Rosin Ester Research Articles

Rosin-based self-healing functionalized composites with two-dimensional polyamide for antimicrobial and anticorrosion coatings

The design of polymer-based composites possessing good mechanical and self-healing properties remains a challenge in the development of high-performance self-healing materials. In this study, we used two-dimensional polyamide (2DPA), biomass rosin ester, and a dynamic crosslinking agent poly (urethane-urea) as raw materials, and prepared biomass rosin-based composites via in situ polymerization. The composites with 1 wt% 2DPA exhibited excellent self-healing properties (self-healing efficiency of 94 % after 24 h at 80 °C) and mechanical properties (tensile strength = 7.8 MPa). Moreover, the composites were applied to anticorrosion and antimicrobial coatings, which possessed excellent anticorrosion and antimicrobial properties. This study provides a new strategy for developing high-performance bio-based self-healing composites.

Preparation and structural characterization of epoxidized soybean oils-based pressure sensitive adhesive grafted with tea polyphenol palmitate

Vegetable oils-based pressure sensitive adhesives (PSAs) are green and sustainable but face unsatisfactory adhesion strengths and are prone to aging during storage and application due to the existence of residual double bonds and massive ester bonds. Nine common antioxidants (tea polyphenol palmitate (TPP), caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, and tea polyphenols) were grafted into epoxidized soybean oils-PSA (ESO-PSA) system to enhance antiaging properties and adhesion strengths. Results showed ESO-PSAs grafted with caffeic acid, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, tea polyphenols, or TPP didn't occur failure with TPP having best performance. The optimal conditions were ESO reacted with 0.9 % TPP, 70 % rosin ester, and 7.0 % phosphoric acid at 50 °C for 5 min, under which peel strength and loop tack increased to 2.460 N/cm and 1.66 N, respectively, but peel strength residue reduced to 138.09 %, compared with control (0.407 N/cm, 0.43 N, and 1669.99 %). Differential scanning calorimetry and thermogravimetric results showed TPP grafting increased the glass transition temperature of ESO-PSA slightly but improved its thermal stability significantly. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance results showed TPP, phosphoric acid, and rosin ester all partially participated in the covalently crosslinking polymerization of ESO-PSAs and the rest existed in the network structures in the free form.

Bio and waste-based binders with hybrid rubberized-thermoplastic characteristics for roofing

Non-bituminous binders with sustainable characteristics have been developed as potential roofing materials. A vegetable colophony rosin ester, waste cooking oil, waste crumb rubber and a blend of recycled high-density polyethylene (HDPE) and polypropylene (PP) have been used for binder formulations. Rheological, calorimetric and technological characterizations have been performed to assess the compatibility among binder components and optimal compositions. Additionally, thermal conductivity, heat capacity and solar radiation tests have been performed on selected non-bituminous and bitumen-based binders. Solar radiation experimental set-up has been simulated by Computational Fluid Dynamics (CFD) in order to get a deeper insight into heat transmission mechanisms involved. A binder formulation composed of 40 wt% maleic-modified rosin ester, 32 wt% waste oil, 20 wt% crumb rubber and 8 wt% recycled HDPE/PP blend has shown suitable mechanical properties and solar behaviour for roofing materials. The use of recycled thermoplastics and elastomers imparts material with a hybrid character, showing enhanced flexibility and softening points, respectively, at low and high in-service temperatures. Its solar behaviour is comparable to that of the modified bitumen, with a similar heat absorption from Sun (about 30 %) but lower heat storage capacity at ambient temperature.

Recent Progress on Catalytic of Rosin Esterification Using Different Agents of Reactant

Gum rosin is an important agricultural commodity which is widely used as a raw material for various industries. However, gum rosin has low stability, crystallizes easily, and tends to oxidize. This is due to carboxyl groups and conjugated double bonds in gum rosin’s structure. Therefore, to reduce these weaknesses, it is necessary to modify the rosin compound to achieve better stability via the esterification process. This paper surveys esterification agents such as glycerol, pentaerythritol, methanol, ethylene glycol, polyethylene glycol (PEG), allyl group, and starch Rosin ester. The product is used in the manufacture of pressure-sensitive adhesives, drug delivery, solder flux for electronic devices, as a plasticizer, and as a coating agent in fertilizers. In general, the esterification reaction between alcohols and carboxylic acids is very slow without a catalyst. Heterogeneous catalysts have the advantage of controlling size, structure, spatial distribution, surface composition, thermal-chemical stability, and selectivity. Among the catalysts for gum rosin esterification are ZSM-5, Fe3O4, ZnO, Calcium, TiO2, Kaolin, and Al2O3, among others. Different catalysts and esterification agents can produce various physical and chemical properties of rosin ester and will result in specific rosin ester products, such as glycerol ester, pentaerythritol ester, methyl ester, glycol ester, allyl ester, and acid starch-based rosin.

