Abstract
Solvent-free and highly branched water-soluble polyester (WPET) is prepared through self-emulsification methodology, using dimethyl terephthalate (DMT), sodium dimethyl isophthalate-5-sulfonate (SIPM), trimethylolpropane (TMP), and ethylene glycol (EG) by the transesterification and polycondensation. The WPET were first utilized as surface-sizing agents for cellulose fiber paper. The structure, average molecular weights, and physical properties of the water-soluble polyester were characterized by FTIR, 1H NMR, gel permeation chromatography (GPC), dynamic light scattering (DLS), X-ray diffraction (XRD), and dynamic rheometer. The effects of polymer structure and properties, as well as the surface sizing of the paper, were investigated. WPET displayed better surface sizing properties when it was prepared under the following conditions: –COO/–OH molar ratio of 1:2, the SIPM content of 17.98%, and TMP content of 11.10%. The relationships between the WPET structure and sized paper were clearly illustrated. The mechanical properties and water resistance of sized paper did not only depend on multi-branched hydroxyl groups of the WPET chains but also relied on the interactions among polymers and fibers, as well as the high toughness of surface sizing agent. The sizing paper possesses excellent mechanical properties as well as water resistance.
1 Introduction
Water-soluble polyesters (WPETs) are widely used as fundamental materials for preparing the dye, water-soluble chemical fiber (1,2,3,4,5), and many other materials. As the existence of similar groups to polyester, water-soluble polyesters can bond well with polyester fibers and are capable to improve its adhesion to fibers. Water-soluble polyesters have a better sizing performance than other normal compounds such as starch, polyvinyl alcohol, and polyacrylic acid. Hence, the synthesis of water-soluble polyesters has been the focus of research in relevant fields (6,7,8). It has good water solubility due to the introduction of hydrophilic groups into the molecular structure, which not only meets the needs of sizing but also is easy to desizing. Water-soluble polyesters can reduce viscosity and improve liquidity, which is quite suitable for the surface sizing agent (9,10). At the same time, solvent-free synthesis can reduce not only costs but also harmful gas emissions. The water-soluble polyesters with multichain hydroxyl groups have more polar groups. Thus, they can react with the hydroxyl groups on the paper fibers to form hydrogen bonds. In summary, the water-soluble polyester is used as a paper surface sizing agent to improve various properties of the paper.
Surface sizing is a cost-effective and efficient roll-to-roll manufacturing technique widely used in the paper industry to improve the physical properties of paper, including surface strength, wet ability, surface morphology, and barrier properties (11,12). The most widely used surface sizing agent in papermaking is polyvinyl alcohol (PVA) (13,14,15) due to excellent transparency, elasticity, and high strength. However, a single PVA film can be poor in heat resistance, water resistance, paper strength, and surface properties (16). Moreover, PVA has poor biodegradability and relatively large environmental pollution (16). Water-soluble polyester has water-soluble, stable colloidal dispersion, solubility, good film-forming, hygroscopic, heat resistance, thermal viscosity (17), and excellent mechanical properties, which can well meet the requirements of paper surface sizing. Water-soluble polyester contains an organic macromolecular structure capable of having high adhesion to the fiber macromolecules. At the same time, polar groups of water-soluble polyester react with the hydroxyl group on the paper fiber. After drying, hydrogen bonds are formed to form a network structure of plant fibers, resulting in the increase of the strength of paper and other physical properties. In conclusion, applying the water-soluble polyester to the surface sizing of paper can not only improve the various properties of paper but also contribute to environmental protection. It is a new type of environmentally friendly surface sizing agent. Currently, the application of water-soluble polyester on paper surface sizing has not been reported.
In this article, solvent-free multibranched water-soluble polyester was prepared by introducing trimethylolpropane and adopting a two-step transesterification-co-polymerization method, which increases the activity of water-soluble polyester. Hence, the toughness of the polymer and the ability to form hydrogen bonding with fiber hydroxyl are increased. The prepared water-soluble polyester is first applied to the paper surface sizing, providing a new idea for the research and development of the surface sizing agent. The properties of WPET are investigated based on the average relative molecular weight, dynamic light scattering (DLS), and rheology. Subsequently, the paper features are studied by testing folding endurance, tear resistance, deflection, tensile index, and contact angle. Finally, the surface sizing process is studied through SEM.
2 Materials and methods
2.1 Materials
Dimethyl terephthalate (DMT, >99%), sodium dimethyl isophthalate-5-sulfonate (SIPM, >99%), trimethylolpropane (TMP, >99%), and ethylene glycol (EG, >99%) were analytically pure and purchased from Shanghai McLean Biochemical Technology Co. Ltd. N,N-Dimethyl ethanolamine (DMEA, >99%) were analytically pure and purchased from Tianjin Fuchen chemical reagent factory. All the solutions were prepared in distilled water.
