Addition Of Polyvinyl Acetate Research Articles

A facile strategy to fabricate low viscosity and high cold tack soy protein-based adhesive for particleboard production

The utilization of soy protein as a wood adhesive has been successfully implemented in the industrial production of plywood. However, it is still a significant challenge to directly utilize soy protein-based adhesive for the fabrication of particleboard owing to its high viscosity and low cold tack. In this study, polyvinyl acetate (PVAc) emulsion was used to modify soy protein-based adhesive to reduce its viscosity and enhance its cold tack. By incorporating a content of 30% PVAc emulsion, the viscosity of the adhesive was reduced to 880 mPa·s, which was much lower than the pure soy protein-based adhesive value. Simultaneously, the cold tack was significantly increased by nearly 500 times after the addition of PVAc. The obtained adhesives met the requirements for particleboard production. In addition, the internal bonding strength of the produced particleboard reached 0.7 MPa, significantly exceeding the requirements for P6-grade particleboards (≥ 0.40 MPa, GB/T4897–2015). Moreover, it exhibited no formaldehyde emissions, making it a high-quality particleboard suitable for furniture applications. This study successfully presents a soy protein-based adhesive suitable for particleboard production using a simple blending modification approach, thereby expanding the application scope of soy protein-based adhesives.

Preparation of bamboo scraps/magnesium oxychloride lightweight composites with high water resistance by PVAc

In this paper, in order to continuously promote the carbon peak and neutrality targets, and accelerate the construction of the waste material recycling systems, a lightweight construction material was prepared by compounding magnesium oxychloride cement (MOC) inorganic cementitious material and waste bamboo scraps, and foaming them with hydrogen peroxide. However, the poor water resistance of MOC composites makes it difficult to meet the needs under special environmental conditions, which seriously affects their popularization and application range. To solve this problem, Polyvinyl acetate (PVAc) was used to enhance the water resistance. It was deduced that the hydrolysis products of PVAc combined with each other, under the effect of hydrogen bonding induction, can form a hydrated polymer protective film covering the exterior of MOC crystals, thus reducing the contact of water with the crystals. In addition, the protective film and the hydroxyl groups on the cellulose of bamboo scraps are interconnected by hydrogen bonding, which improves the bonding strength of MOC gelling particles to bamboo scraps. Moreover, the PVAc hydrolysis products were combined with water molecules, bamboo scraps, and phase 3 crystals in MOC by hydrogen bonding to form a gelling structure, which further improved the adhesive tightness of MOC gelling particles. These three aspects led to the increase of the softening coefficient of the modified material by approximately 14%, and a substantial increase of the water resistance. Furthermore, the addition of PVAc improved the foaming effect of the material and increased the porosity, leading to a further decrease of the density and strength of the foamed material. The study of the water resistance of this lightweight composite material effectively provides a theoretical support and technical reference for the application of water-resistant and energy-saving materials in the construction fields.

Blend membranes comprising polyetherimide and polyvinyl acetate with improved methane enrichment performance

A clean and sustainable energy source, biogas is widely accessible worldwide. The caloric value of biogas is related to its methane content, and therefore removal of other gases is essential for reaping the benefits of this cleaner resource. In contrast to other classical techniques, membrane technology is relatively new yet extremely promising for methane enrichment. The methane enrichment performance of polymeric membranes is constrained, hence newer material combinations have been investigated to enhance membrane performance. In this study, blend membranes comprised of polyetherimide (PEI) and polyvinyl acetate (PVAc) in varying proportions were prepared by adopting the wet-phase inversion technique. The generated pure, and blend membranes were characterized for the morphological, thermal, and structural study. The interactions of PEI and PVAc in blend samples were verified by FTIR analysis. On the other hand, SEM investigation indicated that the membranes have an anisotropic porous structure with a dense skin layer at the top. Subsequently, a single glass transition temperature (Tg), as validated by DSC analysis, indicates that the blended polymers are miscible. Furthermore, membranes’ performance for gas separation was assessed regarding selectivity and permeance at feed pressures ranging from 2 to 6 bar. The permeation results showed that the CO2 permeance has increased by 40.47% with the addition of 4 wt % PVAc at 2 bar pressure. Furthermore, ideal selectivity improves as the blend ratio increases; nonetheless, the highest value for CO2/CH4 ideal selectivity was attained with a 2 wt % PVAc addition and at 2 bar pressure, which is approximately 26% greater than the pure PEI membrane. At 4 bar pressure, optimum CO2/N2 selectivity value of 22.50 was achieved. The findings indicate that PVAc is an excellent option for expanding the separation performance of blended polymeric membranes for biogas enrichment.

