Photo‐Crosslinking Strategy Constructs Adhesive,Superabsorbent, and Tough PVA‐Based Hydrogel through Controlling the Balance of Cohesion and Adhesion

An ideal hydrogel with excellent adhesive performance has drawn much attention in research and applications. In this paper, a photo‐crosslinked polyvinyl alcohol bearing styrylpyridinium group/cellulose nanocrystals (PVA‐SbQ/CNC) composite hydrogel is designed through photo‐crosslinking technology for preventing the physical crosslinking of polyvinyl alcohol to maintain enough hydroxy groups in the hydrogel. Thus, the hydrogel exhibits excellent adhesive behavior not only for various solid substrates (plastics, rubbers, glasses, metals, and woods) but also muscle and fat. In addition, the formation mechanism, the swelling behavior, and mechanical strength are also investigated. Also, these results show that photo‐crosslinked PVA‐SbQ/CNC hydrogel possesses high swelling rate, super stretchability, and high toughness. Moreover, adhesive, mechanical, and swelling properties of PVA‐SbQ/CNC hydrogels can be changed with the increase of total incident light intensity. It is anticipated that the photo‐crosslinked PVA‐SbQ/CNC hydrogel would play a significant role in the applications of wound dressing, medical electrodes, tissue adhesives, portable equipment, and super absorbent materials. In this sense, the simple photo‐crosslinking strategy would provide new ideas for designing soft and adhesive materials through controlling the balance of cohesion and adhesion.     

耐水胶合板用环保乳清蛋白基水性胶粘剂

乳清蛋白是干酪加工过程中所产生的一种副产品,除被用作食品添加剂外,仍有相当数量乳清蛋白并未得到有效利用。为了实现乳清蛋白的高附加值利用,本文以乳清蛋白为原料,研制了具有良好耐久性和环保的乳清蛋白基胶合板用水性胶粘剂,并评价了变性处理、改性剂种类及其用量对乳清胶粘剂的胶合性能及游离甲醛释放量的影响。结果表明,热变性使乳清蛋白胶粘剂的胶接耐久性提高;不同改性剂对乳清蛋白胶粘剂的性能影响不同。采用1％多异氰酸酯改性胶接耐久性最好;采用0．15％戊二醛／1％乙二醛改性胶接强度最高。中试结果表明,所研制的耐水性环保乳清蛋白基胶合板胶粘剂的干胶接强度达到1．98MPa,煮－烘－煮28h后湿胶接强度为1．14MPa,游离甲醛释放量仅为0035mg／L（干燥器法）,达到了1ISK6806--2003环保结构胶合板用胶粘剂要求。     

Properties of novel diallyl phthalate resin modified with sulfur‐containing allyl ester compounds

Sulfur‐containing allyl ester, which reacts with diallyl phthalate (DAP) resin to have allyl groups, was synthesized by the reaction of allyl phthalic acid with bisphenol having sulfur atoms. The sulfur‐containing allyl ester compound was blended with DAP resin to improve the adhesive properties to copper. By modification with sulfur‐containing allyl ester compound, the T‐peel adhesive strength and the lap shear adhesive strength to copper was improved. In particular, the adhesive strength was greatly improved when the resin was modified with the allyl ester compound having a disulfide bond (?S?S?) (DADS). It is concluded that this result is due to the improvement of the interfacial adhesive strength because the sulfur atom was found to be located in the surface of the copper by Fourier transform infrared (FTIR) analysis. The glass transition temperature (T_g) and the thermal decomposition temperature (T_d) of the cured DAP resin modified with DADS slightly decreased with increasing concentration of DADS. The lowering of T_g is because the crosslinking density of the DAP resin modified with DADS is smaller than that of DAP resin. Moreover, from thermogravimetric analysis, the lowering of Td of the DAP resin modified with DADS is because DADS is likely to pyrolyze. © 2013 Society of Chemical Industry     

