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1.
Effect of Orientation on the Morphology and Mechanical Properties of PLA/Starch Composite Filaments 总被引:1,自引:0,他引:1
Randal L. Shogren Gordon Selling J. L. Willett 《Journal of Polymers and the Environment》2011,19(2):329-334
Polylactic acid (PLA)/starch fibers were produced by twin screw extrusion of PLA with granular or gelatinized starch/glycerol
followed by drawing through a set of winders with an intermediate oven. At 30% starch, fibers drawn 2–5x were highly flexible
(elongation 20–100%) while undrawn filaments were brittle (elongation 2–9%). Tensile strength and moduli increased with increasing
draw ratio but decreased with increasing starch content. Mechanical properties were better for composites made with gelatinized
starch/glycerol than granular starch. In conclusion, orientation greatly increases the flexibility of PLA/starch composites
and this may be useful not only in fibers but also possibly in molded articles. Other advantages of starch addition could
include fiber softness without added plasticizer, moisture/odor absorbency and as a carrier for active compounds. 相似文献
2.
This paper investigates and compares the performances of polylactic acid (PLA)/kenaf (PLA-K) and PLA/rice husk (PLA-RH) composites
in terms of biodegradability, mechanical and thermal properties. Composites with natural fiber weight content of 20% with
fiber sizes of less than 100 μm were produced for testing and characterization. A twin-screw extrusion was used to compound
PLA and natural fibers, and extruded composites were injection molded to test samples. Flexural and Izod impact test, TGA,
soil burial test and SEM were used to investigate properties. All results were compared to a pure PLA matrix sample. The flexural
modulus of the PLA increased with the addition of natural fibers, while the flexural strength decreased. The highest impact
strength (34 J m−1), flexural modulus (4.5 GPa) and flexural strength (90 MPa) were obtained for the composite made of PLA/kenaf (PLA-K), which
means kenaf natural fibers are potential to be used as an alternative filler to enhance mechanical properties. On the other
hand PLA-RH composite exhibits lower mechanical properties. The impact strength of PLA has decreased when filled with natural
fibers; this decrease is more pronounced in the PLA-RH composite. In terms of thermal stability it has been found that the
addition of natural fibers decreased the thermal stability of virgin PLA and the decrement was more prominent in the PLA-RH
composite. Biodegradability of the composites slightly increased and reached 1.2 and 0.8% for PLA-K and PLA-RH respectively
for a period of 90 days. SEM micrographs showed poor interfacial between the polymer matrix and natural fibers. 相似文献
3.
Jutarat Prachayawarakorn Pornnipa Ruttanabus Pimvilai Boonsom 《Journal of Polymers and the Environment》2011,19(1):274-282
Biodegradable polymer was prepared as thermoplastic starch (TPS) using rice and waxy rice starches. In order to increase mechanical
properties and reduce water absorption of the TPS, cotton fiber was incorporated as the fiber reinforcement into the TPS matrix.
The effect of cotton fiber contents and lengths on properties of the TPS was examined. Internal mixer and compression molding
machine were used to mix and shape the samples. It was found that the thermoplastic rice starch (TPRS) showed higher stress
at maximum load and Young’s modulus but lower strain at maximum load than the thermoplastic waxy rice starch (TPWRS). In addition,
stress at maximum load and Young’s modulus of both TPRS and TPWRS increased significantly with the addition of the cotton
fiber. Cotton fiber contents and lengths also affected mechanical properties of the TPRS and TPWRS composites. Moreover, water
absorption of the TPRS and TPWRS composites decreased by the use of the cotton fibers. FT-IR and XRD techniques were used
to study a change in functional group and crystallinity of the thermoplastic starch composites. Morphological, thermal and
biodegradable properties of different thermoplastic starch composites were also investigated. 相似文献
4.
Maria T. B. Pimenta Antonio J. F. Carvalho Fabiola Vilaseca Jordi Girones Joan P. López Pere Mutjé Antonio A. S. Curvelo 《Journal of Polymers and the Environment》2008,16(1):35-39
Treated sisal fibers were used as reinforcement of polypropylene (PP) composites, with maleic anhydride-grafted PP (MAPP)
as coupling agent. The composites were made by melting processing of PP with the fiber in a heated roller followed by multiple
extrusions in a single-screw extruder. Injection molded specimens were produced for the characterization of the material.
