Effect of crosslinking monomers on the performance of electron beam-induced biodegradable Bionolle–rubber blends

To find out the better crosslinking monomer for vulcanization of natural rubber under electron beam (EB) radiation, the dry rubber was masticated with different polyfunctional monomers like TMPTA, NVP, and ethylene glycol diacrylate of different numbers of CH₂ CH₂ O group, such as 1G, 3G, 7G, and 10 G. The masticated films were irradiated with different doses under EB at 10 kGy/pass. The highest tensile strength (25 MPa) of the rubber was observed in the presence of TMPTA (3phr) at 150 kGy dose. The gel content of the rubber increased with an increase of dose. Bionolle was mixed with the masticated rubber containing 3 phr TMPTA at different proportions; films of these blends along with Bionolle were irradiated under EB with different doses. The concentration of rubber in Bionolle and radiation dose were optimized. The elastomer with 5% masticated showed the highest tensile strength (62 MPa). The gel content of the blends was found to increase with an increase of radiation dose as well as rubber concentration in Bionolle. The elastomers or blends were found to possess good thermal properties. The elastomers exhibited a much lower loss of tensile strength due to the thermal aging compared with pure Bionolle. The elastomers sustained their original shape for 300 min at 180°C, whereas Bionolle sustained its shape for only 3 min at 120°C under the same load (50 g). Among all the elastomers, 5% rubber containing elastomer was found to be better in all respects. It was observed from scanning electron microscopy and differential scanning calorimetry studies that 5% rubber is well mixed with Bionolle. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 799–807, 2001     

Improvement of Physicochemical Properties of Rubber Blends Between Nonirradiated and Irradiated Rubber Latexes by Radiation Vulcanization

Abstract

Nonirradiated natural rubber latex (NRL) and irradiated (12 kGy) rubber latex were blended in ratios of 100:0, 85:15, 65:35, 50:50, 35:65, 15:85, and 0:100 (v/v) to improve properties of the rubber latex. The blends were irradiated using different irradiation doses (0–20 kGy) in the presence of a radiation vulcanization accelerator (RVA), normal butyl acrylate (n-BA). The physicochemical properties of the nonirradiated latex, irradiated latex, and blend films were determined after leaching with distilled water. It was observed that the tensile strengths of the blend films increases with an increase in the content of the irradiated proportion and radiation doses. The composition of the blends and the doses of radiation were optimized. The maximum tensile strength (31.41 MPa) was found for the 50:50 composition of the blend with a 5 kGy radiation dose. The 100:0 blends, when irradiated, give the highest tensile strength (27.69 MPa) with 12 kGy but a 15:85 nonirradiated blend gives the tensile strength of 26.18 MPa.     

Effect of electron beam irradiation on mechanical and dielectric properties of polypropylene films

In the present investigation the effect of electron beam irradiation on the mechanical properties of thin films of Polypropylene (PP) were measured. The dielectric properties of PP films were carried out in the frequency range from 20 Hz to 1 MHz at various DC bias potential. All measurements were carried out at room temperature. It is found that the electron beam irradiation caused an increase in Young's Modulus of PP film dose of up to 70 kGy were applied, but tensile strength and % elongation at break were found to be decrease with the increasing dose rate. The significant changes were observed in the case of dielectric constant and dielectric loss for electron irradiated PP films. The DSC results indicate that irradiation on PP films changes the thermal behavior. Minor differences in FTIR spectra were observed after irradiation treatment. It is observed that, the effect of radiation damage results in improvement in mechanical strength of the films. The increased dielectric constant and dependence of the bias voltage in case of irradiated and unirradiated PP films has been reported. It is suggested that, the PP films modified with the electron beam irradiation can be used as a good dielectric material for different electronic devices. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physico-Mechanical and Degradation Properties of Gamma-Irradiated Biocomposites of Jute Fabric-Reinforced Poly(caprolactone)

Jute fabric-reinforced poly(caprolactone) biocomposites (30–70% jute) were fabricated by compression molding. Tensile strength, tensile modulus, bending strength, bending modulus and impact strength of the non-irradiated composites (50% jute) were found to be 65 MPa, 0.75 GPa, 75 MPa, 4.2 GPa and 6.8 kJ/m², respectively. The composites were irradiated with gamma radiation at different doses (50–1000 krad) at a dose rate of 232 krad/hr and mechanical properties were investigated. The irradiated composites containing 50% jute showed improved physico-mechanical properties. The degradation properties of the composites were observed. The morphology was evaluated by scanning electron microscope.     