2.2 Synthesis of water-soluble polyester (WPET)
WPET was synthesized according to the reaction pathway presented in Scheme 1. The synthesis of the water-soluble polyester was performed through two steps of transesterification and polycondensation. In the first step, DMT, SIPM, EG, and TMP as monomers with catalysts of dibutyltin oxide were placed in a 500 mL three-neck flask equipped with a magnetic stirrer and a thermometer. The mixture was heated in an oil bath at 180°C until dissolved. Then, the mixture was reacted for 1 h with methanol flowing out. Finally, the temperature of the mixture was gradually increased to 190°C and was held there for 4 h until no methanol flowed out. The esterification reaction was completed.

Schematic of the synthesis of WPET.
In the second step, the mixture was heated to 200°C and stirred for 1 h. Then, the pressure in the reactor was reduced to about 100 Pa. Meanwhile, the mixture was heated to 210°C and reacted for 1 h until no diols flowed out. After determination, the distillate of diol was about 30 mL. The reaction stopped. Finally, the viscous product obtained was decanted into a ceramic bowl and cooled to a hard tough resin.
According to our experiments and the following conditions: –COO/–OH molar ratio of 1:2, we synthesized four water-soluble polyesters with different raw material ratios, which are presented in Table 1.
Proportion of raw materials
| Product number | SIPM (mol) | DMT (mol) | TMP (mol) | EG (mol) |
|---|---|---|---|---|
| WPET1 | 3.5 | 6.5 | 1 | 19 |
| WPET2 | 3 | 7 | 2 | 18 |
| WPET3 | 2.5 | 7.5 | 3 | 17 |
| WPET4 | 2 | 8 | 4 | 16 |
2.3 The dispersing process of water-soluble polyester solution
Twenty milliliters of distilled water and 0.2 g dry WPET were added into a 50 mL three-neck flask and stirred. The mixture was heated to 90°C and maintained at the temperature under stirring to dissolve the sample. Finally, N,N-dimethyl ethanolamine was added into the WPET solution to adjust the pH to 7, which was to meet the paper surface sizing requirements.
2.4 Surface sizing of cellulose fiber paper
A sheet of pristine 80 g/cm2 cellulose fiber paper was placed on the working plate of an ST-1-260 coater (Shaanxi University of Science and Technology, China). Before surface sizing, the paper sheet was firmly pressed onto the working plate to prevent any folding or curling and was then fixed. Next, the sizing solution was poured on one side of the paper sheet, and a coating roller was used at a constant rate of 3.0–4.0 mm/s for the purpose of sizing the paper uniformly. The sized paper sheet was dried for 5 min at 100°C. The sizing schematic diagram is shown in Figure 1.

Schematic diagram of water-soluble polyester sizing solution sizing on paper surface.
2.5 Characterization of water-soluble polyester (WPET)
Fourier transform infrared (FTIR) spectra were recorded on an FTIR spectrometer (VECTOR-22, Bruker) in the range of 4,000–500 cm–1 using the KBr pellet technique (resolution = 4 cm–1, number of scans = 10).
The 1H NMR spectra were recorded on a Bruker AVANCE-400 MHZ nuclear magnetic resonance (Bruker, Germany) using dimethyl sulfoxide (DMSO) as solvent of the water-solution polyester.
The molecular weight was determined by a waters/1,515 gel permeation chromatography (GPC). Dimethylformamide (DMF) was used as a solvent, and polystyrene standards were used for calibration.
The Zetasizer nano-ZS90 laser light scatterer was used to measure the particle size and particle size distribution of the emulsion (Malvern, UK). The test temperature was 25°C. The laser angle was 90°, and the laser wavelength was 633 nm.
The Ultima IV X-ray powder diffractometer (Nippon Science Co, Ltd) was used to measure the diffraction peak of water-soluble polyester with a step length of 0.02° with the range from 5° to 50°.
The AR2000ex dynamic rheometer was used to measure the viscosity curve and flow curve of 20% water-soluble polyester emulsion at 30°C, 60°C, and 90°C. The shear rate range was 10–200 s−1.
2.6 Characterization of the sized cellulose fiber paper
The sized cellulose fiber paper characteristics are as follows:
For each folding endurance test, seven specimens (15 × 100 mm2) were prepared, and all tests were performed on an YQ-Z-31 vertical folding tester (Sichuan Changjiang Paper Instrument, China).