In order to improve the adhesion between fiber and matrix and to eliminate odorous substances, sisal fibers were treated with
boiling water and with NaOH solutions at 3 and 10 wt.%. The mechanical properties of the composites were assessed by tensile,
bend and impact tests. Additionally, the morphology of the composites and the adhesion at he fiber–matrix interface were analyzed
by SEM. The fiber treatment led to very light and odorless materials, with yields of 95, 74 and 62 wt.% for treatments with
hot water, 3 and 10 wt.% soda solution respectively. Fiber treatment caused an appreciable change in fiber characteristics,
yet the mechanical properties under tensile and flexural tests were not influenced by that treatment. Only the impact strength
increased in the composites with alkali-treated sisal fibers. 相似文献
5.
C. Wretfors S.-W. Cho M. S. Hedenqvist S. Marttila S. Nimmermark E. Johansson 《Journal of Polymers and the Environment》2009,17(4):259-266
The next generation of manufactured products must be sustainable and industrially eco-efficient, making materials derived
from plants an alternative of particular interest. Wheat gluten (WG) is an interesting plant material to be used for production
of plastic similar materials due to its film-forming properties. For usage of plastics in a wider range of applications, composite
materials with improved mechanical properties are demanded. The present study investigates the possibilities of reinforcing
WG plastics with hemp fibers. Samples were manufactured using compression molding (130 °C, 1600 bar, 5 min). Variation in
fiber length, content (5, 10, 15 and 20 wt%) and quality (poor, standard, good) were evaluated. Mechanical properties and
structure of materials were examined using tensile testing, light and scanning electron microscopy. Hemp fiber reinforcement
of gluten plastics significantly influenced the mechanical properties of the material. Short hemp fibers processed in a high
speed grinder were more homogenously spread in the material than long unprocessed fibers. Fiber content in the material showed
a significant positive correlation with tensile strength and Young’s modulus, and a negative correlation with fracture strain
and strain at maximum stress. Quality of the hemp fibers did not play any significant role for tensile strength and strain,
but the Young’s modulus was significantly and positively correlated with hemp fiber quality. Despite the use of short hemp
fibers, the reinforced gluten material still showed uneven mechanical properties within the material, a result from clustering
of the fibers and too poor bonding between fibers and gluten material. Both these problems have to be resolved before reinforcement
of gluten plastics by industrial hemp fibers is applicable on an industrial scale. 相似文献
6.
Processing and characterization of a new biodegradable composite made of a PHB/V matrix and regenerated cellulosic fibers 总被引:1,自引:0,他引:1
Ch. Bourban E. Karamuk M. J. de Fondaumière K. Ruffieux J. Mayer E. Wintermantel 《Journal of Polymers and the Environment》1997,5(3):159-166
In this study, a biodegradable composite consisting of a degradable continuous cellulosic fiber and a degradable polymer matrix—poly(3-hydroxybutyrate)-co-poly(3-hydroxyvalerate
(PHB/V with 19% HV)—was developed. The composite was processed by impregnating the cellulosic fibers on-line withPHB/V powder in a fluidization chamber. The impregnated roving was then filament wound on a plate and hot-pressed. The resulting
unidirectional composite plates were mechanically tested and optically characterized by SEM. The fiber content was 9.9 ±0.9
vol% by volumetric determination. The fiber content predicted by the rule of mixture for unidirectional composites was 13.8
±1.4 vol%. Optical characterization showed that the fiber distribution was homogeneous and a satisfactory wetting of the fibers
by the matrix was achieved. Using a blower to remove excess matrix powder during processing increased the fiber content to
26.5 ±3.3 vol % (volumetric) or 30.0 ±0.4 vol% (rule of mixture). The tensile strength of the composite parallel to the fiber
direction was 128 ±12 MPa (10 vol% fiber) up to 278 ±48 MPa (26.5 vol% fiber), compared to 20 MPa for the PHB/V matrix. The
Young’s modulus was 5.8 ±0.5 GPa (10 vol% fiber) and reached 11.4 ±0.14 GPa (26.5 vol% fiber), versus 1 GPa for the matrix. 相似文献
7.