Preparation and characterization of composites: Ethylene–propylene–diene terpolymer‐graft‐maleic anhydride/CaCO3

In this paper, a new method was applied to form crosslinking networks in the ethylene–propylene–diene terpolymer (EPDM) matrix with calcium carbonate(CaCO₃) particles, which were chemically treated by maleic anhydride (MAH). The tensile test showed that the tensile strength and the elongation at break of the composites were improved significantly, and when the content of CaCO₃ was about 20 wt % in the composites, the maximum tensile properties were achieved. The results of swell and solution text showed that the composites had evident crosslinking structure. The results of attenuated transmission reflectance‐Fourier transform infrared (ATR‐FTIR) spectrum proved that the Acid‐Base reaction between CaCO₃ and MAH had happened. SEM micrographs showed that the interfacial adhesion between CaCO₃ and copolymer was well. The thermogravimetric analysis curves showed that the composites had a new change in mass between 655 and 700°C, which might be the decomposition temperature of calcium maleicate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1810–1815, 2006     

Preparation and characterization of composites: EPDM‐g‐AA/CaCO3

In this study a new method was applied to form crosslinking networks in the ethylene‐propylene‐diene terpolymer (EPDM) matrix with calcium carbonate (CaCO₃) particles, which were chemically treated with acrylic acid (AA). The tensile test showed that the tensile strength and the elongation at break of the composites were improved significantly, and that when the content of CaCO₃ was about 20 wt% in the composites the maximum tensile properties were achieved. The results of swell and solution tests showed that the composites had an evident crosslinking structure. The results of ATR‐FTIR spectrum proved that the acid–base reaction between CaCO₃ and AA had occurred. The SEM photos show that an interfacial adhesion between CaCO₃ and copolymer was good. The TGA curves show that the composites had a new change in mass between 650°C and 750°C, which might be the decomposition temperature of calcium acrylic acid. POLYM. COMPOS., 26:587–592, 2005. © 2005 Society of Plastics Engineers     

Formulation of a novel soybean protein‐based wood adhesive with desired water resistance and technological applicability

A novel soybean protein‐based wood adhesive with good bond strength, excellent water resistance, and the desired technological applicability was formulated by combining thermal alkali degradation, thermal acid treatment, and crosslinking. The characterization results indicated that thermal alkali degradation could effectively improve the technological applicability, thermal acid treatment could positively improve the water resistance, and appropriate crosslinking modification could significantly enhance the bond strength and water resistance of the soybean protein adhesive. The crosslinker species, crosslinker level, and ratio of thermal alkali‐degraded soybean protein (DSP) to thermal acid‐treated soybean protein (TSP) had important effects on the primary properties of the soybean protein adhesives. The modified polyamide aqueous solution was the most preferable crosslinker because of its low viscosity, good crosslinking efficiency, and excellent miscibility with soybean protein solution. The optimal soybean protein adhesive that was formulated from 20 wt % modified polyamide as the crosslinker and a DSP/TSP ratio of 1:3 had a solid content of more than 35 wt %, suitable viscosity (～2180 mPa s), a long work life (>16 h), good dry bond strength (2.94 MPa), and 28 h of boiling–dry–boiling cycled wet strength (1.29 MPa) that met the required values for structural use according to JIS K6806‐2003 commercial standards. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43586.     

Preparation and characterization of nano‐CaCO3 encapsulated by copolymerization of styrene and maleic anhydride

