Synthesis and characteristic applications of silicon resins for the modifying agent in heat conduction

Heat energy retention and dissipation have become key points of global smart textiles in recent years. This study describes the designing of silicon resin by using a sol–gel process, which acts as the modifying agent for siloxane substrate. The modifying agent was effectively blocked by silicon resin mixed with the ethylene or aluminum bond group, to control the molecular weight. Advanced polymer chromatography confirmed that the number average molecular weight (Mn) of silicon resin is 41,301 g mol−1, the weight average molecular weight (Mw) is 47,982 g mol−1, and the molecular weight distribution is 1.1617, which is relatively narrow. When the addition of vinyl groups is 5%, the silicone resin Mn decreases to 18,906 g mol−1 and Mw decreases to 28,641 g mol−1. When the addition of aluminum bond groups is 5%, the silicone resin Mn decreases to 17,497 g mol−1 and Mw decreases to 27,114 g mol−1. The result of thermogravimetric analysis shows that the pyrolysis temperature rises from 265.43°C to 266.17°C after the ethylene is added to the silicon resin, and the index of heat tolerance increases from 179.14°C to 191.38°C. After the addition of aluminum bond groups, the pyrolysis temperature rises from 265.43°C to 309.37°C, and the index of heat tolerance increases from 179.14°C to 193.09°C, meaning the silicone resin has higher thermal stability.

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Molecular Structure and Macroscopic Properties of Synthetic Cis-Poly(Isoprene)

Rubber Chemistry and Technology ◽

10.5254/1.3540444 ◽

1974 ◽

Vol 47 (2) ◽

pp. 342-356 ◽

Cited By ~ 8

Author(s):

V. A. Grechanovskii ◽

I. Ya Poddubnyi ◽

L. S. Ivanova

Keyword(s):

Molecular Weight ◽

Functional Groups ◽

Chemical Structure ◽

Sol Gel ◽

Average Molecular Weight ◽

Dense Network ◽

Green Strength ◽

Gel Fraction ◽

Rubber Compounds ◽

Processing Properties

Abstract By changing the sol-gel ratio and the structure of the gel fraction it is possible to obtain various grades of synthetic cis-poly(isoprene) which show promise for different applications in the tire and mechanical rubber goods industries. The processability of commercial SKI-3 rubber (at a given average molecular weight of sol) depends mainly on the structure of the gel fraction. Thus, for example, inferior processing properties of rubber compounds is associated primarily with the presence of tight gel. The content and structure of the gel fraction also significantly affect plasto-elastic properties of raw rubbers, e.g. a low plasticity of raw rubbers owes to the increased content of gel fraction. The reduced green strength of compounds based on SKI—3 rubber is accounted for by its chemical structure. Conventional methods used to change the properties of rubbers (including the variation in molecular weight, molecular weight distribution, branching degree, and variation in the content and structure of gel fraction) cannot be considered to be adequate to tackle the problem of the green strength of SKI—3 black stocks. The way to solve the problem appears to be the introduction of functional groups into the polymer chain at the stage of synthesis or processing. These functional groups should be active as to the formation of labile rubber—carbon black—rubber and/or rubber—rubber bonds. High purity of microstructure is necessary but not sufficient for obtaining the required level of green strength of compounded SKI—3. The gel fractions of SKI—3 rubber yield vulcanizates with a more dense network than the corresponding sol vulcanizates. The temperature dependence of the tensile strength is controlled by the network density of vulcanizates from high cis-1,4 poly(isoprene).

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Growth of PLZT Thick Films by Polymer Modified Sol-Gel Processing for Optical Shutting

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.136.67 ◽

2008 ◽

Vol 136 ◽

pp. 67-74 ◽

Cited By ~ 1

Author(s):

Z.H. Du ◽

T.S. Zhang ◽

H.M. Shang ◽

X.L. Chen ◽

Jan Ma

Keyword(s):

Molecular Weight ◽

Critical Thickness ◽

Thick Films ◽

Sol Gel ◽

Average Molecular Weight ◽

Liquid Phase Sintering ◽

Optical And Electrical Properties ◽

Densification Behavior ◽

Free Films ◽

Gel Processing

PLZT9/65/35 thick films were prepared from the solution containing PVP360 (polyvinylpyrrolidone, with average molecular weight of 360000). With the solutions, the critical thickness of a single PLZT layer could increase to ~624nm compared with 77nm-thick films prepared without PVP360. Furthermore, by adding 20~35% excess of Pb to the precursor solutions, the nano-porous rosette-like structures and a small amount of pyrochlore remnant, which were found very common in the PVP-modified films, could be eliminated. 35% Pb excess was also found to initiate liquid-phase sintering, leading to dense and crack-free films. The effect of Pb excess on the rosette removal and densification behavior of the films was discussed. Moreover, the optical and electrical properties of the PLZT films with 35% Pb excess were also studied.