TPS/PCL Composite Reinforced with Treated Sisal Fibers: Property, Biodegradation and Water-Absorption 总被引:1,自引:0,他引:1
Adriana de Campos Gustavo H. D. Tonoli José M. Marconcini Luiz H. C. Mattoso Artur Klamczynski Kay S. Gregorski Delilah Wood Tina Williams Bor-Sen Chiou Syed H. Imam 《Journal of Polymers and the Environment》2013,21(1):1-7
Sisal fibers bleached with sodium-hydroxide followed by hydrogen peroxide treatment were incorporated in a thermoplastic starch/ε-polycaprolactone (TPS/PCL) blend via extrusion processing. These samples with smooth and homogenous surfaces were examined for their property, biodegradability and water absorption. Scanning electron microscopy revealed that the fibers were well dispersed in the matrix. In addition, it was found that the fibers and matrices interacted strongly. Blends with 20 % (dry weight-basis) fiber content showed some fiber agglomeration. Whereas blends with 10 % fibers showed increased crystallinity and lower water absorption capacity. The CO2 evolution study showed that the thermoplastic starch samples without any additives had the highest rate and extent of degradation whereas the neat PCL samples had the lowest degradation rate. Addition of fiber to the TPS/PCL blend exhibited the degradation rates and extents that were somewhere in between the pure TPS and neat PCL. This work demonstrates that TPS/PCL composites reinforced with bleached sisal has superior structural characteristics and water resistance and thus, can be used as polymeric engineering composites for different applications. 相似文献
8.
Vanessa Cheesbrough Kurt A. Rosentrater Jerry Visser 《Journal of Polymers and the Environment》2008,16(1):40-50
Interest in renewable biofuel sources has intensified in recent years, leading to greatly increased production of ethanol
and its primary coproduct, Distillers Dried Grain with Solubles (DDGS). Consequently, the development of new outlets for DDGS
has become crucial to maintaining the economic viability of the industry. In light of these developments, this preliminary
study aimed to determine the suitability of DDGS for use as a biofiller in low-cost composites that could be produced by rapid
prototyping applications. The effects of DDGS content, particle size, curing temperature, and compression on resulting properties,
such as flexural strength, modulus of elasticity, water activity, and color were evaluated for two adhesive bases. The composites
formed with phenolic resin glue were found to be greatly superior to glue in terms of mechanical strength and durability:
resin-based composites had maximum fiber stresses of 150–380 kPa, while glue composites had values between 6 kPa and 35 kPa;
additionally, glue composites experienced relatively rapid microbial growth. In the resin composites, both decreased particle
size and increased compression resulted in increased mechanical strength, while a moderate DDGS content was found to increase
flexural strength but decrease Young’s modulus. These results indicate that DDGS has the potential to be used in resin glue-based
composites to both improve flexural strength and improve potential biodegradability. 相似文献
9.
Yanan Song Jun Liu Shaozhuang Chen Yubin Zheng Shilun Ruan Yuezhen Bin 《Journal of Polymers and the Environment》2013,21(4):1117-1127
This research dealt with a novel method of fabricating green composites with biodegradable poly (lactic acid) (PLA) and natural hemp fiber. The new preparation method was that hemp fibers were firstly blending-spun with a small amount of PLA fibers to form compound fiber pellets, and then the traditional twin-screw extruding and injection-molding method were applied for preparing the composites containing 10–40 wt% hemp fibers with PLA pellets and compound fiber pellets. This method was very effective to control the feeding and dispersing of fibers uniformly in the matrix thus much powerful for improving the mechanical properties. The tensile strength and modulus were improved by 39 and 92 %, respectively without a significant decrease in elongation at break, and the corresponding flexural strength and modulus of composites were also improved by 62 and 90 %, respectively, when the hemp fiber content was 40 wt%. The impact strength of composite with 20 wt% hemp fiber was improved nearly 68 % compared with the neat PLA. The application of the silane coupling agent promoted further the mechanical properties of composites attributed to the improvement of interaction between fiber and resin matrix. 相似文献
10.
