Thermal,mechanical, and structural investigation of the effect of electron beam‐irradiation in Bayfol nuclear track detector

Samples from sheets of the polymeric material Bayfol have been exposed to electron beam in the dose range 10–100 kGy. The resultant effect of electron beam irradiation on the thermal properties of Bayfol has been investigated using thermogravimetric analysis. The onset temperature of decomposition T₀ and activation energy of thermal decomposition E_a were calculated, results indicating that the Bayfol polymer decomposes in one main weight loss stage. Also, the electron irradiation in the dose range 40–100 kGy led to a more compact structure of Bayfol polymer, which resulted in an improvement in its thermal stability with an increase in activation energy of thermal decomposition. The variation of transition temperatures with electron dose has been determined using differential thermal analysis. The results indicate that the electron irradiation in the dose range 40–100 kGy causes crosslinking that destroys the crystalline structure depressing the melting temperature and this is most suitable for applications requiring the molding of this polymer at lower temperatures. In addition, the mechanical and structural properties of Bayfol samples were measured and the results revealed that the tensile strength, elongation at break, yield strength, and intrinsic viscosity were affected by the electron doses. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films were extensively investigated by means of several series of model latexes with varying backbone polymer crosslinking density and interfacial crosslinking functional groups. It was found that the tensile strength of crosslinked model latex films increased with increasing gel content (i.e. crosslinking density) of latex backbone polymers up to about 75% and then decreased with further increase in gel, while their elongation at break steadily decreased with increasing gel content. These findings showed that latex particle coalescence was retarded above a gel content of about 75% so that the limited coalescence of latex particles containing gel contents higher than 75% prevented the tensile strength of crosslinked latex films from increasing by further crosslinking the latex backbone polymers. This was contrary to the theory of rubber elasticity that the tensile strength increases with increasing molecular weight and crosslinking density. This limitation was found to be overcome by the interfacial crosslinking among latex particles during film formation and curing. This paper will discuss the effects of both latex backbone polymer and interfacial crosslinking on latex film properties. It will also discuss the development of self-curable latex blends and structured latexes containing co-reactive groups: oxazoline and carboxylic groups.     

Preparation and Characterization of Bioblends from Gelatin and Linear Low Density Polyethylene (LLDPE) by Extrusion Method

Abstract

Bioblends are composites of at least one biodegradable polymer with a non-biodegradable polymer. Successful development of bioblends requires that the biodegradable polymers be compatible with other component biodegradable/synthetic (non-biodegradable) polymers. Bioblends from LLDPE and gelatin were prepared by extrusion and hydraulic heat press technique. The gelatin content in the bioblends was varied from 5 to 20 wt%. Various physico-mechanical properties such as tensile, bending, impact strength (IS), thermal ageing and soil degradation properties of the LLDPE/gelatin bioblends with different gelatin contents were evaluated. The effect of thermal ageing on mechanical properties was studied. The mechanical properties such as tensile modulus (TM), bending strength (BS), bending modulus (BM) were found to increase with increasing gelatin content up to 20 wt%, however tensile strength (TS) and elongation at break (%E _b) were decreased with increasing gelatin content. Impact strength value increased with increasing gelatin content up to 10 wt% and then decreased slightly with increasing gelatin content. The blend containing 20 wt% gelatin showed relatively better mechanical properties than other blends. The values of TS, TM,%E _b, BS, BM and IS for the bioblend with 20 wt% gelatin content are 5.9MPa, 206.3MPa, 242.6%, 12.1MPa, 8 MPa and 13.7 J/cm², respectively. Water uptake increases with increasing soaking time in water and weight loss due to soil burial also increases with increasing gelatin content in the blends but both are significantly lower than that of pure gelatin sheet. Weight loss values after thermal ageing increase with time, temperature and increasing gelatin content in the blend but are much lower than pure gelatin. Mechanical properties such as TS, TM are increased and %E _b is decreased after thermal ageing at 60°C for 30 min. Consequently, among all of the bioblends prepared in this work the blend having 20% gelatin content yields properties such that it can be used as a semi-biodegradable material.     