Exploring Film Forming Ability of Newly Synthesized Rosin Esters

The present investigation was planned to confirm the film-forming potential of synthesized rosin esters. The free films of rosin esters were prepared by solvent evaporation and characterized for the physicochemical and mechanical attributes. Suitable concentrations of rosin esters were used for coating tablets, and coated tablets were evaluated for official and unofficial quality control tests. The free films had low tensile strength, higher percent elongation value, and smooth surfaces. Therefore, the plasticizer was used to provide tensile strength to the films. The tablets were coated rapidly without agglomeration, confirming the suitability of rosin esters as a coating agent. The drug release from tablets was delayed up to 6 to 8 hours because of 10% w/w coating of rosin ester, and regioselectivity was achieved by coating with hydroxypropyl methylcellulose with sodium bicarbonate. The pH-dependent solubility of rosin esters produces chrono-triggered drug release from coated tablets. The present investigation confirms the suitability of newly synthesized rosin esters in in designing a region selective chrono- triggered drug delivery system.

Pentaerythritol and Glycerol Esters Derived from Gum Rosin as Bio-Based Additives for the Improvement of Processability and Thermal Stability of Polylactic Acid

Gum rosin esters are some of the most common gum rosin derivatives used in different applications, such as coatings, paper, varnishes, chewing gum, and food industries. In this study, gum rosin esters are used as additives for polylactic acid (PLA) to improve its processability and thermal stability. Blends of an amorphous PLA with two different gum rosin esters, pentaerythritol ester and glycerol ester, were prepared by melt extrusion process in concentrations from 1, 3, and 5 phr. Besides the comparison of thermal degradation, microstructure assessment, and melt flow index (MFI) analysis, the processability performance during testing samples production by injection molding process was evaluated. Experimental results showed that MFI values of PLA-gum rosin ester blends increased by 100%, 147%, and 164%, along with increasing content of gum rosin esters addition, in both cases. Also, both derivatives slightly improved PLA thermal stability (around 3ºC higher). Injection molding temperature decreased by at least 20 °C for PLA-gum rosin ester blends compared with neat PLA. Furthermore, the maximum tensile strength of PLA-gum rosin esters was negligibly affected in formulations with low content of gum rosin esters, and the FESEM images revealed a good dispersion and compatibility of gum rosin ester particles into PLA matrix in both concentrations.

Epoxidized Soybean-Oils-Based Pressure-Sensitive Adhesives with Di-Hydroxylated Soybean-Oils Copolymerizing and Antioxidant Grafting.

Vegetable-oils-based pressure-sensitive adhesives (PSAs) are being developed as a substitute for petrochemical-based PSAs for application in daily life. However, vegetable-oils-based PSAs face the problems of unsatisfactory binding strengths and easy aging. In this work, the grafting of antioxidants (tea polyphenol palmitates, caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate (PG), tea polyphenols) was introduced into an epoxidized soybean oils (ESO)/di-hydroxylated soybean oils (DSO)-based PSA system to improve the binding strengths and aging-resistant properties. PG was screened out as the most suitable antioxidant in the ESO/DSO-based PSA system. Under optimal conditions (ESO/DSO mass ratio of 9/3, 0.8% PG, 55% rosin ester (RE), 8% phosphoric acid (PA), 50 °C, and 5 min), the peel adhesion, tack, and shear adhesion of the PG-grafted ESO/DSO-based PSA increased to 1.718 N/cm, 4.62 N, and >99 h, respectively, in comparison with the control (0.879 N/cm, 3.59 N, and 13.88 h), while peel adhesion residue reduced to 12.16% in comparison with the control (484.07%). The thermal stability of the ESO/DSO-based PSA was enhanced after PG grafting. PG, RE, PA, and DSO were partially crosslinked in the PSA system, with the rest being free in the network structures. Thus, antioxidant grafting is a feasible method for improving the binding strengths and aging-resistant properties of vegetable-oils-based PSAs.