For each tear resistance test, seven specimens (63 × 75 mm2) were prepared, and all tests were performed on an SLD-J paper tear degree tester (Sichuan Changjiang Paper Instrument, China).
For each deflection test, seven specimens (70 × 38 mm2) were prepared, and all tests were performed on a Derrick DRK106 paper board stiffness tester (Sichuan Changjiang Paper Instrument, China).
For each tensile index test, seven specimens (250 × 15 mm2) were prepared, and all tests were performed on a ZL-100A/300A paper and cardboard tensile testing machine (Sichuan Changjiang Paper Instrument, China).
For each contact angle test, seven specimens (10 × 15 mm2) were prepared, and all tests were performed on a Static drop contact angle tester.
The papers without sizing and after sizing were cut into 100 × 100 mm2. The weight of the paper without sizing was determined as w 0, and the weight of the paper after sizing was determined as w. Then, the paper dried to the constant weight in an oven at 105°C. The glue-hanging quantity in the paper was calculated according to Eq. 1:
The surface and cross-sectional morphology of the paper sheets were observed on an environmental scanning electron microscope (SEM; s-4800 Hitachi, Tokyo, Japan). All of the samples were coated with gold under a vacuum before SEM observation.
3 Results and discussion
3.1 Water-soluble polyester properties
3.1.1 FTIR and 1H NMR analysis
WPET3 sample was used for testing the IR and 1H NMR spectrum of WPET. The IR spectrum of WPET and SIPM is shown in Figure 2. The infrared spectrum of SIPM is shown in Figure 2a. The stretching vibration peak of the ester group (C═O) is at 1,735 cm−1. The peak of out-of-plane bending absorption of (C–H) on the aromatic ring is at 752 cm−1. The peaks at 1,228, 1,138, and 1,049 cm−1 are the characteristic absorption peaks of S═O of sulfonic acid groups. The infrared spectrum of WPET is shown in Figure 2b. The absorption peaks with a broad distribution at 3,608 and 3,278 cm−1 are the alcoholic hydroxyl groups. The peaks at 2,954 and 2,887 cm−1 are attributed to the –CH3, –CH2–, and tertiary alkyl groups, indicating that trimethylolpropane is polymerized to the molecular chain. The absorption peaks of carboxylic acid ester (C═O) on the aromatic ring are at 1,720, 1,460 cm−1. The peak of out-of-plane bending absorption of (C–H) on the aromatic ring is at 752 cm−1. The absorption peaks with strong bands are at 1,271, 1,121, and 1,028 cm−1, which showed the absorption peak of S═O in WPET (26), which could be regarded as the presence of –SO3Na that could improve the water solubility of WPET and contribute to its better performance in sizing.

FTIR spectra of WPET.
Figure 3 shows the 1H NMR spectra of water-soluble polyesters. The resonance overlapping peaks of para-disubstituted and meta-substituted hydrogen on the benzene ring appear at 8.09 and 8.41 ppm, respectively. The absorption peak of active hydrogen hydroxyl hydrogen appears at 4.97 ppm. The proton peaks of the near carbonyl group of trimethylolpropane and ethylene glycol appear at 4.66 and 4.32 ppm, respectively. The absorption peaks of hydrogen on a methylene carbon bonded to the hydroxyl group appear at 4.51 and 3.72 ppm, respectively. The hydrogen on the methylene carbon and hydrogen on the terminal methyl group of trimethylolpropane appear at 1.36 and 0.91 ppm, respectively. Based on the spectra, it can be concluded that the target product (WPET) is successfully prepared (28,29).

1H NMR spectra of WPET.
3.1.2 Average molecular weight and particle size of WPET
The molecular characteristics of water-soluble polyesters are presented in Figure 4. For polymer solutions, weight-average molecular weight (M w) represents the average molecular weight per unit weight. The values of M w are shown in Figure 4. It can be revealed that the M w decreased from 19,143 to 8,731 g/mol when the SIPM content increased from 16.43% to 23.95%, as expected for the synthesis method used. This is due to the increase of steric resistance caused by the mesosulfonic acid group of SIPM, resulting in drop of the polymerization degree. Meanwhile, the smaller molecular weight is beneficial to permeate the paper fiber (18) and to make the physical crosslinking effect of surface sizing solution on paper fiber more obvious.

Average molecular weight at different mass concentrations of SIPM.