Effect of <Emphasis Type="Italic">in situ</Emphasis> co-crosslinking on mechanical properties and rheology of nylon 11/EVOH/DCP composites

Nylon 11/ethylene-vinyl alcohol (EVOH) composites with various concentration of dicumyl peroxide (DCP) were prepared using a single-screw extruder. The influence of DCP concentration on the mechanical properties and rheological behavior of nylon 11/EVOH composites as well as gel content was investigated. The experimental results showed that the impact and tensile strength were significantly improved when the DCP loading was in the range of 1.0~1.5 wt% while the elongation at break reduced. All nylon 11/EVOH melts with and without DCP were pseudoplastic and exhibited shear-thinning behavior. The apparent viscosity of composites was increased dramatically with the addition of DCP and was up to the maximum value at 1.5 wt% DCP level, which indicated that the interfacial adhesion owe to co-crosslinking between nylon 11 and EVOH was increased markedly.     

Effects of molecular weight on selected physical properties of polyaromatic ether-ketones

Polyaromatic ether-ketones with various inherent viscosities were prepared and their thermal properties and stress–strain relationships were studied. It was found that the polymer should have an inherent viscosity greater than 0.8 in order to give flexible films, but there was no difference in thermal and stress–strain properties among polymers with viscosities greater than 0.8. Values of 110 MPa and 13% are considered to be the standard values of tensile strength and elongation, respectively, for these polyaromatic ether-ketones. The crosslinking effects on these properties were also studied, using polymers containing 1 and 5 mol % of crosslinkable biphenylene units, but no significant changes in the properties due to crosslinking were observed.     

液态三元乙丙橡胶固化和力学性能的研究

液体EPDM（三元乙丙橡胶）是相对低分子量的乙烯-丙烯-共轭二烯三元共聚物,针对它的研究较少。该文主要研究了采用DCP过氧化物硫化体系硫化的液体EPDM的固化和力学性能。液体EpDM在引发剂DCP和助交联剂TAIC的作用下。凝胶含量随DCP增加无明显变化,而随TAIC增加而增大。力学性能有相似变化,不随DCP增加而改变,但随TAIC增加而增大。结果表明,交联产物的凝胶含量所表现出的其交联程度的状况导致相同的力学性能变化。实验表明,当DCP为4％、TAIC为12％时,液体EPDM的交联产物有较好的力学性能。     

Preparation and characterization of ethylene-butene copolymer (EBC)/mica composites

Composites of ethylene-butene copolymer (EBC) with various amounts of untreated mica and silane modified mica were prepared by the melt blending technology. The morphological, thermal, dielectric and mechanical properties of composites were investigated. The results showed that both of raw mica and treated mica were uniformly dispersed in the polymer matrix. Attributed to the heterogeneous nucleating effect of mica, the crystallization ability of composites was increased and the crystals of the polymer matrix were arranged more closely. With increasing the filler content, the thermal stabilities of composites were improved, whose increasing rate was decreased when the filler content was up to a certain amount. The dielectric properties of samples were influenced by the filler content, surface treatment of mica and the testing frequency. The mechanical properties showed that the tensile strength and elongation at break of composites were not decreased apparently until the filler content was up to 30 wt%. And the hardness and modulus at 100% elongation of samples were increased with the increase in the filler content, ascribed to the reinforcing effect of mica.     

Structure and properties of bio-based poly(trimethylene terephthalate)/polyamide 56 blends prepared by melt mixing

The extensive use of conventional petroleum-based polymers consumes large amounts of energy and emits a lot of carbon dioxide. Therefore, the development and popularization of bio-based polymer materials are highly significant for ecological reasons. Herein, a series of poly(trimethylene terephthalate)/polyamide 56 (PTT/PA56) blends with different weight ratios were prepared by melt blending of two bio-based polymers, PTT and PA56. The phase structure, miscibility, crystallization and melting behaviors, crystal structure, and mechanical and water absorption properties of PTT/PA56 blend systems were investigated. The results showed that PTT and PA56 were immiscible in the whole range of compositions. The immiscibility of the blend system intensified with the increase of dispersed phase content. As PA56 content increased, tensile strength and elongation at break of samples assumed an increasing trend, whereas impact strength initially remained almost unchanged and then gradually decreased. In contrast, increasing PA56 content gradually increased water absorption of samples. Comprehensive analysis indicated that the best combination of different properties was obtained for the PTT/PA56 blends including 60–80 wt% PA56.     