Cross-linked self-healing polymers containing rosin moiety based on dynamic urea and multiple hydrogen bonds

In recent years, the use of renewable biomass resources to prepare self-healing polymers has become a hot research topic because of the shortage of fossil resources. Herein, a novel type of rosin-based cross-linked polymer (PR) with dynamic urea and multiple hydrogen bonds is fabricated by copolymerizing a rosin ester with a dynamic crosslinking agent poly(urethane-urea) through a simple UV-initiated reaction. Owing to its robustly dynamic bonds, the resulting PR has both good mechanical properties and ideal self-healing ability. Specifically, the PR with 25.4% biomass rosin reaches a tensile strength of up to 4.1 MPa, an elongation at break of 112%, and stress self-healing efficiency of 91.3% at 80 °C for 24 h. Remarkably, the PR with a glass transition temperature above room temperature exhibits good shape memory behavior and excellent weldability (afford 2500 g after healing at 80 °C for 5 h). Finally, by surface platinum spraying and pre-stretching treatment, strain sensors based on microcracking mechanisms are realized.

Non-bituminous binders formulated with bio-based and recycled materials for energy-efficient roofing applications

Non-bituminous binders have been designed as potential roofing materials with sustainable characteristics. To that end, three bio-based rosin esters (R), a waste cooking oil (O) and a recycled polyethylene from greenhouse agriculture (LDPEr) have been used in their formulations. A comprehensive rheological, microstructural, calorimetric, and technological characterization have been performed on binary (polymer/oil or rosin/oil) and ternary (polymer/rosin/oil) blends, allowing the compatibility among binder compounds to be studied. Additionally, thermal conductivity and solar radiation tests have been conducted on a selected non-bituminous binder and compared with a reference polymer modified bitumen. The formulation composed of 61.0% phenolic-modified rosin, 30.5% oil and 8.5% LDPEr has shown suitable mechanical properties for roofing materials, and has exhibited enhanced energy efficiency derived from its light yellowish to brownish color. Under the experimental radiant flux conditions, surface temperature of the non-bituminous binder was 8 °C lower than that of the black bitumen. Moreover, conduction heat transfer through this roofing material was about 14% lower than that conducted through a bitumen-based membrane with the same thickness. Accordingly, developed binders are expected to behave as reflective building materials aiming to reduce the heat island effects and save energy.

Preparation and Recognition Properties of Molecularly Imprinted Nanofiber Membrane of Chrysin.

The separation and extraction of chrysin from active ingredients of natural products are of great significance, but the existing separation and extraction methods have certain drawbacks. Here, chrysin molecularly imprinted nanofiber membranes (MINMs) were prepared by means of electrospinning using chrysin as a template and polyvinyl alcohol and natural renewable resource rosin ester as membrane materials, which were used for the separation of active components in the natural product. The MINM was examined using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The adsorption performance, adsorption kinetics, adsorption selectivity, and reusability of the MINM were investigated in static adsorption experiments. The analysis results show that the MINM was successfully prepared with good morphology and thermal stability. The MINM has a good adsorption capacity for chrysin, showing fast adsorption kinetics, and the maximum adsorption capacity was 127.5 mg·g−1, conforming to the Langmuir isotherm model and pseudo-second-order kinetic model. In addition, the MINM exhibited good selectivity and excellent reusability. Therefore, the MINM proposed in this paper is a promising material for the adsorption and separation of chrysin.

Preparation and biological evaluation of novel 5-Fluorouracil and Carmofur loaded polyethylene glycol / rosin ester nanocarriers as potential anticancer agents and ceramidase inhibitors

With advancing trends on the applications of nanotechnology to pharmacology, it has been drawn considerable attention towards the development of drug loaded nanocarriers with high performance in drug delivery systems. Herein, novel carmofur (CAR) and 5-fluorouracil (5FU) loaded PEG/rosin-pentaerythritol-ester (RPE) based nanocariers were developed as smart drug delivery systems in cancer therapy. Surface and chemical characterizations of the PEG/RPE-NPs were determined by different techniques such as STEM, DLS, UV–visible, and FTIR. The computer-aided STEM results were utilized for a data analytical characterization using an artificial intelligent approach. Results showed that the nanoformulations had a spherical shape and uniform distributions in the range of 108–204 nm. The cumulative releases (%) were calculated in a different medium (pH:1.2, pH:7.4). In-vitro experimental results showed that 5FU-NPs and CAR-NPs were highly cytotoxic on MCF-7 and MDA-MB-231 breast cancer cells, whereas they had no significant cytotoxicity on normal HUVEC cells. Furthermore, ASAH1, S1P, Bcl-2 expression levels were decreased with CAR-NPs and 5FU-NPs. The novelty of this study was to evaluate in vitro antitumor efficacy and cytotoxicity of the prepared 5FU-NPs and CAR-NPs on MCF-7 and MDA-MB-231 breast cancer cell lines. Consequently, the biological and pharmacological evaluations of nanocarriers showed that they were promising nanomaterials for drug delivery systems in clinical applications.

