Wheat Straw Fibers Research Articles

On the Design of Novel Biofoams Using Lignin, Wheat Straw, and Sugar Beet Pulp as Precursor Material.

In this paper, we report the synthesis and characterization of pyrolyzed lignin compacts reinforced with 50 wt % wheat straw (WS) or sugar beet pulp (SBP) fibers. The compacts were pyrolyzed at 300, 500, 700, and 900 °C in an Ar atmosphere. Detailed thermogravimetric analysis (TGA), thermomechanical analysis (TMA), Fourier transform infrared (FTIR) spectroscopy, and microstructure analysis were performed on these samples. FTIR analysis showed that pyrolysis of lignin–WS and lignin–SBP resulted in aromatic char. Scanning electron microscope (SEM) studies showed that foams obtained by pyrolyzing both lignin–50 wt % SBP and lignin–50 wt % WS composites have a cellular structure. X-ray tomography and energy-dispersive spectrometry (EDS) studies showed that pyrolysis of wheat straw caused the formation of mineral-rich nodules in the pyrolyzed lignin matrix, which was responsible for the denser and uniform microstructure of the lignin–WS composites. Due to this reason, the lignin–WS composites were denser and had a better mechanical strength as compared to the lignin–SBP composites. Both the compositions also showed temperature-dependent wettability behavior.

Influence of treated bio-fibers on the mechanical and physical properties of cement mortars

Alfa plant (Stipatenacissima L.) and wheat straw fibers were investigated as reinforcement in cementitious matrix. The fibers were used separately in three states: raw, wet (by immersion in water) and alkali treated. A reference mortar without fibers and mortars with 1% and 1.5% by volume of the two different bio-fibers were used. The mechanical and physical properties of mortar specimens were studied as well as the morphological analysis was carried out after 28 days of curing. The results exhibit that both Alfa and Straw fibre addition changed the mechanical performance of mortars in comparison to the reference mortar. A higher porosity and water absorption were observed after the addition of raw and wetted fibers. The alkali treatment caused morphological changes that were proved more efficient. This treatment provided a good result in terms of mechanical and physical properties. Furthermore, the addition of 1% by volume of alkali treated fibers affords both mechanical and physical properties better than the control mortar. SEM micrographs confirmed the good fibers/matrix adhesion of the alkali treated fibers.

Production of Sustainable and Biodegradable Polymers from Agricultural Waste.

Agro-wastes are derived from diverse sources including grape pomace, tomato pomace, pineapple, orange, and lemon peels, sugarcane bagasse, rice husks, wheat straw, and palm oil fibers, among other affordable and commonly available materials. The carbon-rich precursors are used in the production bio-based polymers through microbial, biopolymer blending, and chemical methods. The Food and Agriculture Organization (FAO) estimates that 20–30% of fruits and vegetables are discarded as waste during post-harvest handling. The development of bio-based polymers is essential, considering the scale of global environmental pollution that is directly linked to the production of synthetic plastics such as polypropylene (PP) and polyethylene (PET). Globally, 400 million tons of synthetic plastics are produced each year, and less than 9% are recycled. The optical, mechanical, and chemical properties such as ultraviolet (UV) absorbance, tensile strength, and water permeability are influenced by the synthetic route. The production of bio-based polymers from renewable sources and microbial synthesis are scalable, facile, and pose a minimal impact on the environment compared to chemical synthesis methods that rely on alkali and acid treatment or co-polymer blending. Despite the development of advanced synthetic methods and the application of biofilms in smart/intelligent food packaging, construction, exclusion nets, and medicine, commercial production is limited by cost, the economics of production, useful life, and biodegradation concerns, and the availability of adequate agro-wastes. New and cost-effective production techniques are critical to facilitate the commercial production of bio-based polymers and the replacement of synthetic polymers.