Improvement of Physico-Mechanical Properties of Radiation-Vulcanised Natural Rubber Latex Films by Adding Urea

The role of urea as an additive on the physico-mechanical properties of radiation vulcanised natural rubber latex (RVNRL) films was investigated. RVNRL films were prepared by the addition of urea with the concentration range 0–1.0 phr (parts per hundred rubber) and irradiated with various radiation doses (0–20 kGy). The concentration of urea and radiation doses were optimised and found to be 0.5 phr urea and 12 kGy radiation dose. Tensile strength, tear strength and cross-linking density of the rubber films increased with increasing the concentration of urea as well as radiation doses. The tensile and tear strengths of the films enhanced by 39 and 41%, respectively, at the optimum conditions. Elongation at break, permanent set and swelling ratio of the films decreased with increasing urea concentration and radiation doses until they attained approximately constant values.     

Surface analysis and printability studies on electron beam-irradiated thermoplastic elastomeric films from LDPE and EVA blends

The electron beam-initiated surface modification of films prepared from various blends of low-density polyethylene (LDPE), ethylene vinyl acetate (EVA), and ditrimethylol propane tetraacrylate (DTMPTA) was carried out over a range of radiation doses (20-500 kGy) and concentrations of DTMPTA. The films were characterized by Fourier transform infrared-attenuated total reflectance (FT-ATR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurements, and peel adhesion. The printability of the films was also measured. FT-ATR and XPS revealed that the surface polarity of the films made from a 50 : 50 blend of LDPE and EVA increased up to a radiation dose of 100 kGy, compared with the unirradiated sample. The polarity decreased after 100 kGy radiation. Surface pitting and roughness were observed in the SEM photomicrographs of the same films, irradiated at higher radiation doses. Higher values of the surface energy were obtained at 100 kGy for the samples without DTMPTA and for the samples containing 3 wt% DTMPTA. Excellent printability was observed for all the films irradiated above an irradiation dose of 20 kGy. The data on the printability and peel adhesion of the irradiated films could be explained by surface energy, XPS, and SEM results.     

Structure and mechanical properties of isotactic polypropylene and iPP/talc blends functionalized by electron beam irradiation

The structure and mechanical properties of isotactic polypropylene (iPP) functionalized by electron beam irradiation are investigated by differential scanning calorimetry, wide‐angle X‐ray diffraction, thermogravimetry, thermomechanical analysis, melt index and mechanical measurements. The experimental results show that the degree of crystallinity, the thermal degradation temperature and the dimensional stability increase with dose in the range 0–5 kGy. At 5 kGy, the initial and final degradation temperatures of the irradiated iPP are raised by 66 °C and 124 °C, respectively. The melt index increases with increasing dose. The mechanical measurements show that the stiffness of iPP is greatly enhanced by electron beam irradiation. A small dose of irradiation (0.75 kGy) can increase the Young's modulus to 1284 MPa compared with 1112 MPa for unirradiated iPP. Adding 10 % by weight of irradiated iPP powder into iPP/talc (70/20 % by weight) blends, changes the processing parameters significantly and makes the Young's modulus rise substantially. At a dose of 40 kGy the Young's modulus of iPP/talc blend jumps to 3611 MPa against the original 2201 MPa. © 2000 Society of Chemical Industry     

Mechanical and barrier properties of carbon nanotube reinforced PCL‐based composite films: Effect of gamma radiation

