Aromatic polyamides with imide pendent groups

Aromatic polyamides with imide pendent groups were prepared from 4,4′-diaminodiphenylether and imide-diacid chlorides by solution polycondensation. Imidediacid chlorides used included the diacid chlorides of 5-maleimidoisophthalic, 5-dichloromaleimidoisophthalic, 5-tetrahydrophthalimidoisophthalic, 5-chlorendimidoisophthalic, 5-nadimidoisophthalic, 5-methylnadimidoisophthalic and 5-phthalimidoisophthalic acid. The pure aromatic polyamide from 4,4′-diaminodiphenylether and isophthaloyl chloride was also prepared for comparative reasons. Polyamide-imides are soluble in polar organic solvents and show good thermal resistance. They are film-forming and the films have good mechanical properties. Those polyamide-imides which contain unsaturated carbon-carbon bonds may be crosslinked by heating to 220°C, giving rise to insoluble materials with improved mechanical resistance.     

Characterization of reworkable high-temperature adhesives for MCM-D application

The need to have a high-temperature adhesive that can withstand temperatures in excess of 350°C for MCM-D silicon substrate process application, yet which can be reworkable at slightly high temperature ∼ 400°C for the removal from the glass pallet, is important. A novel, reworkable, high-temperature adhesive based on polyimide–amide–epoxy (PIAE) copolymer was developed and investigated using modulated differential scanning calorimetry (MDSC), thermal gravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and solid-probe pyrolysis mass spectroscopy (MS). Compared with commercial polyimide–amide (PIA) adhesives, FTIR spectra reveal that the thermally degradative ester groups contribute to the reworkability of the PIAE adhesive at a specific temperature (400°C), yet they remain thermally stable at a lower working temperature (350°C). FTIR spectrum comparison of the residuals of PIAE and PIA are similar after exposure to 400°C. MS spectra of outgassed products identify that the components of radical fragmentation from PIAE are due to polymeric chain degradation at 400°C, while only volatile trace water and N-methyl pyrolidone (NMP) are evolved from the commercial PIA adhesive. TGA results suggest a complementary explanation for the variation of total ion current (TIC) curves on these two adhesives. MDSC curves further verify that the reworkable PIAE adhesive is a copolymer. Furthermore, a reasonable thermal degradation mechanism is presented on the adhesive reworkability. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 997–1005, 1999     

改性耐高温胶粘剂的研究进展

综述了近年来国内外改性耐高温胶粘剂的发展现状,对环氧树脂(EP)、酚醛树脂(PF)、有机硅、含氮杂环以及无机耐高温胶粘剂的性能、应用和改性方法进行了详细的论述,主要介绍了提高各种胶粘剂耐高温性能的改性方法和技术途径,并对今后改性耐高温胶粘剂的发展趋势作了展望。     

耐高温有机胶粘剂的研究进展

对当前国内外耐高温胶粘剂进行了综述。介绍了环氧树脂、酚醛树脂、有机硅、聚酰亚胺、聚苯并咪唑和聚苯基喹嗯啉等耐高温胶粘剂的物理化学性能,以及提高耐高温胶粘剂耐高温性能的一些技术途径和改性方法,并对耐高温胶粘剂的发展趋势进行了展望。     

The preparation and performance of high-temperature adhesives for graphite bonding

Two kinds of high-temperature adhesives (HTAs) were prepared. One was composed of phenol-formaldehyde (PF) resin and boron carbide (PF+B₄C), the other was composed of PF resin, B₄C and fumed silica (PF+B₄C+SiO₂). Graphite materials were bonded by the above adhesives and heat-treated at temperatures ranging from 200 to 1500 °C. The joining strength was tested at room temperature. The results show that the graphite joints exhibit satisfactory bonding strength and that ceramics fillers show a marked property modification effect. The strength of graphite joints bonded by PF+B₄C and PF+B₄C+SiO₂ adhesive and treated at 1500 °C are 9.3 and 17.1 MPa, respectively. The property modification mechanism of ceramics fillers is also discussed in this paper. A strong chemical bonding force is introduced at the bonding interface and the volume shrinkage is restrained, which can be responsible for the good adhesive properties of HTAs for graphite bonding.     