Thermal and acoustic characteristics of novel thermal insulating materials made of Eucalyptus Globulus leaves and wheat straw fibers

A novel research about using dried Eucalyptus Globulus leaves (EGL) as a biodegradable natural thermal insulating and sound absorbing material for building walls is presented. The EGL is used as leaves alone or hybrid with wheat straw fibers. Cornstarch is used as a binder for the leaves or for the hybrid specimens. Two bound specimens are made; one used leaves alone with the binder and the other used wheat straw alone. Four more hybrid specimens are made with different densities and compositions. Thermal conductivity coefficients are determined at different temperatures for all specimens. In addition to that, sound absorbing coefficient and three bending moment tests are obtained for the bound specimens. Scanning electron microscopy (SEM), Fourier transformation Infra red (FT-IR) spectral analysis, Thermo-gravimetric analysis, differential scanning calorimetry and moisture content are conducted for the leaves. Results show that the average thermal conductivity of the dried leaves is in the range 0.045–0.055 W/mK for a temperature range from 10 to 60 °C, respectively and the upper value of the hybrid specimens is about 0.065 W/mK at the maximum temperature of 60 °C. Sound absorbing coefficient has values greater than 0.5 in the range of frequency between 500 to 1600 Hz for most specimens. Thermo-gravimetric analysis shows that the leaves are stable up to 210 °C and the moisture content of the leaves is 16% at the environment conditions of Riyadh. These results ensure the promising effect of using Eucalyptus Globulus leaves as a new thermal insulating and sound absorbing material for buildings which have low environmental impact by using renewable natural resources for thermal insulation in buildings rather than the synthetic insulation materials.

Effects of Fiber Content and Size on the Mechanical Properties of Wheat Straw/Recycled Polyethylene Composites

Wheat straw/recycled polyethylene composites (WRPCs) were manufactured with wheat straw fibers (WS) and recycled polyethylene (rPE) using extrusion followed by hot pressing moulding. The chemical structure and the fiber morphology of WS were analyzed by FTIR and L&W fiber tester. The influence of WS size and content on the mechanical properties, thermal stability and moisture absorption of WRPCs were investigated. The results showed that the performance of rPE based composites was certainly enhanced with the addition of WS. The WRPCs filled with long particle size and high length-to-diameter (L/D) ratio WS could obtain the optimal tensile and flexural performances. With increasing WS contents, the tensile and flexural strength of composites exhibited an increasing trend and the elongation at break decreased gradually. The strength properties of WRPCs decreased when the fiber content was over 50%. The length and content of WS had a significant influence on the moisture absorption of WRPCs. Thermogravimetric (TG) analysis found that WS size had no remarkable impact on the thermal stability of WRPCs. The scanning electron microscopy (SEM) indicated the dispersity of WS in composites increased with the decreasing of WS size, while the interfacial adhesion of WRPCs decreased gradually with the increasing of WS content.

Nitrous oxide emissions from oilseed rape cultivation were unaffected by flash pyrolysis biochar of different type, rate and field ageing

Nitrous oxide (N2O) emission from winter oilseed rape (WOSR) cultivation may compromise the sustainability of oilseed rape biodiesel. Typically, greenhouse gas budgets of WOSR cultivation assume an N2O emission factor (EF) of 1% of the N added in fertilizer and crop residues. Management options to reduce direct soil emissions of N2O include the application of biochar, but efficacy and mechanisms of N2O suppression are elusive. We measured N2O emissions in a WOSR field trial on a sandy loam soil in Denmark over 402 days in 2017–2018, comparing biochar applications from two feedstocks (wheat straw and pig manure fibers), two application rates (1.5 and 15 Mg ha−1) and field ageing of up to three years. Further, a controlled incubation experiment was performed to examine the effect of biochar dose and ageing on N2O production and consumption by denitrification. Biochar treatments had no significant effects on cumulative N2O emissions (1.71–2.78 kg N ha−1 yr−1). Likewise, no significant effects were found on crop yield, yield-scaled N2O emission, soil mineral N content, gravimetric soil moisture or pH. The fertilizer induced EF was 0.51% which is well below the IPCC Tier 1 EF of 1%. High doses of fresh, but not field-aged biochar suppressed N2O production under anoxic conditions ex situ, suggesting that biochar with sufficient liming capacity could mitigate N2O emissions from denitrification also under field conditions. Yet, rates of up to 15 Mg ha−1 flash pyrolysis biochar in the current in situ study, which comprised a pronounced summer drought, showed no significant N2O mitigation. This highlights the need for selecting dedicated biochars and doses and test them in multi-year studies to conclude on their N2O mitigating effect. Yet, in relation to sustainability of WOSR cultivation for biodiesel, the current study suggests that C sequestration by biochar is not compromised by increased N2O emissions.