Impact energy absorption of block copolymer/tackifier blends: Effect of compatibility, viscoelasticity, and laminate structures

AbstractThis work studied the effects of tackifiers on the impact energy absorption properties of block copolymers (BCPs) comprising poly(styrene)‐b‐poly(isoprene)‐b‐poly(styrene) (SIS) and poly(methyl methacrylate)‐b‐poly(n‐butyl acrylate)‐b‐poly(methyl methacrylate) (MAM). A rosin ester resin (RE) and an aliphatic petroleum resin (C5PR) were compared as the tackifiers. Analyses of Hansen solubility parameters and observations using electron microscopy indicated that both tackifiers were highly compatible with the poly(isoprene) component of the SIS, while the RE also showed good compatibility with the poly(n‐butyl acrylate) phase of the MAM. The impact energy absorption characteristics of laminates made by applying layers of BCP/tackifier blends to cured epoxy substrates were evaluated using a pendulum impactor. The extent of energy absorption by these laminates was found to increase within specific tackifier concentration ranges. However, the C5PR showed poor compatibility with the MAM and had almost no effect on the energy absorption of the laminates. The energy absorption of the laminates could be described based on the calculated loss factor,η, determined using the RUK equation including the viscoelastic parameters (both tanδand storage modulus) for the BCP/tackifier blends, considering the time–temperature superposition principle, and for the laminate structures.

Synthesis and evaluation of new coatings based on chemically modified rosin and PMMA for steel substrates

Rosin derivatives used as coatings on a variety of substrates provide electrical insulation and corrosion protection. This paper explores the feasibility of using two chemically modified rosins, which are the glycerol rosin ester (GRE) and GRE-poly(methyl methacrylate) (GRE-PMMA) used as stainless steel coatings to reduce friction and wear rate. The chemical structures of GRE and GRE-PMMA are investigated via FTIR to evaluate frictions and wear characteristics of coated stainless steel-substrates; these are tested on a ball-on-disc tribometer, followed by a careful observation of the obtained surface using an optical microscope. The FTIR results reveal structural differences among rosin, GRE, and PMMA; which relates to the suppression of –COOH groups and the appearance of new –OH and –COOR groups. The GRE and GRE-PMMA coatings on the substrate, reduce the friction coefficient by 49% and 46% (before coating 0.59 and after coating 0.30 and 0.32) and wear rate by 29% and 26% (before coating 6.8 and after coating 4.8 and 5.0) respectively. These findings suggest that GRE and GRE-PMMA are effective coatings as protective agents for stainless-steel substrates due to the attractive forces between the organic molecule and the metal surface.

The Analysis of Lean Manufacturing in Waste Reduction During Rosin Ester Production at PT XYZ

Waste are commonly generated during the utilization of raw materials. Therefore, they are become important to consider lean manufacturing to achieve the overall business objectives. PT XYZ is a major company in processing pine resin and its derivatives, including gum rosin, turpentine and rosin ester, mainly used as featured commodities. During production, a certain amount of unwanted materials in the form of defect and in the form of work-in-process (WIP) that caused waiting wastes are obtained, particularly at the rosin ester floor. This study aims to identify the waste types and their dominant factors that caused waste occurred in PT XYZ, as well as recommend improvement strategies in boosting production efficiency. Based on the identification results, two dominant wastes occurred in the form of defects and waiting. The defect and scrap portions were prevalent in gum rosin drops, flakes, brushed dust and products that did not fulfill color and size specifications at 63.72 kg/shift that equal to 2,08% scrap rate per shift. Meanwhile, waiting waste refers to work-in-process (WIP) on Oleo Pine Resin (OPR) storage and delay interval for a complete sampling process. The WIP circumstance was also observed at the packaging workstation. Furthermore, repairing tank leaks, allocating special workers to flaking workstations, extending workers’ supervision, combining flake cooling and transportation processes, procuring cooling conveyors and increasing the quantity of esterification reactors were recommendations for optimum production. These proposed activities have the capacity to enhance the process cycle efficiency (PCE) value from 4.65 to 6.34%.