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On the structure alteration of crosslinkable gelatin coupled with methacrylic acid and its hydrogel

e-Polymers ◽

10.1515/epoly.2012.12.1.151 ◽

2012 ◽

Vol 12 (1) ◽

Author(s):

Xiaohong Hu ◽

Dan Li ◽

Feng Zhou ◽

Changyou Gao

Keyword(s):

Molecular Weight ◽

Triple Helix ◽

Sol Gel ◽

Average Molecular Weight ◽

Gel Permeation Chromatography ◽

Apparent Molecular Weight ◽

Small Range ◽

Scanning Calorimetry ◽

Physical Chemical ◽

Substitution Degree

AbstractPhysical structures of a crosslinkable gelatin derivative (GM) were studied in terms of alteration of apparent molecular weight, triple helix content and mechanical strength. The GM with a substitution degree (DS) of 49% and 79% was prepared by grafting mechacrylic acid (MA), which was able to form injectable hydrogel by photoinitiating polymerization. The zeta potential was increased along the increase of DS. After modification, the apparent number-average molecular weight (Mn) detected by gel permeation chromatography was decreased to about 2/3 of gelatin, while the apparent weight-average molecular weight (Mw) was changed within a small range. Differential scanning calorimetry and circular dichroism (CD) revealed that ability of triple-helix formation of GM was decreased along with the increase of DS and decrease of GM concentration. After photocrosslinking, the sol-gel transition of GM49 physical-chemical hydrogel still existed, but completely disappeared for its chemical hydrogel. The physical-chemical hydrogel showed a larger storage modulus at 20°C than at 37°C as a result of additional physical crosslinking.

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Molecular Weight Defined in Sol-Gel Analysis and Its Application to Evaluate Branching

Rubber Chemistry and Technology ◽

10.5254/1.3538743 ◽

1995 ◽

Vol 68 (2) ◽

pp. 287-296 ◽

Cited By ~ 1

Author(s):

Asahiro Ahagon

Keyword(s):

Molecular Weight ◽

Crosslink Density ◽

Sol Gel ◽

Average Molecular Weight ◽

Degree Of Polymerization ◽

Gel Point ◽

Linear Polymers ◽

Molecular Parameter ◽

Branch Points ◽

Number Average Molecular Weight

Abstract It is considered that many “linear” polymers are actually branched; however, it is difficult to show this with ordinary methods for an arbitrarily chosen polymer. Branching can be regarded as premature crosslinking below the gel point. Attention is then paid to the well-established Charlesby-Pinner Equation used for sol-gel analysis in crosslinking studies. It contains the number average degree of polymerization before crosslinking as a parameter. The molecular parameter is considered here to be that of the virtual linear polymer which would be obtained by unlinking any branch points contained in the polymer. Evidence is shown to support this. It is then possible to estimate the total number of linear components on an average molecule of a branched polymer by taking the ratio of the number average molecular weight measured by two methods, i.e., sol-gel analysis and an ordinary method like GPC. Further information about the branching structure can be obtained by additional measurements of effective crosslink density for a series of polymers obtained from similar polymerization processes.

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Physical and electrochemical properties of low molecular weight poly(ethylene glycol)-bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

Journal of Applied Polymer Science ◽

10.1002/app.25367 ◽

2006 ◽

Vol 103 (4) ◽

pp. 2752-2758 ◽

Cited By ~ 1

Author(s):

C. Y. Yuan ◽

S. Y. Chen ◽

J. C. Tang ◽

H. C. Yang ◽

Y. W. Chen-Yang

Keyword(s):

Molecular Weight ◽

Ethylene Glycol ◽

Sol Gel ◽

Low Molecular Weight ◽

Composite Electrolytes ◽

Poly Ethylene Glycol ◽

Sol Gel Process ◽

Bridged Polysilsesquioxane ◽

Poly Ethylene ◽

Inorganic Composite

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Hierarchically porous monoliths based on low-valence transition metal (Cu, Co, Mn) oxides: gelation and phase separation

National Science Review ◽

10.1093/nsr/nwaa103 ◽

2020 ◽

Vol 7 (11) ◽

pp. 1656-1666 ◽

Cited By ~ 1

Author(s):

Xuanming Lu ◽

Kazuyoshi Kanamori ◽

Kazuki Nakanishi

Keyword(s):