Using PVA and Attapulgite for the Stabilization of Clayey Soil.

Considering that, in the context of the ecological restoration of a large number of exposed rock slopes, it is difficult for existing artificial soil to meet the requirements of mechanical properties and ecological construction at the same time, this paper investigates the stabilization benefits of polyvinyl acetate and attapulgite-treated clayey soil through a series of laboratory experiments. To study the effectiveness of polyvinyl acetate (PVA) and attapulgite as soil stabilizer, a triaxial strength test, an evaporation test and a vegetation growth test were carried out on improved soil with different amounts of PVA content (0, 1%, 2%, 3%, and 4%) and attapulgite replacement (0, 2%, 4%, 6%, and 8%). The results show that the single and composite materials of polyvinyl acetate and attapulgite can increase the peak deviator stress of the sample. The addition of polyvinyl acetate can improve the soil strength by increasing the cohesion of the sample; the addition of attapulgite improves the soil strength mainly by increasing the internal friction angle of the sample. The strength of the composite is greatly improved by increasing the cohesion and internal friction angle of the sample at the same time. The effect of adding materials increased significantly with increasing curing age. Moreover, polyvinyl acetate and attapulgite improve the soil water retention of the soil by improving the water-holding capacity, so that the soil can still ensure the good growth of vegetation under long-term drought conditions. The scanning electron microscopy (SEM) images indicated that the PVA and attapulgite of soil affect the strength characteristics of soil specimens by the reaction of PVA and water, which changes the structure of the soil and, by the interweaving of attapulgite soil particles, acts as the skeleton of the aggregate. Overall, PVA and attapulgite can effectively increase clayey soil stability by improving the cohesive force and internal friction angle of clayey soil.

A novel PEG/PMMA based binder composition for void-free metal injection moulding of Ti components

The use of polyethylene glycol (PEG) and poly methylmethacrylate (PMMA) as a binder for metal injection moulding (MIM) operation results in void formation in the MIM feedstock. In order to formulate a practicable PEG/PMMA binder system, we identified a crystallisation inhibitor - polyvinyl acetate (PVAc) – to suppress the void formation. Rheological behaviour of the feedstocks with varying amounts of PVAc was compared with a previously reported feedstock based on the crystallisation inhibitor polyvinypyrrolidone (PVP). The analysis of rheology tests reveals that the incorporation of PVAc into PEG/PMMA binder system does not affect the overall rheology of the feedstocks. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and microstructural analysis along with impurity measurement of the sintered samples were carried out for complete evaluation. The DSC analysis suggests interactions between components of the binder system. These interactions were further verified using Fourier-transform infrared spectroscopy (FTIR), which reveals possible complex hydrogen bonding interactions in the ternary blend systems. Overall, the results show that the addition of PVAc into the PEG/PMMA binder system produces Ti-MIM feedstocks with good rheological properties resulting in void-free injection moulded samples, and acceptable mechanical properties (tensile strength ~550 MPa; elongation ~10%).

Application of enzymatic calcification for dust control and rainfall erosion resistance improvement

Globally, most cities are facing severe challenges associated with dust pollution and it is of great significance to propose an effective and environmentally friendly dust control method. This study used enzymatically induced calcite precipitation (EICP) technology for dust control. Moreover, polyvinyl acetate (PVAc) was added to the cementation solution to improve its rainfall erosion resistance. The results showed that the optimum ratio of urease solution to cementation solution differed according to the concentrations of reactants in the cementation solution. Under combined EICP and PVAc (50 g/L) treatment, the stability of the dust-slope significantly improved. Moreover, little dust soil loss was washed out by simulated rainfall because of the more stable spatial structure of CaCO3 precipitation. Furthermore, PVAc addition increased the surface strength of slopes, while the cemented layer became thinner. With this combined EICP and PVAc (50 g/L) treatment, in a field test, the treated area of the slope had higher surface strengths and stronger erosion resistance than untreated areas. These higher surface strengths were attributed to the smaller particle size, and the stronger cementing effect of grass seeds. These results demonstrated that EICP-PVAc treatment significantly controlled dust and mitigated surface erosion of dust-slopes. This represents promising potential for the prevention of dust pollution.