In this study, sodium sulfonate (–SO3Na) in the SIPM unit is a strong ionic group that exhibits high polarity. The amount of –SO3Na ionic groups changes therewith. This directly leads to the variation of WPET polarity and the interaction of WPET molecules and water, which allow the homogeneous dispersion in water. Favorable water solubility of a sizing agent is good for uniform dispersion of WPET molecules in water and is conducive to the surface sizing. The better the dispersibility in water, the smaller the particle size of the solution. Figure 5 shows the effects of the SIPM content on the particle size. It is clear that the particle size of the WPET solution decreases from 220.2 to 126.2 nm and decreases first and then increases with the increasing SIPM content. However, the particle size of the WPET solution reaches a minimum of 126.2 nm when the SIPM content is 17.98%. It can be ascribed that the sodium sulfonate (–SO3Na) in SIPM is present in small quantity, and SIPM will have difficulty dissolving. Nevertheless, when the amount of is more than 17.98%, the particle size increases. It may be due to the larger steric hindrance of the sulfonate group, which reduces the solubility. Meanwhile the much sulfonic acid groups will add more hydrophilic chain segments, resulting in poor water-resistance after surface sizing.

Particle size of emulsion at different mass concentrations of SIPM.
To sum up, SIPM mole is 2.5 mol (SIPM mass concentration is 17.98%) and DMT mole is 7.5 mol.
3.1.3 Crystallization properties
The XRD patterns of different content of TMP are shown in Figure 6. In agreement with the literature, WPET shows main diffraction peaks at 21.03, assignable to (021) reflection planes of the a-form crystal (19,20) when the molar number of TMP is 1 and 2. Conversely, as the TMP content increases, the diffraction peak intensity of WPET decreases, showing patterns typical of an amorphous polymer. In conclusion, the decreasing crystallinity is due to the destruction of the original linear molecular chain structure and the formation of the branched structure. The branching structure destroys the regularity of the molecular chain and weakens the movement ability of the chain segment, resulting in a decreased crystallization rate. According to the previous studies (24,25), increasing the flexibility of polymer segments and reducing the crystallinity of polymers are effective methods to improve polymer toughness, resulting in an enhancement of the strength of the paper. Therefore, TMP mole is 3 mol (TMP mass concentration is 11.10%) and EG mole is 17 mol.

XRD patterns of different contents of TMP.
3.1.4 Rheological behavior
At a certain shear rate, the flow of water-soluble polyester solution conforms to the power law (Ostwald–de Waele) model, namely,
where τ is shear stress (Pa). γ is the shear rate (s−1), K is the viscosity coefficient, and n is the flow exponent. Taking the logarithm of both sides of Eq. 2 can yield the following equation:
WPET3 sample was used for testing the rheological behavior of WPET. Figures 7 and 8 show, respectively, viscosity curves and rheological curves of water-soluble polyester solutions. Combined with Table 2 and Figure 7, it can be seen that the regression coefficient (R 2) of water-soluble polyester solutions at different temperatures is close to 1. It is indicated that the Ostwald–de Waele model can be used to describe the rheological behavior of water-soluble polyester solutions. Figure 8 shows that the viscosity of water-soluble polyester solution decreases with the increase of the shear rate. Furthermore, it indicates that water-soluble polyester solution presents shear thinning behavior and is a typical pseudoplastic fluid, which is conducive to the sizing process of the paper surface (21,22).

Viscosity of WPET at different temperatures.

Rheological of WPET at different temperatures.
Rheological parameters of WPET at different temperature
| Temperature (°C) | n | k | R 2 |
|---|---|---|---|
| 30 | 0.42 | 5.36 | 0.99517 |
| 60 | 0.47 | 3.98 | 0.99976 |
| 90 | 0.59 | 2.21 | 0.99836 |
Figure 8 shows that the relationship between lgτ and lgγ is linear, which is in line with the characteristics of pseudo-plastic fluids. At the same time, as the flow index n increases with the increase of temperature, the flow performance will increase. It can be ascribed to the molecular chain section containing hydrophobic chain of dimethyl terephthalate. The hydrophobic chain joints are arranged in a curly conformation in water and will aggregate with each other due to the hydrophobic action, which indicates certain microscopic heterogeneity. As the temperature increases, the thermal movement of hydrophobic segments increases and the hydrophobic effects are weakened. Meanwhile, the hydrophobic microzone is vulnerable to shear failure and the crimp conformation is easy to stretch in the shear flow field (27). Therefore, the flow degree and flow index n increase. In Table 2, it is clear that the consistency coefficient (k) decreases with the temperature increases, which indicates the decrease of the fluid viscosity. Therefore, the retention of the water-soluble polyester fluid on the paper can be increased, which affects the strength of the paper and other physical indicators.