Phase Separation ◽

Sol Gel ◽

Average Molecular Weight ◽

Reaction Parameters ◽

Valence Transition ◽

Hierarchically Porous ◽

Sol Gel Process ◽

Crystalline Metal ◽

Hydrolysis And Polycondensation ◽

Mn Oxides

Abstract Hierarchically porous monoliths based on copper (Cu), cobalt (Co) and manganese (Mn) oxides with three-dimensionally (3D) interconnected macropores and open nanopores were prepared using metal bromides as precursors via a sol–gel process accompanied by phase separation. The difficulty of gelation for low-valence metal cation was overcome by introducing a highly electronegative Br atom near to the metal atom to control the rates of hydrolysis and polycondensation. The 3D interconnected macropores were obtained using appropriate polymers to induce phase separation. The domain sizes of macropores and skeletons can be controlled by reaction parameters such as concentration and/or average molecular weight of polymers, and the amount of hydrochloric acid. The crystalline metal oxide monoliths with their 3D interconnected macroporous structure preserved were obtained after heat treatment in air.

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Effect of organic modifiers on the thermo-optic characteristics of inorganic–organic hybrid material films

Journal of Materials Research ◽

10.1557/jmr.2003.0264 ◽

2003 ◽

Vol 18 (8) ◽

pp. 1889-1894 ◽

Cited By ~ 11

Author(s):

Eun-Seok Kang ◽

Jang-Ung Park ◽

Byeong-Soo Bae

Keyword(s):

Molecular Weight ◽

Hybrid Material ◽

Sol Gel ◽

The Other ◽

Organic Modifier ◽

Organic Modifiers ◽

Organic Hybrid ◽

Prism Coupler ◽

Sol Gel Process ◽

Organic Hybrid Material

The thermo-optic coefficient (dn/dT) of inorganic–organic hybrid material films prepared by the sol-gel process of organoalkylsilanes is measured using a prism coupler equipped with a hot stage. The effect of the organic modifier on the variation of dn/dT in inorganic–organic hybrid material films has been investigated. The value of dn/dT becomes more negative with increasing molecular weight of the organic modifier or with an increase in the proportion of modifier in the sample. On the other hand, dn/dT increases with an increase in the degree of organic photopolymerization. From these results, it can be seen that the value of dn/dT in these films can be varied between −0.83 × 10−4/°C to −2.43 × 10−4/°C by changing the organic modifier concentration and type.

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High molecular weight poly(ethylene oxide)/silica hybrids by the sol-gel process

Materials Science and Engineering C ◽

10.1016/s0928-4931(98)00047-2 ◽

1998 ◽

Vol 6 (2-3) ◽

pp. 115-120 ◽

Cited By ~ 14

Author(s):

Anna B. Wojcik ◽

Alvin Ting ◽

Lisa C. Klein

Keyword(s):

Molecular Weight ◽

Ethylene Oxide ◽

High Molecular Weight ◽

Sol Gel ◽

Sol Gel Process ◽

Poly Ethylene Oxide ◽

Silica Hybrids ◽

Poly Ethylene ◽

High Molecular Weight Poly

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Synthesis of High Molecular Weight Vinylphenyl-Con Taining MQ Silicone Resin via Hydrosilylation Reaction

Coatings ◽

10.3390/coatings9100605 ◽

2019 ◽

Vol 9 (10) ◽

pp. 605 ◽

Cited By ~ 1

Author(s):

Jianye Ji ◽

Xin Ge ◽

Weijie Liang ◽

Xiaoyan Pang ◽

Ruoling Liu ◽

...

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

High Performance ◽

Average Molecular Weight ◽

Silicone Resin ◽

Hydrosilylation Reaction ◽

Base Resin ◽

Liquid Silicone ◽

Linear Poly ◽

Application Requirements

To overcome the inherent limitation that the preparation of high molecular weight MQ copolymers (Mw ≥ 30,000 g/mol) via the hydrolysis and condensation of solicate salts generally results in an intractable gel, vinylphenyl-containing MQ silicone resin with a high molecular weight was designed and synthesized through the hydrosilylation reaction of vinyl-containing MQ silicone resin and linear poly(diphenylsiloxane) with two terminal Si–H bonds. The weight average molecular weight of these modified copolymers reported here is at least 30,000 dal·mol−1. These polymers have favorable thermal stability and a higher refractive index than that of the base resin due to the formation of novel regular macromolecular structures and the introduction of phenyl groups. These inorganic/organic hybrid materials could be used as a potential component for temperature-resistance electronics adhesive, heat-resistant coatings and high-performance liquid silicone rubber. Moreover, the proposed process also provides a possibility to choose higher molecular weight MQ silicones according to application requirements.

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