Physical–chemical and structural stability of PHBV/wheat straw fibers based biocomposites under food contact conditions

AbstractThis aricle aims at investigating for the first time the ability of using poly(3‐hydroxylbutyrate‐co‐3‐hydroxyvalerate) (PHBV)/wheat straw fibers (WSF) biocomposites as food contact materials for packaging applications. For that purpose, the impact of the filler size and content on overall migration and mechanical properties was assessed under standardized testing conditions using the food simulant liquids (FSL). Very high overall migration values were noticed in the case of hydrophilic FSL, that is, water, acetic acid 3% (wt/vol), ethanol 20% (vol/vol), and ethanol 95% (vol/vol), related to the leaching of water extractable components of WSF. Low migration values were obtained in contact with isooctane and olive oil, demonstrating the possibility of using biocomposites in contact with fatty products. To answer the lack of methodologies to simulate different types of food for which PHBV‐based composites could be more specifically dedicated, including food products of low or intermediate water activity such as fruits and vegetable, bread, and cheese, a new range of new solid food models based on agar‐agar gels have been developed. Results showed that the water activity (aw) was the main parameter governing the overall migration of PHBV/WSF materials, suggesting that such composite materials could only be used as food contact materials in the case of food products with an awequal or lower than 0.90.

Study of the mechanical and physical properties of bio-composite material based on wheat starch and wheat straw fibers

Natural fiber reinforced bio-composites are taking a big role in various sections around the world such as industry, construction, and health section. In this study, a bio-composite material based on wheat starch matrix and natural wheat fibers is prepared. Five different specimens with following fiber contents 50,54.5,58.3,61.5, and 64.2% by weight are added to wheat starch matrix. Mechanical and physical tests are performed for different fiber weight contents. Charpy impact test results showed that impact energy is decreasing with increase in fiber content. Three-point deflection test data show that as higher fiber content as higher flexural stress is obtained. Shore D hardness test results show that the hardness values increase as fiber content increase. Water uptake test results showed that water absorption also decreases by increasing fiber content. An optical investigation is performed to calculate the average length and width of chopped fibers used as reinforcement. The average length and width of fibers were found to be 5.73mm and the average width is 0.38mm.

Thermal Analyses of Loose Agave, Wheat Straw Fibers and Agave/Wheat Straw as New Hybrid Thermal Insulating Materials for Buildings