Carbon nanotube (CNT) reinforced (0.05–0.5% by wt) polycaprolactone (PCL)‐based composites were prepared by compression molding. Addition of 0.2% CNT caused a 131% improvement of tensile strength (TS) of PCL films. The tensile modulus (TM) and elongation at break (Eb) of PCL were also significantly improved with the addition of CNT. The water vapor permeability of PCL was 1.51 g·mm/m²·day but 0.2% CNT containing PCL films showed 1.08 g·mm/m²·day. Similarly, the oxygen transmission rate (OTR) of PCL films was found to decrease with the addition of CNT. But, carbon dioxide transmission rate (CO₂TR) of PCL film was improved due to incorporation of CNT. Effect of gamma radiation on PCL films and CNT reinforced PCL‐based composites were also studied. The TS of the irradiated (10 kGy) PCL films gained to 75% higher than control sample. The TS of the 0.2% CNT reinforced composite film was reached to 41 MPa at 15 kGy dose. The barrier properties of non‐irradiated and irradiated (10 kGy) PCL films and composites (0.2% CNT reinforced) were also measured. Both PCL films and composites showed lower values of WVP upon irradiation and indicated better water vapor barrier. The OTR and CO₂TR of the irradiated (10 kGy) PCL films and composites were decreased compared to their counterparts. Surface and interface morphologies of the composites were studied by scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Gamma radiation induced property modification of poly(lactic acid)/hydroxyapatite bio‐nanocomposites

Poly(lactic acid)/hydroxyapatite (PLA/HAP) nanocomposite films with various compositions, 2 ? 70 parts HAP per 100 of the PLA polymer (pph), were made via the solution casting method. Transmission electron microscopy images of the PLA/HAP films exhibited spherical particles in the size range from nearly 10 nm to 100 nm dispersed within the polymeric matrix. Fourier transform infrared spectra of the nanocomposites revealed an interaction between PLA and HAP nanoparticles by carbonyl group peak shift. Incorporation of HAP nanoparticles in the PLA matrix stimulated crystal growth verified by differential scanning calorimetry. The films irradiated with γ‐rays at a dose of 30 kGy also showed an increase in crystallinity. The X‐ray diffraction patterns of the irradiated PLA exhibited two new peaks at around 16° and 19°, assigned to the α crystalline phase of PLA; these were absent in the unirradiated nanocomposites. Significant ductile behavior was observed in both irradiated and unirradiated PLA nanocomposites containing 2 and 10 pph of HAP. However, the irradiated nanocomposites had higher tensile strength. © 2013 Society of Chemical Industry     

Jute Reinforced Polymer Composite by Gamma Radiation: Effect of Surface Treatment with UV Radiation

Jute (Hessian cloth) reinforced polymer composites were prepared with a mixture of 2-hydroxy ethyl methacrylate (HEMA) and aliphatic urethane diacrylate oligomer (EB-204), and then cured under gamma radiation. Thick pure polymer films (2 mm thickness) were prepared by using the same monomer and oligomer at different weight ratios, and 500 krad of total gamma radiation dose at 600 krad/hr was selected for the curing of all composites. Total radiation dose, jute content, and monomer concentration were optimized with the extent of mechanical properties. Among all resulting composites, the composite of 38% jute content at monomer:oligomer = 50:50 (w/w) ratios showed the better mechanical properties, such as 108% increase in tensile strength (TS), 58% increase in bending strength (BS), 138% increase in tensile modulus (TM), and 211% increase in bending modulus (BM) relative to pure polymer film. The gel content values were also found to increase with the increase of jute content in the composite. But the elongation at break (Eb) for both tensile and bending was found to decrease with increasing jute content. The best mechanical properties were obtained when jute fibers were pre-irradiated with UV radiation, such as 150% increase in TS, 90% increase in BS relative to polymer film, 19% increase in TS, and 15% increase in BS relative to untreated jute-based composites. A water uptake behavior investigation of the resulting composites was also performed and composites based on UV-treated jute showed the minimum water uptake value.     

Effect of Ultraviolet Radiation on the Mechanical and Dielectric Properties of Hessian Cloth/PP Composites with Starch

Hessian cloth (jute fabrics) reinforced poly(propylene) (PP) composites (45 wt% fiber) were prepared by compression molding and the mechanical properties were evaluated. Jute fabrics and PP sheets were treated with UV radiation at different intensities and then composites were fabricated. It was found that mechanical properties of the irradiated jute and irradiated PP-based composites were found to increase significantly compared to that of the untreated counterparts. Irradiated jute fabrics were also treated with aqueous starch solution (1–5%, w/w) for 2–10 min. Composites made of 3% starch-treated jute fabrics (5 min soaking time) and irradiated PP showed the best mechanical properties. Tensile strength, bending strength, tensile modulus, bending modulus and impact strength of the composites were found to improve 31, 41, 42, 46 and 84% higher over untreated composites. Water uptake, thermal degradation and dielectric properties of the resulting composites were also performed.     