Customizing ultraviolet curable polymer-ink properties via reactive diluent modification and viscosity control

In inkjet 3D printing, material selection plays a crucial role in shaping both printing performance and material characteristics. Achieving the desired properties relies on precisely formulated compositions. In this context, ultraviolet (UV) curable polymers require specific viscosities, typically ranging from 3700 to 5700 mPa·s, to function effectively in 3D printing's material jetting technique, preventing complications during material dispensing. This study formulates UV-curable polymers by blending four distinct monomers: Genomer 4247 Aliphatic Urethane Dimethacrylate, 1,10-Decanediol Dimethacrylate, Isobornyl Acrylate, and Methyl Acrylate, within a controlled dark room environment at room temperature to prevent undesired crosslinking reactions during mixing. The selection of these monomers and their compositions is meticulous, considering their capacity to achieve specified viscosities and enhance overall material performance. This formulation process yields a wide range of UV-curable polymer viscosities. The study employs comprehensive methodologies, including rheometry, Fourier transform infrared analysis, Soxhlet extraction, thermal analysis, and tensile testing, for rigorous evaluation of viscosity, curing efficiency, thermal characteristics, and mechanical performance. Notably, mechanical and chemical performance exhibits marginal differences within the viscosity range, attributed to UV-curable polymer crosslinking, consistently exceeding 99% for all samples. However, the polymer composed of 98% v/v oligomer and methyl acrylate (MA) demonstrates notably better thermal and mechanical properties due to its 99.91% gel content crosslinking. Remarkable polymer fabrication thus occurs within the desired viscosity range.     

Comparison in processability and mechanical and thermal properties of ethylene–octene copolymer crosslinked by different techniques

The crosslinking of metallocene ethylene–octene copolymer was investigated. The crosslinked polymers were prepared using two different techniques, i.e., peroxide crosslinking and silane–water crosslinking. In the former, the crosslinking reaction was conducted in a twin‐screw extruder, in the presence of dicumylperoxide. In the latter, the polymer was first grafted with vinyl trimethoxysilane in the extruder and subsequently crosslinked with water. The paper aims at investigation of the differences between these two techniques, in terms of processing and product mechanical and thermal properties. The results showed that the silane‐crosslinked polymers could be prepared with much higher gel contents than the peroxide‐crosslinked samples. The silane‐crosslinked polymers also retained the elastomeric characteristics of the pure polymer and showed remarkably higher extensibility, better thermal stability, and energy storage capacity. An explanation for the property differences between peroxide‐crosslinked and silane‐crosslinked polymers was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1179–1185, 2004     

Effects of filler–filler and polymer–filler interactions on rheological and mechanical properties of HDPE–wood composites

High‐density polyethylene (HDPE)–wood composite samples were prepared using a twin‐screw extruder. Improved filler–filler interaction was achieved by increasing the wood content, whereas improved polymer–filler interaction was obtained by adding the compatibilizer and increasing the melt index of HDPE, respectively. Then, effects of filler–filler and polymer–filler interactions on dynamic rheological and mechanical properties of the composites were investigated. The results demonstrated that enhanced filler–filler interaction induced the agglomeration of wood particles, which increased the storage modulus and complex viscosity of composites and decreased their tensile strength, elongation at break, and notched impact strength because of the stress concentration. Stronger polymer–filler interaction resulted in higher storage modulus and complex viscosity and increased the tensile and impact strengths due to good stress transfer. The main reasons for the results were analyzed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dynamic thermomechanical and tensile properties of chain-extended poly(ethylene terephthalate)

A series of chemically modified poly(ethylene terephthalate) (PET) samples was received after chain extension of a virgin sample at different reaction times with a new diepoxide as chain extender. These samples showed different intrinsic viscosity and degrees of branching or crosslinking. The effect of this differentiation on thermal properties was studied by dynamic mechanical thermal analysis and the determined T_g values were found to be in good agreement with those obtained by differential scanning calorimetry and thermomechanical analysis. Also, the branching or crosslinking exhibited significant improvement in tensile mechanical properties, which were studied, and the results are discussed. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 797–803, 1998     