Encapsulated nanometer calcium carbonate (nano‐CaCO₃) was prepared using styrene and maleic anhydride (MAH) copolymer in 2‐propanol or methanol–water mixture in the presence of different initiator systems. The particle morphology and physical properties of the encapsulated nano‐CaCO₃ particles, such as the interaction between the encapsulating polymer and the nano‐CaCO₃, and the thermal stability of encapsulated nano‐CaCO₃ were studied by Fourier‐transform infrared spectroscopy (FTIR), Soxhlet extraction experiments, thermogravimetric analysis banded with FTIR (TGA‐FTIR) and transmission electron microscopy (TEM). The encapsulating ratio and the stable encapsulating ratio of encapsulated nano‐CaCO₃ were characterized. The results showed that a strong interfacial interaction was obtained due to the formation of a chemical bond or ion‐dipole between the C?O group of MAH and Ca²⁺ ion of nano‐CaCO₃. The encapsulating ratio and stable encapsulating ratio of nano‐CaCO₃ initiated by AIBN was higher than that initiated by BPO. Addition of maleic anhydride increased the encapsulating ratio and the stable encapsulating ratio of encapsulated nano‐CaCO₃. For the encapsulated nano‐CaCO₃ prepared in methanol–water, the diameter of the encapsulated nano‐CaCO₃ particle increased from 60–70 nm to about 100 nm and the morphology changed from a cube with a sharp edge to spherical with a rough surface. Copyright © 2006 Society of Chemical Industry     

水性木材胶粘剂的制备与性能研究

以PVA(聚乙烯醇)的醇水溶液、羟基丙烯酸酯乳液为主要原料,制得API(水性高分子-异氰酸酯)胶粘剂的主剂;然后以PAPI(多亚甲基多苯基多异氰酸酯)、DOP(邻苯二甲酸二辛酯)为主要原料,制得API交联剂。研究结果表明:PVA水溶液中有乙醇存在时,能有效提高API胶粘剂的胶接强度;当主剂中m(PVA醇水溶液)∶m(羟基丙烯酸酯乳液)=60∶30、m(水)∶m(乙醇)=78.5∶21.5和m(主剂)∶m(交联剂)=100∶15时,API胶粘剂的胶接强度和耐水性俱佳,并且其成本相对较低。     

Determination of green‐bond strength in tacky poly(vinyl alcohol) hydrogels

Pressure‐sensitive tack is the adhesive property related to bond formation. It is a key issue when formulating hydrogel poultices for transdermal delivery, dressings, and bioelectrodes. Quantitative tack gives an indication of the potential ease and success of application when gels are brought into contact with skin. The effects of different dwell times and constant pressures on bond formation between tacky poly(vinyl alcohol) (PVA) hydrogels and a skin model were explored in the current study; these were correlated with viscoelastic properties in order to elucidate structure–function relationships. A rolling tack test was performed using a novel apparatus capable of simultaneously controlling the pressure and dwell time in a hydrogel/skin‐model‐probe system. PVA gels were formed via the freeze–thaw technique using Ca²⁺ ions. Lower calcium availability in PVA gels resulted in longer dwell times required to complete bond formation, decreased creep compliance (at 0.01 s) and a decreased G′_{(ω = 40)}/G′_{(ω = 0.01)} ratio, all three leading to a loss in tack strength. All tested gels were found to have pressure‐sensitive tack. The results of this study support the applicability of a rheological methodology and a novel tack‐testing procedure to quantify green‐bond formation in pressure‐sensitive‐adhesive PVA hydrogels. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2130–2135, 2003     

木材加工用水性聚氨酯胶粘剂的研究

为了获得稳定性较好的水性聚氨酯(WPU)胶粘剂,以丙酮为溶剂、聚醚(N210)为软段、二苯基甲烷-4,4′-二异氰酸酯(MDI)为硬段、二羟甲基丙酸(DMPA)为亲水性扩链剂、三乙胺(TEA)为成盐剂和聚乙烯醇(PVA)为增稠剂等,制备了环保型木材粘接用WPU胶粘剂。研究了MDI、N210、DMPA、TEA和PVA用量等对乳液稳定性、胶粘剂剪切强度及黏度的影响。结果表明:当n(MDI)∶n(N210)∶n(DMPA)∶n(TEA)=2.4∶1∶0.8∶0.64、w(PVA)=2.0%～3.0%时,可制得常温(20～30℃)存放90 d以上、剪切强度超过4.2 MPa的稳定WPU胶粘剂。     

