Synergistic effect of short reinforced fibers and gamma rays on the thermal and mechanical properties of waste poly(propylene) composites

Compressed molded waste poly(propylene) was reinforced with short carbon and/or glass fibers for investigation. The prepared composites were γ‐irradiated to estimate the role of the ionizing radiation as a compatibilizing agent. TGA and DSC were used to investigate the influence of exposure dose and the incorporation of short fibers on the thermal parameters of the prepared composites. The mechanical properties of different composites were also studied. It was observed that the mechanical and thermal parameters were highly affected by the kind of incorporated fibers and γ‐irradiation. The structural and morphological studies were made by means of XRD and SEM to investigate the structure change caused by the incorporation of short fibers and exposure to γ‐irradiation. The results show that the irradiation of carbon fiber–containing composite magnified its thermal stability and its tensile strength. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1741–1747, 2005     

The effect of alumina particulate morphology on the properties of reinforced poly(propylene) and poly(ethylene-co-vinyl acetate) composites

The effect of alumina particulates on a thermoplastic matrix is investigated, in particular the effect altering the alumina particle size and morphology has on the mechanical properties. Different grades of alumina are used and two thermoplastic matrices; namely poly(propylene) and poly(ethylene-co-vinyl acetate). Investigations showed that optimum properties were achieved with the alumina of smallest particle size and lowest aspect ratio. Preliminary work has also been performed on the use of silane coupling agents and they have proved effective in increasing the tensile properties of the composites.     

Investigation on the microstructure and the electric property of poly(propylene)/chlorinated poly(propylene)/poly(aniline) composites

The article presents results of studies on composites made from poly(propylene) (PP) modified with poly(aniline) (PANI) doped with dodecylbenzene sulfonic acid (DBSA) and chlorinated poly(propylene) (CPP). The volume resistivity of PP/CPP/PANI composites was detected, and the results show that the volume resistivity decreases with increasing CPP content, and there exists a minimum volume resistivity. Effects of CPP on the microstructure and crystalline structure of the PP/CPP/PANI composites and the relationship between the effects and the electric property were carefully analyzed by scanning electron microscope (SEM) and wide angle X‐ray diffraction (WAXD). The method that the specimens of SEM are polished is appropriate to investigate the morphology of conducting polymer composites. The obtained results illuminate that the area of conducting parts and insulating parts obtained from the digital analysis of the SEM image is obviously influenced by the CPP content, the parameters of the lamellar‐like structure are immediately related to CPP content and denote the dispersion of PANI‐DBSA, and the percent crystallinity and mean crystal size of PP are directly correlated with the CPP content. The increasing area of conducting parts, the increasement of layer distance, the decreasement of size and layer number of the lamellar‐like structure of PANI‐DBSA, and the increasement of the percent crystallinity and mean crystal size of PP are beneficial to the improvement of the conductive property of PP/CPP/PANI composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(trimethylene terephthalate) nanocomposite fibers comprising different organoclays: Thermomechanical properties and morphology

Poly(trimethylene terephthalate) (PTT) nano composites were synthesized by in situ polymerization at high temperature with two thermally stable organoclays: 1,2‐dimethylhexadecylimidazolium‐montmorillonite (IMD‐MMT) and dodecyltriphenyl phosphonium‐MMT (C₁₂PPh‐MMT). PTT hybrid fibers with various organoclay contents were melt‐spun at various draw ratios (DRs) to produce monofilaments. The thermomechanical properties and morphologies of the PTT hybrid fibers were characterized using differential scanning calorimetry, thermogravimetric analysis, wide‐angle X‐ray diffraction, electron microscopy, and mechanical tensile properties analysis. The nanostructure of the hybrid fibers was observed by both scanning and transmission electron microscopy, which showed that the clay layers were well dispersed into the matrix polymer, although some clusters or agglomerated particles were also detected. Unlike the hybrids containing IMD‐MMT, the clay layers of the C₁₂PPh‐MMT hybrid fiber were more dispersed into the matrix polymer. The thermal stability and tensile properties of the hybrid fibers increased with increasing clay content for DR = 1. However, as DR increased from 1 to 9 the ultimate strength and initial modulus of the hybrid fibers with IMD‐MMT increased slightly whereas those of C₁₂PPh‐MMT hybrid fibers decreased slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4535–4545, 2006     