LDPE/SEBS复合材料化学交联及相关性能的研究

采用二段混炼的方法,制备低密度聚乙烯/苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(LDPE/SEBS)复合材料。探究SEBS的不同含量对LDPE/SEBS力学性能的影响。通过双叔丁基过氧异丙基苯(BIBP)化学交联LDPE/SEBS,制备LDPE/SEBS/BIBP复合材料,探究LDPE/SEBS/BIBP的力学性能、微观形貌、凝胶含量、热学性能和流变性能。结果表明:SEBS用量为50份时,LDPE/SEBS具有较好的力学性能。当BIBP用量为0.9份,LDPE/SEBS/BIBP的力学性能最佳,拉伸强度为26.22 MPa,断裂伸长率为732.23%。随着BIBP用量的增加,LDPE/SEBS/BIBP的界面相容性、凝胶含量和黏度上升,熔融温度、结晶度和损耗模量下降,储能模量曲线的斜率先下降后趋于稳定。     

Synthesis of starch‐based plastic films by electron beam irradiation

Starch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007     

Preparation and characterization of vinyltrimethoxysilane and dicumyl peroxide–cured (ethylene propylene diene monomer)/polypropylene thermoplastic vulcanizates

The present investigation deals with understanding the influence of vinyltrimethoxysilane (VTMS) concentration on the mechanical, thermal, thermomechanical, rheological, morphological, gel content, crosslinking density, and compression set properties of dynamically vulcanized ethylene propylene diene monomer (EPDM)/polypropylene (PP) (60/40, w/w) ‐based thermoplastic vulcanizates. It was determined that the values of crosslinking density, gel content, tensile strength, Young's modulus, elongation at break, and viscosity increased; whereas that of compression set, melting temperature, enthalpy of melting, crystallinity, and damping factor decreased with increased addition of VTMS in the EPDM/PP‐based thermoplastic vulcanizate. This is attributed to the physical crosslinking caused because of VTMS grafting on EPDM and chemical crosslinking induced by VTMS between PP and EPDM. This has been confirmed by Fourier‐transform infrared spectroscopy spectra, whereas the thermomechanical and scanning electron microscopy analysis confirmed increased compatibility between EPDM and PP on the addition of VTMS. J. VINYL ADDIT. TECHNOL., 23:312–320, 2017. © 2015 Society of Plastics Engineers     

Weld lines and mechanical properties of injection molded polyethylene/polystyrene/copolymer blends

In this article, we investigate the effect of weld lines on the tensile mechanical properties of unmodified and copolymer modified high density polyethylene (HDPE) and polystyrene (PS) blends. The homopolymers were melt blended in the proportion of 20 wt% HDPE and 80 wt% PS using a twin screw extruder at a temperature of 200°C. The results show that the mechanical properties are generally lower when weld lines are present. The decrease of the mechanical properties is much more pronounced for the blends. The addition of small amounts of a commercial styrene/butadiene copolymer significantly improves the strength and the elongation at break of this blend. An optimum copolymer concentration was observed at 3 wt%. This value coincides with the interphase saturation concentration of the copolymer obtained from the analysis of the DMTA (dynamic mechanical and thermal) properties of the blends. The copolymer was also found to induce important changes in the morphology of the blend. The interdiffusion of the polymer fronts in the weld region was also improved by the presence of the copolymer. It is believed that these two aspects contribute to the enhanced properties obtained with copolymer modified blends in presence of weld lines. An important effect of the injection temperature on the tensile strength and the elongation at break of welded samples with copolymer modified blends was observed. The effect of mold temperature on these properties was less important mainly at low injection temperatures. Only a slight effect of these two parameters was observed for the tensile modulus in the range of mold and injection temperatures considered in this study.     