ABSTRACT Agave (AF) and wheat straw (SF) fibers are good raw materials for thermal insulation. In this study, loose agave or wheat straw fibers and hybrid boards of agave/wheat straw with different compositions and densities are tested for their thermal insulation qualities. Three new novel hybrid specimens are considered. In all specimens, cornstarch (CS) was used as a binder for the fibers. Thermal conductivity coefficient is obtained for each specimen in the temperature range 10–60°C with the resulting average value in the range 0.04555–0.06835 W/m K. Without binding, loose fibers of agave and wheat straws have an average thermal conductivity of 0.043592 and 0.044678 W/m.K, respectively, at the same range of temperature. Micrographs of the wheat straw fibers (SF) are conducted using the scanning electron microscope (SEM) which showed an average outer diameter between 1.28 and 1.98 mm and an average diameter of the bound porous tubes (multicellular) within the straw in the range 34.5 to 75.6 μm. Fourier transformation infrared (FT-IR) analyses of the wheat straw fiber are carried out which indicated stretching wavenumbers which present different chemical functional groups. Thermogravimetric analysis of the wheat straw fiber (TGA and DTGA) showed that the straws lose less than 3% of its mass at temperatures as high as 184°. Finally, the differential scanning calorimetry (DSC) analysis test of the wheat straw fiber indicates that endothermic transition starts at 342°C with a peak value at 749°C. Three-point bending moment tests for bound specimens are made and show an increase in both flexural stress and flexural modulus of the hybrid specimens. Using these hybrid specimens, agro, renewable and environmentally friendly materials in buildings will share in energy saving when used as insulation materials for building walls.

Preparation and application of nanocellulose from non-wood plants to improve the quality of paper and cardboard

The study describes the preparation of pulp and nanocellulose from non-wood plant materials, as well as an improved properties of paper and cardboard for mass production. The pulps from wheat straw, kenaf and flax fibers were prepared by the environmentally friendly organosolv method—cooking in a solution of isobutanol or peracetic acid. The organosolv pulps used to prepare nanocellulose had traces of lignin and mineral substances. The process of hydrolysis of the investigated organosolv pulps was optimal when carried out under the following conditions: 43% sulfuric acid, temperature 60 °C, hydrolysis time 90 min and ultrasonic treatment 60 min. Using the methods of SEM, XRD, TEM, AFM and TGA, the structure and properties of organosolv pulps and nanocellulose were studied. The use of nanocellulose in bulk and on the surface of mass types of paper and cardboard—paper for corrugation, offset paper, recycled containerboard and cardboard for flat layers of corrugated cardboard were investigated. We established the positive effect of nanocellulose application on the physical and mechanical properties of paper and cardboard. Low consumption of nanocellulose allows production of the paper and cardboard with properties that meet the requirements to appropriate standards and replacement of synthetic reinforcing materials.

Effect of Modification Methods of Wheat Straw Fibers on Water Absorbency and Mechanical Properties of Wheat Straw Fiber Cement‐Based Composites

Five modification methods are adopted for wheat straw fibers (WSFs). The effects of modification methods on the water absorbency of wheat straw fiber/wheat straw fiber cement‐based composite (WSFCC) and the mechanical properties of WSFCC are analyzed. The crystallinity, chemical structure, and micromorphology of WSFs and WSFCC 28‐day specimens are characterized by XRD, FTIR, and SEM methods. The results show that the water absorption of WSFs modified with sodium silicate solution, pure acrylic acid emulsion, and silicone waterproof emulsion surface spraying is 10.67%, 5.18%, and 1.05% lower than that of unmodified WSFs, respectively. Alkali modification is the ideal method for improving the strength of WSFCC. Establishing a fitting formula of the relationship between water absorption of WSFs and strength of WSFCC specimens has important theoretical and practical guiding significance for development and application of WSFCC.

Effects of surface treatment on the properties of wheat straw fiber-reinforced rHDPE composites