3.2 Surface sizing agent strengthening mechanism
Water-soluble polyester contains the organic macromolecular structure and the existence of highly branched hydroxyl. Simultaneously, the paper fiber has more hydroxyl groups. Hydroxyl groups on water-soluble polyester combine with hydroxyl groups on paper fiber to form hydrogen bonding force, which can improve the adhesion strength of the fiber and shorten the distance between the fibers to form a dense mesh structure. The strength of the paper and waterproof performance and other properties of paper are improved. Subsequently, WPET3 sample was used for testing the paper performance.
3.2.1 Effects on paper performance
Figure 9a and b show the effects of different WPET mass concentrations on the properties of sized paper. The water-resistance and mechanical properties of sized paper are improved with the appropriate mass concentration of WPET. It is clear that the mechanical properties (folding endurance, tear resistance, deflection, and tensile index) of sized paper increase first and then slightly decrease with the increasing WPET mass concentration. It can be observed that hydroxyl groups on water-soluble polyester increase with the increasing WPET mass concentration. Hydrogen bonding force combining with hydroxyl groups is increased. Thus, it can improve the adhesion strength of the fiber and decrease the distance between the fibers to form a more dense mesh structure. In addition, more dense mesh structure has better resistance to an external extension force, and the strength of the joint between the fibers can be improved, resulting in the improved tensile strength, tear resistance, and other surface strengths.

Mechanical properties of paper at different WPET mass concentrations: (a) folding endurance and deflection and (b) tear resistance and tensile index.
However, the mechanical properties of sized paper slightly decrease when WPET mass concentration is larger than 4% (relatively to dry pulp) since it may react with the hydroxyl group on PVA to produce a self-crosslinking phenomenon, resulting in difficulties to penetrate into the paper. The folding strength decreases slightly from 115 to 105 times when WPET mass concentration is more than 4% (relatively to dry pulp), owing to the increased self-crosslinking and rigidity.
The graph of the paper contact angle with different WPET mass concentrations is shown in Figure 10. As WPET mass concentration increases, the paper contact angle continues to increase first and then slightly decreases (range from 60.96° to 85.95°). The sizing paper displays the optimum water resistance when WPET mass concentration is 4% (relatively to dry pulp). The phenomena prove that the paper water resistance enhances with the appropriate WPET mass concentration, which can be ascribed to the increase of the ester group content and the hydrophobic groups, resulting in their tight alignment outward and formation of a low energy surface on the surface of the paper. In addition, the water-soluble polyesters have a macromolecular structure similar to fibers, which can increase the adhesion to fibers (23) and decrease the fiber-to-fiber distance to form a firm and tight mesh structure, resulting in an improved water resistance.

Contact angle of paper at different WPET mass concentrations.
3.2.2 Effects of temperature
The glue-hanging quantity in the paper of WPET and PVA sizing fluid with different temperatures are shown in Figure 11. It can be seen that the glue-hanging quantity in the paper of WPET and PVA gradually increases and then slightly decreases when there is an increase in the temperature. Meanwhile, glue-hanging quantity in the paper of WPET is better than PVA. The viscosity of PVA or WPET sizing solution decreases with the increase of the temperature. A lower viscosity is conducive to a better sizing. It is also observed that the hydrogen bonding between PVA and water molecules weakens at the sizing temperature of 80°C, which makes the water solubility become worse. At the same time, some PVA molecules will collect on the surface of the aqueous solution to form a small amount of skinning, which can reduce the glue-hanging quantity in the paper. However, the water-soluble polyesters sizing solution presents a light blue, nonflocculating fluid at 80°C and has a low viscosity, which can increase the glue-hanging quantity in the paper. But the viscosity is too low when the water-soluble polyesters sizing solution is higher than 80°C, which will affect the sizing percentage.

Glue-hanging quantity in the paper of WPET and PVA sizing fluid at different temperatures.
3.2.3 Morphology analysis
Figure 12 shows surface SEM morphology of original paper and sized paper. It can be observed that the space between the fibers is large on the original paper. The distance of fibers in paper sized with WPET dispersion becomes tight, suggesting that a dense mesh structure is able to form on the surface of the paper. In addition, a homogeneous film of WPET can be formed on the surface of the paper, and the gap between fibers is filled with WPET. These phenomena indicate that WPET is able to penetrate into the paper, improve the adhesion strength of the fiber, and enhance the bond strength between fibers.

SEM surface morphology of unsized paper (a) and sized paper (b) at different magnification.
