Polymers

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10 pages, 1672 KiB

Open AccessArticle

Colloidal Crystal Films with Narrow Reflection Bands by Hot-Pressing of Polymer-Grafted Silica Particles

by Sawa Matsuura, Mami Obara, Naoto Iwata and Seiichi Furumi

Polymers 2022, 14(23), 5157; https://doi.org/10.3390/polym14235157 - 27 Nov 2022

Cited by 1 | Viewed by 1109

Previous reports have shown that colloidal crystal (CC) films with visible Bragg reflection characteristics can be fabricated by the surface modification of monodisperse silica particles (SiPs) with poly(methyl methacrylate) (PMMA) chains, followed by hot-pressing at 150 °C. However, the reflection bands of the [...] Read more.

Previous reports have shown that colloidal crystal (CC) films with visible Bragg reflection characteristics can be fabricated by the surface modification of monodisperse silica particles (SiPs) with poly(methyl methacrylate) (PMMA) chains, followed by hot-pressing at 150 °C. However, the reflection bands of the CC films were very broad due to their relative disordering of SiPs. In this report, we attempted to fabricate the CC films using SiPs surface-modified with poly(n-octyl acrylate) (POA) chains by hot-pressing. When the cast films of POA-grafted SiPs were prepared by hot-pressing at 100 °C, the reflection bands were narrow rather than those of CC films of PMMA-grafted SiPs. This can be ascribed to easy disentanglement of POA chains during the hot-pressing process, thereby enabling the formation of well-ordered CC structures. Moreover, the reflection colors of CC films could be easily tuned by controlling the molecular weight of POA chains grafted on the SiP surface. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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12 pages, 4858 KiB

Open AccessArticle

Preparation and Corrosion Performance of PPy/Silane Film on AZ31 Magnesium Alloy via One-Step Cyclic Voltammetry

by Chuang Peng, Nana Cao, Ziheng Qi, Yongde Yan, Ruizhi Wu and Guixiang Wang

Polymers 2021, 13(18), 3148; https://doi.org/10.3390/polym13183148 - 17 Sep 2021

Cited by 4 | Viewed by 1747

Abstract

PPy/silane composite film on a magnesium alloy surface was prepared by one-step cycle voltammetry. The mixed solution of methanol and water was used as the hydrolysis solvent of a γ-(2,3-glycidoxypropyl) trimethoxysilane coupling agent (KH-560). The surface morphology of the PPy/silane film, the electro-polymerization [...] Read more.

PPy/silane composite film on a magnesium alloy surface was prepared by one-step cycle voltammetry. The mixed solution of methanol and water was used as the hydrolysis solvent of a γ-(2,3-glycidoxypropyl) trimethoxysilane coupling agent (KH-560). The surface morphology of the PPy/silane film, the electro-polymerization progress of KH-560 and PPy, the influence of the silane coupling agent and the corrosion behavior of the coated AZ31 Mg alloy were all investigated. The results indicated that the PPy/silane film on AZ31 Mg alloy via one-step cyclic voltammetry could provide better corrosion protection for an Mg alloy when the volume fraction of KH-560 in the hydrolysis solution was 15% and the time span of hydrolysis was 24 h with the 5.935 × 10⁻¹⁰ A cm⁻² corrosion current density. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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18 pages, 1618 KiB

Open AccessArticle

Thermal Stability of Nanosilica-Modified Poly(vinyl chloride)

by Jolanta Tomaszewska, Tomasz Sterzyński and Damian Walczak

Polymers 2021, 13(13), 2057; https://doi.org/10.3390/polym13132057 - 23 Jun 2021

Cited by 13 | Viewed by 3403

Abstract

The thermal stability of PVC with 1 wt % of spherical porous nanosilica, prepared by roll milling at processing time varied from 1 to 20 min, was investigated by means of visual color changes, Congo red, and thermogravimetric tests (TGA and DTG), as [...] Read more.