Influence of gamma irradiation on waste poly(propylene) composites containing talc and high crystallinity poly(propylene)

Commercial polyolefin, such as poly(propylene), are widely used because of their easy processing and their excellent mechanical and thermal properties. Although their recycling is well established, the mechanical and thermal properties of the recycled waste poly(propylene)(WPP) are normally lower than those of the virgin material. The introduction of talc can improve the toughness, without compromising the processability and recycling capabilities. However, the thermal properties of these blends should be assessed to limit degradation during recycling. The effect of gamma radiation on the thermal and mechanical properties of WPP/High Crystallinity Poly(propylene)/Talc was studied. TGA, DSC, and electrical conductivity performed the characterization of WPP composites. Mechanical properties and electrical conductivity of the composites were evaluated. The results showed that the addition of Talc to WPP was found to improve the thermal stability of WPP composites. The compatibilisation of the blends using gamma radiation resulted decrease the weight loss with increasing the temperature. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers     

Preparation and properties of biodegradable poly(propylene carbonate)/starch composites

Biodegradable composites of poly(propylene carbonate) (PPC) reinforced with unmodified cornstarch were compounded in a batch mixer followed by compression molding. The effects of reinforcement on the morphology, static and dynamic mechanical properties, as well as thermal properties of PPC/starch composites, were investigated. Tensile tests showed that incorporation of starch improves the stiffness and tensile strength of composites significantly. Scanning electron microscopic examination revealed the existence of good interfacial adhesion between the fillers and PPC matrix. Moreover, experimental results indicated that the starch addition leads to a significant improvement in the thermal stability of the composites. This paper demonstrates that the incorporation of low‐cost and biodegradable cornstarch into PPC provided a practical way to produce completely biodegradable and cost‐competitive composites with good mechanical properties. Polym. Eng. Sci. 44:2134–2140, 2004. © 2004 Society of Plastics Engineers.     

纳米碳酸钙性质对聚氯乙烯复合材料界面及性能的影响

选择了不同的表面处理剂对纳米CaCO₃进行表面改性. 研究了不同表面处理剂对CaCO₃/PVC纳米复合材料微观结构、界面结合强度、力学性能及加工性能的影响.研究表明,钛酸酯偶联剂处理可使纳米CaCO₃颗粒在PVC基体中达到良好分散,明显改善纳米CaCO₃颗粒与PVC基体之间的界面结合,并提高其界面结合强度.力学性能和流变性能研究表明,钛酸酯处理的纳米CaCO₃填充PVC具有更高的拉伸强度、冲击强度以及更低的平衡转矩, 而且CaCO₃/PVC复合材料的冲击韧性在填充量为20%(mass)时达到最大值26.5 kJ•m^-2,是纯PVC的4倍.     

Effect of short polyethylene terephthalate fibers on properties of ethylene-propylene diene rubber composites

The alteration in some properties of electron beam (EB) cured ethylene-propylene diene rubber (EPDM) reinforced by polyethylene terephthalate (PET) fiber was investigated in this study. Bonding system Resorcinol/Hexamethylenetetramine/Silica (RHS) was used to enhance the fiber/EPDM adhesion and to maintain optimum composite strength properties. Mechanical properties of composites namely; tensile strength, hardness and modulus at 100 % elongation have been enhanced by adding PET fibers and increasing irradiation dose. Moreover, the effect of fiber loading and irradiation dose on the soluble fraction behavior of the composite in benzene was also investigated. The soluble fraction of the composites decreased with increasing the fiber loading and irradiation dose. The extent of fiber alignment and strength of fiber-rubber interface adhesion were analyzed from the anisotropic swelling measurements. In addition, thermal stability of the composites was increased. Besides, the mechanical properties like tensile strength and stiffness were improved by thermal ageing. Scanning electron microscopy (SEM) for the fractured surfaces and Wide- angle X- ray diffraction (WAXD) of the investigated samples confirmed that the adhesion occurred between fibers and EPDM.     