4 Conclusions
By introducing trimethylolpropane and adopting a two-step transesterification-co-condensation polymerization method, solvent-free multi-branched water-soluble polyester was prepared at high temperature. The properties of WPET and its surface strengthening mechanisms are studied. The average relative molecular weight of the obtained polymer is 9,632, the particle size of the water-soluble polyester microemulsion is 126.2 nm, and the dispersion coefficient is 0.010 when the mass concentration of sodium dimethyl isophthalate-5-sulfonate (SIPM) is equal to 17.98%. WPET solution exhibits good dispersion and stability. With the increase of the TMP content, the crystallization rate of polyester decreases, showing patterns typical of an amorphous polymer. The viscosity of water-soluble polyester solution decreases with the increase of shear rate and the temperature. The flow performance increases and the consistency coefficient decreases with the increase of temperature, suggesting that WPET solution is a pseudoplastic fluid and conducive to the sizing process of the paper surface. The glue-hanging quantity in the paper of WPET and PVA gradually increases and then slightly decreases with the increase in temperature. At the temperature of 80°C, the water-soluble polyesters sizing solution exhibits good stability and the glue-hanging quantity in paper attains 5.95%.
In this study, trimethylolpropane is introduced in the synthesis of polyester, which can improve the activity of polymer and enhance the ability of forming hydrogen bonding with fiber hydroxyl. The prepared water-soluble polyester is used for paper surface sizing for the first time. The mechanical property of paper is studied under the different mass concentrations of WPET. When the ratio of the mass concentration of WPET (relatively to dry pulp) is 4%, the sizing paper mechanical properties reach the optimum. Compared with pure PVA, the sizing paper mechanical properties clearly enhanced. Finally, the surface sizing process is studied through SEM. Compared with the original paper, the sizing paper forms a homogeneous film and a dense mesh structure on the surface of the paper, resulting in enhancing the bond strength between fibers.
Acknowledgements
We would like to acknowledge financial support from the Natural Science Foundation of China (5160030644), the Scientific Research Fund of Shaanxi University of Science and Technology (2016QNBJ-15), and the Scientific Research Fund of Shaanxi Provincial Education Department (17JK0101).
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© 2021 Wangwang Duan et al., published by De Gruyter
This work is licensed under the Creative Commons Attribution 4.0 International License.
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- Gel point determination of gellan biopolymer gel from DC electrical conductivity
- Composite of polylactic acid and microcellulose from kombucha membranes
- Synthesis of highly branched water-soluble polyester and its surface sizing agent strengthening mechanism
- Fabrication and characterization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) modified with nano-montmorillonite biocomposite
- Fabrication of N-halamine polyurethane films with excellent antibacterial properties
- Formulation and optimization of gastroretentive bilayer tablets of calcium carbonate using D-optimal mixture design
- Sustainable nanocomposite films based on SiO2 and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) for food packaging
- Evaluation of physicochemical properties of film-based alginate for food packing applications
- Electrically conductive and light-weight branched polylactic acid-based carbon nanotube foams
- Structuring of hydroxy-terminated polydimethylsiloxane filled by fumed silica
- Surface functionalization of nanostructured Cu/Ag-deposited polypropylene fiber by magnetron sputtering
- Influence of composite structure design on the ablation performance of ethylene propylene diene monomer composites
- MOFs/PVA hybrid membranes with enhanced mechanical and ion-conductive properties
- Improvement of the electromechanical properties of thermoplastic polyurethane composite by ionic liquid modified multiwall carbon nanotubes
- Natural rubber latex/MXene foam with robust and multifunctional properties
- Rheological properties of two high polymers suspended in an abrasive slurry jet
- Two-step polyaniline loading in polyelectrolyte complex membranes for improved pseudo-capacitor electrodes
- Preparation and application of carbon and hollow TiO2 microspheres by microwave heating at a low temperature
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- Study on preparation and properties of bentonite-modified epoxy sheet molding compound
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- Applying design of experiments (DoE) on the properties of buccal film for nicotine delivery
- Preparation and characterizations of antibacterial–antioxidant film from soy protein isolate incorporated with mangosteen peel extract
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- In situ polymerization of PEDOT:PSS films based on EMI-TFSI and the analysis of electrochromic performance
- Effect of laser irradiation on morphology and dielectric properties of quartz fiber reinforced epoxy resin composite