Damping and Electromechanical Behavior of Ionic-Modified Brominated Poly(isobutylene-co-isoprene) Rubber Containing Petroleum Resin C5

To improve the damping properties of rubbers, organic tackifiers such as hydrocarbon resins, rosin esters, and polyterpenes are often incorporated to increase the intermolecular friction of the rubber, thus increasing the energy dissipation (damping) during dynamic loading. However, this is often at the expense of the cross-linking density and mechanical properties of the rubbers. Ionic cross-links introduce unique properties to rubbers, such as a combination of mechanical reinforcement and high extensibility, as well as self-healing and damping, thanks to the reversible ionic association. Hence creating an ionic network would be an interesting alternative to adding small molecular tackifiers to rubbers. The reversible ionic association inevitably causes structural instability over time (i.e., creep) or at elevated temperatures (ionic transition generally happens at 60–80 °C). To balance the dynamic damping, viscoelasticity, and mechanical stability of these materials, we prepared 1-vinyl imidazole modified brominated poly(isobutylene-co-isoprene) (BIIR) elastomers by solid-state rubber compounding and curing processes, and we investigated the effects of ionic networks and an aliphatic petroleum resin (C5) on the viscoelastic and electromechanical properties of the ionic-cross-linked elastomers. We found that the mechanical reinforcement can be achieved simultaneously with a broad effective damping temperature range through optimizing the ionic network and C5 concentrations. The polar ionic clusters also increased the dielectric permittivity while maintaining a low dielectric loss of the elastomers. The ionic modified BIIR exhibited actuation and energy harvesting properties similar to those of the commercial VHB-4910 elastomer under similar configurations, which provides alternative dielectric elastomers with reprocessability for vibration and energy harvesting applications.

Development and evaluation of a hydrogenated rosin (β-acryloxyl ethyl) ester–bonded silica stationary phase for high-performance liquid chromatography separation of paclitaxel from yew bark

Paclitaxel (PTX) is a complex diterpenoid anticancer drug whose separation from yew biomass poses a significant challenge. In this study, a new stationary phase comprising hydrogenated rosin (β-acryloxyl ethyl) ester (HRE)–bonded silica (HRE@SiO2) is developed to separate and purify PTX from crude yew-bark extract using high-performance liquid chromatography. In HRE@SiO2, HRE molecules, which are functional ligands, are bonded to the surface of a silica gel matrix using a coupling agent, (3-mercaptopropyl)trimethoxysilane. The proposed HRE@SiO2 stationary phase was characterized by Fourier-transform infrared spectroscopy, elemental analysis, thermogravimetric analysis, scanning electron microscopy, laser diffraction granulometry, and nitrogen gas adsorption. The HRE@SiO2 column exhibited excellent chromatographic performance, satisfactory performance reproducibility, and typical reversed-phase chromatographic behavior. An HRE@SiO2 column was used to separate PTX and its analogs, achieving resolutions exceeding 7.43 for consecutively eluted species. Stoichiometric displacement theory for retention (SDT-R), the van Deemter equation, and van 't Hoff plots were used to analyze the separation mechanism and properties of the HRE@SiO2 column. The results showed that hydrophobic interactions determine the analyte retention and the separation of PTX and its analogs on an HRE@SiO2 column is an exothermic process driven by enthalpy. Furthermore, an HRE@SiO2 column was employed to separate and purify PTX from crude yew-bark extract, increasing PTX purity from 6% to 82%. The findings of this study provide insights for developing rosin-based stationary phases for the separation of natural products.

Characteristics and Kinetics Study of Glycerolabietate from Glycerol and Abietic Acid from Rosin