Conductivity and foldability enhancement of Ag patterns formed by PVAc modified Ag complex inks with low-temperature and rapid sintering

In the research area of conductive inks for printed electronics, the preparation of conductive circuits generally shows high requirements on the process temperature, process efficiency, electrical conductivity, foldability and so on. In this paper, a new type of Ag complex conductive ink modified by PVAc (poly vinyl acetate) was proposed to enhance the conductivity and foldability of rapidly sintered Ag patterns. The conductive ink was fabricated by mixing silver oxalate as Ag precursor, 1,2-Diaminopropane as complexing reagent, methanol and isopropanol as organic solvents, and a small amount of PVAc as binding agent. Compared to the Ag complex ink without PVAc, the modified ink shows a better sintered microstructure with higher flatness and density after fast sintering at 140 °C–200 °C for 2 min, indicating that the addition of PVAc has a positive effect on the stability of Ag nucleation and microstructure formation. A low resistivity of 5.17 μΩ cm and an improved foldable property can be achieved at 180 °C by sintering the PVAc modified Ag complex ink on PI (polyimide) substrate, which indicates that the proposed ink is promised to be applied in printed circuits and flexible electronics.

Influence of aluminum nanoparticles and binders on the laser initiation of cyclotrimethylenetrinitramine

Aluminum nanoparticles were added into cyclotrimethylenetrinitramine (RDX) to enhance the laser absorption and lower the initiation energy of pulse laser. Polyvinyl acetate (PVA), polyvinyl butyral (PVB), and fluororubber (F2314) were added into RDX as binders to prepare the RDX-based composite explosives with desirable mechanical behavior. The influence of aluminum nanoparticles and binders on the light absorption, thermal behavior, laser initiation energy and the electron temperature in aluminum plasma were investigated using reflectance spectroscopy, differential scanning calorimetry, laser initiation and laser-induced breakdown spectroscopy. Results showed that the addition of aluminum nanoparticles could prominently lower the laser initiation energy of the RDX-based explosives. The RDX doped with 2.0% aluminum nanoparticles could be reliably initiated with 1.5 J/cm2 laser energy (1064 nm, 8 ns). The laser initiation energy increased to 1.7, 2.4 and 2.9 J/cm2 with the additions of 0.5%, 1.0% and 2.0% F2314 binders, respectively. When the addition of PVA and PVB increased to 2.0%, the RDX-based explosives couldn’t be initiated by pulse laser. When the pulse laser radiated on the surface of the RDX-based composite explosives, the aluminum nanoparticles absorbed the laser energy and were heated to high temperature to initiate the explosives. The addition of binders can provide desirable mechanical behavior, but the laser initiation energy increased because the heat transmission from aluminum nanoparticles to RDX was hindered.

EFFECT OF ADDING POLYVINYL ACETATE AND COCONUT SHELL ON CONCRETE

Manufacture of concrete with a mixture of coconut shell and polyvinyl acetate. The material used in this study are from the coconut shell coconut waste treatment process which is crushed to a maximum size of 20 mm, whereas polyvinyl acetate condition is milky white emulsion. This study uses laboratory experiments concrete according to standards ISO 7656: 2012 for normal concrete and developed into concrete innovation. Coconut shell as a substitute for gravel with a rate of 8% and 10%, while the addition of polyvinyl acetate in the amount of 8% and 10%. At the time of fresh concrete workmanship, testing the slump test to control the workability and homogeneity. Treatment (Curing) specimen is done by covering the paper specimens with wet cement. Compressive strength testing carried out during the 28 days of the test specimen. The results obtained on the compressive strength with the highest average percentage of materials such as concrete polyvinyl acetate 8% and 8% of coconut shell Amounting to 351 kg/cm2 with an average density of 2199 kg/cm3. In each of the test object with a weight value is the quality efficiency in concrete polyvinyl acetate 8% and 8% of coconut shell.