Study on the Properties of Blend Rubber Between Grafted Rubber Latex and Natural Rubber Latex by Gamma Radiation

Blend rubber films were prepared by mixing styrene grafted rubber latex and natural rubber latex (NRL) with varying proportions by gamma radiation from Co-60 source at room temperature. Tensile strength, modulus at 500% elongation, elongation at break, permanent set, and swelling ratio were measured. Tensile strength and modulus at 500% elongation attain maximum at 8 kGy radiation dose for blend rubber films. The increase in tensile strength is insignificant, but modulus increases from 5.61 to 7.46 MPa with increased proportion of grafted rubber latex from 40 to 70% in the blend at this radiation dose. Elongation at break, permanent set, and swelling ratio of blend rubber decreases with increase in radiation dose as well as proportion of grafted rubber.     

Jute composite with MMA by gamma and UV radiations in the presence of additives

Jute yarns treated with MMA + MeOH solutions were irradiated either with Co‐60 gamma source or with UV radiation. In gamma radiation, polymer loading of MMA (methyl methacrylate) onto jute increased quite substantially, but the strength of the composite decreases sharply after 15% polymer loading. The gamma‐treated jute samples were very brittle. On the other hand, jute yarns irradiated in situ under UV radiation was found to be grafted with MMA. The tensile strength of the UV‐cured jute yarn composite increases with an increase of grafting level, in contrast to the behavior observed with the gamma‐irradiated jute composite samples. The tensile properties of the composites can be further enhanced by the incorporation of certain additives and coadditives into MMA + MeOH solutions. This opens diverse applications for jute materials. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 900–906, 1999     

Improvement of Physicochemical Properties of Natural Rubber and Polyvinyl Alcohol Blends by Radiation Vulcanization

Variable compositions of natural rubber latex (NRL) and polyvinyl alcohol (PVA) have been blended. The contents of PVA in the blends were varied from 0.5 phr to 3.0 phr and the total solids contents of NRL was fixed to 50%. The blends were irradiated at different irradiation doses (0–20 kGy) in the presence of normal butylacrylate (n-BA). The permanent set; swelling ratio and elongation at break point of the blended films at all compositions decrease with the increase of radiation doses whereas increase is observed in cross-linking density, gel content, tensile strength and modulus. Sharp changes of all the properties were observed between 3–5 kGy radiation doses. On the other hand, at higher radiation doses, ≥ 5 kGy, the permanent set, swelling ratio, gel content did not show any appreciable change whereas cross-linking density, tensile strength, modulus and elongation at break point are changed. The maximum cross-linking density of blend is observed with 2.0 phr PVA at 12 kGy radiation. The highest value of modulus and tensile strength of the same blend are found at 10 kGy and 5 kGy respectively. Blends with 2.0 phr PVA for all compositions proved to be optimum for improving varies properties at 5–12 kGy radiation doses.     

The influence of EB-crosslinking on barrier properties of HDPE–mica composites

High-density polyethylene (HDPE) was compounded with untreated and surface-treated mica (10, 20, 40 wt %) and composites were injection-molded. The composites were radiation crosslinked (100, 300, 700 kGy) and hydrocarbon permeability, tensile impact strength, and tensile strength at 25 and 80°C of the composites were examined. The permeability of HDPE decreased from 7 to 3.6 g/(d × m²) by compounding the polymer with 20 wt % mica, and the permeability was additionally reduced to 1.3 g/(d × m²) by irradiation of the compounds (700 kGy). When surface-treated mica was used, the permeability of the composite furthermore decreased to about 1.0 g/(d × m²). Upon irradiation, the E modulus measured at 25°C increased 5% when the dose was 300 kGy. At 80°C, the corresponding increase was 40%. The tensile impact strength of an unfilled polymer increased more than three times by an irradiation dose of 700 kGy, and for a polymer with 10 wt % mica, the tensile impact strength was twice the level of an unirradiated composite. © 1996 John Wiley & Sons, Inc.     