Nanostructured PZT synthesized from metal–polyvinyl alcohol gel: Studies on metal–polymer interaction

PbZr_0.53Ti_0.47O₃ (PZT) nanoparticles of size distribution ～1–6 nm were synthesized by single‐step autoignition of metal–polyvinyl alcohol (PVA) gel. The physical and chemical bonding between the metals ions and PVA in gel was analyzed from the results of the characterization by FTIR, SEM, and XRD techniques. The appearance of a doublet band between 3500 and 3200 cm^?1 and the shifting of stretching frequency of O? H band in the FTIR spectra of gel indicated strong electrostatic interaction between the metal ions and the polar OH groups of the polymer. The electrostatic interaction decreased the extent of hydrogen bonding drastically due to engagement of polar OH groups in complex formation with the metal ions. Microstructural study of the dried gel by SEM coupled with its FTIR analyses indicated crosslinking in the metal–polymer gel. The loss of crystallinity of PVA in gel detected by XRD also indicated the drastic degradation of hydrogen bonding in PVA due to the formation of coordination complex with the metal ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Singlet oxygen generation and adhesive loss in stimuli‐responsive,fullerene‐polymer blends,containing polystyrene‐block‐polybutadiene‐block‐polystyrene and polystyrene‐block‐polyisoprene‐block‐polystyrene rubber‐based adhesives

The adhesive properties, as measured by bulk tack and peel strength analysis, were found to decrease in polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) and polystyrene‐block‐polyisoprene‐block‐polystyrene (SIS) PSA films containing common singlet oxygen generators, acridine, rose bengal, and C₆₀ fullerene, when irradiated with a tungsten halogen light in air. The addition of the singlet oxygen quencher, β‐carotene, to the C₆₀ fullerene samples was found to significantly deter the rate of adhesive loss in the fullerene‐SBS and ‐SIS PSA nanocomposites. The presence of oxygen was essential to the mechanism of adhesive loss and, in combination with the effects of singlet oxygen generators and a singlet oxygen scavenger, strongly supports a singlet‐oxygen mediated process. FTIR investigations of fullerene‐SBS and ‐SIS systems suggest the initial formation of peroxides which, upon further irradiation, lead to the generation of carbonyl‐containing compounds of a ketonic type after crosslinking. Rates of SBS and SIS C‐H abstraction were comparable and found to decrease when the high‐pressure, mercury xenon irradiation source was filtered to allow only light of λ > 390 nm. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Poly(vinyl alcohol)/CaCO3‐diacid nanocomposite: Investigation of physical and wetting properties and application in heavy metal adsorption

Poly(vinyl alcohol) (PVA) nanocomposite and modified CaCO₃ nanoparticles (NPs) were fabricated by ultrasound agitation method with particle content altering from 3, 5, and 8 wt %. The CaCO₃ surface was successfully treated by 10 wt % of bioactive dicarboxylic acid (DA). The influences of loading modified NPs on the thermal, mechanical, adsorption, contact angle, and physical properties of the poly(vinyl alcohol) nanocomposite films were thoroughly studied. The results showed that incorporation of modified CaCO₃ into the PVA matrix had better performance than the pure PVA. Meanwhile, tensile strength, Young's modulus, and thermal stability are enhanced from 33.36 MPa, 1.26 GPs, and 242.918C (neat PVA) to 81.7 MPa, 4.81 GPa, and 312.95 °C (PVA/CaCO₃‐DA NC 5 wt %), respectively. Also, the adsorption capacity of the PVA/CaCO₃‐DA NCs 5 and 8 wt % revealed that the NC films could act as an appropriate absorbent for the removal of Cd(II) ions with maximum adsorption capacity of about 20.70 and 25.19 mg g^?1 for Cd(II), respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45414.     