Rheological, crystallization and foaming behaviors of high melt strength polypropylene in the presence of polyvinyl acetate

Polyvinyl acetate (PVAc) is a kind of CO2-philic materials with high solubility of CO2. For improving the supercritical carbon dioxide (Sc-CO2) foaming behavior of isotactic polypropylene (iPP), a high melt strength polypropylene (HMSPP) was prepared using styrene (St) as grafting monomer. The effect of PVAc on the preparation, rheological, crystallization and foaming behaviors of HMSPP was investigated. The high temperature gel permeation chromatography (HT-GPC) results showed that the PVAc had a promotive effect on melt grafting reaction. With the addition of PVAc, the weight-average molecular weight (Mw) of HMSPP increased from 217,158 to 240,733 g/mol. Thus, the HMSPP presented higher complex viscosity and storage modular, and lower loss angle, which indicated that the melt viscosity and melt strength of HMSPP was increased by adding PVAc. The crystallization behavior of HMSPP was investigated using differential scanning calorimetry (DSC). Double crystallization peaks were observed on the DSC cooling curves of HMSPP in the presence of PVAc, which was ascribed to incomplete molten of iPP with long chain branching (LCB) structure at low end melting temperature. Moreover, the prepared HMSPP exhibited better foaming behavior in the presence of PVAc. With the addition of PVAc, the average cell diameter of HMSPP decreased from 93 to 59 μm, and the cell density increased from 2.83 × 107 to 9.79 × 107 cell/cm3.

Development and use of polymer-modified cement for adhesive and repair applications

Limited attempts are made to develop speciality cement possessing improved tensile and bond properties resulting from inter-grinding clinker with elastomer polymeric latexes such as styrene-butadiene rubber (SBR) or polyvinyl acetate (PVA). This type of ready-to-use cement can be of particular interest in adhesive applications requiring enhanced bond to substrates (i.e., tile adhesives, patching mortars, waterproofing slurries) as well as repair and injection works necessitating improved durability and adhesion to embedded steel bars. Test results demonstrated that latexes remain efficient after grinding to alter cement properties, including higher workability and improved flexural and pull-off bond strengths. The SBR and PVA addition rates should be limited to less than 0.4% and 0.3% of cement mass, respectively, given that clinker grindability including Blaine fineness and sieve residue could be detrimentally affected. The validity of polymer-modified cement to produce tile adhesives as per EN 12004 standard requirements is discussed.

Synthesis and characterization of bio-composite nanofiber for controlled drug release

In the present study, nanofiber mats of polyvinyl alcohol (PVA), polyvinyl acetate (PVAc) and 1:1 (w/w) PVA & PVAc (multi-component composite) have been developed and evaluated for the sustained release of broad spectrum antibacterial drug ‘ciprofloxacin HCl’. These nanofiber mats were developed through electrospinning the solutions of these non-toxic and biocompatible polymers (i.e. Drug PVA and PVAc) individually, as well as in 1:1 (w/w) mixed condition (i.e. composite). Prior to the electrospinning (about 1.5h), 5%, 10% and 15% w/w ciprofloxacin HCl (CipHCl) was also homogeneously mixed in these polymer solutions. Results indicate that the average diameter of PVA, PVAc and multiple-component composite (PVA/PVAc) fibers without drug loading was 59.5, 93.3 and 183.7nm, respectively. Moreover, the average diameter for drug multiple-component composite (1:1) fibers with increasing drug concentration (i.e. 5%, 10% and 15%) was 171, 163.5 and 162.4nm, respectively. XRD analysis of these nanofiber mats showed higher surface property, which is indicated by only weak signals for the characteristic peaks with increasing drug concentration. For 5% CipHCl loading, the drug released from drug-multiple-component composite was intermediate (∼29%) as compared to PVA (∼50%) and PVAc (∼13%). However, the drug multiple-component composite mats exhibited the property of extended drug release for 10days as compared to complete drug release of 6days in case of both drug PVA and PVAc nanofiber mats. It indicates that the addition of PVAc promotes the sustained release of drug via its enhanced water stability, and reduced fiber swelling and initial burst of drug release.