Solution properties of poly(propylene sulphide)

Poly(propylene sulphide) (PPS) initiated by cadmium bis(phenyl allyl thiolate) was fractionated from benzene-methanol, and the fractions were examined by viscosity, osmotic pressure and light scattering determinations. Gel permeation chromatography with Styragel columns was found unsatisfactory in tetrahydrofuran (THF) and toluene at room temperature. Polymer stored in the dark at room temperature underwent a very slow degradation which broadened the distribution in the fractions. The following quantitative relationships were found at 25°C:

Extrapolations to derive the unperturbed coil dimensions indicate a possible, but doubtful, solvent effect. The value derived from the θ-mixture gives $\text{A = 696 × 10}{}^{\mathrm{?11}}\text{cm mol}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{g}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$ and a steric factor σ = 1.49, consistent with a high ‘chain flexibility’ expected from the relatively long C-S-C linkages.     

Viscoelastic properties of poly(propylene glycols)

The relaxational and retardational properties of poly(propylene glycol) liquids, of nominal molecular weights 400 and 4000, are described. The viscoelastic behaviour of each liquid has been determined over a wide temperature range, using high frequency shear wave techniques operating at 30 and 454 MHz. It is found that the complex compliance $\text{J1(jω)}$ is described in terms of the viscosity ν, the limiting high frequency compliance J_∞, the retardational compliance J_r and a characteristic retardation time $\text{т}{}_{\mathrm{r}}$ by:

$\text{J}{}^1\text{(jω)=J}{}_{\mathrm{\infty }}\text{+}\text{1}\text{jωη}\text{+}\text{j}{}_{\mathrm{r}}\text{(1+jωτ}{}_{\mathrm{r}}\text{)}{}^{\mathrm{\beta }}$

where β is a parameter of the retardation time distribution.For the lower molecular weight liquid, $\text{J}{}_{\mathrm{r}}\text{J}{}_{\mathrm{\infty }}\text{= 17.4}$, β = 0.45 and $\text{т}{}_{\mathrm{r}}\text{т}{}_{\mathrm{m}}$ increases with decreasing temperature, reaching a limit of 170 near 0°C. This liquid shows no evidence of polymeric behaviour.For the other, $\text{J}{}_{\mathrm{r}}\text{J}{}_{\mathrm{\infty }}$, β = 0.76, $\text{т}{}_{\mathrm{r}}\text{т}{}_{\mathrm{m}}\text{= 15.4}$ and is constant over the temperature range investigated. The main difference between the two liquids appears as an additional retardational or relaxational process for the higher molecular weight material which occurs in the initial or low frequency part of the relaxation region. This process is characterized by a single time, but with relaxation time $\text{1}\text{7}$ and a stiffness 7 times the values calculated for the first Rouse mode of polymer chain motion.     

Electrical properties of poly(propylene terephthalate)

Direct current (dc) and alternating current (ac) electrical behavior of a laboratory‐synthesized semicrystalline poly(propylene terephthalate) is investigated. The dc charging/discharging currents and electrical conductivity are studied as a function of temperature and time of applied voltage. The conduction mechanisms are pointed out and related to the structural characteristics of the polymer. The ac properties (dielectric constant and loss factor) are investigated over a wide temperature and frequency range. The relaxation processes, which take place in the material, are disclosed and their origin is analyzed. The electrical behavior of poly(propylene terephthalate) is finally related to that shown by other thermoplastic polyesters. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2271–2275, 2002     

Effect of morphology on barrier properties of poly(ethylene terephthalate)

The effects of morphology on the barrier properties of poly(ethylene terephthalate) (PET) have been investigated. Various levels of crystallinity can be developed in PET as a result of thermal exposure, orientation, and heat setting. The morphologies of the crystalline phase are affected by the conditions of their formation. As a result of morphological differences, samples with equivalent levels of crystallinity have been found to exhibit different oxygen barrier properties. These differences are most apparent at low and intermediate levels of crystallinity. For thermally crystallized systems, at the same crystalline content, increasing superstructure size in the crystalline phase leads to greater tortuosity for the permeant molecules, resulting in lower permeability. For stretched and heat set PET, transport properties can be correlated with birefringence as well as overall orientation, measured in terms of fraction of molecules in the trans or extended chain conformation. At high levels of crystallinity, where the spherulites become volume filling, permeation takes place primarily through the interlamellar regions of the crystalline phase and is controlled by level of crystallinity, independent of the mode of crystallization. The barrier properties of PET, before spherulitic impingement occurs, are governed by the size and number of spherulites as well as by the amorphous orientation present in non‐crystalline regions. POLYM. ENG. SCI., 45:400–409, 2005. © 2005 Society of Plastics Engineers     