Properties of waterborne polyurethane‐fluorinated marine coatings: The effect of different types of diisocyanates and tetrafluorobutanediol chain extender content

Three series of waterborne polyurethane‐ (WBPU) fluorinated coatings were prepared with single aliphatic (4,4′‐dicyclohexylmethane diisocyanate, H₁₂MDI), aromatic (4,4′‐diphenylmethane, MDI) and a mixture of aliphatic and aromatic diisocyanates (1 : 1). Different contents of 2,2,3,3‐tetrafluoro1,4‐butanediol (TFBD) as a chain extender were used in the WBPU coatings. The fluoro‐enriched surface of the WBPU coatings was obtained with a combination of a high TFBD content (8.77 mol %) as well as the aliphatic or mixed diisocyanates. The tensile strength, Young's modulus, elongation at break (%) and adhesive strength were characterized with respect to the TFBD contents. The mechanical strength and adhesive strength increased with increasing TFBD content in the three series. In artificial salt water, the maximum adhesive strength of WBPU was observed for this coating, which was achieved by TFBD bonded H₁₂MDI of mixed diisocyanates with a higher TFBD content (8.77 mol %). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39905.     

Effects of calcium carbonate as the expanding inhibitor on the structural and mechanical properties of expanded starch/polyvinyl alcohol blends

In this study, expanded starch/PVA/CaCO₃ blends (ESPCs) were prepared using the pilot system composed of a supermixer and a twin‐screw extruder to investigate the effects of CaCO₃ as the expanding inhibitor on the structural and mechanical properties of ESPCs. The pore ratio of ESPCs with the interconnecting open‐cell structure decreased with increasing CaCO₃ content and the structure of ESPCs became more compact. The inhibiting process of CaCO₃ during the expansion of starch/PVA blends was proposed and certified by FTIR spectroscopy and X‐ray diffraction. At least two parts of CaCO₃ were required to obtain a sufficient inhibiting effect on the expansion. The mechanical properties of ESPCs such as tensile strength, elongation at break, modulus, and specific work of rupture were improved by the addition of CaCO₃ as the expanding inhibitor. As CaCO₃ content increased from one to four parts, the tensile strength increased 2.6‐fold, from 70 to 180 kPa, whereas elongation at break increased about 1.5‐fold. The moduli of ESPCs also increased with increasing CaCO₃ content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1762–1768, 2004     

A starch‐based biodegradable film modified by nano silicon dioxide

The purpose of this work was to improve the properties of the starch/poly(vinyl alcohol) (PVA) films with nano silicon dioxide (nano SiO₂). Starch/PVA/nano‐SiO₂ biodegradable blend films were prepared by a solution casting method. The characteristics of the films were assessed by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The results obtained in this study indicated that the nano‐SiO₂ particles were dispersed evenly within the starch/PVA coating and an intermolecular hydrogen bond and a strong chemical bond C? O? Si were formed in the nano‐SiO₂ and starch/PVA. That the blending of starch, PVA and nano‐SiO₂ particles led to uniform starch/PVA/nano‐SiO₂ blend films with better mechanical properties. In addition, the nano‐SiO₂ particles can improve the water resistance and light transmission of the blend films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

An All‐Natural Adhesive for Bonding Wood

A novel adhesive that is solely based on natural materials of defatted soy flour (SF) and magnesium oxide (MgO) has been investigated for preparation of five‐ply plywood panels. The resulting plywood panels met the industrial water‐resistant requirement for interior plywood. In this study, mechanisms by which an aqueous mixture of SF and MgO served as a strong and water‐resistant adhesive for bonding wood were investigated. SF was first fractionated into soy protein isolates (SPI), a water‐soluble fraction, and insoluble carbohydrates (ICs) that were mixed with MgO, respectively, for preparation of maple laminates. The water resistance of the resulting maple laminates was evaluated by a three‐cycle water‐soaking‐and‐drying (WSAD) test and a two‐cycle boiling‐water test (BWT). The mixture of MgO and the soluble fraction was not able to bond maple veneers together. The shear strengths of the resulting maple laminates before and after WSAD and BWT all had the following order: MgO–SPI > MgO–SF > SF only > MgO–IC. The water solubility of SF in the heat‐cured SF–MgO mixture was much lower than that of the heat‐cured SF. We believe that the low water solubility of SF–MgO and close interactions between MgO and soy proteins instead of soy carbohydrates were responsible for the superior strengths and high water resistance of the soy‐MgO adhesive.     