Polyblend CPP and Bionolle with PP‐g‐MAH as compatibilizer. II. Biodegradability

The biodegradability of Bionolle and a CPP/Bionolle blend in two biotic environments, that is, soil and a lipase‐enzyme solution, were evaluated using the mechanical properties and weight‐loss data. It was noted that upon soil burial the tensile strength and elongation at break of polyblends were significantly reduced, particularly after 3 months. The time of complete loss of strength as predicted from the curve‐fit model was found sequentially to be 6.80, 5.03, 4.84, 11.49, and 140.25 months for Bionolle, compatibilized Bionolle, and CPP/Bionolle (25/75), (50/50), and (75/25), respectively. Meanwhile, the weight loss of polyblends during soil burial were observed to generally increase with increasing Bionolle content. Even a synergistic effect on the weight loss was shown by compatibilized Bionolle and CPP/Bionolle (25/75). Additionally, the time for complete weight loss as estimated from the curve‐fit model was 12.57, 7.33, 7.01, and 13.90 months for Bionolle, compatibilized Bionolle, and CPP/Bionolle (25/75) and (50/50), respectively. From the enzymatic degradation, it was recognized that in the early stage of biodegradation both the amorphous phase and the crystalline parts were randomly attacked. It was found that the weight loss that resulted from enzymatic degradation was satisfactorily described by a generalized kinetic curve derived from a first‐order reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1283–1290, 1999     

Radiation modification of functional properties in PVC/mica electrical insulations

Summary The effects of γ-irradiation on poly(vinyl chloride) blended with fillers (plasticizer, lead stabilizer and mica) are presented. Mechanical and electrical investigations were carried out on samples that received doses of maximum 160 kGy. The results on tensile strength, volume resistivity and loss factor prove that poly(vinyl chloride) may be used as electrical insulator after short γ-exposure. Because mica plays a role of absorbent for hydrochloric acid formed by PVC degradation, favorable properties are obtained for dose up to 120 kGy. The volume resistivity decreases constantly while tan δ remains unchanged for a large frequency range (10²–10⁵ cps). Mica content of 14% induces a decrease in unirradiated PVC of one order of magnitude. After irradiation at 160 kGy volume resistivity increases of about five times relative to 40 kGy irradiated samples. At 150 kGy tensile strength decreases only with 10%, and elongation at break presents a light modification in the selected dose range. The largest differences between the maximum current values obtained for applied doses are presented by PVC with the highest concentration of mica (14%). At 40 kGy, when the degradation becomes relevant, the dipoles are not efficiently trapped by mica and the current does not attend a steady state for a long period (more than half an hour). For higher doses the steady-state current is reached after only 1–3 minutes, due to crosslinking. Some considerations concerning the consequences of high energy exposure of poly(vinyl chloride) on electrical behaviour are presented.     

Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by ⁶⁰Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (T_o) and the temperature of maximum weight‐loss rate (T_p) of control and irradiated PHBV were in line with the heating rate (°C min^?1). T_o and T_P of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that ⁶⁰Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (T_m) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry     

电子束辐射效应对双马来酰亚胺结构与热性能的研究

文章研究了电子束辐照效应对二苯甲烷双马来酰亚胺(BMI)结构和热性能的影响。结果表明,在电子束辐照作用下,由于交联结构的形成,辐照BMI的凝胶率显著增加,达到400kGy时的58.2%;同时,相比于为辐照BMI,辐照BMI的初始分解温度显著提高,升至400kGy时的336℃。     

A Comparative Study on the Mechanical,Degradation and Interfacial Properties of Jute/LLDPE and Jute/Natural Rubber Composites

Jute fabric (hessian cloth) reinforced low-density polyethylene (LLDPE) composites (40 wt%) and solid natural rubber-(NR) based composites (40 wt%) were fabricated by compression molding. Tensile strength (TS), tensile modulus (TM) and percentage elongation at break (Eb) of jute/LLDPE composites were found to be 29, 680 MPa and 20%, and for jute/NR-based composites were also found to be 15, 122 MPa and 94%, respectively. Interfacial shear strength (IFSS) of the jute/LLDPE and jute/NR systems was investigated by using the single fiber fragmentation test (SFFT). Scanning electron microscopy (SEM) and aqueous degradation tests were also performed.