改性有机耐高温胶粘剂的研究进展

对有机耐高温胶粘剂的研究进展进行了综述。对环氧树脂、酚醛树脂、有机硅、聚酰亚胺、氰酸酯等改性有机耐高温胶粘剂进行了讨论,并对耐高温胶粘剂的发展趋势进行了展望。     

耐高温环氧树脂胶粘剂的研究进展

对耐高温环氧树脂胶粘剂的研究进展进行了综述,分析了环氧树脂胶粘剂耐高温性的影响因素及提高环氧胶粘剂耐高温性的途径。重点阐述了几种提高环氧树脂胶粘剂耐温性的新方法,对其发展前景进行了展望。     

耐高温热固性树脂胶粘剂的研究动态

综述了耐高温热固性树脂胶粘剂的发展过程与研究现状,介绍了近年来国内外几种性能优异的热固性树脂胶粘剂,提高其高温性能的一些主要途径和改性方法,并介绍了新型功能填料在树脂中的应用情况,最后对耐高温热固性树脂胶粘剂的总体发展趋势进行了展望。     

Preparation of high-temperature organic adhesives and their performance for joining SiC ceramic

Two kinds of high-temperature organic adhesives were prepared and successfully applied to join SiC ceramic. One adhesive was composed of preceramic polymer (V-PMS) and B₄C powder (HTA-1), and the other was composed of V-PMS, B₄C powder and low melting point glass powder (HTA-2). The properties of the obtained adhesives were investigated by TGA, XRD, bonding test and SEM analysis. The results show that the obtained adhesives exhibit outstanding heat-resistant property and excellent bonding strength. The bonding strength of HTA-1 treated at 200 °C, 400 °C, 600 °C were 26.8 MPa, 18.9 MPa, 7.3 MPa, respectively. When the temperature increased to 800 °C or even higher, the shear strengths of the joints were enhanced to over 50 MPa. Moreover, by adding glass powder as the second filler, it was found that the minimum shear strength of HTA-2 was enhanced to 16.4 MPa. The excellent performances of the obtained adhesives make them as promising candidates for joining SiC ceramics for high-temperature applications.     

External lubrication of high-temperature thermoplastic polymers

External lubrication of high-temperature thermoplastic polymers was studied experimentally. It was found that the nature of the lubrication fluid has a pronounced effect upon the behavior of the contact. It is postulated that premature failure of PEEK-lubricated contacts is caused by the migration of linear carboxylic acids into the polymer matrix at elevated temperatures, thereby producing significant plasticization. A sequence of events leading to failure is given and some rationale for it provided. © 1993 John Wiley & Sons, Inc.     

ATBN改性的耐高温环氧胶粘剂的研究

介绍了一种用端胺基丁腈橡胶(ATBN)增韧的环氧树脂胶粘剂，该胶可在室温下固化并具有较好的粘接性能、耐介质性能和电绝缘性能，使用温度为-55～200℃，可满足耐高温的需要。     

新型耐高温无溶剂环氧胶粘剂的研制

采用DTGM53、DDRS3521这2种多官能环氧树脂,以低黏度的甲基四氢苯酐为固化剂,在促进剂E-24作用下,制备了综合性能优异的新型耐高温无溶剂环氧胶粘剂。同时,对该环氧胶粘剂的黏度、凝胶化时间、粘接性能、活化能等作了系统的研究。结果表明,该胶粘剂具有优异的高温拉伸剪切强度,200℃时高达16.1 MPa。     

WD3102室温固化耐高温胶粘剂的研制

通过对环氧树脂、液体橡胶、固化剂的选择,研制了一种可以室温固化、耐高温性能好的双组份环氧胶粘剂。     

有机硅改性酚醛环氧树脂耐高温胶粘剂的研制

采用甲基苯基硅树脂对酚醛环氧树脂进行改性,硼酚醛树脂与自制固化促进剂作为固化剂,辅以纳米蒙脱土、绢云母粉作为填料,制备出一种能在300℃条件下长期使用的耐高温胶粘剂。在不同的配方及固化工艺条件下測定了有机硅改性酚醛环氧树脂体系的剪切强度,分析了甲基苯基硅树脂／酚醛环氧树脂比例关系、硼酚醛树脂与自制固化促进剂比例关系、固化剂用量、固化工艺条件、纳米蒙脱土的加入量对体系的影响。     

Pressure sensitive adhesives of acrylic polymers containing functional monomers

Pressure sensitive adhesives possessing good cohesive strength have been prepared by copolymerizing n-butyl acrylate with various functional monomers. The effect of the polar nature and of the concentration of comonomer on tack, adhesion and cohesion was studied. The cohesive strength of the adhesive was determined on various surfaces. A comparative study was made to assess the effectiveness of a particular comonomer on the basis of the results obtained.     