- The optimization of Carreau model and rheological behavior of alumina/linear low-density polyethylene composites with different alumina content and diameter
- Properties of polyurethane foam with fourth-generation blowing agent
- Hydrophobicity and corrosion resistance of waterborne fluorinated acrylate/silica nanocomposite coatings
- Investigation on in situ silica dispersed in natural rubber latex matrix combined with spray sputtering technology
- The degradable time evaluation of degradable polymer film in agriculture based on polyethylene film experiments
- Improving mechanical and water vapor barrier properties of the parylene C film by UV-curable polyurethane acrylate coating
- Thermal conductivity of silicone elastomer with a porous alumina continuum
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- Topical Issue: (Micro)plastics pollution - Knowns and unknows (Guest Editor: João Pinto da Costa)
- Simple pyrolysis of polystyrene into valuable chemicals
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- In situ photo-crosslinking hydrogel with rapid healing, antibacterial, and hemostatic activities
- A novel CT contrast agent for intestinal-targeted imaging through rectal administration
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Articles in the same Issue
- Research Articles
- Research on the mechanism of gel accelerator on gel transition of PAN solution by rheology and dynamic light scattering
- Gel point determination of gellan biopolymer gel from DC electrical conductivity
- Composite of polylactic acid and microcellulose from kombucha membranes
- Synthesis of highly branched water-soluble polyester and its surface sizing agent strengthening mechanism
- Fabrication and characterization of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) modified with nano-montmorillonite biocomposite
- Fabrication of N-halamine polyurethane films with excellent antibacterial properties
- Formulation and optimization of gastroretentive bilayer tablets of calcium carbonate using D-optimal mixture design
- Sustainable nanocomposite films based on SiO2 and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) for food packaging
- Evaluation of physicochemical properties of film-based alginate for food packing applications
- Electrically conductive and light-weight branched polylactic acid-based carbon nanotube foams
- Structuring of hydroxy-terminated polydimethylsiloxane filled by fumed silica
- Surface functionalization of nanostructured Cu/Ag-deposited polypropylene fiber by magnetron sputtering
- Influence of composite structure design on the ablation performance of ethylene propylene diene monomer composites
- MOFs/PVA hybrid membranes with enhanced mechanical and ion-conductive properties
- Improvement of the electromechanical properties of thermoplastic polyurethane composite by ionic liquid modified multiwall carbon nanotubes
- Natural rubber latex/MXene foam with robust and multifunctional properties
- Rheological properties of two high polymers suspended in an abrasive slurry jet
- Two-step polyaniline loading in polyelectrolyte complex membranes for improved pseudo-capacitor electrodes
- Preparation and application of carbon and hollow TiO2 microspheres by microwave heating at a low temperature
- Properties of a bovine collagen type I membrane for guided bone regeneration applications
- Fabrication and characterization of thermoresponsive composite carriers: PNIPAAm-grafted glass spheres
- Effect of talc and diatomite on compatible, morphological, and mechanical behavior of PLA/PBAT blends
- Multifunctional graphene nanofiller in flame retarded polybutadiene/chloroprene/carbon black composites
- Strain-dependent wicking behavior of cotton/lycra elastic woven fabric for sportswear
- Enhanced dielectric properties and breakdown strength of polymer/carbon nanotube composites by coating an SrTiO3 layer
- Analysis of effect of modification of silica and carbon black co-filled rubber composite on mechanical properties
- Polytriazole resins toughened by an azide-terminated polyhedral oligomeric silsesquioxane (OADTP)
- Phosphine oxide for reducing flammability of ethylene-vinyl-acetate copolymer
- Study on preparation and properties of bentonite-modified epoxy sheet molding compound
- Polyhedral oligomeric silsesquioxane (POSS)-modified phenolic resin: Synthesis and anti-oxidation properties
- Study on structure and properties of natural indigo spun-dyed viscose fiber
- Biodegradable thermoplastic copolyester elastomers: Methyl branched PBAmT
- Investigations of polyethylene of raised temperature resistance service performance using autoclave test under sour medium conditions
- Investigation of corrosion and thermal behavior of PU–PDMS-coated AISI 316L
- Modification of sodium bicarbonate and its effect on foaming behavior of polypropylene
- Effect of coupling agents on the olive pomace-filled polypropylene composite
- High strength and conductive hydrogel with fully interpenetrated structure from alginate and acrylamide
- Removal of methylene blue in water by electrospun PAN/β-CD nanofibre membrane
- Theoretical and experimental studies on the fabrication of cylindrical-electrode-assisted solution blowing spinning nanofibers
- Influence of l-quebrachitol on the properties of centrifuged natural rubber