Environmentally friendly green composites were prepared by blending Wheat gluten (WG) as matrix, dialdehyde starch (DAS) as
filler and glycerol as plasticizer followed by compression molding of the mixture at 110 °C. The properties of the WG/DAS
composite are compared with those of the WG/native wheat starch (NWS) composites. While tensile strength and strain at break
decrease with increasing NWS content in the WG/NWS composites, a small content of DAS could improve tensile strength and strain
at break simultaneously in the WG/DAS composites. The WG/DAS composites exhibit reduced moisture absorption in comparison
with the WG/NEW composites. Formation of chemical bonding between DAS and WG is beneficial for the dispersion of DAS in the
WG matrix and WG/DAS composites exhibit improved mechanical properties and reduced moisture absorption over the WG/NWS composites. 相似文献
11.
High density polyethylene (HDPE)/bamboo composites with different nanoclay and maleated polyethylene (MAPE) contents were
fabricated by melt compounding. The compounding characteristics, clay dispersion, HDPE crystallization, and mechanical properties
of the composites were studied. The equilibrium torque during compounding decreased with use of clay masterbatch and increased
with the addition of MAPE. The X-ray diffraction (XRD) data showed that the clay was exfoliated only when 1% clay was added
to pure HDPE without MAPE. For HDPE/bamboo systems, MAPE was necessary to achieve clay exfoliation. For pure HDPE system,
both dynamic and static bending moduli increased, while impact strength decreased with increased clay loading. For the HDPE/bamboo
fiber composites, tensile strength, bending modulus and strength were improved with the use of MAPE. The use of the clay in
the system led to reduced mechanical properties. Techniques such as pre-coating fibers with clay–MAPE mixture are needed to
enhance the synergetic effect of the clay and bamboo fiber on the composite properties in the future study. 相似文献
12.
Merlin Aydın Hale Tozlu Sebnem Kemaloglu Ayse Aytac Guralp Ozkoc 《Journal of Polymers and the Environment》2011,19(1):11-17
In this study, the influence of alkali (NaOH) treatment on the mechanical, thermal and morphological properties of eco-composites
of short flax fiber/poly(lactic acid) (PLA) was investigated. SEM analysis conducted on alkali treated flax fibers showed
that the packed structure of the fibrils was deformed by the removal non-cellulosic materials. The fibrils were separated
from each other and the surface roughness of the alkali treated flax fibers was improved. The mechanical tests indicated that
the modulus of the untreated fiber/PLA composites was higher than that of PLA; on the other hand the modulus of alkali treated
flax fiber/PLA was lower than PLA. Thermal properties of the PLA in the treated flax fiber composites were also affected.
Tg values of treated flax fiber composites were lowered by nearly 10 °C for 10% NaOH treatment and 15 °C for 30% NaOH treatment.
A bimodal melting behavior was observed for treated fiber composites different than both of neat PLA and untreated fiber composites.
Furthermore, wide angle X-ray diffraction analysis showed that the crystalline structure of cellulose of flax fibers changed
from cellulose-I structure to cellulose-II. 相似文献
13.
Justin R. Barone 《Journal of Polymers and the Environment》2009,17(2):143-151
Short fiber reinforced polymer composites were prepared from lignocellulose fibers and feather keratin polymer (FKP). The
FKP matrix was prepared from the reactive processing of poultry feather keratin, glycerol, water, and sodium sulfite. Lignocellulose
fibers of varying source, length, and mass fraction were used and it was found that positive reinforcement of FKP was affected
by all three. Positive reinforcement was defined as an increase in elastic modulus when normalized by FKP with the same amount
of glycerol but no fibers. Positive reinforcement was only able to occur for modulus but not stress at break indicating that
the composites were of high physical properties only under small deformations. At large deformations, fiber pull-out was observed
in the composites using scanning electron microscopy. The most likely origin of this behavior appeared to be from weak fiber–polymer
interactions dominated by friction and rationalized by a force balance across the fiber–polymer interface. High fiber loadings
were shown to be reinforcing because of the formation of a network of lignocellulose fibers. The addition of lignocellulose
fibers increased the thermal stability of the material. 相似文献
14.
Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier 总被引:1,自引:0,他引:1
Poly(vinyl chloride) (PVC) and natural fiber composites were prepared by melt compounding and compression molding. The influence
of fiber type (i.e., bagasse, rice straw, rice husk, and pine fiber) and loading level of styrene-ethylene-butylene-styrene
(SEBS) block copolymer on composite properties was investigated. Mechanical analysis showed that storage modulus and tensile
strength increased with fiber loading at the 30% level for all composites, but there was little difference in both properties
among the composites from various fiber types. The use of SEBS decreased storage moduli, but enhanced tensile strength of
the composites. The addition of fiber impaired impact strength of the composites, and the use of SEBS led to little change
of the property for most of the composites. The addition of fiber to PVC matrix increased glass transition temperature (Tg), but lowered degradation temperature (Td) and thermal activation energy (Ea). After being immersed in water for four weeks, PVC/rice husk composites presented relatively smaller water absorption (WA)
and thickness swelling (TS) rate compared with other composites. The results of the study demonstrate that PVC composites
filled with agricultural fibers had properties comparable with those of PVC/wood composite. 相似文献
15.
Alireza Ashori 《Journal of Polymers and the Environment》2010,18(1):65-70
Hybrid composites of thermoplastic biofiber reinforced with waste newspaper fiber (NF) and poplar wood flour (WF) were prepared.
The weight ratio of the lignocellulosic materials to polymer was 30:70 (w:w). Polypropylene (PP) and maleic anhydride grafted
polypropylene (MAPP) were also used as the polymer matrix and coupling agent, respectively. The mechanical properties, morphology
and thermal properties were investigated. The obtained results showed that tensile and flexural modulus of the composites
were significantly enhanced with addition of biofibers in both types (fiber and flour), as compared with pure PP. However,
the increasing in WF content substantially reduced the tensile, flexural and impact modulus, but improved the thermal stability.
This effect is explained by variations in fiber morphological properties and thermal degradation. Increasing fiber aspect
ratio improved mechanical properties. The effect of fiber size on impact was minimal compared to the effects of fiber content.
Scanning electron microscopy has shown that the composite, with coupling agent, promotes better fiber–matrix interaction.
The largest improvement on the thermal stability of hybrid composites was achieved when WF was added more. In all cases, the
degradation temperatures shifted to higher values after addition of MAPP. This work clearly showed that biofiber materials
in both forms of fiber and flour could be effectively used as reinforcing elements in thermoplastic PP matrix. 相似文献
16.
Amnuay Wattanakornsiri Katavut Pachana Supranee Kaewpirom Matteo Traina Claudio Migliaresi 《Journal of Polymers and the Environment》2012,20(3):801-809
Green composites obtained from biodegradable renewable resources have gained much attention due to environmental problems resulting from conventionally synthetic plastics and a global increasing demand for alternatives to fossil resources. In this work we used different cellulose fibers from used office paper and newspaper as reinforcement for thermoplastic starch (TPS) in order to improve their poor mechanical, thermal and water resistance properties. These composites were prepared by using tapioca starch plasticized by glycerol (30 % wt/wt of glycerol to starch) as matrix reinforced by the extracted cellulose fibers with the contents ranging from 0 to 8 % (wt/wt of fibers to matrix). Properties of composites were determined by mechanical tensile tests, differential scanning calorimetry, thermogravimetric analysis, water absorption measurements, scanning electron microscopy, and soil burial tests. The results showed that the introduction of either office paper or newspaper cellulose fibers caused the improvement of tensile strength and elastic modulus, thermal stability, and water resistance for composites when compared to the non-reinforced TPS. Scanning electron microscopy showed a good adhesion between matrix and fibers. Moreover, the composites biological degraded completely after 8 weeks but required a longer time compared to the non-reinforced TPS. The results indicated that these green composites could be utilized as commodity plastics being strong, inexpensive, plentiful and recyclable. 相似文献
17.