Chemical stability of some poly(amide imide) type polymers

The stability of some heterocyclic poly(amide imide)s in acidic and alkaline medium was compared to the structurally related polyimide and poly(amide imide)s without other heterocyclic groups. All the polymers have high stability in acidic medium. The introduction of additional heterocycles such as 1,3,4-0xadiazole or phenylquinoxaline into the macromolecular chain of a poly(amide imide) increases substantially the resistance to alkaline medium. Polyamides containing imide rings only in the side chain are more stable to hydrolysis than related polyamide having imide units in the main chain.     

The study of polymers by high-temperature ATR spectroscopy

A new high-temperature attenuated total reflectance apparatus (HATR) was constructed and used at different temperatures for making infrared measurements on the same liquid or solid sample. It was found that this method was applicable to the continuous quantitative analysis of changes occurring during chemical reactions such as polymerization, isomerization, and crosslinking. In the bulk polymerization of styrene, the process of monomer consumption could be followed progressively. In the crosslinking reaction of high cis-polybutadiene by sulfur-accelerator or peroxide crosslinking systems, the decrease of cis content and its partial isomerization to trans structure was measured. Furthermore, in the crosslinking reaction of ethylene–propylene terpolymers (EPDM), the consumption of double bonds was observed over the course of the reaction with both sulfur-accelerator and peroxide crosslinking systems. The effect was greatest in the case of methylenenorbornene-type EPDM.     

Developing antibacterial surgical adhesives: An enhancement of cyanoacrylate polymers

Surgical site infections (SSIs) and traumatic wounds have a significant risk of becoming contaminated by microbial pathogens of both endogenous and nosocomial origins, including Staphylococcus aureus and Enterococci sp.. One preventative approach is to protect wounds from infection by using a rapidly curing adhesive to seal the wound and prevent further contamination. Here, we demonstrate the covalent incorporation of an antimicrobial, quaternary ammonium chloride monomer (quat) into a 2-octyl cyanoacrylate (2oc) polymer adhesive. Copolymerization was confirmed via nuclear magnetic resonance spectroscopy. Cytotoxicity of the copolymer was assessed against: S. epidermidis and E. coli, and 3T3 mouse fibroblasts. The CA-Quat polymer was found to exhibit dose-dependent bacteriostatic and bactericidal effects against both E. coli and S. epidermidis, importantly without showing any demonstrable toxicity against mammalian 3T3 fibroblast cells. The described experiments provide promising data to suggest successful copolymerization, effective antibacterial properties, and remarkably low cytotoxic effects of the copolymer on mammalian cells.     

Aromatic triblock polymers from natural sources as protective coatings for stone surfaces

Aromatic triblock polymers were synthesized, characterized, and tested as protective coatings for stone surfaces. Syntheses were carried out by a ring opening polymerization process from specifically synthesized monomers ((3S)‐6‐methyl‐3‐phenyl‐1,4‐dioxan‐2,5‐dione or 1,4‐benzodioxepin‐3‐methyl‐2,5‐dione) and a perfluoropolyether diol (Fluorolink D10‐H), as chain initiator. Polymers were characterized through spectroscopic and analytical techniques while their stability under photo‐oxidative conditions was tested using a Solar Box. An excellent stability to environmental conditions was noticed with very low degradation during accelerated aging tests up to 1000 h, as detected by FTIR, molecular weight, DSC and weight loss. Furthermore, these polymers formed an excellent protective coating on the stone surface as shown by capillary water absorption test. Finally, as expected, very stable coatings were obtained as shown by aging tests. The stone surface showed negligible changes of color and a good hydrorepellency confirming a good durability of treatments. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43377.     

Outstanding performance of parylene polymers as electrets for energy harvesting and high-temperature applications

Parylene C is used in many applications due to its high properties but it remains a material with moderate performance as long as it is intended for use as an electret. Hence, the generally accepted idea, rightly so, in the scientific and industrial community not to necessarily select parylene (i.e., parylene C) for applications where the endurance of the electret is a strong criterion. Our study provided a new perspective on the performance of parylenes as electret. In this case, we will talk about fluorinated Parylenes of the VT-4 type and especially AF-4 variant. Their thermal stability is outstanding and a charge stability is almost total up to 100 °C. A 50% reduction in the charge is recorded at a temperature as high as of 220 °C (9 μm thick Parylene AF-4), making it one of the most efficient polymer electrets to date. Negatively and positively charged Parylene AF-4 electrets presented similar performance over long durations, which is out of ordinary for the commonly employed polymeric electrets. Finally, these fluorinated polymers are therefore particularly promising new candidates for applications in electret-based converters for energy harvesting. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48790.