties of PVC/CaCO3 composites

The ultraviolet radiation aging behaviors of PVC/CaCO₃ and PVC/CaCO₃/macromolecular modifier composites were studied through whiteness measurement, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, scanning electron microscopy, and mechanical properties test. It was found that nano‐CaCO₃ particles used as ultraviolet light screening agents could significantly enhance the antiaging properties of PVC materials. Due to the macromolecular modifier coated on nano‐CaCO₃ particles, the compatibility of nano‐CaCO₃ and PVC matrix was improved, resulting in uniform dispersion of nano‐CaCO₃ in PVC matrix. Therefore, the PVC/CaCO₃/MP composite exhibited better antiaging properties than PVC/CaCO₃ composite. After 12 h of ultraviolet irradiation, the tensile strength retention, elongation at break retention, and impact strength retention of PVC/CaCO₃/MP composite were 79.5%, 74.5%, and 75.3%, which were much higher than that of neat PVC and PVC/CaCO₃ composite. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

软质PVC环/氧树脂共混物性能的研究

考察了PVC/环氧树脂(E51)共混物(未固化与固化)的力学性能和加工性能,采用电子扫描显微镜观察了粒子在基体中的分散情况。结果表明:①在试验条件下,E51质量分数为5%(以PVC/E51质量为100%计,下同)时,试样的力学性能较好。②当E51质量分数为10%时,共混物的最大转矩最低;当E51质量分数为13%时,共混物的平衡转矩最低。③经过固化的试样的力学性能优于未固化的试样。④E51的加入能够改善试样的相容性与粒子的分散效果。     

改性无机黏土/PVC复合材料的制备及性能

比较了3种无机黏土(超细无机黏土A、偶联剂表面改性无机黏土B、实验室自制大分子表面处理剂DF包覆改性无机黏土C)对PVC材料力学性能、微观形貌的影响,重点研究了无机黏土C对PVC材料动态力学性能、耐热性能的影响。结果表明:①适量添加无机黏土可以提高PVC材料的拉伸性能和冲击性能;②无机黏土C/PVC复合材料具有很好的耐热性能;③无机黏土C的填充效果较好。     

剑麻短纤维补强环氧化天然橡胶/PVC复合材料的性能研究

研究了剑麻短纤维用量和环氧化天然橡胶（ＥＮＲ）／ＰＶＣ共混比对剑麻短纤维补强ＥＮＲ／ＦＶＣ复合材料性能的影响。结果表明,该复合材料具有同的硬度和纵向拉伸强度、较低的扯断伸长率和扯断永外变形、良好的耐油和耐老化性能。剑麻短纤维的用量宜为３０份,ＥＮＲ／ＰＶＣ的共混比宜为７０／３０。