Plant fiber-reinforced thermoplastic composites have been widely used due to their interesting and advantageous properties. However, the biggest problem has been the incompatibility of the fiber and matrix. In this paper, composites were prepared with wheat straw fiber (WSF) and recycled high density polyethylene (rHDPE). Compared with chemical modification, biological enzyme modification has advantages of low pollution and additive modification with low energy consumption and strong specificity compared with traditional physical modification. The effects of alkali and enzyme treatment were used to study the interfacial properties of the composites. The results showed that the mechanical properties of the composites were enhanced after modification, and the effect of enzyme treatment was better than that of alkali treatment (AT). The maximum tensile strength, flexural strength, and flexural modulus of the composites with xylanase and cellulase combined treatment (XCT) increased by 14%, 19.9%, and 28% compared to the untreated composites, respectively. The samples with xylanase and cellulase combined treatment showed good thermal properties, and the crystallinities of the composites were improved after modification. Water absorption behavior indicated that composites made by enzyme-modified WSF showed lower water sorption than those of the alkali treated samples, and the water absorption values of the composites with xylanase and cellulase combined treatment were the lowest. SEM found that composites with xylanase and cellulase combined treatment showed better interfacial adhesion. From the combined results, it could be stated that xylanase and cellulase combined treatment is able to improve the compatibility and properties of the composites. Therefore, it can provide some theoretical guidance for the preparation of composites, which has innovative application significance for improving the utilization rate of waste thermoplastics and crop waste straws.

Development of high-performance binderless fiberboards from wheat straw residue

This study aims to develop fully bio-based lignocellulosic fiberboards from wheat straw fibers without any additional bonding agents. The wheat straw biomass was used to produce a semichemical pulp, which was treated by means of enzymatic refining, on the one hand, and mechanical refining, on the other. The morphological analysis for both refined fibers was assessed and compared to that of wheat straw semichemical fibers. The results revealed that length and width were decreased, whereas, fines in length were increased after the enzymatic treatment and mechanical refining. The fibers were used to produce high-density fiberboards by means of wet process. The physical and mechanical properties of the resulting binderless fiberboards from both refined fibers were characterized and compared to that of fiberboards from wheat straw semichemical pulp and the commercial ones. In both cases, it was found that the mechanical properties of the fiberboards were significantly higher than those commercial fiberboards, as well as the required by the standard regulations. These results lead not only to synthetic resin elimination, but also to the exploration of using agricultural waste in several sectors, as the panel-housing could be.

Evaluation of the durability of lignin-reinforced composites based on wheat straw/recycled polypropylene blends

The influence of a lignin additive at different loading levels on the surface properties, mechanical, and thermal performance of recycled polypropylene composites reinforced with wheat straw, before and after accelerated weathering, was studied. Eight groups of samples were exposed to an ultraviolet (UV) accelerated weathering tester for a total of 1200 h. The weathered surface morphology, chemical change, and color change were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and chroma meter analyses, respectively. Furthermore, the mechanical properties and oxidation induction time (OIT) were tested. It was shown that the use of lignin had a positive effect in improving mechanical properties and in reducing OIT values of filled composites due to the enhanced fiber/matrix interface bonding and its functions of anti-oxidation. Less fibers were falling off and shallower cracks occurred on the weathered surface of the lignin reinforced composites. The carbonyl index of wheat straw fibers reinforced recycled polypropylene composites (WSF/RPP) with 5 wt% lignin content showed a notable decrease of 4.9% when compared with the growth rate of the control groups. When the stabilizer was introduced to the blends, the mechanical properties and antioxidant capacity of the composites were improved during weathering.

Lignocellulosic nanofibrils produced using wheat straw and their pulping solid residue: From agricultural waste to cellulose nanomaterials

Each year millions of tons of agricultural wastes are produced, however, not well utilized in China. Considering the economic development and environmental protection, the valorization of these wastes is increasingly necessary and important. Here we used p-toluenesulfonic acid hydrolysis followed by mild disk grinding for on-farm valorization of wheat straw (WS) and their pulping solid residue (waste wheat straw, WWS) to produce lignocellulosic nanofibrils (LCNF). Alkaline peroxide post-treatment was further conducted to obtain purified lignocellulosic nanofibrils (P-LCNF) with lower lignin content and thinner diameters. The raw materials and resulting LCNF and P-LCNF were investigated in each process for their chemical component, crystal structure, morphology, and thermal properties. Interestingly, although WS fiber had higher lignin content than WWS fiber, the WS fiber with lower ash content resulted in LCNF and P-LCNF with smaller height and lower thermal stability, but higher crystallinity and higher specific surface area. Higher ash content in WWS fiber protected cellulose and lignin from depolymerization and degradation, respectively, which endowed LCNF and P-LCNF with entangled network structure. Overall, this study indicated that the low-temperature fractionation process on WS and WWS fibers could yield cellulose nanomaterials with potential value-added application and achieve the efficient utilization of agricultural wastes.