Study on the influence of electron beam irradiation on the thermal,mechanical, and rheological properties of ethylene‐octene copolymer with high comonomer content

Ethylene‐octene copolymer (EOC) was irradiated using electron beam irradiation at different dosages (30, 60, 90, and 120 kGy). Effect of irradiation dosage on thermal and mechanical properties was studied. When compared to low density polyethylene, EOC exhibited higher degree of crosslinking reflected in increased gel content, higher elastic modulus (G′), and lower tan δ obtained by rheology measurement at 150°C. Crosslinking caused improvement in high‐temperature creep and room temperature and also elevated temperature elastic properties. Differential scanning calorimetry revealed that e‐beam irradiation has caused a gradual reduction in crystallinity and a presence of a fraction with higher melting temperature. In the case of EOC, as the extent of crosslinking increased, stress at break showed an increasing trend whereas irradiation dosage had an inverse effect on elongation at break. Radiation dosage has positive effect on thermal stability estimated by thermogravimetric analysis. After 30 min of thermal degradation at 220°C, slightly higher C?O peak for crosslinked sample was found by Fourier transform infrared spectroscopy while for room temperature samples no C?O peak was detected. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electron beam irradiation of low-density polyethylene filled with metal hydroxides for wire and cable applications

The effects of electron beam irradiation for crosslinking of polymers used for wire and cable insulations are still being researched. In this research, the influence of electron beam irradiation on the different blends of low-density polyethylene (LDPE) filled with aluminum trihydrate and magnesium hydroxide (ATH, MH) were studied. It was revealed by melt flow index, tensile strength, and elongation at break tests that addition of MH to LDPE increases the adhesion forces inside polymer matrices more efficient than similar ATH/LDPE compounds. Field emission scanning electron microscopy test showed that MH is platy in structure and more homogenous mixed than ATH with LDPE. The results on thermogravimetric analysis and limiting oxygen index tests revealed that the thermal stability and incombustibility properties of MH blends are more efficient than similar ATH blends. Meanwhile, it was observed by smoke density test that MH blends produce the lowest smoke density compared with virgin LDPE and similar ATH blends. It was also observed that increasing irradiation by electron beam had impressive affections on the density, gel content, and mechanical properties for all the polymeric samples in this study.     

Mechanical and Morphological Properties of Polypropylene and Regenerated Tire-Rubber Blends

Mechanical properties and morphology of blends prepared from polypropylene (PP) and 5–20 wt% of regenerated tire-rubber (RgR) were studied. The samples were prepared in a twin-screw extruder. The addition of maleic anhydride-functionalized polypropylene (PP-g-MAH) was also investigated. Tensile and flexural moduli, tensile strength at break, elongation at break and Izod impact resistance at 23°C were increased by the addition of 15 wt% of regenerated rubber and 5 wt% of PP-g-MAH. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) analyses showed some interaction between PP and RgR and considerable modification of the compatibilized mixture morphology. The fracture surface of the blend with PP-g-MAH showed a better interaction between the PP matrix and the regenerated rubber domains, for all blends. Well-dispersed particles of the rubber in the polypropylene matrix were observed. DSC showed that PP crystallizes on cooling at lower temperatures as the RgR content increases. The decrease in crystallization temperature is more evident for blends with 5 wt% PP-g-MAH.     

Hyperbranched‐modified epoxy thermosets: Enhancement of thermomechanical and shape‐memory performances

In this study a complete characterization of the thermomechanical and shape‐memory properties of epoxy shape‐memory polymers modified with hyperbranched polymer and aliphatic diamine was performed. Focusing on the mechanical properties that are highly desirable for shape‐memory polymers, tensile behavior until break was analyzed at different temperatures and microhardness and impact strength were determined at room temperature. As regards shape memory performance, the materials were fully characterized at different programming temperatures to study how this influenced the recovery ratio, fixity ratio, shape‐recovery velocity, and switching temperature. Tensile testing revealed a peak in deformability and in the stored energy density at the onset of the glass transition temperature, demonstrating that this is the best programming temperature for obtaining the best shape‐memory performances. The Young's moduli revealed more rigid structures in formulations with higher hyperbranched polymer content, while microhardness showed higher values with increasing hyperbranched polymer content due to the increased crosslinking density. Impact strength was greatly improved as the aliphatic diamine content increases due to the energy dissipation capability of its flexible structure. As regards the shape‐memory properties, increasing the programming temperature has a minor effect on formulations with a lower hyperbranched polymer content and worsens these properties when the hyperbranched polymer content is increased. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44623.