An investigation on the rheology,morphology, thermal and mechanical properties of recycled poly (ethylene terephthalate) reinforced with modified short glass fibers

This work was done with the aim to solve an important environmental issue regarding poly (ethylene terephthalate), (PET) wastes. Samples of recycled PET (r-PET) were reinforced with 10 to 30 wt% modified short glass fibers (SGF) through a melt mixing process in an internal mixer and their performance were assessed and compared with those of commercial glass reinforced PET through investigation of their rheology, morphology, thermal, and mechanical properties. It was found that the mechanical properties of the glass reinforced r-PET composites in most cases were comparable or even higher than those of the commercial grades. The impact strength of the 30 wt% SGF filled r-PET composite was about 30% higher than the commercial grades. This led to a conclusion that the PET wastes can be successfully converted to easily moldable thermoplastic materials by incorporation of 30 wt% SGF having a good balance of properties. Through investigation of rheological and morphological properties the optimum conditions for the best reinforcement performance were determined. The r-PET with 30 wt% glass fiber content showed the highest level of orientation and improved interaction with the r-PET matrix while having an acceptable flow behavior and processability. In spite of significant fiber breakage during the melt mixing process, leading to about 20 times reduction in the fiber aspect ratio, the composites maintained their good mechanical properties and showed a shear thinning behavior at high shear rates. The incorporated glass fibers acted as nucleating agents and improved the crystallization rate of r-PET leading to an overall increase in the crystallinity. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Effect of clay on the morphology of blends of poly(propylene) and polyamide 6/clay nanocomposites

PP/NPA6 blends composed of poly(propylene) (PP) and polyamide 6/clay nanocomposites (NPA6) were prepared by twin‐screw extrusion and melt‐drawn into ribbons by a ribbon extrusion process. The influence of clay on the morphology of PP/NPA6 ribbons was investigated by means of field‐emission scanning electron microscopy and optical microscopy. The results show that at low clay content (3, 5 wt%), NPA6 exhibited continuous lamellar structure in PP as pristine PA6 did in a PP/PA6 blend, but at a higher clay content (10 wt%) only ellipsoids or elongated ellipsoids were observed. In order to explain the morphological difference, two factors, ie the compatibilization effect and melt rheology, have been taken into consideration. It has been found that both factors, and probably mainly the variation in melt rheology, were responsible for the morphological difference in the PP/NPA6 blends with different clay contents under the extensional flow field. Copyright © 2004 Society of Chemical Industry     

Crystal morphology and nonisothermal crystallization kinetics of short carbon fiber/poly(trimethylene terephthalate) composites

The crystal morphology and nonisothermal crystallization kinetics of short carbon fiber/poly(trimethylene terephthalate) (SCF/PTT) composites were investigated by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The optical micrographs suggest that the more content of SCF in composites, the smaller size of the spherulites is. Moreover, the addition of SCF can lead to forming banded spherulites in composites. The Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of nonisothermal crystallization of various composites. The results suggest that the SCF served as nucleation agent, accelerates the crystallization rate of the composites, and the more content of SCF, the faster crystallization rate is. Effective activation energy calculated by the differential iso‐conversional method developed by Friedman also concludes that the composite with more SCF component has higher crystallization ability than that with less SCF content. The kinetic parameters U* and K_g are determined, respectively, by the Hoffman–Lauritzen theory. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of an organic phosphorus nucleating agent on crystallization behaviors and mechanical properties of poly(propylene)

The effects of an organic phosphorus nucleating agent on the crystallization behavior and mechanical properties of poly(propylene) were investigated. As the concentration of nucleating agent increased from 0 to 0.8%, the tensile and flexural strengths of the nucleated poly(propylene) resin increased by 15%, the flexural modulus increased by 35%, the crystallization peak temperature increased by 10°C, and the nucleation density (calculated with the nonlinear Voltrra integral equation) increased by 10⁶ times. Mechanical properties increased with nucleation density. Linear equations between the mechanical properties and the logarithmic nucleation density were revealed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 297–301, 2003     