Comparative study of effect of different coupling agent on mechanical properties and water absorption on wheat straw-reinforced polystyrene composites

The present work deals with the effect of various treatments on the mechanical properties and water absorption of wheat straw (WS)-reinforced polystyrene (PS) composites. Four different surface treatments of the filler, that is, alkali treatment of WS by 20% sodium hydroxide (NaOH) solution, maleic anhydride (MA) treatment of WS by 2% MA solution, WS treatment with 1% silane (ATS) and WS treatment with 20% NaOH and 1% silane, with 5–25% filler loading were carried out. There is an enhancement in tensile modulus, impact strength and water absorption and a decrease in tensile strength of WS fiber-filled PS composite with an enhancement in fiber loading when it is treated with 20% NaOH, 2% MA, and 1% silane. There is an enhancement in tensile strength, tensile modulus, Izod impact strength, and water absorption value when the WS fiber is treated with 20% NaOH and 1% silane, with an enhancement in fiber loading. Treatment with 20% NaOH and 1% silane exhibits better results as compared to the rest of the surface treatments.

Thermal insulation materials based on agricultural residual wheat straw and corn husk biomass, for application in sustainable buildings

The high energy consumption in buildings is a major contributor to climate change and atmospheric pollution in south cities of Chile. In this context, insulation materials are a key factor to reduce the energy demand during the operational stage of a building. These materials are however commonly fabricated from petrochemicals with high energy consumption, causing significant detrimental effects on the environment during the production and discarding stage. Due these reasons, insulation materials based on natural fibers waste appear as an excellent alternative, due to abundant availability in south regions of Chile, potential low cost, low energy consumption during the production stage and high bio-degradation rate at the end of life. In this research, block type insulation based on wheat straw and corn husk residual fibers were developed. Taguchi method was applied to investigate the effect on thermal conductivity and density of four control factors in three levels, namely fiber length, boiling time; NaOH concentration and blending time; in a L-9 orthogonal array. Furthermore, flexural and compressive stress were determined and compared with expanded polystyrene block insulation. The results show thermal conductivity values were between 0.046 and 0.047 W/mK. In addition, flexural stress results were good compared to those of the standard expanded polystyrene type IX. Finally, optimum conditions of the process were determined to obtain a final block, which was morphologically analyzed using scanning electron microscopy (SEM), while the thermal behavior was studied by thermogravimetric analysis (TGA).

Modified pullout test for indirect characterization of natural fiber and cementitious matrix interface properties

Abstract Fiber-matrix interfacial bond characterization using conventional fiber pullout test is unsuitable for natural fiber based cementitious composites. Therefore, a modified pullout test method is proposed in this study for the indirect characterization of interfacial properties of natural fiber and cementitious matrix interface. To this end, a cementitious matrix medium is prepared by mixing Type I Portland cement, clay and water in a specific ratio such that suitable consistency is obtained and setting time is delayed with the purpose of avoiding the formation of adhesive chemical bond between fiber and matrix interface. For experimentation, wheat straw natural fibers are chosen in this study and pullout test specimens are prepared by embedding the fibers in cementitious matrix medium for lengths of 10 and 20 mm. Pullout tests are carried out at 1 mm/min displacement rate, and load-displacement curves are obtained. While the peak pullout load and pullout energy obtained from modified pullout tests are observed to increase by 93.2% and 304% with an increase in embedment length from 10 to 20 mm, the interfacial sliding shear strength remained constant for wheat straw fibers at 2.63 KPa. Slip softening is observed to be the governing pullout mechanism for wheat straw natural fiber in the modified pullout test. For indirect validation of the proposed method, the trends of peak pullout load and interfacial sliding shear strength for polypropylene and steel fibers are obtained from both modified and standard pullout test and are compared. Similar trends are observed for polypropylene and steel fibers in both the tests which to a certain extent confirms the validity of the proposed method.