Rosin is a natural resin from the coniferous tree sap, which separated from its oil content (terpenes). Rosin is brittle. Therefore modifications are needed to improve its mechanical properties. The main content of rosin is abietic acid which has a carboxylic group, so it can form an ester group when reacted with polyhydric alcohol (polyalcohol) such as glycerol. The research aimed to study the kinetics of the esterification reaction between the hydroxyl group in glycerol and the carboxylic group in abietic acid from rosin at various reaction temperatures and reactant compositions. This reaction is carried out in a three-neck flask at atmospheric pressure without a catalyst. The reaction temperatures used were 180˚C, 200˚C, and 220˚C, and the ratio of rosin and glycerol was 1:1, 1:3, and 1:5. The reaction kinetics calculations were analyzed with acid number data over the reaction time using three different models. The calculations showed that this reaction involves positioning a hydroxyl group on glycerol, which the primary and secondary hydroxyl groups contribute to forming a rosin ester (glycerolabietate). The rate of reaction constants of primary hydroxyl of glycerol and abietic acid were in the range 6.25x10-4 - 3.90x10-3 g/(mgeq.min), while reaction rate constants of secondary hydroxyl and abietic acid were in the range 1.06x10-5 - 1.15x10-4 g/(mgeq.min). FTIR analysis showed a change in the hydroxyl, carboxylate, and ester groups which were assigned by a shift of wavenumber and a difference of intensity at 3200-3570 cm-1, 1697.36 cm-1, and 1273.02 cm-1.

Characterization and evaluation of novel sustainable polymers derived from renewable rosin

PurposeThis study aims to prepare low-cost biomaterials from renewable natural resources (rosin).Design/methodology/approachPreparation of different biomaterials, ethylene glycol maleic rosin (EGMR), glycerol maleic rosin, pentaerythritol maleic rosin and sorbitol maleic rosin (SMR) esters, then evaluated by stability studies, moisture absorption, swelling index parameters, thermogravimetric analysis and skin irritation studies.FindingsThe prepared rosin derivatives had excellent moisture safety, according to the results. From EGMR to SMR, the swelling indices increase.Research limitations/implicationsThese rosin biomaterials were used in coating, especially in the field of pharmaceutical coating, and good results were obtained in this study.Practical implicationsAs these biomaterials rosin derivatives have excellent moisture resistance, they are recommended for use as coating materials for moisture-sensitive drugs.Originality/valueThere has recently been a lot of interest in researching the effects of rosin derivatives in various drug delivery systems.

Phase structure and adhesion properties of acrylic block copolymer/tackifier blends as nanocomposite‐like pressure‐sensitive adhesives

AbstractIn a blend of acrylic block copolymer consisting of poly(methyl methacrylate) and poly(n‐butyl acrylate) blocks and a special rosin ester resin (RE) tackifier as a model pressure‐sensitive adhesive (PSA), RE exists in two states: as nm‐sized agglomerated particles (A) and as dissolved molecules (B). The effect of A and B ratio on the PSA properties were investigated using REs with four different weight‐average molecular weights (Mws) in the range from 680 to 1700. The formation of A increased with increasing of Mw because of lowering of miscibility. The glass transition temperature increased with increasing of Mw. The tack at lower temperatures and the fracture energy were improved by B, whereas the tack at higher temperatures was improved by A. A and B enhanced the cohesive strength and the wettability of PSA, respectively. However, the improvement of cohesive strength by the RE with highest Mw was remarkably low. This seems to be caused by the larger size of agglomerated particles. 1H pulse nuclear magnetic resonance analysis was useful for estimating the degree of A formation. The model PSA investigated in this study was nanocomposite‐like.

Stress-Strain and Stress-Relaxation Behaviors of Solution-Coated Layers Composed of Block Copolymers Mixed with Tackifiers.

The relationship between the mechanical properties and the structure of block copolymers mixed with tackifiers whose relative solubility to the respective components of block copolymers differs was examined. Coated layers were prepared by solution coating using a block copolymer composed of polystyrene (PS) and polyisoprene (PI), which forms spherical microdomains of PS in the PI matrix, mixed with three types of tackifiers: aliphatic (C5) resin, aliphatic–aromatic (C5–C9) resin, and rosin ester (RE) resin. Furthermore, the correlation between the changes in the nanostructure and mechanical properties including the stress-relaxation behaviors was clarified by two-dimensional small-angle X-ray scattering measurement. The amount of the PI-bridge conformation in the case of C5 resin is the lowest, resulting in the lowest stress. On the contrary, the largest amount of RE resin was solubilized in the PS phase so that it can be considered that pulling out of the PS chains took place easily. We were able to explain the stress-relaxation behavior by fitting with the three-component exponent functions. The triple exponential decay functions indicate the hierarchy of the structures that are the origins of the ″fast mode″ relating to the local relaxation due to the rotation of the repeating unit of polymer chains; the ″intermediate mode″ of the disentanglement of the mid-PI chains; and the ″slow mode″ relating to, in this particular case, pulling out of the PS chains from the PS sphere.