Biodegradable Polyester-Based Blend Reinforced with Curauá Fiber: Thermal,Mechanical and Biodegradation Behaviour 总被引:1,自引:1,他引:0
Fernanda Harnnecker Derval dos Santos Rosa Denise Maria Lenz 《Journal of Polymers and the Environment》2012,20(1):237-244
Biodegradable composites can be produced by the combination of biodegradable polymers (BP) as matrix and vegetal fibers as
reinforcement. Composites of a commercial biodegradable polymer blend and curauá fibers (loaded at 5, 15 and 20 wt%) were
prepared by melt mixing in a twin-screw extruder. Chemical treatments such as alkali treatment of the fiber and addition of
maleic anhydride grafted polypropylene (MA-g-PP) as coupling agent were performed to promote polymer/fiber interfacial adhesion so that mechanical performance can be
improved. The resulting composites were evaluated through hardness, melt flow index and tensile, flexural and impact strengths
as well as water absorption. Thermal analysis and Fourier transform infrared spectroscopy were also employed to characterize
the composites. The polymer/fiber interface was investigated through scanning electron microscopy analysis. The biodegradability
of composites was evaluated by compost-soil burial test. The addition of curauá fiber promoted an increase in the mechanical
strengths and composites treated with 2 wt% MA-g-PP with 20 wt% curauá fiber showed an increase of nearly 75% in tensile and 56% in flexural strengths besides an improvement
in impact strength with respect to neat polymer blend. Nevertheless, treated composites showed an increase in water absorption
and biodegradation tests showed that the addition of fiber retards degradation time. The retained mass of BP/20 wt% fiber
composite with MA-g-PP and neat BP was 68 and 26%, respectively, after 210 days of degradation test. 相似文献
18.
James S. Fabiyi Armando G. McDonald David McIlroy 《Journal of Polymers and the Environment》2009,17(1):34-48
The effects of weathering on the constituents of wood and polymer matrix behavior in wood plastic composites (WPCs) were investigated.
WPCs were produced from pine, extractives-free pine, and pine holocellulose fibers (60%) together with HDPE (40%). These composites
were subjected to xenon-arc accelerated and outside weathering for a total of 1200 h and 120 days, respectively. The color
and chemical changes that occurred on the surface of the WPCs were analyzed using a set of analytical techniques. For pine
and extractive-free pine filled composites, the results showed that the total color change, lightness, and oxidation increased,
while the lignin content decreased. In addition, the weight average molecular weight (Mw) and number average molecular weight (Mn) of extracted HDPE decreased with an increase in exposure time of the composites. However, HDPE crystallinity increased with
longer exposure time. Lightness of holocellulose-based WPC changed the least while the change in its HDPE crystallinity was
not significant compared to the other composite types. Therefore, holocellulose-based WPC may be preferred for applications
where color stability is of high priority. 相似文献
19.
Application of Cellulose Microfibrils in Polymer Nanocomposites 总被引:1,自引:0,他引:1
Cellulose microfibrils obtained by the acid hydrolysis of cellulose fibers were added at low concentrations (2–10% w/w) to polymer gels and films as reinforcing agents. Significant changes in mechanical properties, especially maximum load and tensile strength, were obtained for fibrils derived from several cellulosic sources, including cotton, softwood, and bacterial cellulose. For extruded starch plastics, the addition of cotton-derived microfibrils at 10.3% (w/w) concentration increased Young’s modulus by 5-fold relative to a control sample with no cellulose reinforcement. Preliminary data suggests that shear alignment significantly improves tensile strength. Addition of microfibrils does not always change mechanical properties in a predictable direction. Whereas tensile strength and modulus were shown to increase during addition of microfibrils to an extruded starch thermoplastic and a cast latex film, these parameters decreased when microfibrils were added to a starch–pectin blend, implying that complex interactions are involved in the application of these reinforcing agents. 相似文献
20.
Long Jiang Jijun Huang Jun Qian Feng Chen Jinwen Zhang Michael P. Wolcott Yawei Zhu 《Journal of Polymers and the Environment》2008,16(2):83-93
In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber (BPF) composites were prepared by melt compounding and injection molding. The
crystallization ability, tensile strength and modulus, flexural strength and modulus, and impact strength were found substantially
increased by the addition of BPF. Tensile and flexural elongations were also moderately increased at low fiber contents (<20%).
BPF demonstrated not only higher strength and modulus, but also higher failure strain than the PHBV8 matrix. Boron nitride
(BN) was also investigated as a nucleation agent for PHBV8 and maleic anhydride grafted PHBV8 (MA-PHBV8) as a compatibilizer
for the composite system. BN was found to increase the overall properties of the neat polymer and the composites due to refined
crystalline structures. MA-PHBV8 improved polymer/fiber interactions and therefore resulted in increased strength and modulus.
However, the toughness of the composites was substantially reduced due to the hindrance to fiber pullout, a major energy dissipation
source during the composite deformation. 相似文献