Behavior of Fiber-Reinforced and Lime-Stabilized Clayey Soil in Triaxial Tests

The beneficial role of combining fiber reinforcement with lime stabilization in altering soil behavior has been established in the literature. However, the coupling effect of their combination still remains unclear in terms of its magnitude and microscopic mechanism, especially for natural fibers with special microstructures. The objective of this study was to investigate the coupling effect of wheat straw fiber reinforcement and lime stabilization on the mechanical behavior of Hefei clayey soil. To achieve this, an experimental program including unconsolidated–undrained (UU) triaxial tests and SEM analysis was implemented. Static compaction test samples were prepared on untreated soil, fiber-reinforced soil, lime-stabilized soil, and lime-stabilized/fiber-reinforced soil at optimum moisture content with determining of the maximum dry density of the untreated soil. The lime was added in three different contents of 2%, 4%, and 6%, and 13 mm long wheat straw fiber slices with a cross section one-quarter that of the intact ones were mixed in at 0.2%, 0.4%, and 0.6% by dry weight of soil. Analysis of the derived results indicated that the addition of a small amount of wheat straw fibers into lime-stabilized soil improved the intensity of the strain-softening behavior associated with mere lime stabilization. The observed evidence that the shear strength increase brought by a combination of 0.4% fiber reinforcement and 4% lime stabilization was smaller than the summation of the shear strength increases brought by their presence alone in a sample demonstrated a coupling effect between fiber reinforcement and lime stabilization. This coupling effect was also detected in the comparisons of the secant modulus and failure pattern between the combined treatment and the individual treatments. These manifestations of the coupling effect were explained by a microscopic mechanism wherein the fiber reinforcing effect was made more effective by the ways in which lime chemically stabilized the soil and lime stabilization development was quickened by the water channels passing through the surfaces and honeycomb pores of the wheat straw fibers.

Effect of Intercalation Structure of Organo-Modified Montmorillonite/Polylactic Acid on Wheat Straw Fiber/Polylactic Acid Composites.

In this work, an easy way to prepare the polylactic acid (PLA)/wheat straw fiber (WSF) composite was proposed. The method involved uses either the dopamine-treated WSF or the two-step montmorillonite (MMT)-modified WSF as the filler material. In order to achieve the dispersibility and exfoliation of MMT, it was modified by 12-aminododecanoic acid using a two-step route. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed to characterize the modified MMT and the coated WSF. As for the properties of PLA/WSF composites, some thermal (using Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis) and mechanical properties (flexural, tensile, and impact) were analyzed. The results showed that the dopamine was successfully coated onto the WSF. Furthermore, Na-MMT was successfully transformed to organo-montmorillonite (OMMT) and formed an exfoliated structure. In addition, a better dispersion of MMT was obtained using the two-step treatment. The interlayer spacing of modified MMT was 4.06 nm, which was 123% higher than that of the unmodified MMT. Additionally, FT-IR analysis suggested that OMMT diffused into the PLA matrix. The thermogravimetric analysis (TGA) showed that a higher thermal stability of PLA/WSF composites was obtained for the modified MMT and dopamine. The results also showed that both the dopamine treated WSF and the two-step-treated MMT exhibited a positive influence on the mechanical properties of PLA/WSF composites, especially on the tensile strength, which increased by 367% compared to the unmodified precursors. This route offers researchers a potential scheme to improve the thermal and mechanical properties of PLA/WSF composites in a low-cost way.