Properties of starch‐based blend films using citric acid as additive. II

Starch/polyvinyl alcohol (PVA) blend films were prepared by using corn starch, polyvinyl alcohol (PVA), glycerol (GL), and citric acid (CA) as additives and glutaraldehyde (GLU) as crosslinking agent for the mixing process. The additives, drying temperature, and the influence of crosslinker of films on the properties of the films were investigated. The mechanical properties, tensile strength (TS), elongation at break (% E), degree of swelling (DS), and solubility (S) of starch/PVA blend film were examined adding GL and CA as additives. At all measurement results, except for DS, the film adding CA was better than GL because hydrogen bonding at the presence of CA with hydroxyl group and carboxyl group increased the inter/intramolecular interaction between starch, PVA, and additives. CA improves the properties of starch/PVA blend film compared with GL. TS, % E, DS, and S of film adding GLU as crosslinking agent were examined. With increasing GLU contents, TS increases but % E, DS, and S value of GL‐added and CA‐added films decrease. When the film was dried at low temperature, the physical properties of the films were clearly improved because the hydrogen bonding was activated at low temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2554–2560, 2006     

Chemical phosphorylation improves the moisture resistance of soy flour‐based wood adhesive

A green‐chemistry approach to improve the moisture resistance of soy flour (SF)‐based wood adhesive is described. Chemical phosphorylation of SF (PSF), using POCl₃ as the phosphorylating agent, dramatically increased its wet bond strength. The optimum POCl₃:SF ratio that produced maximum wet bond strength was about 0.15 (g g^?1). The increase in wet bond strength of PSF (PSF0.15) was mostly due to the phosphate groups incorporated into the proteins and carbohydrates, and to a lesser degree to phosphorylation‐induced protein denaturation. The attached phosphate groups acted as cross‐linking agents, either via covalent esterification with hydroxyl groups on wood chips or via ionic and hydrogen‐bonding interactions with functional groups in wood chips. At hot‐press temperatures above 160°C the wet bond strength of PSF0.15 was >2.6 MPa, a level that might be acceptable for interior‐used hardwood plywood and particleboard. POCl₃ is a low cost, general‐purpose reagent and therefore PSF‐based adhesive is expected to be environmentally friendly. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40451.     

Effects of polyisocyanate on properties and pot life of epoxy resin cross‐linked soybean meal‐based bioadhesive

In this study, polyisocyanate (pMDI) was introduced into epoxy resin modified soybean meal‐based bioadhesive to address the issue of low dry bond strength. Specifically, we investigated the effects of adding pMDI in terms of amount and storage time on dry bond strength, water resistance, and pot life of adhesive. Factors examined included shear strength, apparent viscosity, chemical reaction, crystallinity, and morphology of modified adhesives. Results indicated that the dry bond strength and water resistance of the resultant plywood was respectively improved 29.5% and 39.7% by adding 2% pMDI. In addition, the pot life of modified adhesive reached in 4 h. Results also shown that the cross‐linking reactions between epoxy group and carbonyl as well as isocyano and amino increased the cross‐linking density and formed a denser cross‐linking network structure of cured adhesive. The composite cross‐linked soybean meal‐based adhesive is environmental‐friendly and high‐performance, which will promote the industrial application of the soy protein‐based adhesives. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43362.