Effect of chemical treatment on newspaper fibers reinforced polymer poly(vinyl chloride) composites

Natural fibers used as reinforcement in composite materials present specific mechanical properties, which are comparable to glass fibers. In addition, they have the advantage of being renewable and recyclable. However, their main drawback is their inherent susceptibility to moisture expansion, which has the effect of inducing a decrease in mechanical properties, and of debonding in the composite. In this study, lignocellulosic fibers from newspapers were modified with acetic anhydride, NaOH, and KMnO₄ in order to enhance the interfacial adhesion between poly(viny lchloride) (PVC) matrix and the newspaper fibers. Composites samples were prepared with different treated fibers at the same loading (20 wt%). X‐ray and scanning electron microscopy (SEM) were used to characterize the fiber's surfaces. The mechanical, morphological, and thermal properties of PVC/newspaper composites were also studied. Moreover, the maximum improvement in the mechanical properties (tensile strength) was obtained for the permanganate treated PVC/newspaper composites. J. VINYL ADDIT. TECHNOL., 22:173–181, 2016. © 2014 Society of Plastics Engineers     

Preparation of biobased poly(propylene 2,5-furandicarboxylate) fibers: Mechanical,thermal and hydrolytic degradation properties

In this work, a fully biobased poly(propylene 2,5-furandicarboxylate) (PPF) was synthesized from 2,5-furan dicarboxylic acid (FDCA) and 1,3-propanediol (1,3-PDO) via traditional two-step melting polycondensation. Then, the resultant PPF was characterized with ¹H NMR, FTIR, GPC, intrinsic viscosity, TGA, and DSC measurements, respectively. Next, the prepared PPF was melt-spun into fibers. The morphology and thermal stability of the as-spun PPF fibers were firstly investigated by SEM and TGA. Furthermore, the mechanical properties of the PPF fibers were evaluated. The results showed that the tensile of the PPF fibers increased with increasing of the draw ratios following gradual decrease of the breaking elongation from 307.1% to 48.9%. In addition, the crystallization ability and the hydrolytic degradation behavior of the as-spun PPF fibers were investigated in detail as well. The results presented that comparing to traditional fossil-based poly(trimethylene terephthalate) (PTT) fibers, the PPF fibers exhibited lower crystallinity, however, it displayed a better hydrolytic degradation performance. Based on these results, it confirmed that the PPF fiber based on biomass polymer is a kind of promising environmentally friendly synthetic fiber for potential application in various fields.     

Effect of epolene E‐43 as a compatibilizer on the mechanical properties of palm fiber–poly(propylene) composites

Composites of palm fibers and poly(propylene) (PP) were compounded in an extruder at 200°C. The composites were subsequently injection molded into standard tensile specimens for mechanical characterization. The fracture morphology of the specimens was analyzed by scanning electron microscopy. It was observed that the composite modulus increased with the increase of fiber content, indicating the existence of adhesion between PP and the much stiffer palm fibers. However, the adhesion was not satisfactory and resulted in a decrease in the composite tensile strength with fiber addition. The compatibilizer Epolene E‐43 was used to minimize this incompatibility between the wood fibers and the PP matrix. The maleated PP additive enhanced the fiber–matrix adhesion, resulting in an improvement in composite performance. Also, small fibers showed better mechanical properties than those of long fibers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2581–2592, 2004     

Effects of raw and poly(propylene oxide) grafted nanosilica on the morphology and thermal and mechanical properties of polyurethane foam

Poly(propylene oxide) (PPO)‐grafted nanosilica (NS)/polyurethane foam (PUF) composites were synthesized by a ring‐opening polymerization catalytic process and reaction‐molding technology. The raw NS and PPO–NS were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. Scanning electron microscopy, dynamic mechanical analysis, and compressive strength tests were used to compare the morphology and thermal and mechanical properties of the PPO–NS/PUF and raw NS/PUF composites with a series of filler contents. The PPO–NS/PUF composites generally exhibited better morphology, thermal and mechanical properties than raw NS/PUF composites. Moreover, the PPO–NS/PUF composites with lower contents (0.5, 1 php) of filler showed even higher mechanical reinforcement than that with higher contents (1.5, 2 php) of filler, which was caused by the interaction between additives and PUF matrix. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42400.