The thermal stability of PVC with 1 wt % of spherical porous nanosilica, prepared by roll milling at processing time varied from 1 to 20 min, was investigated by means of visual color changes, Congo red, and thermogravimetric tests (TGA and DTG), as a function of rolling time and composition of PVC matrix. The melt flow rate (MFR) measurements were realized to identify the degradation-induced changes of processing properties. A high level of gelation of the PVC matrix for all samples was verified by DSC (differential scanning calorimetry). It was found that the addition of porous nanosilica to absorb a certain volume of HCl, produced by dehydrochlorination reaction, leads to an improvement of thermal stability, an effect observed in a form of minor color changes of the samples, lower evolution of gas hydrogen chloride, and slight changes of the MFR value. It was demonstrated that the TGA measurements are not sufficiently sensible to detect the degradation of PVC at the processing conditions, i.e., at the temperature equal to 220 °C and below this temperature. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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9 pages, 12836 KiB

Open AccessArticle

Improvement of the Centrifugal Force in Gravity Driven Method for the Fabrication of Highly Ordered and Submillimeter-Thick Colloidal Crystal

by Ting-Hui Chen, Shuan-Yu Huang, Syuan-Yi Huang, Jia-De Lin, Bing-Yau Huang and Chie-Tong Kuo

Polymers 2021, 13(5), 692; https://doi.org/10.3390/polym13050692 - 25 Feb 2021

Cited by 3 | Viewed by 1585

Abstract

In this paper, we propose a modified gravity method by introducing centrifugal force to promote the stacking of silica particles and the order of formed colloidal crystals. In this method, a monodispersed silica colloidal solution is filled into empty cells and placed onto [...] Read more.

In this paper, we propose a modified gravity method by introducing centrifugal force to promote the stacking of silica particles and the order of formed colloidal crystals. In this method, a monodispersed silica colloidal solution is filled into empty cells and placed onto rotation arms that are designed to apply an external centrifugal force to the filled silica solution. When sample fabrication is in progress, silica particles are forced toward the edges of the cells. The number of defects in the colloidal crystal decreases and the structural order increases during this process. The highest reflectivity and structural order of a sample was obtained when the external centrifugal force was 18 G. Compared to the samples prepared using the conventional stacking method, samples fabricated with centrifugal force possess higher reflectivity and structural order. The reflectivity increases from 68% to 90%, with an increase in centrifugal force from 0 to 18 G. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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9 pages, 2595 KiB

Open AccessArticle

Fast Curable Polysiloxane-Silphenylene Hybrimer with High Transparency and Refractive Index for Optical Applications

by Kyungkuk Koh and Honglae Sohn

Polymers 2021, 13(4), 515; https://doi.org/10.3390/polym13040515 - 09 Feb 2021

Cited by 4 | Viewed by 2499

Abstract

In this study, a fast curable polysiloxane-silphenylene hybrimer (PSH) was synthesized by the nonhydrolytic sol–gel condensation of phenyl-vinyl-oligosiloxane (PVO) and tris(dimethylhydrosilyl)benzene (TDMSB) under a Pt catalyst to investigate its optical property and thermal stability. The combination of PVO and tripod-type TDMSB results in [...] Read more.

In this study, a fast curable polysiloxane-silphenylene hybrimer (PSH) was synthesized by the nonhydrolytic sol–gel condensation of phenyl-vinyl-oligosiloxane (PVO) and tris(dimethylhydrosilyl)benzene (TDMSB) under a Pt catalyst to investigate its optical property and thermal stability. The combination of PVO and tripod-type TDMSB results in a hybrimer with a fast curing time of 30 min. The PSH exhibited a high refractive index of 1.60, 1.59, and 1.58 at 450, 520, and 635 nm, respectively. High transmittance of 97% at 450 nm was obtained. The PSH exhibited a very high transmittance of 97% before thermal aging. The high optical transmittance of the PSH was only slightly decreased by 0.5% of the transmittance at 180 °C for 72 h after thermal aging, and high transparency was maintained almost constant even after 72 h of high-temperature treatment. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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14 pages, 4622 KiB

Open AccessArticle

Comparison between SBR Compounds Filled with In-Situ and Ex-Situ Silanized Silica

by Pilar Bernal-Ortega, Rafal Anyszka, Yoshihiro Morishita, Raffaele di Ronza and Anke Blume

Polymers 2021, 13(2), 281; https://doi.org/10.3390/polym13020281 - 16 Jan 2021

Cited by 18 | Viewed by 2274

Abstract

The main advantages of the use of silica instead of carbon black in rubber compounds are based on the use of a silane coupling agent. The use of a coupling agent to modify the silica surface improves the compatibility between the silica and [...] Read more.