Laboratory Study of Water Absorption of Modified Mortar

This study investigates the effects of polymer additives namely polyvinyl acetate (PVAc) on water absorption and compressive strength of mortar. Twelve mortar mixtures were investigated for water absorption test and compressive strength test. Results showed that water absorption were inversely proportional to the percentage of PVAc addition. Final analysis showed that addition of PVAc had significant effects on water absorption. Samples with 1%, 3% and 5% addition of PVAc showed an increase of water absorption capacity in comparison to control mortar.

TVOC and formaldehyde emission behaviors from flooring materials bonded with environmental-friendly MF/PVAc hybrid resins

Polyvinyl acetate (PVAc) was added as a replacement for melamine-formaldehyde (MF) resin in the formaldehyde-based resin system to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. A variety of techniques, including 20-l chamber, field and laboratory emission cell (FLEC), VOC analyzer and standard formaldehyde emission test (desiccator method), were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with five different MF resin and PVAc blends at MF/PVAc ratios of 100:0, 70:30, 50:50, 30:70 and 0:100. Although urea-formaldehyde (UF) resin had the highest formaldehyde emission, the emission as determined by desiccator method was reduced by exchanging with MF resin. Furthermore, the formaldehyde emission level was decreased with increasing addition of PVAc as the replacement for MF resin. UF resin in the case of beech was over 5.0 mg/l, which exceeded E2 (1.5-5.0 mg/l) grade. However, MF30:PVAc70 was <or=E1 (below 1.5 mg/l) grade. Because formaldehyde emission is caused by formaldehyde-based resin, the engineered floorings bonded with PVAc only had emissions of just 0.25 mg/l. The results of formaldehyde emission by the 20-l small-chamber and FLEC methods showed a similar tendency with those from the desiccator method. After the replacement of UF resin by MF resin, PVAc addition further reduced formaldehyde emission. With increasing installation time, formaldehyde emission factors (EFs) were decreased. Furthermore, the results of the desiccator method correlated with those of the 20-l chamber and FLEC methods. VOC emission results by 20-l small-chamber and FLEC methods were similar to the formaldehyde and aldehyde emission results. VOCs were calculated between C6 and C16 as total VOC (TVOC). The TVOC EF results by 20-l small-chamber and FLEC methods were comparable with that of formaldehyde emission by FLEC. Although the major emitted harmful gas from wood-based composites was formaldehyde, it was followed by VOC emission. Although it was hard to compare directly the 20-l chamber and FLEC results because the data were based on the sum of only four VOC compounds, the VOC analyzer can be applied as a pre-test method for TVOC emission test. The TVOC emission results were also similar to the FLEC results. Due to its good correlation with the TVOC emission levels obtained from the standard desiccator, FLEC and 20-l chamber methods, the VOC analyzer can be successfully applied to the measurement of TVOC emissions from adhesives used in building materials. This paper presents TVOC and formaldehyde emission behaviors from the engineered floorings that used in Korean housing recently. To reduce emissions, MF/PVAc hybrid resins were used as bonding material. Normally, TVOC and formaldehyde emissions in indoor conditions are caused by interior materials. The results explained 'materials control' of interior materials are the first way to improve indoor air quality. There is a need to study about environmental-friendly materials for solving indoor air quality problem.

Pyro-piezoelectrics polymers materials—I. Effect of addition of PVA and/or PMMA on overall crystallization kinetics of PVDF from isothermal and non-isothermal data

Since electrical properties such as pyroelectricity, piezoelectricity and ferroelectricity strongly depend on the structural parameters, an important role is played by molecular orientation and crystal structures. So, the overall isothermal and non-isothermal kinetics for different polyvinylidene fluoride (PVDF), polyvinyl acetate (PVA) and polymethyl methacrylate (PMMA) was investigated in order to characterize them from a microstructural point of view.