- Ultrasonic-modified montmorillonite uniting ethylene glycol diglycidyl ether to reinforce protein-based composite films
- Experimental study on the dissolution of supercritical CO2 in PS under different agitators
- Experimental research on the performance of the thermal-reflective coatings with liquid silicone rubber for pavement applications
- Study on controlling nicotine release from snus by the SIPN membranes
- Catalase biosensor based on the PAni/cMWCNT support for peroxide sensing
- Synthesis and characterization of different soybean oil-based polyols with fatty alcohol and aromatic alcohol
- Molecularly imprinted electrospun fiber membrane for colorimetric detection of hexanoic acid
- Poly(propylene carbonate) networks with excellent properties: Terpolymerization of carbon dioxide, propylene oxide, and 4,4ʹ-(hexafluoroisopropylidene) diphthalic anhydride
- Polypropylene/graphene nanoplatelets nanocomposites with high conductivity via solid-state shear mixing
- Mechanical properties of fiber-reinforced asphalt concrete: Finite element simulation and experimental study
- Applying design of experiments (DoE) on the properties of buccal film for nicotine delivery
- Preparation and characterizations of antibacterial–antioxidant film from soy protein isolate incorporated with mangosteen peel extract
- Preparation and adsorption properties of Ni(ii) ion-imprinted polymers based on synthesized novel functional monomer
- Rare-earth doped radioluminescent hydrogel as a potential phantom material for 3D gel dosimeter
- Effects of cryogenic treatment and interface modifications of basalt fibre on the mechanical properties of hybrid fibre-reinforced composites
- Stable super-hydrophobic and comfort PDMS-coated polyester fabric
- Impact of a nanomixture of carbon black and clay on the mechanical properties of a series of irradiated natural rubber/butyl rubber blend
- Preparation and characterization of a novel composite membrane of natural silk fiber/nano-hydroxyapatite/chitosan for guided bone tissue regeneration
- Study on the thermal properties and insulation resistance of epoxy resin modified by hexagonal boron nitride
- A new method for plugging the dominant seepage channel after polymer flooding and its mechanism: Fracturing–seepage–plugging
- Analysis of the rheological property and crystallization behavior of polylactic acid (Ingeo™ Biopolymer 4032D) at different process temperatures
- Hybrid green organic/inorganic filler polypropylene composites: Morphological study and mechanical performance investigations
- In situ polymerization of PEDOT:PSS films based on EMI-TFSI and the analysis of electrochromic performance
- Effect of laser irradiation on morphology and dielectric properties of quartz fiber reinforced epoxy resin composite
- The optimization of Carreau model and rheological behavior of alumina/linear low-density polyethylene composites with different alumina content and diameter
- Properties of polyurethane foam with fourth-generation blowing agent
- Hydrophobicity and corrosion resistance of waterborne fluorinated acrylate/silica nanocomposite coatings
- Investigation on in situ silica dispersed in natural rubber latex matrix combined with spray sputtering technology
- The degradable time evaluation of degradable polymer film in agriculture based on polyethylene film experiments
- Improving mechanical and water vapor barrier properties of the parylene C film by UV-curable polyurethane acrylate coating
- Thermal conductivity of silicone elastomer with a porous alumina continuum
- Copolymerization of CO2, propylene oxide, and itaconic anhydride with double metal cyanide complex catalyst to form crosslinked polypropylene carbonate
- Combining good dispersion with tailored charge trapping in nanodielectrics by hybrid functionalization of silica
- Thermosensitive hydrogel for in situ-controlled methotrexate delivery
- Analysis of the aging mechanism and life evaluation of elastomers in simulated proton exchange membrane fuel cell environments
- The crystallization and mechanical properties of poly(4-methyl-1-pentene) hard elastic film with different melt draw ratios
- Review Articles
- Aromatic polyamide nonporous membranes for gas separation application
- Optical elements from 3D printed polymers
- Evidence for bicomponent fibers: A review
- Mapping the scientific research on the ionizing radiation impacts on polymers (1975–2019)
- Recent advances in compatibility and toughness of poly(lactic acid)/poly(butylene succinate) blends
- Topical Issue: (Micro)plastics pollution - Knowns and unknows (Guest Editor: João Pinto da Costa)
- Simple pyrolysis of polystyrene into valuable chemicals
- Topical Issue: Recent advances of chitosan- and cellulose-based materials: From production to application (Guest Editor: Marc Delgado-Aguilar)
- In situ photo-crosslinking hydrogel with rapid healing, antibacterial, and hemostatic activities
- A novel CT contrast agent for intestinal-targeted imaging through rectal administration
- Properties and applications of cellulose regenerated from cellulose/imidazolium-based ionic liquid/co-solvent solutions: A short review
- Towards the use of acrylic acid graft-copolymerized plant biofiber in sustainable fortified composites: Manufacturing and characterization