The main advantages of the use of silica instead of carbon black in rubber compounds are based on the use of a silane coupling agent. The use of a coupling agent to modify the silica surface improves the compatibility between the silica and the rubber. There are two different possibilities of modifying the silica surface by silane: ex-situ and in-situ. The present work studies the differences between these processes and how they affect the in-rubber properties of silica filled SBR compounds. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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13 pages, 13031 KiB

Open AccessArticle

Effect of SiO₂ Particles on the Relaxation Dynamics of Epoxidized Natural Rubber (ENR) in the Melt State by Time-Resolved Mechanical Spectroscopy

by Rossella Arrigo, Leno Mascia, Jane Clarke and Giulio Malucelli

Polymers 2021, 13(2), 276; https://doi.org/10.3390/polym13020276 - 15 Jan 2021

Cited by 6 | Viewed by 1861

Abstract

The rheological behavior of an epoxidized natural rubber (ENR) nanocomposite containing 10 wt.% of silica particles was examined by time-resolved mechanical spectroscopy (TRMS), exploiting the unique capability of this technique for monitoring the time-dependent characteristics of unstable polymer melts. The resulting storage modulus [...] Read more.

The rheological behavior of an epoxidized natural rubber (ENR) nanocomposite containing 10 wt.% of silica particles was examined by time-resolved mechanical spectroscopy (TRMS), exploiting the unique capability of this technique for monitoring the time-dependent characteristics of unstable polymer melts. The resulting storage modulus curve has revealed a progressive evolution of the elastic component of the composite, associated with slower relaxations of the ENR macromolecular chains. Two major events were identified and quantified: one is associated with the absorption of the epoxidized rubber macromolecules onto the silica surface, which imposes further restrictions on the motions of the chains within the polymer phase; the second is related to gelation and the subsequent changes in rheological behavior resulting from the simultaneous occurrence cross-linking and chain scission reactions within the ENR matrix. These were quantified using two parameters related to changes in the storage and loss modulus components. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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14 pages, 2651 KiB

Open AccessArticle

The Investigation of the Silica-Reinforced Rubber Polymers with the Methoxy Type Silane Coupling Agents

by Sang Yoon Lee, Jung Soo Kim, Seung Ho Lim, Seong Hyun Jang, Dong Hyun Kim, No-Hyung Park, Jae Woong Jung and Jun Choi

Polymers 2020, 12(12), 3058; https://doi.org/10.3390/polym12123058 - 20 Dec 2020

Cited by 28 | Viewed by 4510

Abstract

The methoxy-type silane coupling agents were synthesized via the modification of the hydrolyzable group and characterized to investigate the change in properties of silica/rubber composites based on the different silane coupling agent structures and the masterbatch fabrication methods. The prepared methoxy-type silane coupling [...] Read more.

The methoxy-type silane coupling agents were synthesized via the modification of the hydrolyzable group and characterized to investigate the change in properties of silica/rubber composites based on the different silane coupling agent structures and the masterbatch fabrication methods. The prepared methoxy-type silane coupling agents exhibited higher reactivity towards hydrolysis compared to the conventional ethoxy-type one which led to the superior silanization to the silica filler surface modified for the reinforcement of styrene-butadiene rubber. The silica/rubber composites based on these methoxy-type silane coupling agents had the characteristics of more developed vulcanization and mechanical properties when fabricated as masterbatch products for tread materials of automobile tire surfaces. In particular, the dimethoxy-type silane coupling agent showed more enhanced rubber composite properties than the trimethoxy-type one, and the environmentally friendly wet masterbatch fabrication process was successfully optimized. The reactivity of the synthesized silane coupling agents toward hydrolysis was investigated by FITR spectroscopic analysis, and the mechanical properties of the prepared silica-reinforced rubber polymers were characterized using a moving die rheometer and a universal testing machine. Full article

(This article belongs to the Special Issue Polymer-SiO₂ Composites)

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